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Swapped differential question


UnsafeAtAnySpd

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I did search before asking this, but most of what I found didn't apply directly. Anyway, I have an '04 CTS-V which is notorious for having a horrible rear end. Finally, there looks to be an 'affordable' solution to the problem that uses a 9" rear in the stock cradle. Basically, if I were to pick one of these up, what points would I take? I'd basically be doing it as I drive the car on the street and the stock rear can't handle stock power. The closest thing I see in the rules is this:

32) Changed or modified limited slip differential (or welded/locked OEM LSD) +1

along with this tech bulletin:

No-Points Modifications

17) Motor, Transmission, and Differential mounts and inserts/bushings replacement/upgrade or modification (with up to 1 inch of

relocation of the motor/transmission)and exhaust piping external wrapping

and I suppose info about the driveshaft from this thread as well as that will need to be changed to accommodate:

viewtopic.php?f=2&t=36735&p=270160&hilit=driveshaft#p270160

 

Or is it not allowed being that this situation isn't explicitly allowed in the rules?

Thanks.

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1. Does the car come with an open differential or a limited slip-style differential in its base trim? I would assume some sort of LSD, but I can't say for sure from here.

 

2. Is the proposed differential open or limited-slip style?

 

Mark

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My interpretation is that it would be +1 per Engine/Drivetrain #32, as long as the base vehicle (as listed in the TT rules) also came with a limited slip differential (in other words, it wasn't an option on the base vehicle). Per this item, you could also install a $1500 Quaife differential in your car for the same +1 if the base vehicle already came with an LSD.

 

The final drive ratio is "free" per No-Points Modification #9, if that would apply to you.

 

Either way, please keep us posted on the official response.

 

Mark

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My interpretation is that it would be +1 per Engine/Drivetrain #32, as long as the base vehicle (as listed in the TT rules) also came with a limited slip differential (in other words, it wasn't an option on the base vehicle). Per this item, you could also install a $1500 Quaife differential in your car for the same +1 if the base vehicle already came with an LSD.

 

The final drive ratio is "free" per No-Points Modification #9, if that would apply to you.

 

Either way, please keep us posted on the official response.

 

Mark

 

I tend to agree - A 9 inch, 12 bolt, S60 or Dana swap are pretty common in american V8 cars. Looking for a 2005 CTS-V myself....

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