Shimming a 10 bolt rear end
 

I have an 87 GMC 4X4. It has a 10 bolt 8.5 inch 28 spline rear end with a 3.42 gear ratio. The pinion shaft failed so I bought a case from the wrecker and bolted my ring gear on to it. I'm having problems shimming it for backlash. In order to get the correct backlash (.008) all of the shims need to go on the ring gear side (drivers) with no shims on the pinion side (passenger). I did not touch the pinion setup. Something is screwed up. Any driveline experts out there? This truck is just for farm work so if I can't fix it myself it gets parked. The used case I bought may have been from a 77 Chevelle, guy at wreckers wasn't sure. Maybe 10 bolt car and truck rear ends are different?

Re: Shimming a 10 bolt rear end
 

you may have a different series carrier? ......its been soo long now I forget! hopefully someone else will chime in

Re: Shimming a 10 bolt rear end
 

Moose is correct, you have the wrong carrier or gears. Generally cases only fit one gear series. EG, 2.00 thru 2.99 are one carrier, 3.00 thru 3.99 are another, 4.00 thru 4.99 are different again. You can see the difference by compairing the gears that came off a carrier. laying on thier back the distance from the gear tooth valley to the table will change in thickness or height. You can also stand the carrier on a bench along side another and see the gear mounting flange is higher or lower than another carrier. jim

Re: Shimming a 10 bolt rear end
 

The break for the 10 bolt is different ...2.56 and down , 2.76 and up but ya that is probably whats going on

Re: Shimming a 10 bolt rear end
 

Secondly - maybe I misunderstood - but you can't swap ring gears and leave the old pinion in. You have to swap ring and pinion as a set.

K

Re: Shimming a 10 bolt rear end
 

Ya wonder if he did ?

Re: Shimming a 10 bolt rear end
 

No, I kept the ring and pinion as a set.
Thanks guys for the response. It looks like I got a Series 2 carrier from the wrecker and I'm trying to install it in my Series 3 differential. So either I take back the Series 2 carrier and get a 3, or buy a spacer off ebay. Man, I didn't know any of this 24 hours ago. Isn't the interwebs wonderful! So much for wrecker staff who assured me all GM 10 bolt 8.5 inch are the same. He also claimed he was selling me a 3.42 gear ratio carrier...nope, not even close.