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Discussion Starter #1
I'm sure my '96 Roadie with the factory towing package has the original limited slip diff. Seems it's only spinning it's right wheel now. This wasn't a one time thing, todays Spring weather prompted me to show off with a smokey burnout. Only the right wheel was doing the burning:gaah:
I'm an auto body mech by trade, but my initial guess would be worn clutch.
Any info as to the answer is appreciated. She still drives fine with no undue noises or vibrations.

Steve
 

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If it has an automatic transmission, then it doesn't have a clutch, but a torque converter. I'm not trying to nit-pick, so much as point out a bigger difference. A torque converter is driven with viscous fluid, whereas a clutch is solid material against solid material. This makes them much more prone to wearing out and becoming "worn" and slipping.

how many miles are on the car? Typically on a high mileage b-body, a one wheel peel is an indication that the posi is starting to go. I'm sure someone else won't be far behind to help out with this problem you are having.
 

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I believe he means the clutches in the rear end if I'm not mistaken. I owned a '95 9C1 with a 3.08 limited slip and had the same issues, I tried new fluid with the proper additive and it didn't make much of a difference. I've been told that you can rebuild them.
 

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Discussion Starter #4
"I believe he means the clutches in the rear end if I'm not mistaken" I've been told that you can rebuild them.[/QUOTE]

Correct. Not a biggie for me to pull the entire rear in my shop, however, never rebuilt one and I just hate relying on someone else to do a repair, especially if it isn't a cheap repair. I may just leave it as it is for now since I'm about to start an extensive restoration on a '99 GP GTP (and $ is tight!)

Steve
 

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Depending on the surfaces the posi just may have not been able to cope. If you were on a slick or wet surface on one side and completely dry on the other, it just may have not spun from the difference in friction. Just a thought, i believe that was the reason a member on here "papa D" did a one wheel peel.

Oh, and sorry for the misunderstanding about clutches :eek:k3:
 

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Could work on some surfaces as already said.

It is an old car though and the posi does have clutches that do wear out.
The stock posi is NOT rebuildable. You would need to replace it, few different styles available each with some strengths and weaknesses. Some use clutches and can be rebuilt or exchanged with the manufacturer and some use gears to make the limited slip work and are far less prone to wearing out.

If you change the carrier like that backlash needs to be reset which can be a little bit of trial and error.

I would consider waiting though till you can put a set of 3.42-3.73 gears in with a new carrier. It completely transforms the car. Does require pcm reprogramming to fix the speedo though.
 

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Discussion Starter #7
I actually have a friend who is a car mechanic and he refered me to a local guy that'll set me up with a 3:73 set-up for about $600 if I take the rear out of my car and transport it to him. I'm sure just that change alone would make a noticeable difference in the 'ol girl's get up & go compared to the stock 2:93 gears in it now. Thing is......your still talking about a 4600lb wagon that stock ran a 15.54 @88.6m.p.h. pass at Atco Raceway.What would all the work and expense actually do for my e.t? Maybe 2-3 tenths at best? I'm not overly concerned with less miles per gallon. Not rebuildable ya say? Damn.....
I may just drive it like this until my Grand Prix is on the road. Even with simple bolt-ons the GTP should do about 14.2-14.4s at around 94-96 m.p.h.
Tough call........
Steve
 

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I am not really sure what 3.73s would do for ET, they would make the car feel a LOT lighter when driving though.

Your ET is pretty much exactly the same MPH and ET I got with my old 95 Roady. I bought it with 172K on it raced it at about 180K and then at 227K hit a deer and sent it off to a guy who uses them for demo derby. It was too rotten to save. I actually took it on a road trip to NJ with just over 200K on it. I really liked it but it just rusted too much to be saved. I grewup near Belvidere just south of where rt80 crosses the Delaware. One of these years I will take my car out to race at Island since that is like 15 minutes from my brother.
 

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Discussion Starter #10
I can say with no hessitation my '96 Roadmaaster wagon with the LT1 and factory tow package has a limited slip diff. A couple years ago I did a nice smokey dual wheel burnout that left a nice double set of black stripes up the road to my amusement (yeah,even in my mid 50s I'm still a 20 something year old when it comes to nice burnouts :eek:k3:) I've also witnessed this in the snow.
I really love the wagon which has low-ish miles of 96,500 on it, not bad for a 16 year old daily driver and occassional work horse. There is barely a day that goes by when my foot isn't in it to get around some dumb-ass slow poke or young female on her cell phone. She has never had any rot and is a woodgrain delete car with cloth interior (don't care for leather seats), and most every other option including heated seats.
Steve (just 2 min from Northeast Phladelphia, PA.)
 

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Discussion Starter #11
Just checked the build sticker, it shows a G80. Wonder if draining and flushing the rear fluid, the replacing with the posi additive and gear oil would help at all? Probably never been serviced.
 

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Changing the fluid really won't help if it's already show it's age. The posi's are kind of a crap shoot on how long they last. My 85k Roadmaster Sedan sometimes won't spin them both, yet the unit passes the factory wear test with a torque wrench. I have a tow pack wagon with 180k, and the posi still works sometimes. Then I have a 94 9C1 at 220k that the posi still works. Doubt it was ever replaced. Then I'd had others that were junk as soon as 120k.

$600 for 3.73's in the back is going to be just gears and labor. That doesn't include a new posi, which you would REALLY want to replace at the same time. Might as well go all new bearings, seals, and a new pinion seal/yoke kit. To do it right, is about $1,000. The gears make these cars feel MUCH lighter. I really enjoyed the difference it made in my 96 Caprice 9C1 going from 3.08's to 4.10's.


These wagons can move pretty decent. I have my eyes on 94-96 Wagon that has gone a best of 13.9 on the stock cam, and no adder. This is no stripped down bucket either.
 

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Discussion Starter #14
Thanks a bunch for all the info people! If I spent a cool grand on just re-doing the rear, not only would my upcoming project Grand Prix suffer, but my wife would surely have some very strict words for me. Having a sleeper "grocery getter" that'll run 14s in the 1/4 is tempting, but think I'll see if I like the Pontiac enough to keep it when finished. Doubt I'll be able to afford to keep both so either the GP gets sold or the Roadie.

Steve
 

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Wrong. GU4 is NOT the code for an open Diff. That is the Axle ratio code for a 3.08.
Well crap/ I'm gonna go and do a burn out in the road to see how many stripes I lay down. I was misinformed. Is there a number on the SPID that indicates posi or open?
 

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Well crap/ I'm gonna go and do a burn out in the road to see how many stripes I lay down. I was misinformed. Is there a number on the SPID that indicates posi or open?

G80 is the RPO code for positraction. If it doesn't have G80, then no posi. The other Gxx codes are the axle gear ratio. I don't think you were told wrong, I think you interpreted it incorrectly. Because a GU5 without a G80, would mean it was an open diff. But that is not what GU5 stands for.
 

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G80 is the RPO code for positraction. If it doesn't have G80, then no posi. The other Gxx codes are the axle gear ratio. I don't think you were told wrong, I think you interpreted it incorrectly. Because a GU5 without a G80, would mean it was an open diff. But that is not what GU5 stands for.
Got it. Thanks for the clarification.
 

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Discussion Starter #18
Been doing some under the car work in my shop over the last 2 weeks. Exhaust repairs, new brake line section, new wheel cylinder, new rear diff seal,fluid and additive. I also removed the factory tow hitch which took off approx 65 lbs. Running shorter tires (about 2 in. shorter!), for lower gearing. Ran the 'ol girl down at the local track tonight only to find it's still a one wheel driven "posi" :gaah: Picked up over 1/2 m.p.h. from a previous best of 88.67 to 89.40 m.p.h. E.T. was almost the same 15.544 before,15.573 tonight :lamende:. Had to bring it out easy so as to avoid a wheel peel .I'm sure with a fully functional posi it would have been at least another 1-2 tenths quicker.Bummer.
 

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The stock "posi" uses cone-type clutches. Officially, they are not rebuildable. Many years ago, I ran across a company in PA that resurfaced the cones on an exchange basis. You get "extended life", but nothing like the original life. If you are paying someone to do the work, then it is probably not a great deal in the long run.

You are better off to live with it or buy a new limited-slip differential [correct name] that has rebuildable, plate-type clutches. I remember that at least one of these could be rebuilt with the "housing" unit still installed [no expensive alignment/shimming].

If you had an open differential, there are drop in locker units. Some people love them and some hate them. They also may not be as strong as a true locker setup.
 

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To do a full rebuild of the frictions and steels in the Eaton cost as much as the unit cost new.
If doing it over I would consider a Torsen which uses gears to somehow accomplish a posi effect without clutches to wear out.
The lockers that fit an open diff put all the HP through the crosspin. Some have luck, others break the pin and split the whole axle case wide open and they will not handle as well as a posi.
 
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