Posi rebuild?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

chevy2racr · 09-11-2002, 04:00 PM

ok, 71 C-10, has a posi but its pretty worn, whats it take to rebuild it? I know people have asked before and I could prolly go lookin for a posi rebuild kit for a Truck 12 bolt, but I thoughts I'd ask
thanks
bryce

Michael A. K. G · 09-11-2002, 06:09 PM

SOME Posis are simple to rebuild.

If the ring gear is not too large, and it is the clutch type posi, you remove the cross-pin, C-clips, S-spring, and the rest of the guts. Then replace the clutches and put it all back together.

Some Posi rear ends have ring gears that are too tall to allow the side gears to be removed without popping the ring gear off. The Ford 7.5 inch Posis with 3.73 or higher gear ratios are like that. With those, you can't even get the cross pin all the way out without removing the ring gear (it has a step machined in it so you can get it half way out to remove the C-clips).

If you don't have to remove the ring gear, the diff can stay in place. You just have to raise the rear end on jackstands and pop the cover off. The parking brake has to be free so you can rotate the diff for access if needed. If the ring gear IS big, you have to remove the axles, bearing caps, shims and differential, and then somehow get the ring gear off (DO NOT pound directly on it or you will chip it).

I've never rebuilt a 12bolt, so it's possible that it's put together a bit differently.

chevy2racr · 09-11-2002, 10:12 PM

any others?

*Fast68Chevy* · 09-12-2002, 01:11 AM

GM clutch type units are rebuildable, and the cone type are not rebuildable

you have clutch type if its a 67-72 12 bolt truck axle

JimKshortstep4x4 · 09-12-2002, 07:29 AM

There is a 12 bolt rebuild article in the new Carcraft that is worth reading and rebuild kits are available from Tom's Differentials.

www.tomsdifferentials.com

Jim

09-11-2002, 04:00 PM	#1
chevy2racr So Many Ideas, So Little Money Join Date: Sep 2001 Location: Marshalltown, IA Posts: 1,610	Posi rebuild?? ok, 71 C-10, has a posi but its pretty worn, whats it take to rebuild it? I know people have asked before and I could prolly go lookin for a posi rebuild kit for a Truck 12 bolt, but I thoughts I'd ask thanks bryce __________________ 72 Blazer 3/4 ton running gear 4.10s NP205/TH350 350 4in lift half doors 71 C10 with 454 99 S-10 5.1L SBC 700R4 09 Malibu Marshalltown, Iowa

09-11-2002, 10:12 PM	#3
chevy2racr So Many Ideas, So Little Money Join Date: Sep 2001 Location: Marshalltown, IA Posts: 1,610	any others? __________________ 72 Blazer 3/4 ton running gear 4.10s NP205/TH350 350 4in lift half doors 71 C10 with 454 99 S-10 5.1L SBC 700R4 09 Malibu Marshalltown, Iowa

09-11-2002, 06:09 PM	#2
Michael A. K. G Registered User Join Date: Jul 2002 Location: California central coast Posts: 126	SOME Posis are simple to rebuild. If the ring gear is not too large, and it is the clutch type posi, you remove the cross-pin, C-clips, S-spring, and the rest of the guts. Then replace the clutches and put it all back together. Some Posi rear ends have ring gears that are too tall to allow the side gears to be removed without popping the ring gear off. The Ford 7.5 inch Posis with 3.73 or higher gear ratios are like that. With those, you can't even get the cross pin all the way out without removing the ring gear (it has a step machined in it so you can get it half way out to remove the C-clips). If you don't have to remove the ring gear, the diff can stay in place. You just have to raise the rear end on jackstands and pop the cover off. The parking brake has to be free so you can rotate the diff for access if needed. If the ring gear IS big, you have to remove the axles, bearing caps, shims and differential, and then somehow get the ring gear off (DO NOT pound directly on it or you will chip it). I've never rebuilt a 12bolt, so it's possible that it's put together a bit differently.

09-12-2002, 01:11 AM	#4
Fast68Chevy Account Suspended Join Date: May 2000 Location: IL Posts: 0	GM clutch type units are rebuildable, and the cone type are not rebuildable you have clutch type if its a 67-72 12 bolt truck axle

09-12-2002, 07:29 AM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	There is a 12 bolt rebuild article in the new Carcraft that is worth reading and rebuild kits are available from Tom's Differentials. www.tomsdifferentials.com Jim



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