hey guys, I just realized yesterday that my limited slip diff isn't spinning both tires. I have 3.73 gears in the rear that I just installed like 3 years ago. never really had enough power in the worn out 305 to lay down rubber, but with the new 350 in there I was having fun, went back to take a look at my artwork and came to the sad realization that there was only one tire track.
is there any "quick fix" to solve this? or am I going to have to dismantle the whole rear?

 

If you have the 10 bolt rear end then you have a worn out Auburn differential. There is no fix for it except to replace it with something better. When the Auburn wears out it is scrap metal. Look at a new Eaton Posi, Eaton Truetrac or Yukon Dura Grip.

If you have the 9 bolt rear end then the Borg Warner unit can be reconditiond at least 1 time. This requires some machine work and a new set of cones.

 

Damn. Do you think that additive stuff might help? Or its just done? I have heard about doing a swap to a 4th Gen rear and axle...how hard is that you think? even worth it? also what gears do they have?

 

The oil additive does not make one lock up better. It makes them slip smoother when turning corners. If you have the Auburn in a 10 bolt then it's scrap metal.

The only 4th gen that's worth swapping is the '98 to '02. They had the Torsen differential. The earlier ones still had the Auburn. The 4th gen rear end is about 4 inches wider, but otherwise it's pretty much a bolt in. I think most of them will have the 3.42 gears.

 

I believe its a 10 bolt....even if it is a borg and warner and has a rebuild left in it, I'd be better off getting something new. do you think I could just do a whole rear axle swap? I've been wanting to upgrade to disk brakes in the rear anyhow, would be nice if it was a somewhat easy job.....the original rear gears were a PITA

 

You can do a 4th gen rear end swap, but your tires might stick out when you are done. It's an easy swap, and the 4th gens have the best disc brakes. You will have to make some other changes to the brake system to get everything working correctly, but the rear end is a bolt in.

 

Auburns use cones just like 9-bolts... why cant they be reconditioned?

Im getting ready to pull my 9 bolt posi apart to mill down the cones and remove the ridge in the case so restore posi functionality.

 

The 9 bolt seperates the gear from the cone. When you do the machine work you can use shims between the cone and gear to set the clearance between the gears. The Auburn makes the cone and gear one piece. You could do the machine work to get the cones to work again, but there would be way too much clearance between the gears and they would break.

 

I haven't gotten to look into prices cuz I've been spending nearly every waking moment at work, I was curious if it would be easier and cheaper to just go with a replacement limited slip differential or a 4th Gen one.

 

You need to find out if you have the 10 bolt or 9 bolt. If it's the 9 bolt you can fix the one that you have. If it's the 10 bolt you can buy a Yukon Dura Grip for a little over $400. You will need a set of bearings and shims to install it. You can probably get a 4th gen rear end for less than $400.

 

I have a 10 bolt. But if i got the 4th Gen I'd spend more time and money converting to rear disk brakes right?

 

I'm not an expert on the disc brake conversion, but it would take a little work to convert it. I don't think it's anything huge, just the cables and proportioning valve I think. If you do a search you will probably find the answers. I think there is information in the FAQ about 10 bolts sticky.

 

Ok thanks. Not gonna have money or time to do it for a while, trying to figure out which would be my best decision. I have heard the 10 bolts are a pretty weak rear, is this true? Incase I thought about adding more power in the future

 

My Auburn posi was worn out and even had a crack in one of the cones, so I ended up just getting a Eaton gov-lock out of a 1994ish Blazer from the junkyard for $60 bucks. A shim kit is probably less than $20, so if you're looking for a cheaper option getting a junkyard posi might work. The quality might be hit or miss though, depending on who was driving the donor car.

 

The gov-locs tend to blow up and damage a lot of parts, though. As long as you dont do a lot of burnouts you should be "okay", though. If they "lock" in a situation where you have a lot of traction on it then it can cause problems. They can put holes in the case and damage your gears among other things when they go.

 

Yeah, definitely not a good choice if you like burnouts or have a high-horsepower engine. In my case it's perfectly fine since I do mostly mild road driving, so as long as there's something that will give me more traction in the winter (have to drive my car since it's my only vehicle) it works for me.

 

Yeah I imagine that's why it was in those Blazers in the first place. I cant imagine how much fun an open diff is in the snow... Probably spend a lot of time not getting anywhere.

 

Black Friday / Holidays are a few weeks away...
I picked up my Eaton True track from Summit for $350 a few months back ($50 rebate).... You could upgrade to 28 spline axles too (and match diff)... I think I paid like $200 for Factory 10 28 spline axles... what ratio are you running, may want to change that to at the same time...

Rafael

 

Not for everyone but has worked for me for 5 years now .......

Link = https://www.thirdgen.org/forums/tran...de-photos.html

 

Hey Ron...looked through your link...would "The Rearend Shop", be the one in Riverbank by chance?

 

Hey guys, i wqs chatting with my friend at work (local napa) and i was explaining to him my latest problem (positrak). One of the parts guys who works also as the parts guy in a nearby Toyota dealer came upon a long shot that the diff. Isn't locking...his thought is if I put non-limited slip oil in, that if it's too thick maybe it can't lock up. Figure that's a $15 try I can do and cross my fingers it works lol. I'll let you guys know. I'm sure it won't be the fix but it's cheap enough to try....

 

No, it won't work. It's worn out.

 

I heard that he might have two shops. You would have to talk to them to find out.

The owners name is Dan .

= http://www.rearendshop.com/

I see that the shop in Riverbank also does transmissions so its most likely not affiliated.

 

hey guys, been a long time since i was able to reply on here...had a question for you guys. i know you guys are saying the LSD blew up most likely, however when i was searching on Summitracing, i saw they had listed different LSD's, some were for different gear ratios, including 3.73's. SO, my question is, do you think the LSD isnt locking up because i have 3.73 gears in my rear instead of the stock gears, which the LSD would have been meant for originally.

 

3.08 and less (I think, is series 2) 3.23 and up is series 3.
You need correct LSD carrier for specific gear.
They do make special gears, I think 3.23 that will fit a series 2...

(or something to that extent... I redid mine about a year ago, now that it's done, my brain is emptying things out and filling up with other stuff )

 

luvofjah is correct in that there are two series of carriers, but it will not affect the LSD performance. The carrier is designed to have different gears put on it, so it does not matter that your rear gearing is different from stock. No matter what gears are on it, if a LSD is worn out it will not lock up properly.

 

So if you're going to buy a new one, check or find out how many spline axles your have, 26 or 28... You can get a new set of stronger 28's for $200 or a bit more...

I went with the Eaton True Trac, it has no clutches to wear out...
It also works differently...
While the clutch Eaton LSD, gives more power to the wheel that has lost traction,
The True Trac LSD gives more power to the wheel with traction...

Rafael

 

No, it's not locking up because it's WORN OUT. You need to replace it. Go back and read post number 2 again.

 

I'm not really arguing if it is worn out, I'm sure it probably is, however I am wondering if the gearing has much to do with the positrak locking in. Still thinking of doing a 4th Gen rear swap with the gearing.

 

Gear ratio has nothing to do with how the differential works. If you have the Auburn then it has cones in it that press into tapered holes in the differential case. Everything that causes it to lock up is internal in the case and has nothing to do with the ring & pinion gears. If you have the Governor Lock, which is unlikely, it has clutch plates and a cam plate that locks up the clutches. This is also all internal in the differential case and has nothing to do with the ring & pinion gears.