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Tom' 07-06-2013 08:20 AM

1983 Z28 rearend problems?
Hello. New here I have a 83 z28 the axle codes match for a posi vin mubers too.have read several posts none seem to match my ? I turn wheels by hand other doesn't move at all did have new ring and pinion installed yrs ago. Is it just wore out or could the mechanic have ripped me off and taken my posi unit and put a different unit in. I'm second own .er. Previous never had anything changed .
,can anybody help thanks

lmsport 07-06-2013 09:28 AM

I'm thinking your Auburn posi is just worn out. It will act like a regular open diff when the clutch wears and dissipates all the preload.

Tom' 07-06-2013 09:43 AM

Does sound like a concrete grinder thanks a bunch

killeratrod 07-06-2013 10:36 AM

well to find out both of you questions, only way is to open her up and see what you got.

Tom' 07-06-2013 11:29 AM

I did no springs tried to get numbers on carrier can't see any think I was dupped went to auburns web site didn't look the same

big gear head 07-06-2013 12:42 PM

Can you post a pic?

The '83 would have had the Auburn limited slip differential. When they wear out they stop spinning both tires and at this point they are scrap metal. You can not rebuild them.

Here is something to think about. The 7.5 rear end uses a 2 series differential for 2.14 to 3.08 gears and a 3 series differential for 3.23 to 4.56 gears. If you had a 2 series Auburn and you went to gears in the 3.23 to 4.56 range then the guy who put the gears in might have swapped your 2 series Auburn for a 3 series standard differential so that the gears would fit.

Tom' 07-06-2013 02:22 PM

Car came with 3:73 went back with same will post pic I really appreciate the responses guys

lmsport 07-06-2013 02:50 PM

I dont think it came from GM with a 3.73.

Tom' 07-06-2013 02:53 PM

All the numbers match up with 3:73 vin 5jq is the axle code hayn
es manual says 3:73 posi

Tom' 07-06-2013 03:11 PM

I have pic on profile thanks again

lmsport 07-06-2013 03:40 PM

Thats definitely a standard open diff.

I hate to see people get ripped off by mechanics.

Tom' 07-06-2013 05:00 PM

Thanks he's no longer in business. Good for him

big gear head 07-06-2013 05:22 PM

If it's an original 3.73 Auburn rear end then it will have RPO coded GT4 and G80 on the sticker on the bottom of the console lid or on the back of the spare tire cover.

Just looked at the pic and that is a standard differential. If you had an Auburn then it's gone now.

If you decide to put another differential in it I do NOT recommend using another Auburn. They are at the very bottom of my list of good differentials. I would recommend using a Eaton Posi, Eaton Truetrac or a Yukon Dura Grip, depending on what you want to do with the car. I would also recommend upgrading your 26 spline axles to the later 28 spline axles at the same time.

Tom' 07-06-2013 07:34 PM

Are these manuals known to wrong. Will check spare cover

Tom' 07-07-2013 06:24 AM

Motor has about 330hp just put a world class t5 in .not going to race it but want to do it right without going over board ,is this enough info for a suggestion of what I should get 28 spline definitely. Thanks

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