Ryan3834me

Hello.

I came across a '96 Camaro posi unit with ring and pinion. From what I am aware, 4th gen 10 bolts were 7 5/8.

i have a factory open diff 10 bolt rear in my 1988 TA which I believe is of the 7 1/2 inch ring size.

Will I be able to use the 4th gen posi unit with my 1988 TA 7 1/2" ring and pinon gearset, in my stock 1988 10 bolt housing?

Is the bolt circle between the two carriers the same?

Many thanks in advance!

Apeiron

There's no functional difference between the 7 1/2" and 7 5/8" gear sets. They're interchangeable.

Ryan3834me

I apologize if you have already answered my question.. but...

Is it safe to read into your answer that the posi unit/carrier is of the same dimensions between the two gearsets? I'm aware the the housings are the same, but I would like to know for sure that the newer posi will install with my exisiting gearset before I break it open.

Plan:
remove open diff from my ring gear (7 1/2"), reuse my ring and pinion, and install newer posi unit to my exisitng (older 7 1/2") ring and slap it in old case.

Dont sweat it?

No difference in bolt circles or splines?

DJP87Z28

Your spline count on your 88 is 26 and on the 4th gen it is 28. Big problem, everything else is the same. And the 4th gen axle shafts will not work...2" to long.

Ryan3834me

Thank you for your thoughtful responses.

What do you guys think, order a pair of axles, have some 4th gen ones shortened, or tackle narrowing a 4th rear?

I have swapped complete rears in the past, etc. 3rd gen rear discs are a joke (cept for later PBR setups). I am working on a budget. I am very satisfied with the current rear drum setup. It works overall hands down better than any disc rear pre-90 I have used. (updates being no improvement). This goes against all that I had hoped for a 3rd gen rear brake setup. It is just problematic, and doesn't perform. Drums, I can more than live with. I have C5 brakes up front.
The parking brake takes about 20 lbs less effort to run, etc.

This TA was budget 305 TA from factory. I am OK with the rear drums. I was hoping to just drop in posi in light of it's upgrade to a .510 lift 383 engine.

where is a good source for axles? BTW I wont be racing this car.

Tobias05

summit sells a superior axle kit, 213 bucks gets you 28 spline heavy duty axles, seals, studs, and bearings. It's what I'm running. Content I'm not going to break them either, haha.

Moser makes some as well, but i don't feel their manufacturing process is "superior" in this application.

plus it costs more, and you don't get any of the extras...

sofakingdom

iTrader: (1)

Then of course, there's the issue of "series", which has to do with the gear ratios of the 2 rear ends. A different concern than year model.

Your 88 most likely has a 2.73 or 3.08 ratio, which are 2 series; the 4th gen most likely has a 3.23 or 3.42 ratio, which is 3 series. The carriers are different, because a 2 series pinion is larger than a 3 series one, so the flange on the carrier that the ring gear mounts to, is moved over about .400" or so closer to the pinion in a 3 series version of this model of rear, compared to a 2 series. In other words, if you have a 2 series gear, the 3 series carrier will cause the ring gear to interfere with the pinion by about .400".

And one other thing, is that the carrier in that year of 4th gen is an Auburn; POS. Not as bad as an Eaton Gov-Lock, but still, not a very good unit. Not known for longevity or any of that. IMO OK if you could do it for free, but not a good choice if money has to be spent in order to use it.

I also prefer the Superior axles, in a bone-stock application like this. That's what I have in mine. "Custom" axles like Moser, which aren't heat-treated after the spnies are cut, should be used only in a "custom" situation where they're the only option.