Optimum driveline angles for vibration free high speed operation.

[TheJDMan]

Here's my dilema. I replaced my old ST10 with a new T56 Magnum in Dust Off and since that time I have been fighting driveline vibration at hiway speeds. The driveshaft is a new unit from Strange so I have to believe it is balanced correctly. My crankshaft angle is 3.30 deg down to the rear. I adjusted the pinion to 3.30 deg up to match. The driveshaft is angled up 1.50 deg to the rear. This results in a working angle on the U-joints of 3.30+1.50=4.80 deg. I am pretty sure this is too much working angle. Since I have the G-Link rear suspension I can easily change the pinion angles and ride height but the crankshaft angle is not as easy to adjust. Just for a test I adjusted the rear coilovers up to raise the rear of the car about 1" in an attempt to reduce the driveshaft angle to near zero. A short test drive resulted in dramatically reduced driveline vibration but not completely gone.

I currently have the engine/transmission out of the car to fix a nagging oil leak and so I can massage the firewall and tunnel for about 1/2" more clearance. I also have to do some fabrication on the crossmember to raise the mount location but my question is what is the optimum crankshaft angle I need to shoot for? I'm thinking about trying to get the crankshaft angle to about 2.50deg but I'm hoping Ron has some drive line setup advice for high speed vibration free operation.

[killer69]

if your car is a first gen here is the easiest way I know of to adjust the crank shaft angle

http://www.speedtechperformance.com/index.cfm/page/ptype=product/product_id=264/category_id=30/home_id=-1/mode=prod/prd264.htm

just an option

[Ron Sutton]

Here's my dilema. I replaced my old ST10 with a new T56 Magnum in Dust Off and since that time I have been fighting driveline vibration at hiway speeds. The driveshaft is a new unit from Strange so I have to believe it is balanced correctly. My crankshaft angle is 3.30 deg down to the rear. I adjusted the pinion to 3.30 deg up to match. The driveshaft is angled up 1.50 deg to the rear. This results in a working angle on the U-joints of 3.30+1.50=4.80 deg. I am pretty sure this is too much working angle. Since I have the G-Link rear suspension I can easily change the pinion angles and ride height but the crankshaft angle is not as easy to adjust. Just for a test I adjusted the rear coilovers up to raise the rear of the car about 1" in an attempt to reduce the driveshaft angle to near zero. A short test drive resulted in dramatically reduced driveline vibration but not completely gone.

I currently have the engine/transmission out of the car to fix a nagging oil leak and so I can massage the firewall and tunnel for about 1/2" more clearance. I also have to do some fabrication on the crossmember to raise the mount location but my question is what is the optimum crankshaft angle I need to shoot for? I'm thinking about trying to get the crankshaft angle to about 2.50deg but I'm hoping Ron has some drive line setup advice for high speed vibration free operation.

Hi Steve,

While I have a lot of experience with driveline angles in race cars, I don't have much time spent on steady state cruising like freeway speeds. But I think your issue is pretty clear.

It sounds like you've lowered the car quite a bit ... so the engine/trans combo is lower too. Since you kept the engine & trans around the factory 3° angle (higher in front) 3.3° in your case ... the output of the trans is a lot lower ... so the driveline is running uphill to pinion yoke (1.5° as stated).

It sounds like you followed the common street car recommendation of matching the pinion angle to the crank & trans mainshaft angle to equalize the loads at each end. This is correct for cruising at highway speeds under light throttle loads ... but only if the transmission yoke is higher than the pinion yoke so the driveshaft runs downhill to the pinion yoke ... as it would be in production cars at standard ride heights.

You adjusted the pinion angle up to 3.3° to match the crank & trans mainshaft angle ... so the pinion yoke & driveshaft come together at 4.8° angle ... like an upside down V. What I'm certain of is you never want the pinion yoke & driveshaft to come together at angles like an upside down V. This is causing a binding load under cruising ... and even worse under acceleration. In my experience, this does two things. One it reduces power output to the rear wheels. Second, it can cause harmonic issues.

A part of the problem is how low the transmission yoke is. If we were building a car from scratch, we would design the engine/trans mounting angle to optimize the driveline & pinion angles. But you're working with a production car. I suspect there may not be room under the tunnel to raise the trans. If there is some room, I'd do that to the degree the floor allows to help. But the majority of your fix will be in adjusting the pinion angle.

The good news is your suspension allows for pinion adjustment, so what you want to do is lower the front of the pinion. You want the driveshaft & pinion yoke to form a V pointing downward ... to some small degree. How much driveshaft & pinion yoke angle difference "exactly" is debatable.

Street & racing often have different goals. In racing, we would put the car on a chassis dyno and adjust the driveshaft & pinion yoke angle difference until the car shows the least power loss under timed full throttle acceleration runs to simulate the track we're running. This differs for different tracks due to different gear ratios and different acceleration times. It also varies with different types of rear suspensions & link ends, because they flex different amounts under power.

Street driving varies so much it's hard for me to say what is optimum. Each type of driving has different needs. With different drivers, their priorities of city driving, performance driving, freeway cruising and even track performance can be very different. If the car was driven at 65mph freeway speeds 99% of the time, It may work best with 0.5° angle. But acceleration mode favors more angle.

I can tell you the least we've ever ran in race cars was 2° driveshaft & pinion yoke angle difference ... to form a V pointing downward. And the most we've ever ran was 5°, but on trick suspensions with a lot housing rotation. If you tell me what kind of rear suspension you have ... and what kinds of bushings/rod ends ... I can give you a good baseline starting point.

[dontlifttoshift]

Ron, thanks for bringing the tech again.

As soon as the pinion yoke is higher than the trans yoke, conventional theory (equal but opposite angles at the trans and pinion) goes out the window? I question it because I have always used this method and have never experienced an issue.

[Ron Sutton]

Ron, thanks for bringing the tech again.

As soon as the pinion yoke is higher than the trans yoke, conventional theory (equal but opposite angles at the trans and pinion) goes out the window? I question it because I have always used this method and have never experienced an issue.

Hi Donny,

I'm not an expert on street car driveline dynamics ... but I'm certain you never want the pinion yoke & driveshaft to come together at severe angles ... like Steve's 4.8° ... in an upside down V. There would be "some" binding loads under cruising ... and significant loading under acceleration. This reduces power output to the rear wheels & can cause harmonic issues.

Just for note: When the driveshaft & pinion yoke angle difference form an upside down V, we call that "positive pinion angle" ... meaning the pinion is at a higher angle going forward than the driveshaft. When the driveshaft & pinion yoke angle difference form a correct downward pointing V, we call that "negative pinion angle" ... meaning the pinion is at a lower angle going forward than the driveshaft.

We always want some negative pinion angle at ride height with no power load. All factory production cars & trucks run negative pinion angle. How much is optimum depends on a few factors & your goals ... and will be debatable as long as there are car guys & racers. But it should always be at a negative pinion angle to the driveshaft.

If you've lowered the car enough that the driveline runs uphill to the rear ... and have positive pinion angle ... you can run into issues. I think how much positive angle the pinion is from the driveshaft will define if the issue is minor, noticeable or major. If you're running positive pinion angle ... but less than Steve's almost 5° ... that might be why you haven't seen any harmonics issues. If you're running 5° or more positive pinion angle & still not having any harmonic issues ... I'd be surprised & consider that quite fortunate.

Regardless, the condition of positive pinion angle will still produce less power to the rear wheels under hard acceleration, along with accelerated u-joint, pinion gear & pinion bearing wear. The ideal situation is "some" degree of negative pinion angle.

[83hurstguy]

Good thread here. I was sort of asking the same thing in this thread a little bit ago, but haven't been out in the garage to finish the project yet. https://www.pro-touring.com/threads/103049-Driveline-Angle-Issues-on-Lowered-Car

Once I set my rear end pinion angle to match my engine/trans angle, I would be in the same situation where the driveshaft and rear end pinion angle would be the "upside down V". I was concerned about what would happen with pinion climb in that situation, since it makes the u-joint working angle worse under power, but per Lance's input in that thread (and it seems like Donny's above) that this is the only way to handle driveline angles on an extremely lowered production car, unless you take Andrew's approach and have a shaft with one CV joint made.

Hope we can get to the bottom of this. I like Andrew's approach the best, but would prefer not to have a $700 aluminum driveshaft in there right now.

[Ron Sutton]

Just an FYI & a few tips to anyone following along ...

You don't have to keep your engine & trans at a 3° angle (higher in front). You can mount your engine & trans at less angle or even level if you desire ... providing you make room in the tunnel.

Just be aware some things are designed around that OEM standard of 3° engine angle like ...
* The mounting flange for the carb on intake manifolds.
* The bottom angle of some oil pans.
* The bottom angle of many automatic transmission fluid pans.
* Headers built for production cars.
* I'm sure I'm leaving something off ... :)

At the other end ... different rear ends have different pinion heights. The dimension the pinion centerline is lower than the axle centerline pinion is known as "pinion offset" or "pinion drop" and this varies with different rear end designs.

A few I know ...
a. GM 12-bolt has 1-7/16" pinion drop from the axle CL.
b. Dana 60 has 1-1/8" pinion drop from the axle CL.
c. 9" Ford has 2-1/4" pinion drop from the axle CL.

So for example ...
If we had a car with 275/35ZR18 rear tires (25.6" tall) divide by 2 = 12.8" ... and account for let's say .4" tire sag due to weight ... we end up with an axle CL of 12.4". If the pinion were level ... the center of the yoke on a 12-bolt would be a tick under 11" ... and a 9" Ford diff in the same car would have the center of the yoke a tick under 10-3/16". Just something to take into account as you build your car.

[SSLance]

I never thought of it that way, but that must be why I don't have the drastic upside down V pinion yoke angle on my setup, because of my 9".

I never paid much attention to my driveshaft angle as I was always just trying to get the u-joints in sync so they'd play nice together. Next time I'm under the car with it at ride height I'll measure exactly where my driveshaft angle is.

[killer69]

So Ron to simplify things (correct me if I am stating this incorrectly)
in a perfect world the crank angle would be 0. the drive shaft would be 0 and the pinion angle would be 0. we know the world is NOT perfect.
so assuming the crank and shaft are at 0 then the pinion you would want at neg 1-2 deg?
if the driveshaft runs anywhere off of 0 then what is the best way to approach the problem.
I know the u joints need some angle in them to rotate the bearings or they to will just wear out.

this is partly why I made the first post was to show an easy way to raise the trans tail shaft and decrease the crank angle.

Here is an example in the shop today
69 Camaro big block TH400 12 bolt
Engine is down 2.3deg drive shaft is up 1 deg and pinion is down 1.3deg.
if it was the same car with a T56 and a 9" it would be completely different as the t56 out put is 1.25" higher and the 9" pinion is 1" lower, so actually a better combination . For more reasons than this one.

[dontlifttoshift]

Hi Donny,

We always want some negative pinion angle. All factory production cars & trucks run negative pinion angle. How much is optimum depends on a few factors & your goals ... and will be debatable as long as there are car guys & racers. But it should always be at a negative pinion angle to the driveshaft.



Negative pinion angle at ride height, I am assuming? Or should it be arranged so that it never goes positive?

Honestly, I have never checked the working angle of any u joint so I couldn't tell you if I have ever been near the 4.8* that Steve has.

Full disclosure, I usually cheat the pinion down from parallel .5* to 1* (Bushing dependent) with a link type suspension 1* on a leaf suspension.


This proves two things.....I'd rather be lucky than good and you really do learn something new everyday.

[72BBSwinger]

Negative pinion angle at ride height, I am assuming? Or should it be arranged so that it never goes positive?

Honestly, I have never checked the working angle of any u joint so I couldn't tell you if I have ever been near the 4.8* that Steve has.

Full disclosure, I usually cheat the pinion down from parallel .5* to 1* (Bushing dependent) with a link type suspension 1* on a leaf suspension.


This proves two things.....I'd rather be lucky than good and you really do learn something new everyday.

This^^^, I would roll the pinion nose down 1* from where it is now.

[mitch_04]

Ron, please finish your book. All of these posts are just teasing me with a glimpse into what I can only imagine will be the "bible" of performance.

Thanks so much for all of your help, even if the majority is indirect!

[Ron Sutton]

Hey Blake !


So Ron to simplify things (correct me if I am stating this incorrectly)
in a perfect world the crank angle would be 0. the drive shaft would be 0 and the pinion angle would be 0.
I don't necessarily think that level or 0 angle is the goal. But you're on target that ideally we want the crank & trans centerline to line up with the pinion centerline ... under the dynamic load of hard acceleration.

When we build cars from scratch & have no challenges like floor pans, etc. ... we use a laser to point the crank & trans centerline so it lines up with the pinion centerline. I typically have a target height number I want for the front of the engine, so we adjust the height of the trans tailshaft until the laser lines up perfectly with the pinion. That is where we mount the engine & trans.

From there, we rotate the housing to move the pinion down to achieve our target negative pinion angle number. Usually 2-4° depending on the design & ends on the suspension system. This is not a 2-4° pinion angle. It is a 2-4° angle difference between the driveshaft & the pinion.

we know the world is NOT perfect.
so assuming the crank and shaft are at 0 then the pinion you would want at neg 1-2 deg?
How much "exactly" depends on the rotation & flex in the rear suspension design. Every suspension has some flex in it under high power loads, but accurately predicting how much only comes with experience & testing. The other factor is the ends. Standard mild steel 2-piece rod ends have more clearance than precision 3-piece chromoly rod ends (at least in quality brands). And of course rubber or poly ends provide a lot of flex. The final factor is how is it going to be used. When racing or track driving is the priority, you need more negative pinion angle than normal street driving.

When we're running a track car with a 3-link, quality rod ends & no bushings, we run around 3° negative pinion angle for road courses. 4-links would be the same. I think you run torque arms, and depending on how they connect in the front would play a role in that number. If the front pivot is stable, I'd suggest 1.5° +/-. Decoupled torque arms rotate more, so they need 3-4°.

Frankly, once you're in the ballpark, the only reason to tune it is to reduce parasitic loss through the drivetrain like we do on chassis dynos. If anyone wants to learn what really goes on, put a GoPro style video camera underneath pointed at the rear suspension & pinion area.

if the driveshaft runs anywhere off of 0 then what is the best way to approach the problem.
It's pretty straight forward as long as the driveshaft is running level or downhill to the pinion ... just add 1-4° of negative pinion angle depending on the factors we covered above. The challenge is when the driveshaft runs uphill to the pinion. In this situation with race cars we still run negative pinion angle. But our primary concern is no bind & minimum parasitic power loss ... not harmonics at freeway speeds.

I know the u joints need some angle in them to rotate the bearings or they to will just wear out.
I think this is more of a "little old lady from Pasadena" thing. If the car was always driven "gentle" where the suspension is not moving up & down ... and there is only soft acceleration & deceleration ... the needle bearings in the u-joints don't get loaded & rotate.

If a car is being driven in a spirited performance way often ... or track driven ... the rear end housing is rotating back & forth changing the pinion angle slightly ... and the suspension is moving up & down ... changing the loading on the the needle bearings in the u-joints ... and they rotate. Where I see u-joints fail more often in sportsman level racing ... aside from lack of maintenance or utilizing too small of a u-joint ... is when they have excessive pinion angle (positive or negative).

this is partly why I made the first post was to show an easy way to raise the trans tail shaft and decrease the crank angle.
I agree 100%. Part of Steve's challenge is the trans is so low. It would be interesting to know what rear end he has too.

Here is an example in the shop today
69 Camaro big block TH400 12 bolt
Engine is down 2.3deg drive shaft is up 1 deg and pinion is down 1.3deg.
I sometimes get cloudy when we use "up" & "down" and the direction is not clear. Is the driveshaft running 1° uphill to the pinion? And is the pinion running 1.3° downhill to the front or to the rear?

if it was the same car with a T56 and a 9" it would be completely different as the t56 out put is 1.25" higher and the 9" pinion is 1" lower, so actually a better combination . For more reasons than this one.

You caused me to do a confused head shake there for a minute. Then after a minute ... I think I "got it". Obviously the transmission output is in line with the crank of the engine, so that doesn't change. Do you mean the mount on the T56 places the tailshaft 1.25" higher than a T400?

Regardless, I get what you're saying. With a higher rear trans mounting location & a lower pinion (via 9" Ford) we would end up with the driveshaft running downhill to the pinion, as is normal & preferred.

[TheJDMan]

Ron,
In answer to your question, I'm running a Moser 9" floater, a G-Link 4bar suspension with Pivot Ball rod ends.

So if I understand the conversation so far, I want the pinion at some down angle to be determined. Assuming the crankshaft angle remains at 3.3deg down to the rear, as I rotate the rear end to move the pinion to a down angle to the front, the driveshaft should approach a zero angle or maybe even a down angle to the rear. In theory, this will give me a working "V" angle on the front U-Joint of 3.3deg or less and if the pinion is angled down say 3.3deg this will result in equal working "V" angle on the rear U-Joint.

[Ron Sutton]

Hi Donny,

After I read what I typed, I went back and added some clarification in red so it now reads ...

"We always want some negative pinion angle at ride height with no power load."



Negative pinion angle at ride height, I am assuming?
Yes, at ride height with no load, like in the garage.

Or should it be arranged so that it never goes positive?
It can go positive. You just don't want too much. Frankly you don't want too much negative or positive.

As an example ...
If we had a rear suspension that flexed & allowed the rear end housing and pinion to rotate up in the front by 3° under hard acceleration ... and we adjust the pinion down 3° in the front at ride height ... then when we're accelerating hard, the pinion is more or less inline with the drive shaft. In this mode the the rear u-joint is loaded the least & so are the pinion gear & bearings.

So, if we ...
a. Set the pinion at -3° static ... it would rotate to 0° under hard acceleration ... and be closer to -2° at cruising loads.
b. Set the pinion at -2° static ... it would rotate to +1° under hard acceleration ... and be closer to -1° at cruising loads.
c. Set the pinion at -4° static ... it would rotate to -1° under hard acceleration ... and be closer to -3° at cruising loads.
d. Set the pinion at -6° static ... it would rotate to -3° under hard acceleration ... and be closer to -5° at cruising loads.
e. Set the pinion at 0° static ... it would rotate to +3° under hard acceleration ... and be closer to +1° at cruising loads.
f. Set the pinion at +2° static ... it would rotate to +5° under hard acceleration ... and be closer to +3° at cruising loads.
g. Set the pinion at +4° static ... it would rotate to +7° under hard acceleration ... and be closer to +5° at cruising loads.
h. Set the pinion at +6° static ... it would rotate to +9° under hard acceleration ... and be closer to +7° at cruising loads.

In these examples, we wouldn't "notice" any difference in A & B. A would provide the least parasitic power loss under hard acceleration, while B would be better for moderate street driving. A would provide slightly better gear, bearing & u-joint life under track conditions while B would provide slightly better gear, bearing & u-joint life under moderate street driving. B & C would both provide the same parasitic power loss under hard acceleration ... because they're both 1° different than optimum. But C would cause quicker gear, bearing & u-joint wear in an everyday street driven mode ... and could be on the edge of harmonic issues.

D would have high parasitic power loss, high wear & harmonic issues. E would have the same parasitic power loss under hard acceleration as D, but no wear or harmonic issues on the street. As we go farther positive with the pinion angle in F, G & H ... the parasitic power losses increase under hard acceleration ... and we get into harmonics issues & quicker gear, bearing & u-joint wear.


Honestly, I have never checked the working angle of any u joint so I couldn't tell you if I have ever been near the 4.8* that Steve has.
No worries. But it would be interesting to know where the safe zone is ... and where it ends.

Full disclosure, I usually cheat the pinion down from parallel .5* to 1* (Bushing dependent) with a link type suspension 1* on a leaf suspension.
Gotcha. I "think" that's probably why it's working well for you. If we start getting up into high positive pinion angle numbers like G & H ... or negative numbers like D ... we're gonna have issues.

This proves two things.....I'd rather be lucky than good and you really do learn something new everyday.

:lol: Too true !

[Ron Sutton]

Ron,
In answer to your question, I'm running a Moser 9" floater with the G-Link 4bar suspension with Pivot Ball rod ends.

Gotcha. What size rear tires?

[silvermonte]

Dumb question alert! Where is the correct place to get these measurments. Ive always used the top of the intake or the flat spot on the tranny pan for the crank angle and then just any smooth spot on the driveshaft and I just winged it on the axle.

[tonyvol]

Not sure if this is a good way, but I put a digital angle finder on the face of the harmonic balancer for the engine angle and with the driveshaft removed I put it on the flat part of the pinion yoke where the U-joint mounts for the pinion angle.

[Ron Sutton]

Dumb question alert! Where is the correct place to get these measurments. Ive always used the top of the intake or the flat spot on the tranny pan for the crank angle and then just any smooth spot on the driveshaft and I just winged it on the axle.

Hi Miles,

The top of the intake or the flat spot on the tranny pan are often angled 3° to account for the 3° standard OEM engine mounting angle. Tony's suggestions are good if the engine is assembled. Depending on the state of assembly, the flat machined surface on the front & rear of the block are a true 90° to the crank. I'm sure there are a dozen other ways guys do it.

When I'm mocking up mounts, I'm using an empty block, so I just run a straight edge from the front to the back (where the intake or valley pan sits) with a digital angle gauge. For the pinion, I either work off the face of the housing or off the end of the yoke like Tony.

[wiedemab]

Here is a decent link that I found explaining how to measure the angles and calculate the working angle of the U-joint....thought it might help.

http://spicerparts.com/anglemaster/measuring-angles

[old66tiger]

I worked pretty hard on mine to get it as close as I could to being smooth. I have a similar issue as you have, just less of an angle. I have a digital angle finder and I set the angle finder to zero on the driveshaft and that is the "reference" for all other measurements. I then measure the angle of the engine and the angle of the rear end. If I were to draw a picture facing the side of my car, the engine angles down 2 degrees to the rear of the car and the pinion angles up 1 degree from the rear to the front. Then, there is also that goofy deal with the rear end not being perfectly centered in the GM cars. That actually ADDS to the DL angle and makes things a bit worse.

I wish I could have gotten the transmission higher in the car, but when I installed it, I did minimal cutting to my floor so that I could easily stitch it up later if I choose to go back to the 4-speed.

My DS is a Denny's 3.5" unit and when I ran this in the car with the Muncie, the car was silky smooth at all operating speeds. My vibration only comes in above 70 with the TKO, so it isn't too bad, but it is an annoyance. I learned from others that have this issue that it may not always be the DL angles, but it could be that the shaft is too small in diameter, was not high speed balanced or may be a tad bit too short. If the shaft hangs out of the transmission a bit too far, it could generate a small vibration. I would start by looking at the DS as a possibility. Just because "strange" built it, does not mean that it is not right for your car. My original DS was built and balanced by a local shop and the 3" shaft with 3.55 gears resulted in vibrations. They did not have the capacity to high speed balance the shaft and combined with the shaft being too small in diameter, it was operating too close to the critical speed limit of the shaft. The 3.5" shaft (high speed balanced) moved the critical speed up much further and cured my issue with the Muncie.

[andrewb70]

I am really surprised that no driveline company has stepped up and offered more options using CV joints. Modern muscle cars face unique driveline combinations that just weren't thought of when these cars were designed. When cars are lowered the relationship of the transmission in relation to the centerline of the rear axle changes. They you have a combination of low rear end ratios and O.D. gears that contribute to high driveshaft speeds. Add to that a typical LSx conversion that adds to the problem, and you have a mess, where the front and rear operating angles are way beyond acceptable levels (ideally less than 2 degrees).

By using CV at the front and rear of the driveshaft the angles become a mute point. CVs will run at extreme angles and the front and rear don't have to be equal and opposite. All modern rear drive cars use them. Billet CV slip and pinion yokes can be made with mostly turning operations and shouldn't cost any more than their u-joint counterparts. Companies like The DriveShaft Shop and RCV Performance offer all manner of components that can be used to these driveshafts.

Right now The DriveShaft Shop can take a Spicer yoke and modify it for use with a CV joint. However, there currently is no solution for a pinion yoke, although I see no reason why they can't make one like they do with the slip yoke. But while modified yokes are OK, custom machined yokes would be much better. Surely, with today's modern CNC equipment CV slip and pinion yokes can be made for $150 or less. I think people will gladly pay the extra money to have old cars run down the highway as smoothly as modern cars.

Andrew

[silvermonte]

Hi Miles,

The top of the intake or the flat spot on the tranny pan are often angled 3° to account for the 3° standard OEM engine mounting angle. Tony's suggestions are good if the engine is assembled. Depending on the state of assembly, the flat machined surface on the front & rear of the block are a true 90° to the crank. I'm sure there are a dozen other ways guys do it.

When I'm mocking up mounts, I'm using an empty block, so I just run a straight edge from the front to the back (where the intake or valley pan sits) with a digital angle gauge. For the pinion, I either work off the face of the housing or off the end of the yoke like Tony.



I knew the intake had the 3 degree angle built into it, so should the that point be level while in the car and ready to drive,or should it be tilted at 3 degrees. Ive always assumed it should be level. Ive always installed the motor and tranny and then just shimmed up the tranny at the rear mount till the intake read level. Ive always had a slight shake at 65-70 mph so I just never drove at that speed, and always figured my driveshaft wasnt balanced at a higher speed.

[TheJDMan]

Dumb question alert! Where is the correct place to get these measurments. Ive always used the top of the intake or the flat spot on the tranny pan for the crank angle and then just any smooth spot on the driveshaft and I just winged it on the axle.

I use a socket held against the end cap of the U-Joint and my digital level on the other end of the socket to measure the angle. The trans and pinion yoke caps give you those two angles and a cap in the driveshaft will give you the driveshaft angle but it is easier to just measure the shaft tube. If you have a U-Joint with an external clip, simply remove the clip, take your measurement and reinstall the clip. The driveshaft must be positioned so the yoke caps are straight up & down.

[SSLance]

I use the harmonic balancer and the drain plug guard on the bottom of my diff (yoke face if the driveshaft is out) but in both cases you have to be careful that you have the angle finder exactly square because if it's turned just a bit it'll give a false reading.

I'm learning a ton from this thread, will report back with my findings once I get back under the car again. I can't wait to make a run with my GoPro pointed at my rear axle to watch what is really going on.

[andrewb70]

Here is a Spicer document that covers a ton of great information. It is lengthy, but for anyone that really wants to wrap their brain around the issues that we are discussing, it is highly recommended.

Spicer driveline guide (https://www.pro-touring.com/%7Eandrewb/J3311-1-HVTSS.pdf)

Andrew

[Ron Sutton]

Steve ... what size rear tires do you have ?

[old66tiger]

Here is a Spicer document that covers a ton of great information. It is lengthy, but for anyone that really wants to wrap their brain around the issues that we are discussing, it is highly recommended.

Spicer driveline guide (https://www.pro-touring.com/%7Eandrewb/J3311-1-HVTSS.pdf)

Andrew that is a good read. Especially the compound angle discussion. I wonder how the street rod guys fair with driveline angles. Those cars are much lower and many run carbs and need the 3 degree engine pitch.

[TheJDMan]

Gotcha. What size rear tires?

335/30-18

[Ron Sutton]

335/30-18

Thanks Steve,

Doing a little math ...

A. Rear tire 25.9" tall ÷ 2 = 12.95" - .45" for tire load sag = 12.5" Axle CL.
If the pinion was level in your 9" Ford the 2-1/4" pinion drop would put the yoke at 10.25"
But the 3.3° pinion angle puts the CL of the U-Joint around 10.95"

B. I don't know how long your driveshaft is but using 40" will get us close.
Running uphill to the pinion at 1.5° ... puts the trans yoke approximately 9.9" high.

C. The engine & trans are running uphill to the front at 3.3°
If the rest of my numbers are in the ballpark, that would make the front of the crank about 13.35" high. I estimate the crank height at the motor mounts to be around 12.6".

I was hoping for some more clarity ... and if the "over the internet numbers" combined with my experience & calculations are correct ... I see the problem. The trans yoke at 9.9" was only slightly lower than the pinion CL (if level) at 10.25". But adjusting the pinion up to 3.3° raised the rear u-joint to 10.95" ... and created the upside down V where the pinion & driveshaft come together.

A simple solution is to adjust the pinion down. But a more complete solution would be to reduce the engine/trans angle ... and then adjust the pinion.

I agree with Blake ... if you can raise the transmission ... I would. Also, if there is a way to lower the engine some ... and you have adequate header & oil pan clearance ... I would. These would help your situation ... and mean less pinion adjustment in the rear.

If you could ...
#1 - Lower the engine at the mounts by 1/2"
#2 - Raise the trans at the mount by 3/8"
... this would put the engine/trans combo at a 2.0° angle ... and put the trans yoke approximately 10.47" high.

#3 Adjust the pinion angle down from level to 1.3° running downhill going forward. The rear u-joint will be around 9.98".

#4 This would place the driveshaft at a 0.7° angle running downhill to the rear end ... and provide a 2.0° negative pinon angle to the driveshaft (correct V pointing down).

I'm fairly confident your harmonics issue would go away, and the bonus would be less parasitic power loss under hard acceleration.

[SSLance]

I checked and readjusted my pinion angle this afternoon. Last time I did this was before Ron and I raised the car ride height about an inch and that raise did bring back a bit of drive line vibration in the car at highway speeds. Basically that raise changed my pinion angle up about 2 degrees.

Today I found the engine nose up about 3.70 degrees, the drive shaft nose up 0.90 degrees and the pinion nose up 5.60 degrees. I adjusted the pinion down 2 degrees to 3.60 nose up and tightened everything back up again.

I also did another front wheel alignment on the car this afternoon and tomorrow I hope to put my street wheels back on the car and go for a good long test drive. I'll report back if the slight vibration I had has now gone away.

[SSLance]

Pretty extensive test drive in the books today and I can happily report all drive line vibrations are gone once again.

[old66tiger]

Can you draw a picture of what your setup looks like from the drivers side of the car so that I can get a better idea of your angles?
I checked and readjusted my pinion angle this afternoon. Last time I did this was before Ron and I raised the car ride height about an inch and that raise did bring back a bit of drive line vibration in the car at highway speeds. Basically that raise changed my pinion angle up about 2 degrees.

Today I found the engine nose up about 3.70 degrees, the drive shaft nose up 0.90 degrees and the pinion nose up 5.60 degrees. I adjusted the pinion down 2 degrees to 3.60 nose up and tightened everything back up again.

I also did another front wheel alignment on the car this afternoon and tomorrow I hope to put my street wheels back on the car and go for a good long test drive. I'll report back if the slight vibration I had has now gone away.

[TheJDMan]

Thanks Ron,
I have the engine and transmission out of the car at present but that will allow me easy access to the frame mounts. Sounds like I have some things to ponder.

[Ron Sutton]

Thanks Ron,
I have the engine and transmission out of the car at present but that will allow me easy access to the frame mounts. Sounds like I have some things to ponder.

No worries Steve. My example of changes was based on the assumption you could move the engine down 1/2" & the trans up 3/8" ... but I "obviously" don't know if that is even possible in your car. I'd suggest get all you can & do the rest with pinion angle.

Best wishes.

[tonyvol]

I was reading this post and was wondering if someone could help me out? I have a 67 Camaro and I'm installing a TKO 600. I needed to modify the tubular cross member pad since it was set up for a big block and I now have it set up for a small block. I'm getting ready to tack weld the pad in place that the trans. mount sits on. Here is my question. Right now the engine is pointing rearward down 3.5 degrees. This has the carb base on the intake sloping forward .5 degrees.
My pinion angle is at 1 deg. pointing down. How critical is it to have the carb base as close to 0 deg.? I'm using a Holley 4150 carb. Or should I be more focused transmission and pinion angle. I could raise the rear of the transmission up to be closer to 3 degrees point down? Which would make the carb base closer to 1 deg. sloping forward.

[rchaskin]

Check this. I wondered how DSE sets up their pinion angle.

http://www.youtube.com/watch?v=Vg1vo1tMqaI

[andrewb70]

Check this. I wondered how DSE sets up their pinion angle.

http://www.youtube.com/watch?v=Vg1vo1tMqaI

If I understand that video correctly, they recommend the U configuration under static conditions. They said pinion angle down 2 and engine down 3-4. So under power they expect the pinion to climb quite a bit, even with the QuadraLink.

Andrew

[mmosley]

If I understand that video correctly, they recommend the U configuration under static conditions. They said pinion angle down 2 and engine down 3-4. So under power they expect the pinion to climb quite a bit, even with the QuadraLink.

Andrew

When someone tells me to run 2 degrees down I assume that is a relative number to the transmission. In other words, if you are 3 degrees down slope at the transmission the pinion up 3 degrees would be zero (equal and opposite). The angles are matched. Matched is where you want to be at maximum torque. But, to get there you have to factor in the pinion wanting to rotate upwards under acceleration. So, for my suspension that number would be 1 degree upwards (from earth)... or a resulting angle of 2 degrees nose down relative to the transmission (3-1=2). This is not made clear in the video, too many people when speaking forget that the audience may not understand the language. Pretty sure they mean 2 down in the same sense, in other words the angle at the trans is 3 degrees down (from earth) and the pinion is 1 degree up (from earth), resulting in 2 down from the transmission.

The reason you want the driveshaft running downhill from the transmission to the axle is to minimize the total angle. If your transmission is 3 down, and your driveshaft is level to earth, then the u-joint angle is 3 degrees. If the driveshaft runs downhill a little, the u-joint angle is less. And, as Ron pointed out, if you run the driveshaft uphill the angle is more. 5 degrees is bad. More than 5 is more bad. Having the transmission and rear axle offset from each other increases the u-joint angle. Basically makes it that much worse.

Now, the fun part, what causes the vibration? When your u-joint rotates at an angle, if the input speed is constant the output speed fluctuates. The driveshaft speeds up and slows down as it rotates. If your rear axle angle is matched the input speed to the rear u-joint goes up and down and the output speed changes to be the same as the original input... if the angles are mismatched the output speed at the axle surges. If the angle at the ends is fairly large, the speeding up and slowing down of the shaft as it rotates can cause an ugly vibration at 4x the frequency of the shaft speed.

This might help a little: http://en.wikipedia.org/wiki/Universal_joint

[mmosley]

Sounds like they expect the pinion to climb 2 degrees with the quadralink.

[andrewb70]

As I just stated in my post. I think they mean 3 down at the transmission, 1 up at the diff; for 4 down at the transmission you want 2 up at the diff. 2 down is the difference. They expect the pinion to climb 2 degrees with the quadralink.

The main point of my original post is that the DSE video is not very precise and should include measurements of the driveshaft angle. All this talk about engine down and up and pinion down and up is completely pointless without knowing the angle of the driveshaft.

Ultimately, the most important measure are the front and rear operating angle. If the operating angles are more than 3 degrees, there will be high speed vibration problems.

This is the simplest and clearest illustration of what I am talking about:

https://static1.pt-content.com/images/noimg.gif

Andrew

[Carl @ Chassisworks]

Steve,
We recommend that the Chassisworks g-Link rear systems (http://www.cachassisworks.com/Attachments/Catalogs/BG_400.pdf) be set between1-2 degrees down from parallel with the crank. Taking the front measurement off the balancer is usually easiest.

If you switched to a T56 without modifying the trans tunnel then the engine is pointed down pretty far. This effects not only your u-joint angles but also things like header and steering shaft clearance. Also makes the pinion more likely to bang into the bottom of the tranny tunnel. Get it back up where it belongs with one of these (http://www.cachassisworks.com/p-2789-camaro-67-69-transmission-tunnel-cap-t-56-magnum.aspx).

I know I have sold a lot of them to guys on this forum. You called me and ordered one, didn't you?

https://static1.pt-content.com/images/pt/2014/02/5922f10_2_-1.jpghttps://static1.pt-content.com/images/pt/2014/02/5922f10_3_-1.jpg

[andrewb70]

Steve,
We recommend that the Chassisworks g-Link rear systems (http://www.cachassisworks.com/Attachments/Catalogs/BG_400.pdf) be set between1-2 degrees down from parallel with the crank. Taking the front measurement off the balancer is usually easiest.

If you switched to a T56 without modifying the trans tunnel then the engine is pointed down pretty far. This effects not only your u-joint angles but also things like header and steering shaft clearance. Also makes the pinion more likely to bang into the bottom of the tranny tunnel. Get it back up where it belongs with one of these (http://www.cachassisworks.com/p-2789-camaro-67-69-transmission-tunnel-cap-t-56-magnum.aspx).

I know I have sold a lot of them to guys on this forum. You called me and ordered one, didn't you?

https://static1.pt-content.com/images/pt/2014/02/5922f10_2_-1.jpghttps://static1.pt-content.com/images/pt/2014/02/5922f10_3_-1.jpg

Carl,

With all due respect, while setting the pinion down 2 degrees relative to the angle of the engine seems like simple advice, this doesn't address the overall issue of preparing angles. The angle of the driveshaft is critical because it is what allows you to calculate the front and rear operating angles. Yes, the simple rule is that the transmission and pinion should be equal and opposite, but what people forget is that the operating angles really shouldn't exceed 3-4 degree (less is better) to achieve smooth operation at high speed. I drew a couple of examples to illustrate how angles can be equal and opposite, but too high!

https://www.pro-touring.com/~andrewb/driveline01.jpg

Andrew

[Carl @ Chassisworks]

Andrew, While I can appreciate the academic side of this thread, if the transmission is where it belongs it doesn't usually need to be that complicated. We're not talking about a lifted F350 or a pure road-race car here so the angles won't be as exaggerated. For the average guy, who may be getting confused trying to follow along, it's not always necessary to go quite so in depth. When one of our customers calls us hunting driveline vibrations it can be traced 9 times out of 10 to having a transmission that the car wasn't built to accept underneath a stock floor.

With all due respect. :) Bringing the tech is great and Ron does it really well. Just want to throw out there that sometimes there is a little simple explanation.

[andrewb70]

Andrew, While I can appreciate the academic side of this thread, if the transmission is where it belongs it doesn't usually need to be that complicated. We're not talking about a lifted F350 or a pure road-race car here so the angles won't be as exaggerated. For the average guy, who may be getting confused trying to follow along, it's not always necessary to go quite so in depth. When one of our customers calls us hunting driveline vibrations it can be traced 9 times out of 10 to having a transmission that the car wasn't built to accept underneath a stock floor.

With all due respect. :) Bringing the tech is great and Ron does it really well. Just want to throw out there that sometimes there is a little simple explanation.

I just find that the simple solutions don't always solve the problem, precisely because the whole "academic" discussion is not being comprehended. An explanation should always be valid, not matter the application. For instance, on A-bodies, like my GTO, the simple solution doesn't solve the problem because of the example that I drew in my diagram. As my car sits, the front operating angle is 6-7 degree, and the transmission is as high as it can go without extensive floorpan modifications. I am not even using a T56, but a Richmond, which fits very nicely inside the stock transmission tunnel, much like a Muncie did. With a 6 degree front operating angle, no amount of rear control arm manipulation will solve the problem. The angles can be made "equal and opposite" but they will be too large for smooth high speed operation (anything above 3,000 rpm driveshaft speed, give or take for various materials).

But fair enough...2 degree down it is then...

Andrew

[tonyvol]

I was reading this post and was wondering if someone could help me out? I have a 67 Camaro and I'm installing a TKO 600. I needed to modify the tubular cross member pad since it was set up for a big block and I now have it set up for a small block. I'm getting ready to tack weld the pad in place that the trans. mount sits on. Here is my question. Right now the engine is pointing rearward down 3.5 degrees. This has the carb base on the intake sloping forward .5 degrees.
My pinion angle is at 1 deg. pointing down. How critical is it to have the carb base as close to 0 deg.? I'm using a Holley 4150 carb. Or should I be more focused transmission and pinion angle. I could raise the rear of the transmission up to be closer to 3 degrees point down? Which would make the carb base closer to 1 deg. sloping forward.

Hey guys, I looked at the DSE video. It didn't really answer my questions, plus I have leaf spring set up with Cal Tracs. Rear Leafs are Hotchkis 1 1/2 drop. The front suspension will also be 1 1/2 drop.

-How critical is it to have the carb base as close to 0 deg.?
-Should I be more focused transmission and pinion angle?
-Is 3 degrees good for trans. angle? I think on a big block chevy with the carb base at level, the engine will tilt back 4 degrees from the factory.

[Carl @ Chassisworks]

I just find that the simple solutions don't always solve the problem, precisely because the whole "academic" discussion is not being comprehended.
Andrew

True, simple doesn't always solve it. But it's a good place to start.

[67RSRAG]

Andrew looking at your diagram for your "typical pro touring set up" While I always understood it the way your diagram is sketched, I think DSE is saying that the rear pinion should be pointing downhill 2 degrees not up as you are showing it, forming more a v shape.

[andrewb70]

Andrew looking at your diagram for your "typical pro touring set up" While I always understood it the way your diagram is sketched, I think DSE is saying that the rear pinion should be pointing downhill 2 degrees not up as you are showing it, forming more a v shape.

My diagram shows the optimal scenario with respect to the operating angles. They should be equal, opposite, and as small as possible without being zero. In the DSE video they show their control arms having rubber bushings. I am quite certain that under power the DSE QuadraLink experiences some level of pinion deflection. I don't know what that might be, but I bet it is in the 2-4 degree range. So their video suggests building a certain amount of angle to accommodate the deflection of the pinion under power. This can to be done with all set-ups, some to a greater extent than others, e.g. leaf springs more so than heim jointed 4 links.

Driveline refinements is an area that is neglected by the pro-touring community. We swap in modern suspension, efi engines, and modern brakes, but are still using driveline technology developed in the late 19th century!

Andrew

[83hurstguy]

Andrew looking at your diagram for your "typical pro touring set up" While I always understood it the way your diagram is sketched, I think DSE is saying that the rear pinion should be pointing downhill 2 degrees not up as you are showing it, forming more a v shape.

Right, but if you set it that way without considering the front angle, your u-joint angles potentially won't be canceling. Hence, on a lowered car, you have the situation Andrew sketched. I have the same issue, and I have the stock trans and rear end in the car, so it's not just an "aftermarket trans is at the wrong height" issue. Been too busy with house projects to get out there and figure out my final solution to it.

[jlcustomz]

Been trying to get a better understanding of this subject myself. Did an ls1/ t-56/ 3.73 swap years ago into an 83 el camino/g-body. can't remember what all I tried to figure in on angles back then, but I definitely did slice & splice the trans tunnel to bring the t-56 up.

My issue has been vibration at interstate highway speeds, which osculates some. Annoyingly uncomfortable after a while, but not ridiculous. I have an original 83 steel shaft from a delta 88, which likely went with something near 2.41 gears.

So I'm thinking in keeping it simple here, my first change should be to either have the original shaft rebalanced locally to over 4,000rpms at least if available, or buy a new one of some type balanced at a pretty high rpm. 2nd would be getting adjustable upper arms to adjust pinion angle if measuring shows it to be needed. Haven't had time to persue issue either. Thoughts?

[TheJDMan]

Carl,
Yes I have your tunnel cover installed.

My crankshaft is currently 3.3deg down to the rear and the pinion is 3.3deg up to the front or parallel. Just for the record, 3deg down is virtually a world wide standard for car manufacturers.

According to the DSE video they simply state 2deg down pinion angle not relative to anything. On the other hand, Carl is saying 2deg down from parallel with the crank which in my case would be 1.3deg up pinion angle. I assume that DSE is accounting for the rubber bushings in their links where Chassisworks is saying the ball ends on the G-Link don't deflect as much under power. So at this point it is pretty clear there is no one correct answer. What is clear is that my parallel angles combined with an up driveshaft angle are causing a vibration and the pinion is currently too high.

[andrewb70]

Carl,
Yes I have your tunnel cover installed.

My crankshaft is currently 3.3deg down to the rear and the pinion is 3.3deg up to the front or parallel. Just for the record, 3deg down is virtually a world wide standard for car manufacturers.

According to the DSE video they simply state 2deg down pinion angle not relative to anything. On the other hand, Carl is saying 2deg down from parallel with the crank which in my case would be 1.3deg up pinion angle. I assume that DSE is accounting for the rubber bushings in their links where Chassisworks is saying the ball ends on the G-Link don't deflect as much under power. So at this point it is pretty clear there is no one correct answer. What is clear is that my parallel angles combined with an up driveshaft angle are causing a vibration and the pinion is currently too high.

Steve,

You really need to measure the angle of the driveshaft in addition to the pinion and the trans output shaft angles. This will allow you to calculate the operating angles at rest. From there you can start to fine tune the pinion angle to get the smoothest operation under power. Keep in mind that the pinion can move quite a bit under driving conditions. If you have a GoPro or similar camera you can mount it under the car and observe just how much the pinion is climbing under power.

Andrew

[andrewb70]

I found this video on youtube and it does a good job of explaining how to measure the operating angles. The example is on a big truck, but the procedure is the same for cars. Note how the define "up" and "down". In the video no matter what is being measured, if it is higher in the front than in the rear, that's "down." If it is lower in the from and higher in the rear, that's "up." This is true for transmission output shaft, driveshaft, and pinion shaft.

Andrew

[67RSRAG]

Carl,
Yes I have your tunnel cover installed.

My crankshaft is currently 3.3deg down to the rear and the pinion is 3.3deg up to the front or parallel. Just for the record, 3deg down is virtually a world wide standard for car manufacturers.

According to the DSE video they simply state 2deg down pinion angle not relative to anything. On the other hand, Carl is saying 2deg down from parallel with the crank which in my case would be 1.3deg up pinion angle. I assume that DSE is accounting for the rubber bushings in their links where Chassisworks is saying the ball ends on the G-Link don't deflect as much under power. So at this point it is pretty clear there is no one correct answer. What is clear is that my parallel angles combined with an up driveshaft angle are causing a vibration and the pinion is currently too high.

Steve my angles are exactly like yours. I spoke to DSE they are confirming 2 degrees on the rear pinion pointing downward. Not 2 degrees less than the front. Unfortunately winter won't allow me to test :(

[TheJDMan]

Steve,

You really need to measure the angle of the driveshaft in addition to the pinion and the trans output shaft angles. This will allow you to calculate the operating angles at rest. From there you can start to fine tune the pinion angle to get the smoothest operation under power. Keep in mind that the pinion can move quite a bit under driving conditions. If you have a GoPro or similar camera you can mount it under the car and observe just how much the pinion is climbing under power.

Andrew

All the driveline angles were included in the OP. Once I get the engine back in the car and start driving it I plan to shoot video of the rear axle in operation but I suspect the G-Link will allow very little rotational movement compared to a leaf spring suspension.

[Carl @ Chassisworks]

Carl,
Yes I have your tunnel cover installed.
My crankshaft is currently 3.3deg down to the rear and the pinion is 3.3deg up to the front or parallel. Just for the record, 3deg down is virtually a world wide standard for car manufacturers.

I thought I remembered that you had ordered the cover. Cool, so the engine isn't being forced down at the back and that is borne out by your crank angle measurment. With your car being so low/the rear housing being so far up inside the car it would be better to get the engine flatter but stock is better than what many people have. (On the gStreet Chassis (http://www.cachassisworks.com/Attachments/Catalogs/BG_301.pdf)cars the crank is about zero as it points directly at the third member.)


According to the DSE video they simply state 2deg down pinion angle not relative to anything. On the other hand, Carl is saying 2deg down from parallel with the crank which in my case would be 1.3deg up pinion angle. I assume that DSE is accounting for the rubber bushings in their links where Chassisworks is saying the ball ends on the G-Link don't deflect as much under power. So at this point it is pretty clear there is no one correct answer. What is clear is that my parallel angles combined with an up driveshaft angle are causing a vibration and the pinion is currently too high.

Our recommendation is 1-2 degrees down from parallel for the g-Link and fine tune from there. In your case that is 1.3 deg up from level. We make sure to always use "parallel" when discussing pinion angle so that the car doesn't accidentally end up with a five degree difference between the crank and pinion angles.



All the driveline angles were included in the OP. Once I get the engine back in the car and start driving it I plan to shoot video of the rear axle in operation but I suspect the G-Link will allow very little rotational movement compared to a leaf spring suspension.

Correct! One of the benefits of the g-Link (and most link style suspensions really) is reduced axle tramp/wrap. The pinion is kept from climbing the ring gear and you get less deflection through the u-joints.

Some undercar video could be helpful. It could be something as simple as a bad u-joint or the driveshaft needing to be balanced. Once the engine is back in the car it wouldn't hurt to double check the lateral alignment.


For general knowledge and education, here's what it says in the g-Link Instruction Sheet (http://www.cachassisworks.com/p-1299-camaro-67-69-firebird-67-69-gm-f-body-g-link-pivot-coil-over-suspension.aspx)for the 67-69 Camaro. The instructions are similar for most of our rear kits.



Pinion Angle
Our recommended pinion angle of one to two degrees down, as compared to the engine crankshaft
angle, serves as a starting point for your particular application. Installed components, available
traction, and specifi c application will have some affect on the correct settings for your vehicle.
Pinion angle is to be set at ride height by equally adjusting the upper control arm lengths. Upper arm
must be unbolted from the axle tabs and jam nut loosened for adjustment. Be sure to tighten the jam
nuts and mounting hardware to the torque value specifi ed in this installation guide.

Understanding Pinion Angle
The pinion angle is a very misunderstood measurement. The pinion angle is simply the difference in
degrees of the engine crankshaft or drivetrain angle and the third member. The pinion angle is not a
tuning aid. It is something that has to be set, but you do not adjust it for bite.

Measuring the Drivetrain Angle
This can be taken from the vertical surface of the transmission tailshaft, the oil pan rail, or the front
face of the harmonic balancer. Most production vehicle drivetrain angles will run slightly downhill
towards the rear bumper. A typical measurement may be 2 degrees.

Adjusting the Third Member Angle
The third member should be adjusted so that at ride height there is one to two degrees difference
in the measured drivetrain angle and the third member angle. The pinion must point down 1 or 2
degrees from the engine or drivetrain angle. As an example, the two degrees downhill drivetrain angle
previously established would require the third member to be set at zero degrees or parallel to the
ground for a difference of two degrees. Lengthening the upper control arms to tilt the pinion upward to
a measurement of one degree would give a difference of one degree when compared to the drivetrain
angle.

Greater traction from wider or softer tire compounds combined with higher horsepower levels will
require a greater pinion angle than low traction, low horsepower applications. The object is to get the
two angles to be equal during acceleration. A poly-bushing link is more compliant and will fl ex more
than the pivot-ball link, so poly links may require more initial pinion angle.

[72BBSwinger]

Here is my setup
Engine 3 degrees down
Pinion 2 degrees down, 1 degree up
Leaf springs
havent checked U-joint angle
Heres what is weird, under heavy throttle, with Cal tracks, it has no vibration at all and is smooth as can be. When you let off the gas above 80 mph you get a noticable vibration. One thing I know is I want a different set of leafs because although I have cured the wrap, they still have a stupid amount of UN-wrap.

[Carl @ Chassisworks]

Here is my setup
Engine 3 degrees down
Pinion 2 degrees down, 1 degree up
Leaf springs
havent checked U-joint angle
Heres what is weird, under heavy throttle, with Cal tracks, it has no vibration at all and is smooth as can be. When you let off the gas above 80 mph you get a noticable vibration. One thing I know is I want a different set of leafs because although I have cured the wrap, they still have a stupid amount of UN-wrap.

The way I read your angles, the pinion is 4-5 degrees below parallel. That's fairly aggressive for a street car. Under deceleration the angle is more exagerrated as the tires drag the pinion down further.

Unfortunately, you're not going to cure that vibration with new leaf springs. This is very common for Cal-Trac style cars and leaf springs in general. Cal-Tracs, and all traction bars, are designed to get the car to hook hard under power -not to keep your u-joints and leaf springs in good condition. Drag racers often put the car in neutral when crossing the finish line so they don't drop the driveshaft on the track.

A good adjustable shock, like our VariShocks (http://www.varishock.com/)for instance, can help reduce the wrap by slowing down the forces. The next step would be a link type syspension.

[72BBSwinger]

The way I read your angles, the pinion is 4-5 degrees below parallel. That's fairly aggressive for a street car. Under deceleration the angle is more exagerrated as the tires drag the pinion down further.

Unfortunately, you're not going to cure that vibration with new leaf springs. This is very common for Cal-Trac style cars and leaf springs in general. Cal-Tracs, and all traction bars, are designed to get the car to hook hard under power -not to keep your u-joints and leaf springs in good condition. Drag racers often put the car in neutral when crossing the finish line so they don't drop the driveshaft on the track.

A good adjustable shock, like our VariShocks (http://www.varishock.com/)for instance, can help reduce the wrap by slowing down the forces. The next step would be a link type syspension.
I have it at 2* below parallel which in my case is like 1* up from level, thats why I through that in there. Im betting upon decel im getting alot more than the 2* static setting. Wish I had the cabbage for a torque arm/3link/Watts deal like ive had dreams about but its not in the cards yet.

[83hurstguy]

I figured this is a good thread to add my experience with pinion angle along with some questions. I messed with my pinion angle last fall, and due to other issues finally got the time to work on the car this weekend. I also bought some better tools to get more consistent measurements. My G-body H/O has a 200-4r trans and GM 8.5" 10 bolt with Eibach springs and Currectrac rear control arms.

When I measured the pinion angle initially this weekend, the picture below shows the values I recorded. Note that the angles shown are absolute, and not adjusted for garage floor pitch (approximately 1* down towards back of car, but shouldn't matter as all tires are at the same height on race ramps).


96366

The u-joint angles were not canceling, due to the car being lowered. My next step was to figure out how high I could raise the transmission... I was only able to shim it up 3/8" before the Olds power steering pulley gets reallyclose to the steering box. This was not enough to reverse the angle at the front u-joint to run a traditional driveline configuration (with the pinion angle down relative to driveshaft).

As I see it, I have two options... either get a new driveshaft with CV joint at the front, or run a reverse driveline orientation where the pinion is up relative to the driveshaft. (A third option is significant engine bay surgery to raise engine/trans with custom mounts, but that's immediately ruled out, and hood clearance is already at a premium).

I set the car up with the reverse driveline orientation today with the shimmed transmission mount. The picture below shows the best that I could get at the end of the day.


96365

Does anybody have any thoughts or comments on my setup? Am I missing any other options? I left the pinion angle at this position to account for 2* of pinion rise under power, which would then lead to 2.4* total working angle in the rear. Is 0.4* enough initial angle, or should I have closer to 1* in there static (to ensure u-joint rotation), which would bring it to 3* working angle with an estimated 2* pinion rise?

I can't say I'm happy with it, but I think it's the best I can reasonably do for now. Thanks in advance for any feedback!

[andrewb70]

Luke,

That seems like a very reasonable starting point.

Andrew

[83hurstguy]

Luke,

That seems like a very reasonable starting point.

Andrew

Thanks Andrew! Appreciate all your help and info shared with your experiences.

[icemanrd19]

I'm seeing all of these engine measurements but where are you taking them from? I have my t56 way up hitting the floor and the floor is already raised about a 1" or so.

Im using dse subframe, dse plates, and the angle from the oil pan seems pretty steep still. Everyone is taking these at the car sitting ride height correct? Couldn't i just cancel my transmission angle with adjusting my rear quadralink to compensate for it?

[bryant]

you can take the engine/transmission angles on any surface that is parallel or perpendicular to the the center line through the crankshaft and transmission shafts. like the front face of the blancer or front pulley. along the oil pan rail or valve cover rail, on the back of the block or front of the bellhousing.
the car does not have to be level. the weight of the car needs to be supported on its suspension to have the differential at ride height.
yes you can cancel or the engine/transmission angle with setting pinion angle. just make sure the operating angles on the u-joints dont become too much. the tremic driveline app works very well at determining all of this and its free.

[icemanrd19]

revived.

Currently my engine angle off the balancer is 4 degrees. I can't go any higher on the rear of the trans because i only have 1/2 clearance between my headers and floor. With the rear quadralink i can adjust it to set my driveline angles if need be but having the engine at 4 degrees isn't a big deal is it?

[72BBSwinger]

That's a little more than normal but liveable.

[icemanrd19]

not sure what else to do.

how close can i get the headers to the floor without causing issues? Right now my knuckle can bairly get in between the headers and floor

[72BBSwinger]

Split the difference and raise it a 1/4". Also I level my rockers THEN set my angles. Cars almost always have SOME rake at ride height. Doesn't really matter at the end of the day because you need the pinion about 2* below parallel to the engine angle but still opposing angles to cancel the u-joints from vibration.

[icemanrd19]

Engine 3.92 degrees down
driveshaft 1.10 up
pinion 2.2 degrees down

All angles are looking at it from the passenger side.

I can't move my transmission up anymore. Do i move my pinion angle up or down?

[icemanrd19]

the driveshaft shop gave me some good advice whenever the driveshaft is climbing uphill

can you give me the info off the car like this

1. engine/trans is on ____ angle and it heads up in the back or down in the back
2. The Driveshaft (if not there use a string or a piece of wood to go from the center of the output shaft to the center of the pinion) ____ angle and it heads up in the back or down in the back
3. the pinion ______ angle and it heads up in the back or down in the back
-------------------
Please take not how i have described the water running the parts to make sure were
both understanding the angle up/down thing.
So is the Motor and trans face down at the back (water would run off the back of the trans)
at 2.3 and the shaft heads up to the rear at .5 (water would run down the shaft towards the trans causing a puddle when meeting the trans) (you take 2.3go back to Zero and then up to .5 = 2.8)
the Front operating angle is 2.8

The shaft heads up to the rear at .5 (water would down the shaft towards the trans)
and the Diff points down at 2.5 (water would run off the diff toward the Shaft)
we would have 3 degrees
Rule is no greater then 3 and no more then .5 off, this (if measurements are correct)
would be 2.8 and 3.0 Text book perfect. if this is correct its either a issue with the yoke
not in the back of the trans enough or the shaft is not good.

[ctcz28]

Wow, this is an old thread. The article at the link below should be helpful:

https://www.hurst-drivelines.com/files/Universal_Joint_Alignment_Proc_111606.pdf

[icemanrd19]

Engine is 3.34 degrees down, which raised the driveshaft to .5 degrees up at the trans and down at the rear diff, rear diff is pointing 2 degrees down. That gives me 2.8 degree front working angle and 2.5 rear. Just the slight 3/8 lift in the rear of the trans, bending the headers fixed my issue. Pretty much vibration free up to 125ish mph

[bing98]

Thanks for reviving this thread. It's a good read and perfect timing for me. I have been fussing with the angles and I am quite confused by all this. Right now my angle finder shows my transmission angle is 4 degrees down, the drive shaft is 1 degree down and the pinion is 2 degrees up. If I'm correct that gives me a 3 degree operating angle at each end of the driveshaft.

Much of what I have read says this is what I should strive for. That equal operating angles with ensure proper u-joint operation. Others have said the transmission and pinion angles should be equal, but opposite, which mine are clearly not. I suspect that if I adjust the transmission and pinion angles to be equal, but opposite the resulting driveshaft angle will change my operating angles to something other than equal.

So which is it? Equal but opposite transmission and pinion angles or operating angles?

I happen to be use that hurst-drivelines.com u-joint alignment procedure too. It's a bit confusing. They say to measure tranny, driveshaft and pinion angles like everyone is saying in this tread, but then they introduce some additional angles measured off of the u-joint caps themselves. They have you take the measurment off of the caps at the front and back and then rotate the driveshaft 90 degrees and take a second measurement. All 4 of these measurement on mine are very different.

[andrewb70]

Thanks for reviving this thread. It's a good read and perfect timing for me. I have been fussing with the angles and I am quite confused by all this. Right now my angle finder shows my transmission angle is 4 degrees down, the drive shaft is 1 degree down and the pinion is 2 degrees up. If I'm correct that gives me a 3 degree operating angle at each end of the driveshaft.

Much of what I have read says this is what I should strive for. That equal operating angles with ensure proper u-joint operation. Others have said the transmission and pinion angles should be equal, but opposite, which mine are clearly not. I suspect that if I adjust the transmission and pinion angles to be equal, but opposite the resulting driveshaft angle will change my operating angles to something other than equal.

So which is it? Equal but opposite transmission and pinion angles or operating angles?

I happen to be use that hurst-drivelines.com u-joint alignment procedure too. It's a bit confusing. They say to measure tranny, driveshaft and pinion angles like everyone is saying in this tread, but then they introduce some additional angles measured off of the u-joint caps themselves. They have you take the measurment off of the caps at the front and back and then rotate the driveshaft 90 degrees and take a second measurement. All 4 of these measurement on mine are very different.

I think you are confusing yourself. What you have now are equal and opposite operating angles. Remember, the measurements are taken relative to gravity, but your reference is the driveshaft. If you were to raise the back of the car by the axle so that your driveshaft was level, you would see that the engine is 3 degrees down and the pinion is 3 degrees up.

Andrew

[dondb]

I've read this thread and others several times and have one question. If the yoke out of the pumpkin runs downward to the rear of the car.....is that a positive or negative? I've had vibrations over 70 and would like to correct it. My current angles are 3-1/2 degrees at transmission yoke, 0 driveline and 1.5 degree's at yoke on pinion....running down hill to rear of car. My centerline on the transmission yoke is 9 7/8 and my pinion yoke is 10 1/8 from ground. I am running coilovers and trueturn on front lowered about 1 3/4 inches and Hotchkis leaf spring lowered 1 1/2" with a 12 bolt Moser. I have a LQ9 bottom end with LS3 top end running the full Holley swap kit. My wheels are Vintage wheel works....front tire is245*45*17 and rear 275*40*17. Any help would be appreciated:) I'm in winter Purgatory here in NH so i'd like to straighten this out before driving weather hits.

[andrewb70]

I've read this thread and others several times and have one question. If the yoke out of the pumpkin runs downward to the rear of the car.....is that a positive or negative? I've had vibrations over 70 and would like to correct it. My current angles are 3-1/2 degrees at transmission yoke, 0 driveline and 1.5 degree's at yoke on pinion....running down hill to rear of car. My centerline on the transmission yoke is 9 7/8 and my pinion yoke is 10 1/8 from ground. I am running coilovers and trueturn on front lowered about 1 3/4 inches and Hotchkis leaf spring lowered 1 1/2" with a 12 bolt Moser. I have a LQ9 bottom end with LS3 top end running the full Holley swap kit. My wheels are Vintage wheel works....front tire is245*45*17 and rear 275*40*17. Any help would be appreciated:) I'm in winter Purgatory here in NH so i'd like to straighten this out before driving weather hits.

Draw what you have in this format: engine/trans.....driveshaft.....pinion....(use /--\ notation for angles)

Something like: \ ----\ or \----/

get my drift?

or draw a diagram, take a picture of it and post it here.

Andrew

[dondb]

Yes i do....:)

Transmission yoke \ 3.5 degree's. driveshaft ---------- 0 degrees. Pinion yoke \ 1.5 degree's. Looking at the car from the Drivers side.

The best i can get out of my transmission by raising the tail end is 3.5% without hitting the tunnel.

Thanks Andrew

[icemanrd19]

Yes i do....:)

Transmission yoke \ 3.5 degree's. driveshaft ---------- 0 degrees. Pinion yoke \ 1.5 degree's. Looking at the car from the Drivers side.

The best i can get out of my transmission by raising the tail end is 3.5% without hitting the tunnel.

Thanks Andrew

what rear end? Lower the pinion angle which would make the driveshaft go \ instead of -----most likely by 1/2 degree . Your front working angle if that would happen would be 3.5 degrees min .5 degrees since they are both going down which is 3 degrees and moving your pinion to say 2 degrees down would make that working angle 2 degrees pinion down or like / which would cause the driveshaft and pinion to meet like this \ / causing a working angle of 2 degrees plus .5 degrees equalling 2.5 degrees.

[dondb]

12 bolt Moser, and forgot to mention...a T56 Transmission.

So I would shim the Pinion to / which would require a 3.5 degree shim, that would put my pinion / 2 degree's. That is my confusion, is the pinion considered a - or + from drivers side view currently \ ? That would clarify my mind on the opposing degree's of transmission yoke and pumpkin yoke cancelling each other out along with working angles.
Thanks for the response

[andrewb70]

12 bolt Moser, and forgot to mention...a T56 Transmission.

So I would shim the Pinion to / which would require a 3.5 degree shim, that would put my pinion / 2 degree's. That is my confusion, is the pinion considered a - or + from drivers side view currently \ ? That would clarify my mind on the opposing degree's of transmission yoke and pumpkin yoke cancelling each other out along with working angles.
Thanks for the response

Your set up is not unlike many others. There is actually a really good discussion here:

http://www.corner-carvers.com/forums/showthread.php?t=49015

Currently your front operating angle is 3.5 degrees and the rear is 1.5 degrees. As you go under load the pinion rotates up and increases the amplitude of both the front and rear operating angle. This isn't optimal, but as I said before, many have this issue, including my GTO.

In the link above in post 32 there is this image:

https://static1.pt-content.com/images/noimg.gif

I have never had much luck with the top configuration, but apparently it is also proper. If you read further in the c-c thread, you will see posts from Joe Birk. HIs ultimate solution was an ultra high speed balance from The Driveshaft Shop.

Andrew

[hifi875]

where is the proper spot to measure pinion angle? I have a 10 bolt 8.5 chevy. Can I measure it on the back where the bolts are or what?

[andrewb70]

where is the proper spot to measure pinion angle? I have a 10 bolt 8.5 chevy. Can I measure it on the back where the bolts are or what?

It is best to take the driveshaft off the pinion yoke and measure on the machined flat surface of the yoke.

Andrew

[icemanrd19]

How much of the shaft of the trans yoke do you all have sticking out? I have about a inch of the yoke shaft showing.

I still have that humming/ vibration in my driveline. Engine is 3.5 degrees, driveshaft goes down .5 degrees which creates a front operation angle of 3 degrees. To clairfy if i had a marble it would roll off the trans and down the driveshaft since they are both going downhill. The rear pinion is set at 2 degrees down which the same marble would then get stuck between the driveshaft and yoke since the driveshaft and yoke create a V. Rear operation angle would be 2.5 degrees. Front edge of pinion member to the beginning part of the rubber seal on the transmission the distance is 48 1/4" . strange i dont have any of that vibration or noise unless im going 75mph plus.

Already sent my specs to the driveshaft shop to possible go with a CV joint driveshaft. I literally have my trans 1/8" from the floor by the shifter bolts and i already raised the floor. I can either raise the floor a 1/4" to gain more clearance and raise the trans up some more to get to 3 degrees but its quicker to just get a CV driveshaft.

[downl50]

Great thread, learned a lot so far. Question is about an A body setup (70 Chevelle). Has anyone gotten the motor/tranny (small block/T56) close to parallel without major tunnel modifications? I already have the tunnel patch welded in and have the motor/tranny at stock 3 deg down -- would love tips on getting it flattened out if it doesn't require more metal work.

Thanks

[andrewb70]

Great thread, learned a lot so far. Question is about an A body setup (70 Chevelle). Has anyone gotten the motor/tranny (small block/T56) close to parallel without major tunnel modifications? I already have the tunnel patch welded in and have the motor/tranny at stock 3 deg down -- would love tips on getting it flattened out if it doesn't require more metal work.

Thanks

First thing to check is if any of your front accessories will hit anything if the back of the engine is raised higher.

Andrew

[icemanrd19]

How much of the shaft of the trans yoke do you all have sticking out? I have about a inch of the yoke shaft showing.

I still have that humming/ vibration in my driveline. Engine is 3.5 degrees, driveshaft goes down .5 degrees which creates a front operation angle of 3 degrees. To clairfy if i had a marble it would roll off the trans and down the driveshaft since they are both going downhill. The rear pinion is set at 2 degrees down which the same marble would then get stuck between the driveshaft and yoke since the driveshaft and yoke create a V. Rear operation angle would be 2.5 degrees. Front edge of pinion member to the beginning part of the rubber seal on the transmission the distance is 48 1/4" . strange i dont have any of that vibration or noise unless im going 75mph plus.

Already sent my specs to the driveshaft shop to possible go with a CV joint driveshaft. I literally have my trans 1/8" from the floor by the shifter bolts and i already raised the floor. I can either raise the floor a 1/4" to gain more clearance and raise the trans up some more to get to 3 degrees but its quicker to just get a CV driveshaft.

So I ordered a new driveshaft from the driveshaft shop. They suggested a 3" or a 3 1/2 reg aluminum driveshaft. I went with a 3 1/2 aluminum with a inner vibration reducer and it fixed all my issues. Light throttle rumbling and 70mph up to 120 plus vibration. Talk about night and day difference