Shimming a 10 bolt rear end - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ppscugog · 05-16-2011, 07:49 PM

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?

mooseknuckles · 05-16-2011, 09:36 PM

Quote:

Originally Posted by ppscugog

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?

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

James McClure · 05-17-2011, 08:07 AM

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

ont_guy_38 · 05-17-2011, 09:35 AM

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

Keith Seymore · 05-17-2011, 11:03 AM

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

ont_guy_38 · 05-17-2011, 12:02 PM

Ya wonder if he did ?

ppscugog · 05-17-2011, 06:17 PM

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.

05-16-2011, 07:49 PM	#1
ppscugog Registered User Join Date: Nov 2007 Location: oshawa ontario Posts: 5	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?

05-17-2011, 08:07 AM	#3
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	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 __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

05-17-2011, 09:35 AM	#4
ont_guy_38 Registered User Join Date: Jul 2007 Location: Ontario Canada Posts: 1,006	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

05-17-2011, 11:03 AM	#5
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,230	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 __________________ Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/

05-17-2011, 12:02 PM	#6
ont_guy_38 Registered User Join Date: Jul 2007 Location: Ontario Canada Posts: 1,006	Re: Shimming a 10 bolt rear end Ya wonder if he did ?

05-17-2011, 06:17 PM	#7
ppscugog Registered User Join Date: Nov 2007 Location: oshawa ontario Posts: 5	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.



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