Debased

First so details I'll be running a l33 around 350-400whp. A ctsv t-56 converted to fbody:1st 2.97:1
2nd 2.07:1
3rd 1.43:1
4th 1.00:1
5th 0.84:1
6th 0.56:1
reverse 2.90:1
So which would be better 9 or 10 bolt (at least to start swap really hitting the wallet)? And which gears 3.45/3.42 or 3.73? Just looking for suggestions I'm leaning towards 9 bolt 3.73. Thanks
Matt

DIGGLER

iTrader: (1)

9 bolt vs. 10 bolt isnt much of a difference strength wise, so i wouldnt sweat that. as for gear ratio, im thinking that would depend on the track? autox you will usually be buzzing around in 2nd gear the whole time (from what i can remember at the local ones) and a road course i would imagine maybe 3.42 or 3.73? i doubt you will see much of a difference on times between the 2.

Debased

Well a 3.73 would make 1st run out at around 45-48 a 3.43 would make it into the 51-54. But if going with a 10 bolt I could go 3.91, but also 10 bolt opens up posi options so which has proven better t2r, auburn race, or true trac?

InfernalVortex

iTrader: (4)

Torsen T2R all day long. It's very well suited for twisty stuff.

With a T56 you will want at the very least a 3.73 gear ratio. 4.10s woudl probably be even better, but with a 10-bolt you're risking strength up in that range. I feel like I need 3.90's to autocross well, but 3.90s for a 9-bolt are not cheap. And for either diff 3.90s are a sacrifice in strength.

So if you can deal with operating in the 2000-5000 RPM range, (courses will vary, obviously, we have slightly tighter courses than many of you guys) 3.73's are fine. If you have a big cam and need to go higher, you may want to consider the weight and cost disadvantage of a 9" or 12-bolt or roll the dice on 3.90+ ratios for the 10-bolt.

The Torsen works VERY well for this though. Any torsen type differential is going to be what you want.

Edit: I just looked at your gear ratios.... you'll be fine with 3.73's. My ratios are 2.66 and 1.78. Yours are 2.97 and 2.0 so you're in a lot better shape for making 3.73s work.

Debased

So I guess now I'm leaning toward a 4th gen rear. Already has torsen and more wheel/tire options. I'll be running in SM or the new American sedan class anyway. What do 4th gen rears run?

AlkyIROC

Fourth gen diffs are no stronger or better than a third gen. Your 92 already has 28 spline axles and a 7-5/8" ring gear exactly the same as the fourth gen. The advantage of the fourth gen diff is a better OEM disk brake system. It's also roughly 2" wider per side so different offset rims are required.

You don't need to switch to a fourth gen diff. Just upgrade the posi and gear ratio in the one you already have.

No matter what you do to try and upgrade the strength, the tiny ring and pinion will always be the weak link. Run what you currently have and invest your money in a stronger diff when it finally breaks.

Debased

But I have a 2 series 3.08 open diff it's gotta go

AlkyIROC

Then just keep the upgrades to a minimum until you can afford better. You don't want to be paying twice for a better diff.

InfernalVortex

iTrader: (4)

The thing is you may be able to source a 4th gen rear cheaper than you can grab a torsen for.... They tend to fetch decent moneys and axles can occasionally be had cheap. All 98-02 Z28s and TA's got the Torsen.

I agree in general it's better to stick with a 3rd gen rear... I have 17x11 ZR1's in the back and I'm using 1.25 inch spacers. With a 4th gen rear they would stick out an extra .75 inches and look horrid.

Debased

All good advice I'm not to the point it swap where I have to decide. But I've got some more planning to do.

BrianChevy

Torsen T2R and a 10-bolt is my recommendation. I had a 9bolt Posi in my car and took it out to go with the 10Bolt and Torsen, i have been much happier with the traction in the twisties....

Debased

Yeah I'm looking at options to get a similar setup. Really looks like cheapest way would be to get a 4th gen though

InfernalVortex

iTrader: (4)

Let it be known my 9-bolt behaves really nicely. Even if I lose traction going sideways I can always rely on it to grab and keep the thing motivated to go in the right direction. Thats probably my favorite thing about this car is how easy it is to put it into mild rear drift and it keep hooking forward. I got stupid lucky in that my 9-bolt has really good looking cones and is still well within spec as far as torque ratings. I dont know how long my good fortune will last, but I've already bought myself a 3-series torsen carrier for the 10-bolt that will eventually replace it. I figure even if I get a hot LT1 or LS swap Im not gonna go much past 400-500hp, and since Im not much of a drag race guy, Im gonna hope the 10-bolt can hold up. Maybe silly, maybe not.

But for now, the 9-bolt is holding up well. I wouldnt advocate anyone run out and get one, I only ended up with mine because it was what was available and had the good rear brakes and the 3-series carrier and posi and it was nearby. If I could choose one or the other I'd have a torsen 10-bolt. But I love my 9-bolt for now. I know you had issues with yours, and I think you said you had some gear whine. My 3.70s whine a little bit too and from what I can tell almost all 3.70s in a 9-bolt tend to be noisy for some reason, but mine aren't bad at all. I can only hear it at interstate speeds.

Debased

Well looks like I'm getting a 2000 camaro ss 10bolt with brakes and all. So another rear end question: global west traclink vs umi/bmr torque arm with a relocation bracket?