Leaf Spring Pinion Angle Help!!

[RNation0001]

So i swapped my 78 camaro to a 6.0/4l80e and now my drive line angles are off quite a bit with the trans 3.5 down the driveshaft .5 up and the rear 2.3 up, my question is about the pinion angle shims for leaf springs, ive seen some with two on each side of the axle and some with 1 on each side of the axle. i ordered some off of amazon and it only came with two total and im confused on what to do here, does anyone have some pictures or advice on installing these. i got 6 degree shims

[67rally]

Do you have any driveline vibrations now? I think 6 degree shims are going to be way too much. That's going to put your rear at 8.3 degrees up, and you'll almost certainly have vibrations then.

If you had measured with your driveshaft at 0 degrees, that would put your trans down at 4 degrees, and your pinion up at 2.8 degrees. If you can shim your trans up by 1 degree, you should be in good shape. You probably only need 1/2" or so on the trans.

[RNation0001]

lol now im real confused, i thought the trans and pinion should be parallel? right now they slope towards each other with the driveshaft in the valley kind of like this \__/ so in order to get them on equal but opposite angles i need to bring the pinion up 6 degrees. i have a cycling vibration above 45 ish mph mainly when i decelerate, just got the driveshaft balanced from having it shortened and it took most of the vibration away. but this one seems to be driveline angle related. any help is appreciated

[ctcz28]

Your angles definately appear to be off from your description. I think the 6 degree shims will be way too much. Please read the article by Hurst Drivelines for which I provided the link below. I've also provided a link to the Tremec site where you can download to your smart phone the driveline angle finder from Tremec tool box. I've used the Tremec app to measure my angles and it works very well as confirmed with my digital protractor. These 2 sources should be very helpful. You will need to measure your existing angles first to see what shims you need to install. Some of us who have needed to shim our differentials also put an opposing equal angle shim under the shock plate, but rotated 180 degrees to the shim providing the angle correction to provide a uniform surface on which to install the U-bolt nuts. Hope this helps.

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

http://www.tremec.com/menu.php?m=154

[BonzoHansen]

Tremec makes an app that might help you

[RNation0001]

thanks for the info, ill get to work on it lol

[67rally]

lol now im real confused, i thought the trans and pinion should be parallel? right now they slope towards each other with the driveshaft in the valley kind of like this \__/ so in order to get them on equal but opposite angles i need to bring the pinion up 6 degrees. i have a cycling vibration above 45 ish mph mainly when i decelerate, just got the driveshaft balanced from having it shortened and it took most of the vibration away. but this one seems to be driveline angle related. any help is appreciated

Ok, I misunderstood you. When referring to the rear, you typically describe pinion angle in relation to which way the nose of the pinion is pointing. So if nose of the pinion is lower than the axle, it is pointing down (towards the ground), and if it's above the axle, it's pointing up (towards the floor).

Vibration under deceleration means you need to shim the pinion up. This means putting shims between the leaf spring and the axles leaf spring perches, with the thicker part of the wedge toward the front of the car, and the thinner part towards the rear.

So, we might also be confused on what you mean by the driveshaft is pointing .5 degrees up. I'm assuming it slopes upward from the tail of the transmission to the nose of the pinion? If so, then at 0 degrees of driveshaft angle, you would be at 4 degrees down on the trans, and 1.8 down at the pinion. In which case you would need a 6 degree shim to be roughly parallel. Depending on how stiff the leafs are, you may want to adjust the angle so they are parallel under load, not in a static state. That can be anywhere from a degree to several degrees depending on who you ask. Last but not least, you're going to have pretty large working angles if you end up at 4 degrees down on the trans, and 4 degrees up on the pinion. If there's anyway to shim the back of the trans up a couple degrees, and then reduce the shims on the leafs, your u-joints will be much happier (i.e. 2 degrees down and 2 degrees up).

x2 on the Tremec app, it works well on a smart phone.

[RNation0001]

driveshaft slopes down from the high point being the rear end. ive already shimmed the trans about as far as i can.