Hey guys, first off I love the site. I'm about a two year member over on Ls1tech.com and I have a big passion for our cars and fbody's everywhere. My buddy and I are big into the local car scene. Ok so here is my question and it's for his car. First off here are his specs:

1986 Z28 A4
383 Stroker (Sorry not quite sure on the internals)
700R4 Upgraded to handle the extra power.
Stock Stall < I do not know why I told him he is leaving a lot on the table but the cam is tame enough to run it.
3.23 Gears
Limited Slip

Alright. I posted up over on Ls1tech and was told that I could use the 4th gen posi's in the 3rd gen rears with simply making sure I used the 89-92 28 Spline axles. Is this true? I want to make sure I have everything I'm going to need. Before people start chiming in with just swap the whole rear end in, he isn't really looking to do that. We are just gonna split the cost of a rear and I'm gonna keep the ring and pinion for when I grenade mine again at the track and he is going to use the posi and we will sell the housing and axles. Basically I know that I will be looking for the Zexel-Torsen posi like the one that I have on my car. Will the posi directly swap in with the 89-92 Axles and that's it? As of now on the parts list is just 4th gen posi, newer 3rd gen axles, gear oil, rtv gasket maker, limited slip additive (Gm still recommends it even on the posi units). So help me out guys. Is the swap as easy as it seems or do certain things just not work. We don't want to waste time if I can get help from ya'll. Oh and I apologize but I searched for about 20 minutes and could only come up with the full 4th gen rear swaps so sorry. I'm not a newb to forums I just couldn't seem to have any luck with the search...lol.

Ok guys,

Thanks in advance!

Josh

 

Yes it is true.

However, "true" and "practical", are 2 entirely different things.

Finding someone who will let you bust up an otherwise complete and saleable HIGHLY SOUGHT AFTER rear end, and just sell you the axles, is going to be near impossible. What you will find, is that you will have to buy the WHOLE rear end, and pay WHOLE rear end price for it; and then they will be kind enough to dispose of whatever parts you DON'T use, after you pull out the axles. Probably cost you $200-250 to get axles that way. And then, all you'll have, is a pair of used stock axles.

Better way to go is this.

http://store.summitracing.com/partde...SAG%2DEV10%2D4

FAR FAR better axles than stock, for about the same price as a pair of USED crappy stockers will cost you.

You don't need the additive for a Zexel, regardless of GM's left-over innk from days gone by. That stuff is friction modifier for clutches, which a Zexel doesn't have. Don't use it. Use regular gear lube, preferably synthetic (REAL synthetic such as Mobil 1 or Red Line or Royal Purple, not "me-too" synthetics like Castrol), 75W-90 or 80W-90.

You'll need a pair of new carrier bearings. Re-use the shims that come with the housing, NOT THE ONES WITH THE CARRIER; the housing is the thing that's imprecise, and the shims don't shim the carrier to fit the housing, they shim the housing to fit carriers and gears. If you break the shims (unavoidable sometimes with factory ones) you'll have to buy those too. Probably cheapest and best to just buy a "gear install kit", which will have all the bearings, ring gear bolts, gear marking compound, shims, and so on, all in a package, and just have it on hand.

http://store.summitracing.com/partde...rt=RAT%2D308TK

 

Your saying that the 89-92 rear is hard to find right? I can get a hold of plenty of 4th gen rears with no problem and there still easy to part out and sell. I can understand if your saying that 89-92 axles will be hard to get and honestly your right. They would most likely have pitting and wear on the bearing races. I appreciate your help with the shims and bearings. Any other input guys go ahead and post up. Especially personal experiences!

Thanks again,

Josh

 

Right; it's the 90-92 axles that are hard to come up with.

Don't delude yourself into thinking that it's 89-92.... probably less than 15% of all 89s got the late-model spline. Odds are very poor that if you come across a 89, it will have the right axles.

And yes, the pitting and wear on the bearings, is one of the malfunctions you can get with used axles; being bent is another; leaking seal surfaces is another; worn C-clip grooves is another. Unles you can get a KNOWN GOOD set for absolutely DIRT cheeeep, best to go with new ones.

 

I was just wondering, is there any online stores that still sell the Torsen new? I have seen them on ebay, but I cant use paypal. Also, I think SLP used to carry them, but I cant find it on their site.

These seem good because they "dont wear out" like a clutch posi, but all the ones I see on ebay are usually 80-200k mikes. It seems like it is getting harder to find real low milage torsens.

 

SLP never "carried" them. All they did, was sell the stock ones that they took out of cars that they were turning into SS's and such, when they put the heavy-duty one in. In other words, when they ran out, which was about 3 or 4 years ago, they RAN OUT, forever.

 

Check the dealer for the Torsen. I checked the dealer last year for the bolts that hold the torsen together since 2 of mine broke and they had the torsen for somthing like $140.

 

Actually, I will have to scour my harddrive. I could swear that I had the factory p/n#'s for the 2 and 3 series in a .txt somewhere.

I wonder if GMPD would have them?

 

Well, it looks like I lost the part number. This sucks. Zepher, did they really have a brand new torsen carrier for $140? I could have sworn I had seen it on GM parts direct for either $500 or $700 i forget. But I guess it is better than having a 170k mile one that is just gonna break.

 

One thing I just realized and should ask, are the 3rd Gen carriers the same as the 4th gen carrier (as far as series goes). His car came with a 2 Series 2.73 Carrier so that does mean that I will need to look for the 2 Series 4th Gen posi to work with his ring and pinion correct? If so that makes things even harder since there are so many more 3 series carriers out there.

 

Ya, I went to the dealer to see if they could get me the 2 bolts but all they could source was the complete differential and it was like $140 or so. I don't know if there is an open version (non-LSD) of the Torsen, if there is, that may have been the price for that unit.

 

Well, here is a screenshot I just got off GMPD. No P/N#'s though, I hate their catalog for that now.

And to the origional poster, yes, you will need a 2-series carier, or upgrade to 3-series gears.

 

I have to agree with Sofa on the axle issue. I recently went looking for a "cheap" set of used, 90-92 axles for the same reason. I'm putting a 28 spline posi in an 85 rear. I finally got a set of used ones off flea-bay for a little over $100, but for roughly another $100, I could've bought brand new ones. Take his recommendation on getting the Superior brand as well. Moser seems to have inconsistencies with their replacement axles (i.e. they're not machined identical to stock ones a lot of times). Superiors are machined exactly the same as stock, as well as being stronger and being made of a better alloy than the originals. Hey Slow_90, I remember a post on here about a year ago talking about the part#'s on the factory Torsens. According to the info in that post, the first 4 digits of the factory part# for a 2 series Torsen will be 9032, and 9022 is the first 4 digits for the 3 series. I found this to be true since I have a 3 series Torsen on the workbench in the garage, and it starts with 9022. I think the rest of the part# just has to do with the sequence code, or date it was built. Here's a link to the post: https://www.thirdgen.org/forums/tran...ghlight=torsen

 

What exactly are the carrier series changes for the 10-bolt? I just know my D-44 splits after 3.73 & my 9" is the same from 2.50 all the way to 6.something...

 

2 series-3.08 and down, 3 series-3.23 and up.

 

Hello all! Just found this site about a month ago! Sooo many answers but only more questions!!!! Will a 4th gen rear end bolt right in or is there a reason for the new axles besides them being "worn out"! I've got a '90 RS with a "one tire fire" rear in it! gonna need a stronger rear and "posi" to support the 385 roller I'm installing!! I've also heard that an '88 or so rear from an S-10 4x4 has the exact rear end as an IROC! Torque arm bracket and all!!! Has anyone verified this! Any info at all would be helpful!!!

 

I'm about 99% sure the S-10 rears don't have the torque arm provision on them. The torque arm mount is an f-body only thing. The one thing the S-10 rears do have in common with ours is they use the same 7.5"/7.625" carrier, so those and the gears are interchangeable, unless you have a 9 bolt rear of course. The only thing you have to pay attention to when using S-10 rearend stuff is the axle spline count. On the f-bodies, 82-89 used 26 spline axles, 90-02 all use 28 spline. I'm not sure if the S-10's were ever upgraded to 28 spline or not. Most, if not all of them are 26 spline. Yeah, any 93-02 f-body rear will bolt right into your 90. The only difference is they're about 2 inches wider overall, so your 3rd gen rims will stick out a tad. If you use 4th gen rims, they'll tuck in the way they're supposed to, due to deeper backspacing. The only thing that has to modified when using the 4th gen rears is where your e-brake cables hook up. From what everyone says, it's a real easy mod to do. Since your 90 rear most likely has 28 spline axles, another option would be getting a 98-02, Zexel-Torsen type posi carrier and putting it in your housing. The Torsens are nice because they don't use clutches for the posi action, it's all gears, so they never wear out. The bad thing about the 97-older, factory Auburn units is that once they wear out, there's no parts available to rebuild them, so once they're worn out, you have to replace the whole carrier with either a new one, or if you can find one, another used one that still works. I like my factory 3rd gen rims, and I like them to have the correct offset, so I just picked up a Torsen off ebay to put in my 91 housing. Only cost about $100 shipped for it, and you can't beat that price for a good posi unit!

 

Dude this site rocks!!! Thanks for all the info Pat!! I'm gonna go to a U-pull-it yard to check out the S-10 rear stuff just because a guy I know told me it even had the torque arm bracket! We will see how "sure" he was!