Some autocrossing questions...

Street racing down here is getting sour with more idiots driving and bigger legal penalties so I've decided to try to set up the car for autocrossing. (Only have done it once in a driving school in Road Atlanta and I took 1st out of 30 people :D , we were all driving the same little AWD Impreza) So I'm atleast going to be doing it part time and if I really like it going to try to go as often as I can.

But anyways, a little info on the car before the questions, it was a 96 V6 5-speed and was converted to LT1/4L60E combo setup for Drag (Adj. TA, LCA's, SFC's, STB, and 8-point roll cage, and the motor is stock with just a ramair hood and catback exhaust) So it's not qualified for stock class abviously. And I talked to Stranoparts (which has kick ass customer service) and decided to go with the eibach prokit with the custom valved Bilsteins from strano and the 35mm hollow front sway bar (as soon as I can afford it). I also have a set of the 17" 10 SS wheels on the way too. Also looking into upgrading the front brakes with either the LS1 upgrade or spending more going with the C5 brakes, I already put in a new rear end with 3.23 gears and disk brakes so the back isn't drum anymore... So...

1. With the 8-point roll cage, will I still have to have a bar going diagnal from behind the driver head to the passenger ground?

2. I know I'm not going to go over 50mph, so what gear ratio are you A4 guys running in autocross?

3. Is spending the extra money on C5 brakes over F-body LS1's worth it?

4. Steel braided brake lines? I imagine that's a "yes" :)

5. I usually run Kuhmo's on the street, anyone recommend different tires?

6. Eibach or Hotchkis springs?

7. How many of you guys pull the ABS fuse?

8. Slotted rotors? yay or nay?

That's about it I think. I've searched and didn't find many "definative" answers so any help is greatly appreciated. Thx :D

You'll enjoy the setup you're getting from Strano and I can't stress enough that you need to get the 35mm just as quick as you can. If your current LCA's are poly ended then you should consider putting the stock ones back on. The poly ones will bind and not allow free travel.

1. Your cage is fine just the way it is since a cage isn't required at all.

2. When my car was an A4 I ran 3:42 gears so your 3:23's shpuld be just fine.

3. The LS1 brakes are just fine for autocross but get good street/race pads like the Hawk HP+ and keep the fluid flushed regularly.

4. Steel braided lines are kind of a preference thing but I do run them and like the firm pedal feel.

5. There are a lot of choices on tires and since I'm on R compounds I don't have any good tech.

6. I run the Eibach Pro Kit and like them. If that's what Strano is basing the Bilstein revalving on then I wouldn't stray from that.

7. ABS is your friend do not pull the fuse.

8. Slotted rotors are a waste just get some good quality rotors like the Brembo's that Tire Rack sells.

I suspect once you get the car set up and have a few autocrosses under your belt you'll wonder what the hell you were ever doing drag racing. :D

Sweet, Thx a bunch! :D

Btw... I have little idea what the classes are, what class would these mods put me in? ESP? (I'll be on Kuhmo 712's)

I'm not very good on the SCCA classes since the club I run with doesn't follow them. I know you won't be legal for ESP because of the SFC though.

Searched forever and finally found a .pdf file of the classes. :D

2. I know I'm not going to go over 50mph, so what gear ratio are you A4 guys running in autocross?

3. Is spending the extra money on C5 brakes over F-body LS1's worth it?

5. I usually run Kuhmo's on the street, anyone recommend different tires?

6. Eibach or Hotchkis springs?

7. How many of you guys pull the ABS fuse?

8. Slotted rotors? yay or nay?



Make sure you know what class you want to be in first. Your car, as is, gets bumped out of stock and street prepared. You're not that far out of street prepared, so you have to decide if you want to go to street prepared, or go up to a street mod or prepared class. That will dictate a lot of answers. For instance, if you want street prepared, then that will dictate you must retain the 3.23.

As noted by Jeff, just get a decent pad. You're hard on the brakes in auto-x, but it's not for 20 straight minutes, and you're not slowing from 100+ like on the track.

Tires make the biggest difference of all. Buy some race tires for your new 17x11. The best deal is to find some used tires, especially when you're new. Sometimes it's recommended that one spend their first season on street tires. Kumho MX's fit that bill for fairly cheap. But you'll want to upgrade that for next year to Kumho V710's or Hoosiers or Avon Tech R's etc.

If you buy revalved shocks from Sam, stick with the spring he valved them for. Didn't you get If you're not going to use the pro kits, then tell him before you buy the shock. No sense in throwing good money at something that's not as ideal as what you could have had.

ABS will help keep you from flat spotting tires, and help you turn when you fail to brake soon enough.

Again, just to back Jeff up, solid vented Brembo rotors sold through various outlets, including Tire Rack are probably your best choice.

For instance, if you want street prepared, then that will dictate you must retain the 3.23.



3.42s are legal in ESP in an A4 as long as they are orginal GM gears per the update/backdate rule. :p

3.42s are legal in ESP in an A4 as long as they are orginal GM gears per the update/backdate rule. :p

That's not my understanding of the rule since 3.42's were never offered in conjunction with the A4 in a 4th gen. Not to say I couldn't be wrong, but I was pretty sure I was correct.

That's not my understanding of the rule since 3.42's were never offered in conjunction with the A4 in a 4th gen. Not to say I couldn't be wrong, but I was pretty sure I was correct.

Doesn't matter if it was never offered in conjunction. You can mix and match the parts. Thus the reason you see T-10 tranny's in 84+ 3rd gens, LT-4s and 93 trannys in other years, etc. :cool:

"Standard factory installation methods, locations, and configurations are
allowed. The updating and/or backdating of engines, transmissions
or transaxles must be done as a unit; component parts of
these units may not be interchanged."

Rules 15.1 (C) The 3.42 with an auto wasn't a factory configuration.

There is so much grey area in that rule.

3.42 ratio with an auto is a completely legal ESP mod.

The rule isn't shady at all. The rear axle is component, the trans is a component, the engine is a component. Adding a 3.42 axle to an auto car is an update/backdate/share a line in the rulebook thing, and it's the whole component. Completely legal. Further, since the auto and manual axles are the same but for the gears, he can actually just change his gears from 3.23's to 3.42's as long as he uses GM gears. At that point he just build a completely legal 3.42 axle.

Thanks for the clarifications! :)

Basically what it means though, is if (for example) a 4th gen car came with a 3.42, that gear can go in any 4th gen (as long as the cars are on the same line in the book). You can't take the cam out of an LT4 and put it in a LT1, but you can swap the entire engine.

Since you're out of ESP, SM will be the next logical progression. At that point, the gear and engine issues will be moot anyway. I still have my stock 3.23's with my A4 but when I build the engine for SM, I'll be going to 3.73's.

Thx for the info guys!

Steve: Nice looking car. :D But I noticed that you don't have your T-tops in while racing, for weight savings? I thought it was better to have the T-tops in to help strengthen the chassis a little... Curious because my car has T-tops also. :D

The tops won't make it any stiffer. I've never noticed a difference one way or the other.

A little story for you, straight from the mouth of a chassis development engineer for the F-body platform, circa 1992:

A third-generation F-body test mule was outfitted with strain gages, applied directly to the body in an effort to determine stresses on the chassis. It was track tested at Milford. Once the study was done, the technicians used a sawsall to cut out a rough T-top into the roof of the car, and the test was re-done. The result was a negligble increase in chassis flex. It seems that the tiny bit of flat steel we call our "roof" does not make a significant contribution to the stiffness of the F-body platform.

So go run your T-top car without the tops, and dont worry about it. I *always* autocross without the glass tops in place, unless it's raining out.

A little story for you, straight from the mouth of a chassis development engineer for the F-body platform, circa 1992:

A third-generation F-body test mule was outfitted with strain gages, applied directly to the body in an effort to determine stresses on the chassis. It was track tested at Milford. Once the study was done, the technicians used a sawsall to cut out a rough T-top into the roof of the car, and the test was re-done. The result was a negligble increase in chassis flex. It seems that the tiny bit of flat steel we call our "roof" does not make a significant contribution to the stiffness of the F-body platform.

So go run your T-top car without the tops, and dont worry about it. I *always* autocross without the glass tops in place, unless it's raining out.

I think if they where stress bearing they would shatter

I think if they where stress bearing they would shatter
Not necessarily. Your windshield is a stressed member of your chassis and a significant amount of roofline rigidity is gained from it. That's one of the reasons it is considered a safety hazard to run a cracked windshield. So glass can and is used in stressed bearing applications on cars.


If you were to physically bond in the T-tops they might aid in increasing roofline strength. However, you are probably right in that the tops were not designed to be stressed members like a laminated glass windshield. Thus, they might, or might not take the stress.

I run with the top down. Just like a Miata.

And Miatas rule autocross :p