Pinion angle question

[73chalngr]

Would worn out leaf springs change the pinion angle ? 

[JS29]

It did on mine! Vary bad vibration was in the pinion angle, caused by worn out leaf springs. 

[dodj]

Any rear ride height changes affect pinion angle.
But...people used to put 6" long shackles on the back of cars and didn't hear people complaining about driveline vibes? Too young to care maybe? lol

@JS29 What was the height difference between your worn out and new springs?

[JS29]

 @dodj   Not that much, the chimps that assembled my car before I bought it used coil-over shocks to repair the sag. 

[Scooter]

It's not just the ride height that is effected by worn leafs. Worn leafs also allow more movement of the diff under load which exacerbates the pinion angle under acceleration and deceleration. 

Have this issue in mt 67 Fairlane. I'd get a vibration at about 3k rpm and also when letting off the gas from 3k rpm, so I installed new leafs. I did not get the rear ride height I wanted, it still squatted to the rear. I like a bit of rake so I used shackles to raise the rear (old school look for sure) and get it where I wanted. Re arcing the leafs to get the exact rake you want can be time consuming and expensive. I was quoted over $1k locally. I ended up with maybe 1 degree downward pinion angle.. if any. The new leafs improved the vibration as the new springs did not allow the diff to move as much as the worn out leafs. Looking at the pinion and shaft while parked it looks straight across. I'm collecting parts to add a 4 degree wedge, that should get me 6~7 total.

Slapper bars and caltracks can also help with pinion angle issues.

After I'm done with the rear in the Ford I'm likely going to wedge the Challenger. It has Mopar Performance big block springs installed by the previous owner, still squats in the rear. Has very little negative pinion angle as well but that big spring pack does a good job resisting the torque from the small block.

GL! 

[73chalngr]

I am getting a vibration under load ,3000 plus rpm . Working on putting a b-bony  rear under my car and I guess I should just get new springs ( mine are probably 50 years old ) .

[Brads70]

I am getting a vibration under load ,3000 plus rpm . Working on putting a b-bony  rear under my car and I guess I should just get new springs ( mine are probably 50 years old ) .

This place is only 2 hours from you. Great supplier, I've bought from them before.
https://www.springsnthings.com/leaf-spring.htm

[73chalngr]

Thanks for the link .

[Filthy Filbert]

But...people used to put 6" long shackles on the back of cars and didn't hear people complaining about driveline vibes? Too young to care maybe? lol

Or tolerances were garbage back then, and everyone's car vibrated from out of balance tires, out of balance engines, etc; just nobody noticed because it was normal.   Now that we have engines that idle so smooth and quiet you forget that it's even running, and better tire technology, we've been spoiled by new cars, that we notice when our old cars have vibrations

[Chryco Psycho]

Yes pinion angle changes can cause vibes , I have also seen BFGarbage tires 3/8" out of round brand new .

[Racer57]

I had a vibration after having an Tremec installed. Used every shim from 1 degree to 5 degree without any major change. I even installed air shocks in an effort to figure out what was going on.  After 2 years of fighting it and just living with it, I found out that the rear output bushing was shot. Now its smooth.

[dodj]

I have also seen BFGarbage tires 3/8" out of round brand new .

I'm beginning to get the feeling you are not crazy about BF Goodrich tires......

[73chalngr]

The output bushing on the transmission? Racer57

[Racer57]

The output bushing on the transmission? Racer57

Yes. I got aggressive shifting one day and screwed up causing the tranny to be locked in 4th. Had it rebuilt and the vibration I had was gone. Asked shop about it and they said the bushing showed wear. Tranny is an older 3550.