Chassis guys, question on pinion angle

[My427stang]

My F100 has always been a hopping SOB, it'll wrap up the stock springs like nothing you've ever seen.  I do not have any sort of bar, and do plan to make something up but question for you before I got that route

The crank centerline angle/output shaft is 5.5 degrees down, all factory mounts, all new and in good shape

The pinion angle, no weight on the truck other than itself is 5.5 degrees up

So initially life looks good although pretty steep, but doesn't that mean any wrap at all is causing it to overcenter and unload as the pinion angle becomes less than parallel to the crank?  I think I need the pinion a bit lower, or the engine a couple degrees higher.  Thoughts?

[Drew Pojedinec]

Single piece driveshaft I assume....

Why not raise up the trans a lil bit and lower the pinion?  Get closer to 3 degrees and see what it feels like.

[machoneman]

Sounds too far to me as 3 degrees max. seems to be a universal (pun intended!) setting to shoot for.

Still, check this link for lots (!) of reading on maximum angles:

https://www.google.com/search?q=maximum+pinion+angle&rlz=1T4GGHP_enUS533US533&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwjYtqDB-vzJAhVIqx4KHfG0BkcQ7AkIPw&biw=1097&bih=494

[jayb]

Calvert Racing recommends 2-4 degrees down on the pinion, relative to the trans.  You could leave the engine/trans as is and put 2 degree wedges at the leaf springs to bring the pinion down to 3.5 degrees; that would be a good start.

[turbohunter]

I'm not much of a chassis guy but if I read your post correctly your centerlines are parallel which is perfect for running.
If I get this whole rear end rotation thing, as you accelerate your pinion angle wants to climb so it wants to increase it's angle.
If you're worried about being perfect then you would lower your rear angle a couple degrees so that when it climbs up a couple degrees it becomes parallel again.

I just read Jays post before I post. I think we're all saying the same thing. I'm just leaving my post so that there is another way of saying it which may (or may not) make sense to some.

[My427stang]

Thanks guys, we are all seeing it the same way.

I'll look to see what's easier and/or smarter to either rotate the pinion down a little or jack up the back of the motor.

[Drew Pojedinec]

Yeah, hate to sound dickish about it, but when I was messing with my car and the pinion angle, I kinda did a trial and error kinda thing till it was right where i wanted it.

There are some baselines to start with sure, but until I started shimming stuff and driving it around hard, I never figured exactly what my setup wanted.  Having parallel angles never worked for me, I ended up 2 degrees down on the pinion otherwise it didn't wanna do right on really hard acceleration.