Just interested in a general discussion.

Just how stiff are the 4th Gens? And more importantly, how stiff is stiff enough?

I suppose that there is no such thing as overkill when it comes to chassis other than weight, but I would think there is a point where it's "enough". Kinda like money, almost can't have too much, but if you reach a certain point, you don't need anymore. lol

A salesman from SLP (Don something or other I beleive) told me that with their SFCs and STB on the car, there was nothing I could do to it to cause it any harm, especially in stock trim (excepting a part spontaneously breaking, or me hitting something, or anything else equally unpredictable). I have then bolted, torqued, and welded except for the stitch weld along the thin body seam, that is actually screwed in (god forbid they ever have to come out for any reason, I don't want to have to cut that whole seam off the car). And I'm planning on getting a drive shaft loop, and possibly a tunnel brace on top (underneath? lol) that as well if one'll fit.

Then I was talking to a buddy the other day who has a WRX STi. IIRC, those things have tubular frames already in them. And he mentioned something about getting SFCs and STBs for his car as well. My thought was, why? If that already had a cage of sorts in it, why would SFCs be necessary? And if they were, what did that say about my car (2002 WS6 T/A)? That it had the strength of a warm pile of taffy?


So let's say for turning - auto-x-ing, and track driving (like in Gran Turismo or whatnot), what is really needed, and what is really over kill?

For my specific application I plan on working the suspension entirely (coil overs, tuned springs, adjustable shocks (haven't picked these out yet though), lowered, and possibly 17x11, or 18x10.5 all round with the stickiest tires I can find for the track. And a mess of other things I'm sure, I'm just not there yet, but that's the general plan), but I'm kinda interested in the theory behind it all, in general.

 

Hmm.....Depends on how you look at it. The F-bodies are "relatively" stiff in stock form, but that is only to say that they are much improved over the 3rd gen cars. Just like "there's always a bigger fish", there's always a stiffer, more rigid car. That's not to say that your car, with braces, isn't sufficiently stiff for some track time. Cars can suffer from twisting the unibody, causing panel misalignment and quarter panel ripples (but it takes a hell of a beating to do this). But, I've never ever seen or heard of this happening on a F-car that has been braced. Even one with a nitrous sucking forged 355 that does wheelstands on wrinkle-wall slicks. (Scary car ) I think your car will be fine. I ran road course open-track events for a while with my '94 Z28, and I had SLP SFC's, a shock tower brace, a driveshaft tunnel brace, and some suspension mods. It handled the track fine, with no ill effects (and I had T-tops).

 

That's good to hear. Thanks for the input.

But I noticed you said "some track time". This is not a daily driver. Right now I take it out for cruising, or occasional errand runs when the weather's nice, or when it's not wet out and I can't stand not driving it. lol

I am definitely working toward a car that will be used in auto-x and any road courses I can find/get to. And I'll want to do this as often as possible, for as long as possible. In short, I want the chassis to last forever (accident notwithstanding, but even then I'd want to salvage it). Everything else on the car can be replaced, but the chassis is the car.

I guess there's no long term road race torture tests to tell us the answer, so that's why I said I was interested in the theory.

Plus it's just an interesting topic anyway.

 

SFC's will put you in various autocross classes where you'll not be terribly competitive (ask me how I know). So, if you want to autocross seriously, I'd skip the SFC's for now. For reference, I'm running against tube framed Mustangs on slicks with up to 600 hp (autocross). My car is my daily driver. I still managed 4th out of 7 last time out (one car had 2 drivers), but I'll probably never win this class.

 

Preserving the car is my concern, not where I place in the class or field. And that's also why I was trying to speak in an abstract manner (theory). But for my specific application, I'll come in dead last if it means keeping my car from being fatigued and used up. I'll be racing against myself and the clock in that case.

 

The longest-abused autocross F-car that I've heard of is Steve Eguina's 1996 LT4 Camaro SS. As far as I know, it's still alive and kicking. I read a magazine article on his car a while back, and his modifications were not extensive. He installed SFCs, a convertible front K-member, tunnel brace, and shock tower brace. If you're dead serious about preserving the car, I'd look into installing those, as well as a roll bar. It doesn't have to be a 12-point cage, just a six point roll bar would be a great help (and remember, weld-in bars are generally better for strength and longevity than their bolt-in counterparts). But, rollbars do make the car kind of a pain to live with. And as Trackbird mentoned, you will be in a class with some serious hardware (my instructor's tube-frame Porsche comes to mind). If the minor inconvenience doesn't bother you, and since ultimate chassis strength is your main concern, it may be something to look into. Just a thought.

 

Hang on there...... Steve's car does not have SFC's. It can't. See we race together in ESP, and they aren't legal in the class. And I'm sure Steve wouldn't do that.

The longest surviving autox cars I know of: An '82 body that has been racing Nationally since about '88. I used this car to win ESP in 2002. No SFC's. Also Karen Kraus's '96 1LE. 317k miles last I heard. Bought new, drag raced, autoxed, and open tracked all the time. No SFC's (as a matter of fact an F-stock car), and still very tight. My 2001 also has no SFC's on it, and I won ESP this year as well in it.

Is chassis stiffening bad? Not at all. Would I run SFC's in ESP if they were legal. Very likely on a 3rd gen, possible but not likely on a 4th gen since I don't see a need for it. Let's not forget that 4th gens were designed as convertibles all along and aren't terribly bendy. Also they do very well in crash tests.

Now, let me address the fact that folks install SFC's and proclaim a big difference. It's true, but really only happens with stock shocks on the car. Why? The stock dampers suck, and transmit a TON of shock right into the body instead of damping them out as they should (and as good shocks like Bilstein and Koni do). Consequently the cowl will shake, and you will get rattles and such that otherwise wouldn't show up. Basically the junk suspension dampers cause the chassis look worse than it really is.

 

I guess that answers that question. I must have misread the article on Steve's car. (BTW how does he fit 315's in the front?) Do you think they might change the rules in the near future, or am I going to have to take them out to run ESP class? (good thing I didn't weld them)

 

Don't count on the rules changing to make SFC's legal in SP.
Been years, and many tries already, to no avail.

 

Crap.

 

Thanks for the info, and again, a big releif to hear. I suppose that only leaves the question of how hard those un-braced cars are being pushed in all that driving (g loads and the like).

And not to get off topic, but the SCCA rules are f-d up. I know that a stiffer frame can help the suspension work better, and is therefore kind of like a suspension upgrade in it's own right, but really, it's about protecting the car. Slapping you in with tube-frame one off monsters pretending to be a car just because you put on some SFCs is assinine.

 

Yup. A friend of mine told me they might not be allowed, but I though he was full of sh*t. Guess not. I know I can't run in the higher classes and be competitive. I guess you could just race the clock, but getting your doors blown off isn't much fun.