Driveline Angles

[DA4AD]

I'm hoping someone can chime in here to tell me if these angles are within tolerance.
I know this topic has probably been beaten to death already but I can't find anything to point me in the right direction, everything I find refers to the driveshaft angled down to the differential.
I tried using the Tremec app and it tells me the driveshaft to pinion angle is wrong, but i thing this app is for driveshafts angled down to the diff, not up to the diff.

My car, 1970 Barracuda, lowered on leaf springs (I kept the pinion angle same as stock), specs as follows;
Engine/trans....Points down towards the differential @ 3.0°
Driveshaft.......Points up to the differential @ .85°
Pinion Angle.....Points up to the transmission @ .75°



Any input is appreciated, Thanks In advance.

[srode]

Tremec has an App that works really well to measure and let you know if your set up is good or not.

[dhutton]

You need to raise the ride height or raise the tailshaft of the transmission imho.

Tremec app is useful.

Hopefully an expert will chime in. Donny?

Don

[CarlC]

You need to raise the ride height or raise the tailshaft of the transmission imho.


Don

Agreed.

[Alwhite00]

My 67 chevelle is the same. Pinion higher than the trans. I ended up going with a CV driveshaft to alleviate vibrations.

[dontlifttoshift]

Based on that information your front working angle is 3.85* and your rear working angle is 1.6* I try to keep working angles under 3* when possible, I have gotten away with 6* but I absolutely do not recommend it. The bigger issue is the difference between both working angles. You definitely want to keep the differential under 1* In a perfect world the working angles would both match.

Shimming the tailshaft up and rolling the pinion down will make both working angles less than they are now. I would start with the tail shaft and get it as high as you can without crashing into the tunnel, hitting the floor with your headers or screwing up your exhaust. After that use the wedge shims on the axle housing to roll the pinion down until you are happy.

The real question, is there a problem you are trying to solve?

[DA4AD]

Donny,
I am still building the car. It has not seen the street yet. I just received my driveshaft and was checking angles.
This is what I get on the Spicer app, looks like I have to rotate the pinion up.

From the website.
Basic rules:

Universal joint operating angles at each end of a driveshaft should always be at least one-half degree
Universal joint operating angles on each end of a driveshaft should always be equal within one degree of each other (one half degree for motor homes and shafts in front of transfer cases or auxiliary devices)
For vibration-free performance, universal joint operating angles should not be larger than three degrees. If they are, make sure they do not exceed the maximum recommended angles.

[dontlifttoshift]

Your first image doesn't match the info you wrote in the first post. You posted that pinion was up .75, opposite slope of the driveshaft, and you have it shown as down on the same slope as the driveshaft.

Your second image makes the assumption that you can move the pinion either 3.25* or 4.75* (depending on which pinion measurement is accurate) and not have any effect on the actual angle of the driveshaft. That is not possible.

[DA4AD]

Donny,
Yes, Your are correct. First image is what I have (like you said). Second image is what I need (shaft angle assumed).
Maybe its not as bad as I thought and shouldn't worry about it...

[dhutton]

Something is not right with the first scenario. Pinion angle direction is wrong. It is up, not down if I followed correctly.

Don

[Bigblue73]

Who's kit are you using? The driveline angle is 2.5 degree's down with the cross member from American Powertrain and or Hurst. When you lowered your car in the rear, how did you do it. Blocks/shims or just -1 or -2 springs. I've got a lowered Challenger that I wrestled with for quite a while until I got it right. Lowering the rear of the car really throws everything out of whack since you are technically moving the rear up into the chassis. Imagine the straight line in stock form is 2.5 down and 2.5 up (transmission and diff are equal and opposite). Now throw in the longer Tremec trans and lowering the rear and that line now becomes flatter and is now a killer on U-Joints. In my opinion a 2* shim is what you need.