Someone here has to know this!!!!

I recently made a crossmember for the LS1 T56 I just installed into my '82.More info can be seen here:

https://www.thirdgen.org/forums/fabr...6-gen-1-a.html

My stock trans output shaft angle was -6 degrees with the T10.With the T56 in place at the highest I could get it into the trans tunnel without major cutting of the floor I could only achieve -8 degrees.I then attempted to set the rearend angle with the adjustable torque arm to +8 degrees,making the rearend yoke to trans output shaft angles parallel.I then planned to set the needed -2 degrees PA from there.I could only achieve a rearend yoke angle of 0 degrees.My question is,do these angles NEED to be absolutely parallel?Or can I just set the pinion angle once the driveshaft is in and this won't become an issue with vibrations,etc?

I can probably shim the trans up 1/8"-1/4" and then have the bottom tube/adjusting end of the torque arm milled 1/4" or so to allow more adjustment.I just want to make sure I am not overthinking this OR am I right on track?Shim,mill,set angles and continue on.

 

Have you measured what the angle was with the just the xmember and the trans bolted in place? I would only go no more than two degrees for the driveshaft angle. I can't remember if the rear should be negative or postive but I would recommend taking the measurement with what you have right now.

 

Just the trans and crossmember bolted in nets me -8 degrees.

 

you do not want to make them parrallel - runing more than 3* of pinion angle in the back has only caused driveline vibration for me...

if the car is mostly street duty, set it to about 2* down from the ds, for drag racing 3-3.5

 

I must be wording this wrong,or just really confused.Let me try this again.

Right now at ride height the trans output shaft sits at -8 degrees (downward angle).I have always thought that at that point the rearend yoke angle should then be parallel to that at +8 degrees (or angled up) so that they (trans output shaft angle compared to rearend yoke angle) would run parallel to one another if imaginary lines were drawn through them.Once they are parallel (-8 to +8),one would then set whatever the desired pinion angle may be on the rearend yoke(-2 degrees or so in my case).I am not trying to set my pinion angle to +8 degrees for final use.My plan was to set it to +8 degrees to put it parallel to the trans output shaft angle (-8) and then set the -2 degrees PA from that.Am I correct in this or way off?

 

ahh ok - i see what your doing... the pinion angle is really going to be, and always be independant of the output shaft to ds angle...

to get your -3 on the pinion, you need to measure the ds, and then measure the pinion - subtract the two. the actual angle of what the pinion will be is different for all the cars - all you want to accomplish is setting the ds to pinion angle to be 2-3*. Remember - you have to subtract the ds angle from the pinion angle to get the number...

 

as long as the trans/ ds angle isn't obscene(basically impossible unless you're sitting seriously 4x4 style), set your neg pinion to around 2-3 degress(as desricbed above) and go on. Your trans and rear angle are rarely the same. If they were, your pinion anlge would probably be off.

- Also, I run -6 degrees down pinion anlge, no vibration issues. It's excessive for a street car but mine hooks best there, I can replace u-joints from time to time.