Author Topic: 10 bolt rear diff- need some help  (Read 1380 times)

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Offline skisix38off

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10 bolt rear diff- need some help
« on: September 27, 2010, 06:30:02 PM »
my 2.56:1 rear diff seems to be getting grumpy.  I was turning right last weekend and both tires were spinning, then only one tire was spinning.  This doesn't seem right? Is it worn out? 
1978 Y88 L78 auto, PW
Greg

Offline 4SPEED

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Re: 10 bolt rear diff- need some help
« Reply #1 on: September 27, 2010, 06:42:32 PM »
could be low on diff fluid. 

but the clutch set up in them is JUNK.  it was a GM blunder design.  and you cant fix them.

replace it with a eaton diff.
77 W72 TransAM  (SOLD)
79 TransAM 4SPEED

Offline skisix38off

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Re: 10 bolt rear diff- need some help
« Reply #2 on: September 28, 2010, 07:58:32 AM »
I can check that.  I replaced the fluid and put in the GM LSD fluid when I re-filled.  There haven't been any leaks on my floor.  Where could the fluid go?

There is a procedure on page 4B-11 of the service manual that describes my situation:

In somecase after extended expressway driving in warm ambients, a slip-stick condition occurs in the clutch plates of Saf-T-Track axles during right turns.  This is recognized as chatter noise.  When a customer comes in for his recommended lube change or at the first chatter complaint, flush the rear axle following the procedure below.  If chatter recurs at a later mileage, add additive only.

Sounds like I should at least start with that procedure.  This has been happening for some time but maybe this procedure will keep me going for a while longer until I can buy the Eaton unit above.

I would still like to know where to buy the clutch plates?  Or how to search for them?

Greg
1978 Y88 L78 auto, PW
Greg

Offline 4SPEED

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Re: 10 bolt rear diff- need some help
« Reply #3 on: September 28, 2010, 04:53:03 PM »
I dont think there made any more.   jegs/summit sold them , but all you can get now are the clutch parts for the GM eaton diff
77 W72 TransAM  (SOLD)
79 TransAM 4SPEED

Offline skisix38off

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Re: 10 bolt rear diff- need some help
« Reply #4 on: September 29, 2010, 07:58:17 AM »
I dont think there made any more.   jegs/summit sold them , but all you can get now are the clutch parts for the GM eaton diff


Thanks Doug.  Do you have a part number or anything for this GM Eaton diff.  I suspect that mine are worn and I want to start determining where I have to go, what I have to do and how much I will need to pay.  I'm not planning on doing this right away but getting it planned for.  Does Eaton go by the GM 10 bolt, 8.5" jargon too?

Greg
1978 Y88 L78 auto, PW
Greg

Offline 4SPEED

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Re: 10 bolt rear diff- need some help
« Reply #5 on: September 29, 2010, 06:49:43 PM »
yes,  any eaton 8.5 ,, 28 spline ( I think I'm right on the splines)  do not get the eaton GOV-LOC , that is as bad as what you have now.

when your ready , theres a set screw that holds the pin. GM used about a quart (lol) of lock-tight on the treads.  you'll need a torch to heat the area on the diff to get it out . it will brake if you dont.  then pull the pin , push the axles in , take the C clips out , and pull the axles out.

http://cgi.ebay.com/ebaymotors/CHEVROLET-8-5-28-SPL-EATON-POSI-CARRIER-LG-HUB-2-73-UP-_W0QQcmdZViewItemQQhashZitem1c10547933QQitemZ120533055795QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I found mine new /used for 280.00 the guy got the worng spline.  Keep looking on ebay. you'll find a good deal on one.
77 W72 TransAM  (SOLD)
79 TransAM 4SPEED

Offline skisix38off

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Re: 10 bolt rear diff- need some help
« Reply #6 on: September 30, 2010, 08:05:13 AM »
yes,  any eaton 8.5 ,, 28 spline ( I think I'm right on the splines)  do not get the eaton GOV-LOC , that is as bad as what you have now.

when your ready , theres a set screw that holds the pin. GM used about a quart (lol) of lock-tight on the treads.  you'll need a torch to heat the area on the diff to get it out . it will brake if you dont.  then pull the pin , push the axles in , take the C clips out , and pull the axles out.

http://cgi.ebay.com/ebaymotors/CHEVROLET-8-5-28-SPL-EATON-POSI-CARRIER-LG-HUB-2-73-UP-_W0QQcmdZViewItemQQhashZitem1c10547933QQitemZ120533055795QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I found mine new /used for 280.00 the guy got the worng spline.  Keep looking on ebay. you'll find a good deal on one.


Thank you for the tip- I would have surely broke the pin trying to get it out.  I notice that the link you included says that it fits 2.73 and up- is there a different part number for the one that fits the 2.56 gears I have now?

Again, thank you!

Greg
1978 Y88 L78 auto, PW
Greg

Offline 4SPEED

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Re: 10 bolt rear diff- need some help
« Reply #7 on: September 30, 2010, 04:41:14 PM »
I would call JEGS and talk to them , and get the part #.  then with that you can look on ebay and at swap meets
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Offline skisix38off

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Re: 10 bolt rear diff- need some help
« Reply #8 on: October 05, 2010, 08:10:11 AM »
Drained, flushed and re-filled last Friday.  Then drove it about 300 miles this weekend and the diff. seems much happier.  I know that the assembly will need to be replaced at some point in the future but I would like to avoid that expense right now.

Thanks for your help!

Greg
1978 Y88 L78 auto, PW
Greg

Offline b_hill_86

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Re: 10 bolt rear diff- need some help
« Reply #9 on: October 05, 2010, 09:53:53 PM »

when your ready , theres a set screw that holds the pin. GM used about a quart (lol) of lock-tight on the treads.  you'll need a torch to heat the area on the diff to get it out . it will brake if you dont.  then pull the pin , push the axles in , take the C clips out , and pull the axles out.


That's a great tip I'm sure I'll use in the near future. Crabby wheel bearing that needs tended to. Previous owner had the rear end out i'm pretty sure but good to know none-the-less.
-Brian-

1977 Trans Am 400 4 speed hardtop