pinion angle

[WSSix]

I've been reading so much on this subject trying to figure out the "correct" settings that my head is spinning. I'm tired of reading and would like to minimize the amount of adjusting I need to do so I figured I'd just ask which way should I go.

With the car sitting on it's wheels, the rear of the transmission is pointing down 3*, the pinion is pointing down in the front 2.5*, the drive shaft at the rear is pointing down 0.5*, and is at 0* in the front.

Should I rotate the rear end up or down or adjust the transmission up or down? Can't really go up with the transmission honestly. Keep in mind I'm still riding on leaf springs. 200 lb/in if that matters

The symptoms are I have a bad vibration that comes in around 60 mph. Clutch in/out throttle on/off doesn't matter. The old rear end did this as well only I think it was a slightly higher mph since that was a 3.42 gear and not the 3.90 I have now. It's been too long since I had the car up to those speeds for me to remember exactly though.

In good news, this is the 4th rear I've set up and so far it's dead quiet. Thank you US Gear. The Tru Trac makes for a squirrely good time with my 180k mile stock LT1 Good bye Sumitomos. Your days are numbered.

Thanks

[Vince@Meanstreets]

Originally Posted by WSSix

I've been reading so much on this subject trying to figure out the "correct" settings that my head is spinning. I'm tired of reading and would like to minimize the amount of adjusting I need to do so I figured I'd just ask which way should I go.

With the car sitting on it's wheels, the rear of the transmission is pointing down 3*, the pinion is pointing down in the front 2.5*, the drive shaft at the rear is pointing down 0.5*, and is at 0* in the front.

Should I rotate the rear end up or down or adjust the transmission up or down? Can't really go up with the transmission honestly. Keep in mind I'm still riding on leaf springs. 200 lb/in if that matters

The symptoms are I have a bad vibration that comes in around 60 mph. Clutch in/out throttle on/off doesn't matter. The old rear end did this as well only I think it was a slightly higher mph since that was a 3.42 gear and not the 3.90 I have now. It's been too long since I had the car up to those speeds for me to remember exactly though.

In good news, this is the 4th rear I've set up and so far it's dead quiet. Thank you US Gear. The Tru Trac makes for a squirrely good time with my 180k mile stock LT1 Good bye Sumitomos. Your days are numbered.

Thanks

@ 60 i'd be looking at your tire balance. Them Sumi's suck big time. I had them on my Chevelle and it sound like a Toyota with 35's going down the road.

[Vince@Meanstreets]

[WSSix]

Thanks Vince. It's a bad, high frequency vibration and it started immediately after I finished the suspension work. I figured the ride height changes finally caused the pinion to move enough that it's misaligned.

Yeah, I put the Sumitomos on because I couldn't afford anything better at the time. They will be replaced soon enough.

[Chad-1stGen]

Inland Empire Driveline know a lot about this subject. They have released a few different guides on setup. Here is one. It covers a few different things but page 3 has the info on proper angles to minimize vibration.

http://www.iedls.com/asp/admin/getFi...&TID=28&FN=PDF

[GregWeld]

From your explanation --- your pinion angle is exactly OPPOSITE of where it should be --- if the trans is DOWN 3* --- then your pinion should be UP about 1 or 2*

IIRC you said your pinion angle was DOWN.... and that would be where you're having issues.

You need some working angle on the driveline --- So I'd start by putting the pinion angle UP 1*.... and see if that changes your problem.

Don't over tighten the U-joint U-bolts (straps). Just tighten until the split washer closes and go about another 1/4 turn.