slvr993

I'm planning my winter projects for the 993. I don't race it yet, but I will likely and would like to keep it legal in PCA stock class. Anyway as I look at suspension upgrades would the addition the Evo Uprights and tie rods move my 993 out of class??

Geoffrey

Not legal in stock or prepared class.

slvr993

Thanks - Kinda hoping that was the answer - saves me a couple of grand on the 993

By the way your S2 has had 2 great track seasons. One clutch and a steering rack but other than that it runs like a top. Great momentum car that really holds it's own against much higher horsepower cars.

Thanks

Jeff

Geoffrey

Great to hear. I'm not surprised about the clutch given that it was the original rubber centered one from 1991. They don't last too long when used hard. Any pictures?

George A

Had an interesting conversation with Henderson and Buckley this weekend about the rules (especially camber plates). I came away with the conclusion that most of the expertise on the rules committee is toward the older 911's (SC and earlier).

This (the Evo uprights) is a perfect example of where I think that some things that are illegal may no longer make sense. The real question is why is this illegal? I just bring the front geometry back to the stock position when the car is lowered. Yes I know, you change the mounting point but that's the way you get the geometry back to stock. I'm sure someone can fabricate some tie rods that do something similar, but why?

I'll get off my soapbox.

G.

Geoffrey

The rules committee is made of of a group of people that have a mixture of skills that span the entire model range and year production of all Porsches. I don't believe it to be biased towards the older 911s, although more people have had more experience with them since they have been around much longer than the newer cars.

The GT2 Evo uprights are illegal because they violate the following rule:

2 - Suspension
A. Suspension pick up points must remain as stock in location and type.

You are allowed to update and backdate within a model (993 in this case), however, the only 993s that came with those uprights were the 993 RS street car, Cup, GT2 and RSR race cars, none of which are in the same class, or delivered here in the US. Further, on the cars that ran with the GT2 Evo uprights, the suspension is moved to the outboard position with the upper strut mount in a different location, and uses a different side cross member, neither of which was part of the "as delivered" specification of the standard C2/C4 road car in any Country. The GT2 Evo upright alters BOTH the lower ball joint location and the tie rod location.

If you wanted to run the GT2 Evo upright, you would have to clone a 993RS in every specification with every component. Then it would be a legal modificatin, but you'd be bumped into the 993RS class.

Why do you think the GT2 Evo upright is something illegal that no longer makes sense?

George A

I understand the rules. Yes, it violates them. But the real question I have is "do the rules make sense"? In my opinion, it's a big no.... You know what they say about opinions.

I look at it as what's the outcome. Let's see, it gets the suspension geometry back to it's intended (and as delivered) state. Have you seen what the tie rod and a-arm look like on a lowered 993 (or 964) with stock uprights? It's not pretty. Can you say bumpsteer? That can't be safe... Now you can't suggest that we run as stock ride height, can you?

I hope you don't think I'm bitching at you. I'm just venting about some of my pet peeves.

G.

Geoffrey

Actually, it isn't the fact that the tie rods are pointing up, bump steer is the relationship between the pivot point of the control arm, the length of the control arm, the pivot point of the inner tie rod and the length of the tie rod. This determines the arc the two components travel in which will then affect the amount of toe change that will occur at the various ride heights. The GT2 Evo uprights don't restore the suspension geometry to its "as delivered" geometry at all, it significantly improves it.

I am very aware of what the GT2 evo uprights can do for the stock geometry, in fact, the GT2 Evo tie rods aren't even sufficient, you need an altered tie rod to get reduce the "bump steer" to a minimum (also illegal in stock classes). I know, I've done the tests on my car which runs with GT2 Evo uprights and ERP tie rods with modified spacers set to the required geometry at my ride height.

Bumpsteer is an inherent issue with any production based racing car. I don't think that it is a safety issue when we are speaking about Porsches. It is only a minor annoyance and requires you to adjust your driving to account for it.

I think you have to remember the philosophy of stock class racing and the fact that you are racing against other models. Lets say GT2 Uprights were allowed for a 993 which provide a performance advantage (lets be honest here), then what would you suggest for a Boxster S (996 RSR uprights?), 2.7 Carrera lightweight (935 adjustable arms?) 944 Cup Turbo (nothing available???), 964 RSA (GT2 Evo?) to remain on a competitive playing field? Now this increases the cost of entry for all stock cars in your class. Further, you've now altered the instant centers and therefore, the roll center of the front, but have not yet addressed the instant centers and roll centers in the rear. Should we then allow fixes to the rear suspension too like the GT2 tilt kit, RSR arms?

You can begin to see the larger picture and limitations of stock class racing rules can't you?

George A

Geoffrey,

You are correct, it does open up a can of worms for other models and it does increase the cost. I know the objective and don't disagree with it. I'm actually intrigued with the showroom stock concept. That to me is stock and as delivered from the factory, not what we currently have.

Oh yeah, I'm also in favor for altering the back end... I'm still not sure how adjustable arms (ERP) in the rear of a 993 are legal based on the rules (change in length). From a cost perspective isn't it cheaper to just tilt the carriage? Ops, that changes the mounting point. Each model has it's own quirks and applying general rules sometimes doesn't work.

Let's face it, unless you run in a spec class you are going to have these issues. Is the freedom of any r-compound tire any different. You know you need to run Hoosiers to win (sometimes). How about the person that rebuilds their engine and gets the extra 20 ~ 30 hp from building it right (but still at stock spec)? Is that really as delivered? You know how much that costs, it's not cheap.

BTW, with a stiffly sprung car on a rough track with stock uprights, bumpsteer can be dangerous. I know, soften up the car....

G.

Geoffrey

George, My own personal opinion is that many club racers have moved away from wanting to drive a purely stock car to one that is largely stock, but yet is modified to look and feel like a race car. By this I mean single seat with no interior, lighter weight, adjustable suspension (inc camber plates), possibly brakes, but with a basically stock driveline. Something between stock and prepared with a twist... I don't believe PCA Club Racing shares that opinion though, so I am purely speaking for myself.

Yep, we've been doing the GTC-1 engines like that for years...

jscott82

Sorry for injecting myself into your conversation, but I feel compelled to jump in here....
Having just completed building a 993 G "Stock" class car, I have to agree with Geoffrey... Yes I want a "stock" car that feels like a race car, BUT we really need to limit costs. To take advantage of the limited options avaible today its going to cost upwards of $35k (not including the car). That is me doing most of the work, the quote I got from a race shop was $50k for them to do it... this is to keep it "stock" remember....

They have to draw the line somewhere.. yes I like the idea of having a "perfect" setup, but there will always be that "just one more thing " to make it better/safer... I, for one, am very happy with where it is today... ok, so I dont understand the camberplate thing... but other than that....

Just my 2 cents... maybe less....

George A

Geoffrey, I really like your idea. There should be stock (and I mean stock with rubber bushings, etc.) and there should be a hybrid like you mentioned (no interior, less weight, etc.). Maybe it's time we pressed them....

BTW, I'm being philosophical today because I got the opportunity to drive a SBOX over the weekend and it was a eye opener. Here is something that really made sense. Ok, ok, ok, it's still a boxster.... JK....

jscott82, can you imagine the car you built (btw, I did the same several years ago) with the above mentioned FREE changes (carpet, etc.)? It's expensive to run a 3200 lbs car!!! Think about tires and brakes. Now imagine your car with lets say 300 to 500 pounds lighter... Mmmm, I'm drooling... Heck, I would be willing to move up a class or two if I could just shed some weight. I don't want to go into GT, that just doesn't make sense.

G.

Sean F

+1 gazillion Geoffrey

Tom W

While not common on the East coast where PCA rules dominate, we've tried to accomplish the hybrid class out here in CA with our GTS (GT-Spec) and the GTL (GT-Limited) classes. They are two different approaches to the idea of creating a level playing field and keeping costs constrained.

It is my understanding that GTS class rules have been adopted by PCA for 2009. As we will actually have a few PCA races out here next year, that should be of benefit to us. It appears that my GTL car will simply fall into the GT-3 class. We routinely field 20+ GTS class cars and the GTL field is growing quickly (from 2 to 6 this year)

bobt993

As Sean will confim, this is why NASA GTS rules are much more economical than the stock PCA rules are. If you want to bump your horsepower by tearing down your engine and spending $$$ fine, but you just may move up a class after your dyno (or need ballast). On the other hand if you are short on HP, you can put your car on a diet and remove weight which is usually the most economical thing to do.