Correct Pinion Angle

[VAD Gold Rush]

Hey guys, I'm getting the rear end set up in my 74 Scamp, big block drag race project. I'm trying to decide what to set the pinion angle to before welding the perches on the axle tubes. I've always heard for a leaf spring car, you run between 7-10 degrees pinion down compared to the tail of the transmission. What do you guys run?

 

[GTX JOHN]

We run 3 to 4 Down with SS springs.
We run 1 to 1 1/2 Down with Calvert Bars/Springs.


I know that is probably not what your books suggest!

 

[RustyRatRod]

Hey guys, I'm getting the rear end set up in my 74 Scamp, big block drag race project. I'm trying to decide what to set the pinion angle to before welding the perches on the axle tubes. I've always heard for a leaf spring car, you run between 7-10 degrees pinion down compared to the tail of the transmission. What do you guys run?

7-10 degrees is overly exaggerated. Chrysler recommends 5-7 degrees in the MP suspension manual for a race car.

 

[gregsdart]

7-10 degrees is overly exaggerated. Chrysler recommends 5-7 degrees in the MP suspension manual for a race car.

Yep. If you go beyond seven down, any compression of the springs will add to that seven down setting, and at some point the vibration will
Increase to a level not acceptable.
I had a dana 60 housing break loose from the axle tubes years ago and was surprised how high the pinion angle got before it tore the splines out of the trans second gear carrier. ( It was up about 20 or 30 degrees)So that tells me there is a little wiggle room in upward pinion angle under load, maybe three or five degrees before serious vibration starts? So i like a setting of five degrees down, no more. That way you should be plus 2 or minus 2 degrees under load

 

[33IMP]

If memory serves....
There was a bit of nose down angle built into the pad location, wanna say about three degrees, but I don't remember correctly forl sure. Dr Diff will definitely know.
I'm running super stock springs in my Mopar, using an additional two degree wedge down, so a total of five down on my car.

 

[RustyRatRod]

If memory serves....
There was a bit of nose down angle built into the pad location, wanna say about three degrees, but I don't remember correctly forl sure. Dr Diff will definitely know.
I'm running super stock springs in my Mopar, using an additional two degree wedge down, so a total of five down on my car.

All of the factory rear axles I've ever bothered to check had the spring perches welded in the 5 degree nose down area.

 

[mopowers]

All of the factory rear axles I've ever bothered to check had the spring perches welded in the 5 degree nose down area.

Nose down or nose up? I believe factory A body housings positioned the pinion at 5 degrees nose up with the perches level.

 

[RustyRatRod]

Nose down or nose up? I believe factory A body housings positioned the pinion at 5 degrees nose up with the perches level.

I THOUGHT I had always found nose down.....but it's been a long time since I measured one. I've been out of it for a while now. But I wouldda sworn nose down. But that means nothing. LOL

 

[mopowers]

I THOUGHT I had always found nose down.....but it's been a long time since I measured one. I've been out of it for a while now. But I wouldda sworn nose down. But that means nothing. LOL

It's definitely nose up. My problem is, since I usually weld them upside down... well, you know where I'm going with that.

What is 8 3/4 rearend factory pinion angle ?

 

[VAD Gold Rush]

Thank you all for the input. I ended up shooting for about 4* nose down. I got real close. Once I get the car completely put together, I'll recheck and use wedge shims to adjust from there.