i decided to check my pinion angle today for the hell of it, since i never have before. and it was at +2 at the rear bottom brace of the t.a., which by looking at it from the side was slightly pointing up. the car had a adjustable torque arm when i got it, and i never messed with it. im sure this isn't optimal right?

 

Depends on what your trans angle is. My trans was pointed down -3.6 degrees. I shimmed it to down -2.5 degrees. Then I set the pinion angle up +0.5 degrees so when it launches and moves up 2 degrees the pinion angle and the trans angle will be parallel.

http://www.rosslertrans.com/Pinion%20Angle.htm

http://www.markwilliams.com/driveshafttech.aspx

 

.....although some people will tell you not to worry about the trans angle and just put the pinion -3.
me, i did mine like onfire did his. but since i have solid motor/trans mounts and all rod-ended suspension stuff i run around -1 to -2.

 

the rear should be pointing down not up.... adjust it back to level with the car on the ground with a driver in the car and start there.... if anything angle the nose of the rear -1 to -2 down.


That's how madman does it I do believe

 

Don't want to hurt your feelings, but that's bad advice...Rossler and Mark Williams know a little about PA....read their links.

 

I'm not debating that.... but I'll listen to the guy that makes 4th gen suspension work.

 

You better PM madman about that, the way Tom described is the only way I and every other chassis guy I have ever met does it. The purpose of pinion angle IS to get the driveline angle correct. It is not a suspension tuning tool directly, although changing it can change some things.

If you put the output shaft of the trans level then you can set the pinion to -2 or whatever but most of these cars point the rear of the trans down. What exactly are you referencing the pinion angle to unless you measure the trans, the ground?

I'm a -3.5 trans and +1.5 pinion (I cant see how these suspensions can possibly move more then 2 degrees but some use 3) and have never had a driveline issue. Some people are confusing driveSHAFT angle with driveLINE angle - not really the same thing.

 

yes, the ground. Get the car on level ground and check the angle against it. I know every car is different, but my car at ride height has the trans output shaft level to the ground... hence why I just check the pinion angle to the ground.

 

It has nothing to do with the ground, if your output shaft angle is zero then your pinion angle should be -2. Same result, wrong (but lucky) way of doing it. But by measuting the output shaft angle in relation to the pinion angle the car does not have to be on perfectly ground and is the proper way of doing it.

If your car is raked pretty hard then the trans angle might just be zero degrees on level ground. But if someone's car is level or slightly higher in the front like mine the trans is pointing down. But unless you pull the driveshaft and check you just dont know. different K-members, trans crossmembers, trans mounts all may effect it and two cars may be completely different.

 

I agree with this statment most.. because of the poly tranny bushing it put my driveline up alot more I think then it normally would be, maybe the mount was a little thick I dunno. My car isn't raked that much actually, it's just the tailshaft is up more because of the tranny mount.

Of course now after this conversation I will be going home and putting the car up in the air level with how it sits on the ground and checking with the driveshaft out to make sure it is right.... thanks for another project LOL.

 

Its something that only needs to be done one time, all it takes is a 10.00 magnetic angle finder an hour. Unless its way off you will see very few problems though, but sometimes a bent torque arm or brackets will kill the driveshaft and people just stick a new driveshaft in because the POS stocker broke and it does it it again

 

I have one of those angle finders LOL, came with the bmr tq arm actually. I don't remember how exactly it was set up wen it all went together, bu now Im gonna check. I need to move the tq arm on the crossmember as an experiment next time I go to the track, so I'll just jack the car up level and check the angle while I'm at it, gonna have to reset it when I move the tq arm anyway.

 

When you are checking with the DS out it doesnt have to be level since you are just checking the relationship to each other. The rear suspension should be loaded, I'm sure you know that

 

yup... know that