Pinion angle--revisited. With Caltracs thrown into the mix.

This is assuming the ride hight is the same as yours. If his rear end is is a at a lower ride height than yours then everything changes. Forget about the pinion angle and focus on the u-joint angle. Doesnt matter if the pinion angle is 3* if the rear end is 12" higher than the trans. (gross exageration) the u-joint is only meant to handle angels up to a limit.

Read here

http://www.pro-touring.com/~andrewb/J3311-1-HVTSS.pdf

and

http://www.pro-touring.com/threads/...e-high-speed-operation?highlight=pinion+angle

 

True. ProTouring cars with large OD tire/wheel combinations will run the driveshaft up hill and dramatically alter working angle requirements. Judging by his tire and wheel combo in his pics I assumed that he wasn't working against those issues. I suspect the engine/trans angle is too steep but my point is only to return to as close to stock design angles and work from there.

 

New numbers....

The shims brought the pinion parallel to the shaft and transmission, so we are good there.

Front of vehicle --->

Pinion 1* / direction
Shaft 1* / direction
Engine/trans still 5* / direction.

I may have to pull 2 * out of the rear but I definitely need to lose 2 or 3 up front. If my transmission can move that far before hitting the tunnel.

I will shim the trans as much as I can and see where the shaft moves. It might just line all up if I can get 2* up on the transmission...

Hoping that if I shim up the trans I get something like...

Front of vehicle --->

Pinion 1* / direction.
Shaft 2* / direction
Engine/trans still 3* / direction

which I might be able to live with or might need to remove the 2* shims for...

Front of vehicle --->

Pinion -2* / direction.
Shaft 0* / direction
Engine/trans still 3* / direction

or thereabouts.

 

Pinion "down 2°" is all well and good for stock leafs w/o any traction devices. Caltrac's do not allow the pinion to rotate, so throw that out...

With both pinion and trans angles "down" you add them for 5°, as they are in opposite planes. Not trying to be picky, just correcting a math mistake.

 

I was able to shim up the trans/engine with three of those thick Cragar washers I had for sale last week (actually 6, three on each bolt.

That left me about 3/8" clearance up above everything, shimmed upwards .460" (let's call that 1/2").

Any further up and I would run out of threads to bolt the trans to the mount, and things would start hitting the tunnel and exhaust would start to hit the frame.

Ended up with

Front of vehicle --->

Pinion 1* / direction
Shaft 1* / direction
Engine/trans still 4* / direction

Also rotated the driveshaft 180 while I was under there.

Cannot test drive today...weather went all wet and rainy on me.

So, if I get on it and it hypothetically gains 2* I will have this when cruising, approximately...

Front of vehicle --->

Pinion 3* / direction
Shaft 1* or 2* / direction
Engine/trans still 4* / direction

Hypothetically, that is a pretty darned straight line, isn't it, with everything a degree or possibly 2 within parallel

Even if I only pick up one degree pinion angle due to the Caltracs, still within 2 degrees all around.

 

I was going to check mine the other week but a friend of mine asked..."do you have and vibration?"...I told him no and he said..."don't look"...
I still may peek...

 

No vibes, then leave it alone.

Mine vibes...BAD!

 

MUCH Better!

WAY better. Highway speeds and there is little noticeable drone, get on it a little harder and you can hear a little, but I can easily live with it.

I can see through my rear view mirror again!

Of course, a vid...

https://www.youtube.com/watch?v=UPbRfloZ0JA&feature=youtu.be

When I tear the rearend down for new bearings, disks, and trutrac installation, I will cut off the perches and rotate them around and weld them back on, instead of using 6 degrees of shims. I don't feel safe driving with a bunch of chunks of metal between my springs and axles.

 

A lot of people don`t like shackles,but,if you put a set on & use the top hole closest to the car this will also help you sort your problem out.That hole is only a little lower than the stock shackles,will give you a little more tire clearance & rotate the pinyon angle up slightly.Then w/ shims it`s easier to get your pinyon angle corrected on the money.This has worked since the 1950s & still works great today,just go to the track & you see it everywhere.