BriGuy

We are saving now for a 9" for the wife's car. I am not very familiar with the rears. Which would be better a spool or an auburn differential. It will be a 9" with some 3.90 gears, 31 spine, and 4 channel ABS. Any help with this would be greatly appreciated.

The car is a '00 Formula WS6 with the full compliments of bolt-ons with a TRex and stock heads.

Yes I know that the 3.90 gears aren't the 'ideal' gears for the TRex, but she wants to start off with those first to see how it drives.

DuronClocker

iTrader: (25)

Go with a TrueTrac Better than the Auburn posi (nothing to wear out in a TrueTrac!), and perfectly streetable whereas a spool will be dragging a tire every turn.

Bandit LS1

iTrader: (2)

I second the TrueTrac

Jimmard

iTrader: (12)

I agree. I just ordered one from scott@drivelinesolutions. 4.11s trutrac, I even went with an aluminum center section to save quite a bit of weight (lighter than a 12 bolt now). I should get it by next week

NHRAMAN

iTrader: (1)

I third it.

BriGuy

I should also mention that the car will be used more at the track. She will be points racing. Once the rear goes in the car will be used more at the track, with the occassional egged on race on the street. (No matter how the car sounds someone is always willing to race a female on the street just to see if she knows what she's doing.)

DuronClocker

iTrader: (25)

You're going to love it. I just assembled mine tonight (need to install the axles tomorrow after I get the bearings pressed on). Ordered on a Thursday, received the center section from him by Tuesday, and the rest of the stuff from Moser on Thursday. One week after ordering, it was all at my doorstep

I weighed everything separate and added together...got 181.1lbs not including the center section nuts or the torque arm mount bolts. Not terribly heavy at all. That didn't include the 13.5lb backing plates or rest of braking though.

Jimmard

iTrader: (12)

I think the thing that is exciting me the most is being able to finally do some high rpm clutch dumps on slicks. I'm interested how much of a difference it will make on my otherwise stock car. It will have aftermarket torque arm, driveshaft, clutch, bellhousing etc by that time though. I'm soo excited, I cant wait much longer

Jimmard

iTrader: (12)

If that's the case, I would definitely consider 4.11s or more unless you plan on spraying. Good thing about the 9" is that gear swaps are easy, just get a new center section and bolt it in

DuronClocker

iTrader: (25)

I went 3.89s because 4.10s would put me past my 6800rpm limit at the track on 26" tires on spray :doh:

xpndbl3

iTrader: (23)

duronclocker, if you want to hook it up go with 28" slicks for more contact patch, no reason to run 26" tires if you want to be consistent and make hooking up easier.

oange ss

iTrader: (50)

if it's an M6 i would definitley consider the 4.11 and another vote for the Tru Trac, that's what i have in mine

BriGuy

If the 3.90's don't do what she wants then she is looking at 4.56's. The main reason that she wants the 3.90's is for the 190 mile trip that the car will have to make to go from our house to the track. Although we do have a house to leave the car at once the race season starts.

35th SS

iTrader: (2)

she will want more like the 4.56 and 28inch slicks.

EPP

iTrader: (22)

I agree, go with 28" tall tires. They provide a larger contact patch ( o - O ) on the ground, and the taller sidewall doesn't shock the tread surface as hard, allowing more traction.
A nine inch with a spool is what I would go with for your application.
http://www.exoticperformanceplus.com....html?item=148 Bob