View Full Version : Sorry but need advice with highway vibration
Sorry I know there are a lot of posts about vibrations and some seem similar to mine but like most of you know everyone seems to be a little different. I just wanted to post and see if I am over looking something simple or if my calculations are wrong etc.
The setup: I have a 72 Dodge Dart, stock 360 motor right now, ls1 t56, 50"x3" steel drive shaft with all spicer parts and solid joints, QA1 coilovers front and rear, rack and pinion, triangulated rear, 8.75 rear with 3:91 posi, wilwood disc brakes 12" all four corners, BFG kdw tires 245/35/18 f and 285/30/20 rear, and thats about everything I can think of at the moment
The problem: The vibration has changed a little but its always between 65-75 mph, it comes on pretty strong and i have not went faster due to the fact the sound and vibration get faster and harder. You can tell the sound is like going round and round, and seems to be directly from the rear of the car, it vibrates the shifter and you can feel it a little in the seat and wheel when its really strong. Also when you let off it feels like you are running over the rumble strip on the side of the road untill your under 55mph.
The background: So far I have had the weight of the driveshaft come off at the tranny end twice( the first time though i think it was unbalanced motor) but the second time car felt pretty smooth and then at 70 bang the weight came off and same vibration was back. The drive shaft has been built at 2 different shops in town, both reputable and build stuff for drag racers, i have had the drive shaft balanced prob 5 times now and doesnt seem to change except the most recent balance feels a tad smoother but still vibs at the same speeds. I have had my pinion and trans angles all over the place, I can adjust the trans from 1* point down to 1.6* point down( i can go lower but have some major fab redo xmem), the rear end has been any where from 2* pointing down to 2* pointing up and everywhere in between. The last try at it the trans is at 1.5* down, drive shaft is sitting at 1* down, rear end sitting at .7* up, and vibration seems to come in at 65ish, i did have the setup at 1.5* down, ds @ .7* down and rear @ 1.4* up and vib came in at closer to 73mph but that is the best I have been able to get it. Out side of all that I have had rear 2 tires balanced and checked for run out 3 times, fronts 2 times, axles are new and have barely gotten on the throttle to maybe at most squeal tires( i have a stock rv 360 motor..) , I thought maybe rear bushing in trans maybe bad cause there is a little play about .10-.20 but its not leaking any fluid into the rear seal or out of it which most guys said would happen if tail shaft bushing is bad, i have tried runout myself on the driveshaft and its no more that a few thousands, i have tried 4-6th gear and doesnt matter its still at same mph, also I have had the center section rebuilt, backlash set and bearings checked, i have had it on jack stands with drive shaft out and brought it up to 60-70 mph and its smooth.
At this point im just banging my head, I have dumped way too much into a steel shaft so far I would hate to have to buy a aluminum piece and not be the issue. I just dont know what else to check, I appreciate any and all advice. My next step is taking it to a shop but never sure who you can trust and things like this can take for ever and they just rack you big $$$$$ and possibly get you no where....
peices of eight...
08-26-2014, 04:07 AM
ive had a similar situation, took 6 months and dumb luck to find it. my problem came down to the clamps on the yoke it was a 71 Camaro. I had no problems in town, but on the highway at 60 the car acted up. not sure how your drive shaft is held in place, but mine has 2 u clamps that only have a bit of a shoulder on them ( they only tighten so far), id always thought they'd clamped properly. What had happened is that they had worn off material on the inside of one u clamp which allowed the u joint to slide over direction just enough to vibrate and take out my diff seal and before that my trans seal. when you check it rotate you drive shaft and push and pull beside the u joint. i hope this may help.
peices of eight...
08-26-2014, 04:08 AM
great looking car!
andrewb70
08-26-2014, 06:44 AM
I'd get under there and start checking run-out on all the rotating parts. If it's a cycling kind of noise that makes your rear mirror vibrate and you can feel it in the seat, then it is something driveline related. Anything to do with tires will be more of a slower thumb..thump...kinda vibration...
Andrew
Mach1_Ron
08-26-2014, 07:14 AM
I had a similar issue with my Mach after putting in my T5. I got it cleared up with the Driveline Angle. Trans sits 3* down, so I put 3* shims under the springs to put the Pinion 3* up. Equal but opposite angles.
Pieces of eight... Thanks! I however bought new straps for the joints cause that thought crossed my mind, but that's what I'm looking for is anyone that has fixed their vibration and how they did. Andrewb70 I'll double check some of the run out on different pieces, it is a cycling type noise and so weird cause it's like the noise cycles like every sec it's seems really slow for how fast I'm going but does speed up a bit when I go faster..... Damn cars!!
Ok so I still have not figure out this damn vibration , and for me to drive this car to Crusin the Smokies it needs to get better. The latest I have dropped $$ on new t56 magnum, shortened driveshaft and still same vibration around 60-70mph. What is really weird is out driving it , at one point I down shifted into 4th and was cruising at 75 with very slight vibe(but I think it was just maybe exhaust note), but in 5th or 6 th was still there, but definitely seems the worse at 2000rpms. Weird thing is I couldn't get it to go smooth again by down shifting,(wasn't driving that long either).At 2000rpms in every gear accelerating there's slight vibration, but deceleration seems to be worse, but just at 2000 rpm on the dot. I still need to have someone else check my pinion and trams angles, but would a driveline angle cause a vibration so bad that it feels like it's going to come apart? Also yoke is pushing 1 -1/4" out of trans, would that cause that much of a vib? I've had guys say that's acceptable and others say no more than 3/4". Please any help would still be great.
72BBSwinger
12-20-2014, 05:19 PM
I have suggested pinion angle when you have asked before, and I know that can be at least part if not all of it. If you have no shims and stock axle pads with a T56 I can just about promise that is what it is. It gets worse on decel because the pinion angle gets worse on decel. Other thing it could be if it is depended on RPM rather than speed is your external balance 360, is your flywheel weighted? Do you have the correct balancer? That WILL cause vibration to. I finally had my car pretty much vibration free up to 140 but even then I get a tad on decel, leaf springs suck in this dept.
andrewb70
12-20-2014, 05:44 PM
What are your front and rear operating angles? Does the driveshaft point up towards the rear?
Andrew
bryant
12-20-2014, 06:44 PM
are you using the same drive shaft shop for the balancing?
ive seen drive shaft tubing have a slight oval shape causing a high speed vibration. the shop that built it was adimate the shaft was not the problem. took it to another shop and they found the oval tube right away. they retubed the shaft and no more vibration
is the yoke on the diff worn out? does it hold the ujoint on center?
with your last post its sounding more like an engine balance issue. have you free reved the engine up to 2000rpm and held it their to see if it vibrates at that point? has this motor always been a stick shift? its this flywheel the original flywheel the motor was balanced with?
lastly is the motor and transmission crooked in the car or is the diff crooked in the car?
mmosley
12-20-2014, 07:57 PM
I have suggested pinion angle when you have asked before, and I know that can be at least part if not all of it. If you have no shims and stock axle pads with a T56 I can just about promise that is what it is. It gets worse on decel because the pinion angle gets worse on decel. Other thing it could be if it is depended on RPM rather than speed is your external balance 360, is your flywheel weighted? Do you have the correct balancer? That WILL cause vibration to. I finally had my car pretty much vibration free up to 140 but even then I get a tad on decel, leaf springs suck in this dept.
360 is an externally balanced engine, make sure the harmonic balancer and flywheel are correct for the application. If you are getting vibration under acceleration and deceleration in 6th or 5th at the same rpm, change to 4th at that speed and see if it goes away. If it is purely RPM and not speed related it is your engine. It can also be something like engine mounts that is not obvious. Do what you can to isolate it... if it is purely speed related it is your drivetrain, RPM related it is the engine. If it is safe to do so put the transmission in neutral at that speed with the engine idling and see if it stays or goes.
Ok so I remeasured angles, first off it looks like grage floor is sloped -1, I did not include this into any of my angles. Tans -1/1.5 , driveshaft -1/1.5 and rear is -.5. I can't move the trans up and more in the tunnel, well at least with out modifying the tunnel more, which is possible but don't want to. I've measured from rear wheels to the front wheels and are the same both sides(within 1/4 of an inch).
As for motor I have free reved the motor and it's fine, flywheel is for a 360 bought it new but motor was originally a auto. I only have the rpm vib when driving, almost feels like rumble strips when it's decelerating through 2k, you let off at 3k it's fine until 2k and then it vibs. To make clear this from what I feel is different than the mph vib but they may be related as 5th is around 2k at 60 and seems to be the worse. And when you press clutch in during any gear you slightly feel the 2k vib but if it's left in gear and coming down through rpm it's the worse. I have another motor going in this winter
but I don't want to change too much at once.
Thanks for your guys help
SSLance
12-21-2014, 08:19 AM
Sounds like to me you have a couple of different issues at play here, you need to dissect them separately. First find a steady speed on the highway where the vibration is always present and note the RPMs in 6th gear. Then shift to 5th and go to the same RPM and see if the vibration is the same. If it is, that issue is engine related. If the vibration isn't there at that RPM, speed back up to the speed it happened in 6th and see if it happens there. If it does, it is driveline related.
I used this method to find that my engine creates a vibration through the driveline at less than 1800 RPMs and highway speeds. Just over 1800 RPMs it goes away.
I've also had rear axle bearings cause vibration issues - check them for excessive play up and down or in and out, it doesn't take much play for them to cause a vibration at highway speeds.
I'll echo above on the driveline angles. If the trans is -1.5 down, make the pinion +1.5 up so they are parallel. I know drag racers don't like pointing the pinion up, but for highway smoothness making the trans output and pinion input parallel works wonders.
mmosley
12-21-2014, 01:14 PM
I'll echo above on the driveline angles. If the trans is -1.5 down, make the pinion +1.5 up so they are parallel. I know drag racers don't like pointing the pinion up, but for highway smoothness making the trans output and pinion input parallel works wonders.
Nose down for us drag racers is not relative to the ground, it is relative to the transmission. I assume from your short hand that your transmission is pointing down 1.5 degrees and the nose of the axle is pointing down 0.5, definitely not ideal. If the trans is down 1.5 and the pinion is down .5, then yes that could definitely be an issue. It will get worse under decel. The amount you want the pinion down relative to the trans depends on suspension type. The more rigid, the less difference you want. You have a link rear axle so you don't want as much. Try adjusting it up to get the pinion nose up 0.5, this will give you a delta front to rear of 1 degree instead of 2. Try it, see how it works, you may want to go to 1 degree nose up on the diff, but try 0.5 first. Don't think you want to go all the way to 1.5 as Lance suggested; he has the right idea but there is still some play in the 4 link and the ideal is to have the two parallel under full load.
I'll double check the bearings but they were all new green bearings with the axles. The 3rd member Hs been gone through and check and back lash adjusted.
I checked runout on drive shaft in the middle and back by rear yoke and is within .001/.0012
The vibration occurs at 60mph every gear and fees the same except 5th because at 60 I'm at 2k rpm and seems to feel a little worse than the others. 6th gear at 60 I'm at 1500 rpm with the vib and do not have any vibration in any other gear at 1500 rpm. The vib at 2k I can deal with if I can get the car to go faster lol.
I readjusted pinion to being up around 1, and tomorrow going to try to get a shop to read my angles for me, I think it's time for another set of eyes.
Also just to verify the vib shakes everything in the car. You can feel it I. The seat, shifter, dash is rattling , etc. you put ur hand on the tunnel and definitely feel it coming from the rear. I have not tried another set of wheels(I'm going to soon) but would a bad tire or wheel cause that bad of vib? Wheels were new and tires, but cragar has since stopped producing my wheels. I haven't seen any recalls for them but I though it was odd too that the wheels have 7.5 " of back space on 10" wheel and I can't find another cast wheel like so. Even some forged wheels won't go that much backspace. Just something I was thinking and wanted the ask.
mmosley
12-21-2014, 08:36 PM
I readjusted pinion to being up around 1, and tomorrow going to try to get a shop to read my angles for me, I think it's time for another set of eyes.
And it still shakes?
Also just to verify the vib shakes everything in the car. You can feel it I. The seat, shifter, dash is rattling , etc. you put ur hand on the tunnel and definitely feel it coming from the rear. I have not tried another set of wheels(I'm going to soon) but would a bad tire or wheel cause that bad of vib? Wheels were new and tires, but cragar has since stopped producing my wheels. I haven't seen any recalls for them but I though it was odd too that the wheels have 7.5 " of back space on 10" wheel and I can't find another cast wheel like so. Even some forged wheels won't go that much backspace. Just something I was thinking and wanted the ask.
If the wheel for some reason is not centering on the axle, yes, but you should be able to feel it at just about any speed. Tire balance can cause an issue also. Check runout on the wheel as mounted if possible. Trying a different wheel tire combo is a good idea, at least eliminate the possibility.
Motorcitydak
12-21-2014, 08:45 PM
You said your u joints are spicer which is good but how old are they? You may want to pull the caps off and check out the cross. Some times if you run and low angles (which may have happened while you were toying with the angles) the needle bearings will not move much on the cross and it will actually wear grooves into it giving you excessive play
SSLance
12-22-2014, 04:34 AM
I had a Green Company axle bearing fail last summer with just 150 miles on it, symptoms were exactly as you describe. Took me a while to find it as well as I never suspected the new bearing to be bad.
Good luck... I'm sure you'll narrow it down soon.
andrewb70
12-22-2014, 07:06 AM
Grub,
When you talk about driveline angles, it is unclear when you merely say "up" or "down." The relevant information that is needed is the front and rear operating angles. Refer to this:
https://static1.pt-content.com/images/noimg.gif
Andrew
I have not drove it since I readjusted pinion up.
Spicer joints are all new, and solid ones.
That's good and bad news about green bearings, but I'll definitely check them out. If they are bad will they just have play in them? Or when you turn them you'll feel them grinding?
When it comes to my angles I'm just telling you what I read from my angle finder, trans measured from the yoke, I measured from the driveshaft and the rear I measure from rear yoke without the drive shaft in. To get the working angles you subtract trans from ds and rear you subtract the rear measurement from ds or is it ds subtract the rear?
Update, I drove car today with new angles, trans is down 1 1/2 and rear is pointing up 1 deg, same vib, very very very slightly better like maybe 2 mph that's it. Took it to a guy that builds dirt track cars, he rode in it and says it's definitely coming from rear of car/ drivetrain. We pulled driveshaft out, u joints were a little tight we smacked them and losened them up, drove car again and still same vibration. He mentioned about me rear end possibly being set up wrong or poorly, maybe bad bearing etc. is this a possibility? I had rear end checked out by a reputable mopar guy, he set back lash, checked out bearings, they all looked good and put it back together. I have another rear end that I could try and prob will install tomorrow but it's also "supposedly rebuilt" , backlash is .011 and the meshing on teeth look good.
Also how much yoke should stick out of trans? I think I'm a little close now , can't get rear u joints over the yoke,, I can get it out though.theres maybe 3/8 to 1/2" sticking out pass the trans rear seal, the guy I talked to today said at least another 1/2"
72BBSwinger
12-27-2014, 07:32 PM
The housing could be bent. I'm at a loss. Could be cheap gears. If they're stamped Richmond, I would suspect them. We still need to know where your pinion is relative to the trans. I have a boot seal on my trans and about a 1/4" of yoke showing.
andrewb70
12-27-2014, 08:43 PM
Update, I drove car today with new angles, trans is down 1 1/2 and rear is pointing up 1 deg, ....
This doesn't mean anything. You need to determine the angle of the driveshaft in relation to the trans and the pinion in order to know what the front and rear operating angles are.
There are many components that can cause a vibration and you really need to evaluate every single one in order to nail down what the cause is.
Andrew
The drive shaft is at 1.5 degs Down hill from trans to rear end.
NOT A TA
12-28-2014, 07:36 AM
Have you put a different set of wheels/tires on the car to test and see if it's wheel related?
andrewb70
12-28-2014, 08:12 AM
The drive shaft is at 1.5 degs Down hill from trans to rear end.
So the front working angle is 3 degrees and the rear is 2.5, which is about right since the pinion will want to climb as you drive.
Have you checked the run-out on all of the components?
Andrew
Have not done wheels yet, hopefully have a buddy brining some over next weekend to try, I don't have any other wheels that will fit the car.
I have checked runout on drive shaft and seems fine , was within .001/.008. Outside of that I have not checked out any other runout. I had tires checked and they said they were fine.
SSLance
12-28-2014, 12:58 PM
Update, I drove car today with new angles, trans is down 1 1/2 and rear is pointing up 1 deg
The drive shaft is at 1.5 degs Down hill from trans to rear end.
I'm confused...
If the trans tailshaft is pointing down 1.5* and the drive shaft is pointing down 1.5* that would make the angle of the front u-joint 0*
With the pinion pointing 1.0* up, that is a 1 degree difference in u-joint working angle which will only grow as the pinion rotates up under load. This will cause a vibration if that is truly the case.
Look back at the picture Andrew posted. See how the tailshaft of the trans is directly parallel with the pinion yoke, this is what you need as it makes both u-joint angles exactly the same and they work at the same speed. One u-joint working angle greater than the other causes them to work at different speeds and creates vibration.
I personally do not care about the driveshaft angle when trying to diagnose, pay more attention to the trans yoke and pinion yoke and make sure that they are parallel when the car is sitting at ride height.
andrewb70
12-28-2014, 01:19 PM
I'm confused...
If the trans tailshaft is pointing down 1.5* and the drive shaft is pointing down 1.5* that would make the angle of the front u-joint 0*
With the pinion pointing 1.0* up, that is a 1 degree difference in u-joint working angle which will only grow as the pinion rotates up under load. This will cause a vibration if that is truly the case.
Look back at the picture Andrew posted. See how the tailshaft of the trans is directly parallel with the pinion yoke, this is what you need as it makes both u-joint angles exactly the same and they work at the same speed. One u-joint working angle greater than the other causes them to work at different speeds and creates vibration.
I personally do not care about the driveshaft angle when trying to diagnose, pay more attention to the trans yoke and pinion yoke and make sure that they are parallel when the car is sitting at ride height.
Lance,
You're right. Thanks for catching my mistake. Yes, if the back of the engine is down 1.5* and so is the driveshaft, then the front working angle is zero. However, I would not discount measuring the driveshaft angle. In some configurations it is possible to match the trans and pinion angles correctly, but the resulting operating angles are too high for smooth operation. The operating angles have to be calculated to make sure they are less than 3 degrees. A perfect example is the picture I posted. In the picture the front and rear operating angles are equal and opposite, but they are way too big. That configuration is only suitable for a slow speed tractor PTO shaft, not a driveshaft spinning at 3000RPM (or more).
See this PDF. (http://www.markwilliams.com/servicebull/sb0049.pdf)
Andrew
mmosley
12-28-2014, 02:37 PM
Wow, I wonder if this is something crazy like a bent axle shaft.
Ok so drove car today with different wheels and no luck. Also I switched out the rear chunk, it was supposed to be rebuilt, 4:31 gears, but was loud. The gears were whining really loud any time you touched the gas, from at any speed. So they definitely need gone through,. So weird thing is I switched gear ratio and and the vibration was at the exactly same speeds and same exact feel.
Back to angles could please someone tell me what they should be for an example? I thought -1.5 and +1 in the rear that would make the rear and trans parallel. I'm prob making this more complicated than it needs to be but I still having a prob figuring out the whole angle thing.
Ok so I think I'm saying this wrong, the trans is going down hill 1.5 deg the rear end yoke is pointing up towards the sky 1*, I think I have been saying the rear is +1 but I think it's actually -1 does this make better sense?
SSLance
12-28-2014, 03:48 PM
Did you check the rear axle bearings to see if they had any up and down play? It doesn't take much, any amount of up and down or in and out play on the rear axles will cause vibration.
I didn't check for play, I rotated them and felt pretty solid but I'll double check them next day or two
mmosley
12-28-2014, 05:48 PM
Ok so drove car today with different wheels and no luck. Also I switched out the rear chunk, it was supposed to be rebuilt, 4:31 gears, but was loud. The gears were whining really loud any time you touched the gas, from at any speed. So they definitely need gone through,. So weird thing is I switched gear ratio and and the vibration was at the exactly same speeds and same exact feel.
Back to angles could please someone tell me what they should be for an example? I thought -1.5 and +1 in the rear that would make the rear and trans parallel. I'm prob making this more complicated than it needs to be but I still having a prob figuring out the whole angle thing.
How are you measuring speed? is the speedo gear calibrated for 3.91? If the speedometer says 60mph with 3.91 gears, with 4.31 you are actually going 54 mph. If that is the case, then the vibration is coming from the driveshaft or something in front of it. If you are measuring speed with GPS, or you recalibrated the speedometer and you are measuring actual speed then that means your issue is coming from the rear axle or the tires.
I am measuring speed with my phone with a gps app. It's pretty close due to the cars beside me on the highway. So I'm glad you could help maybe pinpoint it a little further. I tried wheels today and no luck, they came off a friends car that is driving around fine.
72BBSwinger
12-28-2014, 07:48 PM
What im getting is you have a pinion angle that is .5 nose down from being parallel with the trans? Parallel would be trans 1.5* tailshaft down and pinion 1.5* nose up correct? So right now you are 1* nose up at the pinion right? That is OK and should be livable IMO but I would want my pinion at around 0 if trans was like yours with leafs. So the only thing you haven't changed is the rear housing,axles,brakes and axle bearings?
Yes exactly bb, I have rear four link setup so I don't think it moves as much as leafs. But like u said it should be close enough where it's livable and it's not any better. I mean you try to hit 70 and feels like whole arid coming apart. It'ss a harsh vibration and comes on quick. I am down to axles bearings brakes . All which have been new but who knows.
gmorris
12-29-2014, 07:23 AM
I had a similar issue and replacing the pinion yoke solved most of it for me. It was a quality moser yoke but it had a lot of runout.
Kenova
12-29-2014, 05:58 PM
If the vibration is showing up at the same (GPS) speed with both dropouts I would say your problem is somewhere between the yoke and tires.
Have you checked your rear end for a bent axle flange? It wouldn't have to be bent by much to cause a vibration at highway speeds.
Ken
Checking axle housing is my next step. I checked runout on the brake hubs and it's within .001-.005. They are center on the axle, I'm going to double check the axle runout too, but highly doubt it's off if hub isn't. Also put a dial on the caps of the ujoints to see if there was any runout and there was none either. I'm running out of ideas!!
Also one other thing someone has brought up was dialing in the bell housing. We talked about it and kind of ruled it out because it's been related to mph and not rpm. With switching gears and still coming in at the same speed seemed to rule out quite a bit. To me the only constants that keep spinning at 60mph but at different rpms would be tires, wheels, axles, brakes, differential correct? Am I missing anything?
mmosley
12-29-2014, 08:12 PM
Also one other thing someone has brought up was dialing in the bell housing. We talked about it and kind of ruled it out because it's been related to mph and not rpm. With switching gears and still coming in at the same speed seemed to rule out quite a bit. To me the only constants that keep spinning at 60mph but at different rpms would be tires, wheels, axles, brakes, differential correct? Am I missing anything?
Your speed being the same measured by GPS with the different gear ratio points to the rear axle. The driveline, driveshaft, and everything pinion forward is spinning at a higher speed that before. I would pull the axles and roll them on the ground to see if they are straight. Take a good look at the bearings as someone mentioned earlier in the thread they had a similar issue caused by a bad bearing. Prior to pulling the axles, turn the axle without the wheels and tires and make sure the axle flange is running true and the bolt circle is drilled on center.
carbuff
12-30-2014, 12:36 PM
How is the driveshaft spinning faster than before if the GPS speed is the same when he is in different gears? The pinion ratio is fixed, so the driveshaft speed is fixed. Thus, I don't see how this specifically points to the rear axle and excludes the pinion or driveshaft?
mmosley
12-30-2014, 07:29 PM
How is the driveshaft spinning faster than before if the GPS speed is the same when he is in different gears? The pinion ratio is fixed, so the driveshaft speed is fixed. Thus, I don't see how this specifically points to the rear axle and excludes the pinion or driveshaft?
He changed from a center section w/ 3.91 gears to one with 4.30 gears. RPM of the pinion and drivetrain went up to get the car moving at the same speed and it vibrated at the same tire speed. Therefore, it is not the driveshaft or drivetrain, it has to be in the axle or the tires.
mmosley
12-30-2014, 07:33 PM
Gdub - to be complete, found this today when perusing posts on Moparts, might be helpful in visualizing the drivetrain angle thing:
Charts on the bottom of the page for the different suspension types, same basic information as the old Mopar "recipe" books.
http://www.moparts.org/Tech/Archive/axle/8.html
carbuff
12-31-2014, 09:21 AM
He changed from a center section w/ 3.91 gears to one with 4.30 gears. RPM of the pinion and drivetrain went up to get the car moving at the same speed and it vibrated at the same tire speed. Therefore, it is not the driveshaft or drivetrain, it has to be in the axle or the tires.
Ah, I didn't read closely enough... If that's the case, then I agree also. :)
Well hopefully I'm narrowing down a bit, I have my axles back out and going to get them checked. I used a straight edge and they seems. to be straight, one other guy suggested a bent
Housing but my axles slide in and out fine.
mmosley
01-01-2015, 08:55 AM
Well hopefully I'm narrowing down a bit, I have my axles back out and going to get them checked. I used a straight edge and they seems. to be straight, one other guy suggested a bent
Housing but my axles slide in and out fine.
Did you get a good look at the bearings? Your problem is perplexing, hope you get it figured out soon. I really want to know what it is when you do. I hope that we have contributed to your thought process and helped you out.
andrewb70
01-01-2015, 10:02 AM
I want to add something. The vibration that is caused by anything spinning at tire speed is very different than the vibration that is caused by something spinning at driveshaft speed. The former has a much lower frequency and it tends to make the car, for a lack of better word, shake. You tend to feel it more as a general shaking of the whole car. The vibrations that are caused by something that is spinning at driveshaft speed is at a much higher frequency and tends to make the car, again, for a lack of better word, buzz. Driveline vibrations also tend to be felt more in the seat and make the rear view mirror get blurry.
With that said, what's the nature of the vibration that you are experiencing?
Andrew
bryant
01-01-2015, 12:15 PM
over all it sounds like you should have solved your vibration. i know the frustration at this point is huge.
i have a few long shot suggestions.
first while you have been checking and rechecking your pinion angles on the vertical plane, have you checked to see if the rear end is square in the car horizontally?
also is the engine horizontally square in the car?
you could have a bad u joint operating angle on the horizontal plane. is your 4 link adjustable?
the pinion yoke could very well be a problem. ive seen it a few times. in this day and age its hard to even know if an aftermarket one is good, as noted above about the moser yoke. im not even sure on how to check if its true.
are you running the green axle ball bearings or the stock type tapered bearings?
if you have the green bearings, did you remove the shuttle pin in the carrier? if not, it can put a side load on the ball bearing that will cause problems.
if you have the stock tapered bearings, do you have them adjusted correctly?
a bad axle bearing can have a high frequency noise or vibration much like a drive shaft.
these are all long shots but things that you havent noted addressing in this thread yet that i see.
Yes I would think it would have been fixed by now, biggest thing is it hasn't gotten worse or better!!!
Green bearings is what I have and they are tight. I did not remove the pin on the inside of diff but I have my axles shimmed and are not touching it, but I am going to have it removed just for caution.
I have tried to measure as accurately as I can do make sure rear is straight in car and joints are good on a vertical aspect. I think I'm going to schedule it to go to alignment shop just to double check everything.
Ok so I really feel vibration in the back of the seat pretty well. Again it's like a whomp whomp whomp type vibration and sound, and starts kinda slow and then gets quicker and louder faster I go. I think I noticed Around 30-40 I can feel a slight very similar type of vibration, but it's very very faint. Also just to reiterate the vibrations comes on strong at 60 and then if I drive up to like 65-67 and press clutch vibration gets a little worse for a few seconds until mph comes back down.
What do you guys think of this, I was thinking of trying to go backwards to a point and try to make things worse. So my idea is to add some weight to the driveshaft and throw it off balance and see if it gets worse and if it does is it the same vibration and noise?
Also I had axles out and used straight edge and seem to be fine. I tried to measure my rear housing to see if it was bent with some straight edgeds and couldn't get a very good reading. The fee I took seem to be fine, plus I don't have a hard time pulling axles or putting axles in. I can pull axles out by hand and push them all the way in by hand and I'm not a big guy. So to me they install pretty smoothly
bryant
01-02-2015, 08:02 PM
the fact that you can pull and install the axles by hand shows that the housing is straight.
have you checked if the out put shaft is bent on the transmission?
i had a tremic 3550 and a ford c4 that both had bent output shafts on past cars.
mmosley
01-02-2015, 10:17 PM
Ok so I really feel vibration in the back of the seat pretty well. Again it's like a whomp whomp whomp type vibration and sound, and starts kinda slow and then gets quicker and louder faster I go. I think I noticed Around 30-40 I can feel a slight very similar type of vibration, but it's very very faint. Also just to reiterate the vibrations comes on strong at 60 and then if I drive up to like 65-67 and press clutch vibration gets a little worse for a few seconds until mph comes back down.
Borrow some different wheels and tires to make sure this is not the issue. Even something close to stock, just so you car get it out on the road to test. This description sounds almost like a bad tire.
72BBSwinger
01-02-2015, 11:02 PM
The tires could be out of round, flat spotted. That would be a whomp whomp type and get worse as speed increases. I have balanced many tires in my time, mostly trucks 33" and bigger, and a tire can balance fine but still be out of round to a degree you see with your eyes. Did you change to a C6 yoke when you put in the Magnum?
I have tried tires off a buddy's mustang that was on his daily driver and no luck. I changed to c6 style yoke and trans is brand new.
bryant
01-03-2015, 10:51 AM
my tremic 3550 was brand new with the bent out put shaft. just because its new i wouldnt discount it. i would suggest putting a dial indicator on yoke and seeing if you can find any run out on it.
andrewb70
01-03-2015, 03:15 PM
.....
Ok so I really feel vibration in the back of the seat pretty well. Again it's like a whomp whomp whomp type vibration and sound, and starts kinda slow and then gets quicker and louder faster I go. I think I noticed Around 30-40 I can feel a slight very similar type of vibration, but it's very very faint. Also just to reiterate the vibrations comes on strong at 60 and then if I drive up to like 65-67 and press clutch vibration gets a little worse for a few seconds until mph comes back down.
This to me sounds more like a vibration caused by something rotating at tire speed, not driveshaft speed. However, the fact that it gets better when you press the clutch, might mean that it is driveline related. When you press the clutch in, the load it taken off the driveshaft. This tends to unload the slip yoke and the pinion gear, and the pinion gear will drop.
Can you post a picture of the driveshaft installed in the transmission?
Andrew
I'll post a couple pics tomorrow. Also sorry I might of misspoken , when I press in the clutch the vibration and noise increases until mph slows down.
So I took as many pictures as I could to show everyone. I uploaded pics of the angle measurements, first pic is ds, then rear yoke flange, then rear of the trans housing. Let me know what you guys think, the angle finder screen was facing drivers side every time.
Also here are some runout readings I got
Drivers side Axles - .003 , axle pushing and pulling in and out was .008,
Passenger side axle .003 , axle pushing and pulling in and out was .006
The trans yoke was .002
Rear yoke setting gauge on the front of the ears, where the bolts screw in, from one side to the other was .013
Rear yoke from the bottom of where the u joint seats in the cup was .018
No sure how to tell if trans is exactly in line with the rear end
Also those readings came off the dial indicator that I uploaded pic of, just to make sure im reading right each / is .001 correct?
Yoke is about 3/4-1" from where it bottoms in trans, pic is hard to read, also the yoke was closer about 1/2 " and still had same issue i just recently moved the rear end back.
Hey everyone I thought I have done this before and maybe this is my prob but rear end is sitting 1" off center towards the passenger side. I guess this may be my prob?
Here's another pic everything looks dead straight but like I said whole rear end is 1" to the right.
andrewb70
01-04-2015, 07:03 PM
Just because the pinion is offset to one side doesn't mean its wrong. What important is that the rear end is square, so that if looking from the top (or bottom) the pinion and the output shaft of the transmission are parallel.
To me it looks like the driveshaft is way too short. If the front u-joint it too far back it can cause the driveshaft to whip around. This would be felt most when you take the load off it, which is exactly what you described happening. You said that when you put the clutch pedal in you feel the vibration get worse until the car slows down.
Andrew
SSLance
01-04-2015, 07:42 PM
I tend to agree with Andrew, that was my first thought when I looked at that pic. How long or how much of the trans yoke is inside the trans?
Is there any up and down movement at the front u-joint? Where the trans joke is not a tight fit into the tailshaft of the trans.
I can adjust the rear to come closer to the trans and make more of the yoke go into the trans, which is something I already did and did not change a thing. I think next step is to take it to shop for alignment and make sure everything is square.
andrewb70
01-04-2015, 08:20 PM
I can adjust the rear to come closer to the trans and make more of the yoke go into the trans, which is something I already did and did not change a thing. I think next step is to take it to shop for alignment and make sure everything is square.
I don't understand how you can move the rear end that much.
Andrew
mmosley
01-04-2015, 08:31 PM
I don't understand how you can move the rear end that much.
Andrew
4-link. Shorten all four bars.
andrewb70
01-04-2015, 08:33 PM
4-link. Shorten all four bars.
OK, but this is a leaf spring car, right?
Andrew
mmosley
01-04-2015, 09:06 PM
I wasn't 100% sure until I read post #38. Yes 4-link. I think it is an RMS set-up. https://www.reillymotorsports.com/store/home.php?cat=263
Well I cut off the exhaust from mufflers back and vibration is a little better. Comes in around 65 and really gets worse again at 70, all the same issues like before except it did fix my 2000rpm vibration :) so I'm getting somewhere.
SSLance
01-22-2015, 04:57 AM
Curious if you've made any more progress chasing your vibration down.
I stumbled across this video today and it made me think of this thread. Check this out, it's amazing...
https://www.youtube.com/watch?v=gmV4qwLfOMY
Ok so I cured 90% of the vibration!!! So here's what I found out, check with you driveline shops and make sure they are high speed balancing the shaft!! I had the drive shaft balanced again(the 5th time) and it fixed it. The shop that was balancing the shaft the majority of the time had a 500 rpm conputerized balancer, second place I took it to had one that spun at 4000 rpm, and this was the difference. I ruled out the second company a while back because they did balance the shaft for me once before but I think I had bad pinion angle, then when I changed pinion angle the shaft became too long or short and had to be rebuilt, which I took it to the closer shop which had the low rom balancer.
Still have some drone from exhaust to work out and loose bracket on exhaust but everything else seem to do fine at 80. I will say I have a high rom vib but hopefully that changes with my motor swap this winter. Thanks for everyone's help!
Few tips for anyone searching about driveline or driveshaft or speed vibrations
1.Don't change multiple things at once
2. Write down every combination you try(pinion angles, where shaft was built or balanced, etc)
3. Ask your driveshaft shop what rpm they balance at
4. And good luck!
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