Road Racing - rear end for autoX/RR

I have a 98 T/A M6 with a H/C/I Ls6 that should be putting out around mid to high 400rwhp. My rear end is pretty much shot, and I'm looking to replace it. What is a good rear end for autocross/RR application? I've heard 12bolts or 9inch rear ends are too heavy and can upset the handling for AX/RR?? I've also heard the stock 10bolt is way too weak for the HP my car is putting out and is also not worth putting money into to reinforce. Are these statements true?? I'm open to suggestions!

Thanks guys!

i cannot find any thing that says the % of weight over the front wheels. i heard That 1998 ta was at 57% on the front tires (it's a rumor i could be wrong). if i am right then throwing a 12 bold or a 9" would be ok. the idea goes adding weight is a bad thing no mater what, adding weight but increasing reliability is better then a hot stick in the eye, adding weight in the rear of the car is the only acceptable place to add weight if you need to do so. ideal situation you would want to replace your 10 bolt with a irs like off a gto. if your going to stick with a solid axle handling is all in the differential. 10 bolt 12 bolt 9" it doesn't matter. a spool will make your car handle like shit and give you dangerous over steer. a locker will do the same. ideally you will want a viscus or a lighter clutch type lsd to allow the tires to spin at different speeds in the bends. i would recommend weighing your car. check your cross weight if your in the 50-51% range stick with a 10 bolt. if your in the 52-57%+ go with a larger rear end.

Stock rear is all you need, the rear is unsprung weight.

9", a truetrac, or a T2R..

I have a Moser 12 bolt with a Truetrac. I don't like it due to the bizarre torque arm mounting and high spring perch.

Have you looked into getting a Midwest Chassis Fab 9" with aluminum center?

You can get a 9" pretty light if you have the funds.

Right now, I'm just researching to find what most guys are running. Obviously, I do have a budget, but I don't want to skimp on that major of a purpose. I've just been hearing that with my recent motor swap(h/c/i ls6), my rear end will probably take a dive soon. ....besides...Its a hard driven 136k miles old. I'm looking to replace it with a unit that will accommodate fairly high hp and autox....I'm not into drag racing.

Try asking on frrax, nothing but road racing there. You might try asking strano as well.

I run a 31spline 9inch with an iron section and Trutrac. Yeah its heavier and you have to make some room to fit. But other than I just drive the tires off it.
If I had to do it all over again, I would ensure I get the 9inch with tapered roller axle bearings instead of the standard ballbearing axle bearings. The ballbearing axle bearings wear out fast when autoxing and playing on the road tracks.

This would be nice. Im sure this costs more than my car is worth tho.

Custom build a Ford 8.8?

I'll be going with a Midwest Chassis 9". Even with an iron center section, they told me it would only weigh about 10-15 lbs. more than a stock 10-bolt. With an aluminum center section, it might be lighter than a 10-bolt.

This would be nice. Im sure this costs more than my car is worth tho.

I like that a lot:nod:

Is that from a c3 or c4?

Prolly c4, dont know for sure. Didnt know C3s even came with IRS.

Prolly c4, dont know for sure. Didnt know C3s even came with IRS.

The '63 (C2) was the first year of the IRS in the vette. At that time they had one trailing arm per side, and the trailing arms also controlled the toe setting.

The design remained very similar until the C4, which had a separate toe control, and two additional trailing arms were added. The C4 components were also made of aluminum instead of steel. The C4 is what is pictured on the 94 firebird in the picture.

The C5 was the first of the true SLA set ups. Even if you could put an IRS on a road race car, in what class would it be legal, and would it be competitive if everything else on the car remained the same?

This would be nice. Im sure this costs more than my car is worth tho.

That is sweet! What is this from? C5 corvette?

That is sweet! What is this from? C5 corvette?

C4, the guy above your post explained it. If you dig around on tech theres a thread on it somewhere.

C4, the guy above your post explained it. If you dig around on tech theres a thread on it somewhere.

Thanks for the reply! Sorry about that....I read down to that post and got excited and wanted to know what it was and asked before reading the rest of the thread/posts:emb:

9", a truetrac, or a T2R..

What is a T2R...??

C4, the guy above your post explained it. If you dig around on tech theres a thread on it somewhere.

The original thread was deleted, the shop is a non-sponsor. If you look on the last page of this thread, http://www.ls1tech.com/forums/suspension-brakes/1076232-irs-convertion-ls1-camaro-6.html, I compiled a list of all the IRS threads I could find. Also posted 1meanz's car from thirdgen.org, and the GMHTP article.

What is a T2R...??

Torsen T-2R, a race differential carried by some vendors here. It is aimed at road coarse type events.