I have an 88 camaro rearend im building to put in my 85 iroc, I have a auburn positrac from an 88 iroc, i bought a pull off set of 3:42 ring and pinion gears from a 2000 trans-am. I went to put set the preload on the crush sleeve, and the damn thing still has about a 16th - 8th slack. It wont snugg up!!! i took the pinion gear back out and the pinion has splines just a little shorter than the ones that were on the original pinion and there is a thincker spacer between the pinion and the bearing, Will this work in my third gen rearend and how the hell can i get it to work? are the third and 4th gen rears that much different???

 

Nope, they are exactly the same. I don't know much about rebuilding rear-ends, so I can't really give you any advice, but I can assure you that they are identical except for tube and axle lengths.

 

You need more mustard on the nut, is all. You didn't get it tight enough to crush the crush sleeve enough.

The gears are the same.

Assuming of course, that your 85 rear is a 10-bolt, not a 9-bolt.

 

it is a 10 bolt gm not the BW 9, the gears cam from a 2000 TA heres the kicker: the splines on the pinion shaft go about an 8th of an inch further on the old pinion, than on the pinion im tryin to install, that seems like the distance that i need to take the slack out! do i have to use a newer yoke? i just dont want to set this thing up and have it burn up or come flyin apart!! ive got it to the point that it wont tighten anymore, i think its because ive ran out of spline to run on!

 

Shims? I know you sometimes need shims to rebuild rearends, but I don't know what its for..just throwing ideas out.

 

would placing more shims between the pinion gear and the pressed on bearing give me the clearance i need? i need the pinion gear to go further into the housing so that it will take out the slack for preload

 

DO NOT ADD SHIMS ..
you should have reused the shim from the rear that the gears are going in (it is in between the big pinion bearing and the pinion itself )
the bearing must be pressed off to get the shim.. this sets your pinion depth very close .. did you use a new crush sleeve???

 

i have 2 new crush sleeves,just incase one gets damaged! if i use the shim from the gear that came out of the housing, the pinion will be further out of the housing, wouldnt that give me too much space around where the yoke and the pinion mate up? the sleeve that came out of the old gears is only about half the size of the shim on the gears going in!

 

That's because the old one has been crushed (that being its purpose in life) but the new one hasn't because it hasn't been tightened enough yet.

 

I talked to a buddy of mine, he said to get the pinion yoke for a newer car, I got one from a 96 z28, it tightened up!!! when in doubt, ask a GM mechanic!:hail: :hail: :hail:

he told me make sure the shim on the pinion gear was the same as the original one from the old gears,, IT WAS THE SAME! he said the only thing i have left to worry with is setting the backlash for the ring gear, BTW does anyone KNow the proper torque specs for the pinion nut????

 

the way I understand it, you tighten the hell out of the pinion nut, something above-and-beyond 100 ft-lbs of torque, to crush the sleeve, then back it off and set the preload at 15 in-lbs. I know when we tightened down the nut the first time on my buddies '95 Camaro after we installed 4.10's, there was a terrible howling coming from the rear on decel. Turns out we didn't have the nut anywhere tight enough. Took out the 1/2" drive breaker bar, and it took my dad, who weighs about 170 lbs, pretty much pulling himself off the creeper and bouncing his weight on the breaker bar to get it tight enough.