333pg333

You would think that someone here could come up with a solution or a least a lead on that Hans?

thingo

I don't think that would be a problem getting a longer bar, send them an email, tarret bars are really nice products and I found Ira very helpful.

M758

Are you sure they don't. PCA GT right? You are modding the suspension pick up points, but not changing they type of suspension nor tube framing the chassis.

Maybe I am wrong?

BBailey

My read as well, would definitely be legal for PCA GT racing. And I'd go even farther and say partial tube framing is legal so long as you retain the portions of the unibody specified in the rulebook (firewall, floorpan, shock towers, etc).

Landjet

I haven't read the rules for a while, but last I knew you could not move the suspension pick up points. Has this changed? I need to find my new rule book and look it over.

BBailey

Per Rule 3 under Super Classes (GTA, GT-1 thru 6, GTP-1 thru 6)

Suspension is Free except as noted in 1.A above (included below)

1. General Requirements
A. All GT cars, with the exception of those covered in (E) below, must have a Porsche chassis consisting of a stock tub that includes the original floor pan, rocker panel longitudinal frame members, front firewall, and front shock towers. Additionally, 914/924/944/968 chassis cars must have the original rear shock towers, and 911-chassis cars must have a rear firewall, but it can include an access panel for the transmission. Bodywork must be consistent with the underlying chassis. The suspension must be of the same type as found on some stock version of the bodywork type of the car

E. Relates to cars that do not adhere to these rules (pending approval) and Porsche Factory Racecars which are allowed an exception into the GTP classes.

333pg333

Hans, if you had your choice of wheel/tyre combo with a widebody kit, what would you choose sizewise?
If I understand your previous posts I thought that you would not want to go much wider than 305mm anyway if you only had 285's on the front? I suppose if you had 10" and 12" you could do 295mm f 315 mm r ?

HansB

Tire size is sometimes something almost religious: Everybody has their own believe.

My believe in this is that you need to be able to get enough heat in your tires.
From 2 years of measuring this my conclusion is that the F and R tires should be almost the same, and 285'ish is abut the right size for something like 300 RWHP. I've put a bit bigger size on the R just because I could get a set for a nice price.

With more power the size could go up. With my new engine, (+50HP) if it is going to be complete one day, I would start with 285, see what happens, and then step up if needed. The advantage of my current setup and the 3pcs BBS is that this is very uncomplicated to change tire size.

Also there is the question of availability. Some of our racing series require Dunlop tires, and they do not have all sizes to choose from.

JET951

Bearing that in mind, if you had twice the power for example would you think that you'd still do equal sizes? Say 315 & 315?

HansB

Do not know. With twice the power you will probably need 335's or something in the rear. A friend of mine has a 600HP 996, that is what he uses. I can imagine that if you consider F/R load and wear, that 305 F would be enough.

333pg333

I would ideally like 11" f & 12" rear. Then you could have a minor difference between sizes.

HansB

Yes, with your 3.0 animal to be that would be a good option.

Geneqco

Thanks Hans for all your helpful and informative posts!

So you're thinking 305 front and 335 rear for that sort of power?

What sort of diff do you use Hans?

Thanks.

HansB

I think that when you are spending so much money on an engine, it is only peanuts to experiment with different rim and tire sizes. 305 335 would be a good place to start.

I use a standard Porsche LSD,new plates during last rebuild, Turbo gearbox, S2 R&P (shorter gearing).

Geneqco

So that's 40/40 lockup on both acceleration and decel?

Would you opt for a different balance front to rear with a different diff... say 60/80 (ie 60% accel and 80% decel)? What about torque biasing?

Thanks again, this is very helpful... between myself and a few others I can see my pyrometer getting a good workout!