Hi,
I am new to this board and have placed a deposit on the new Evo. If I can get this car classed, I may set one up for racing. The car would be used for roadracing only. The car must be the U.S. spec car. Differentials are free, but I doubt I would be allowed to retrofit ACD/AYC. If this assumption is true, What would be my best options for rear, center and front diffs for my application.
Thanks

 

Quaife, Kazz, Cusco...the list goes on.

 

Thanks for the reply,
You have named brands that are helical gear type as well as plate type. Do I want to mix and match types? If plate type, do I want 1-way, 1.5 or 2-way? What about Ralliart? I realize this is difficult because we don't know what the U.S. spec Evo will be yet, but I'm looking for more specific information.
This car would rarely be driven on the street, and since it would be strictly a roadrace setup and not used for rallying, I'm not looking to powerslide the rear end all over the place. Great grip with minimal understeer is the goal.
The class I am thinking about is SCCA's Touring 2 class where I currently race a Porsche Boxster S. Other cars in this class include the Z-28, Honda S-2000, 350Z, Mustangs and E-36 BMW's.
Thanks again,

 

2 way is mainly for touring, tarmac specs....But 1.5 would be nice for your front, and help w/ launches!

 

Thanks Red,
Launches are not a concern, we do rolling starts. I'm assuming I want to stay away from helical diffs because it's probably possible to lift a wheel on track with this car. Can you elaborate on the feel of 1.5 vs 2-way lockup on plate type LSD's?
Thanks,

 

Thanks Claudius,
I'm assuming the U.S. car will have either an open front diff or a helical type. I will look into the Ralliart parts. Do these kits come with parts to beef up the center diff? Also any thoughts on the rear diff?
Thanks,

 

Claudius (wtz), I think the best setup for road racing would be (just doing the math in my head!), A one way front and center with a 1.5 rear. Here is my logic... from turn in to apex you want the car to be as "free" as possible (all wheels able to follow their own radius) with a little more drag in the rear (1.5 in the back). This will minimize understeer, then when power is applied (just before the apex on slowish <4gear corners, earlier on faster corners) the car should go pretty neutral from there out (if you've done the first bit right)

 

What area of the us are you in?

Better check your SCCA rule book, in my area, no forced induction cars can be in T2... of course they also just "recently" have added a Super Performance class where the turbo and blown cars get stuck.... along with anything else that dosent fit quiet right in other classes

But before this they were in ITA or ITE (cant remeber which)

i dont think you want to power slide (its not approved of in most cases by scca officials and probably not the fastest way to drive on the track anyways)... of course thats your decision... you can take my comment there as a grain of sale.

SCCA might have rules about what you can do to your Diff's (doubt they'd catch it on inspection though)

Are you pro, or do you just race in your region? i guess it depends more on this right here...

 

Claudius, I think a front 2-way diff would have a lot of locking on deceleration which would cause understeer on corner entry. The car has a 60/40 front/rear bias (the same as alot of front drive cars). So I'm thinking you want just a little drag in the back (1.5-way). The only variable is where the drive goes when the center diff is unlocked (front or rear?). This may change the prefered center diff because you would want the rear "connected" to get the turn in we need to overcome the weight bias. Efficient entry is everything as far a corner speed is concerned, you want the car to be "freed up" with as little resistence to cornering as possible. Shocks make a big differience with the entry as well (but can do very little mid corner) as well a a little toe-out in the rear (and front too) then it's up to the springs and bars (and the driver!) to determine the balance the rest of the corner (and of course the amount of locking of the diffs under accel).

Does any one know what the diff settings tend to be for a WRC car on tarmac or any professional curcuit racing team (I know they will vary but it would be interesting info nun-the-less)
fun topic!