Suspension mods for autocross?
 

I just finished my first autocross with my 89 IROC L98 auto. I did poorly due to a general lack of traction. I have the engine running very well but I spent most of my time spinning. My 9 bolt LSD is shot, I know what I need to do for that on a different thread. I have stock new IROC springs, all bushings are poly, Koni yellow shocks and struts. I have J&M rear arms and a Hotchkiss adj. rear track arm. Is there anything else I could use to increase the ability to put power to the ground on an autocross course. Thanks for all replies.

Re: Suspension mods for autocross?
 

subframe connectors are always a must..

Re: Suspension mods for autocross?
 

Thanks, but I don't think those are allowed in ESP class. I could be wrong though. I need to reread the rules. I do agree that they would help greatly with the handling...

Re: Suspension mods for autocross?
 

Yes....Read the rules, decide which class you wanna run in & then decide what to work on.


Sad but true.......The biggest improvement anyone can make in autocross is in themselves. Their driving skills. Hand your keys over to a C-Prepared class F-Body driver & watch their first run destroy your best run by many, many seconds. Very humbling when you *think* your doing good & somebody takes the car you've been driving & whips you their first time out! :lol:

Re: Suspension mods for autocross?
 

No mention of tires? They are kind of important.

Re: Suspension mods for autocross?
 

The gift of understatement right there!! ;)

Re: Suspension mods for autocross?
 

i may be wrong but i think any thing that is done for safty is legal...my roll bar ties the three subframes together...for safty of course.

Re: Suspension mods for autocross?
 

Tires depend on Class so why bother without knowing WHAT class?

Yes, you are wrong. Safety item or not, there is still a big limit on what you can do to compete in each class. IIRC, any kind of caged/roll bar puts you into C-Prepared, which is full of non-street legal cars with stripped interiors, lexan windows, fiberglass everything (not just hoods). SCCA may have created a class that allows the more common true-street cars that run things likes SFCs & 4-point harness cars without them having to compete with the full-on stripped race cars of the C-Prepared cars.

http://www.scca.com/clubracing/content.cfm?cid=44472

You should check your local rulebook for what is allowed. Some areas go by the SCCA Rulebook, some areas have a different set of rules for local competition only that allows more mods for the "lower" classes than what SCCA allows.

Re: Suspension mods for autocross?
 

O rly? Which classes other than the ST classes don't allow R comps?

Sounds like he is running in ESP based upon his second post.

Might want to look into some autoX tires. Just sayin', but what do I know :confused:

Re: Suspension mods for autocross?
 

I was assuming Street Prepared (since he said ESP outright...), although *technically*, the rear arms are not allowed in SP, and you'd be sent to Street Mod if someone wanted to make a big deal out of it.

SFCs are allowed in both SP and SM, and the rules are the same. In summary, you can run SFCs that run longitudinally (cannot cross the centerline of the car), and each SFC can only connect in 3 places. No cutting, no welds along the length, no using the SFC for any other purpose (like torque arm mounts).

If the event is SCCA, they must allow all SCCA classes and the rules that govern those classes. They can add in others if they choose, but if you build a car by the rulebook, you're set. That said, the rules often don't align micely with the typical real-world mods that many do...

I'd look at tire choice, and also tire pressures and swaybar combination. I'd like to get more info also about current tire choice, swaybar combo on the car, and exactly where on the course the biggest issues were. If you're spinning an inside rear most of the time, then most of this will be moot until you get the limited slip taken care of. You need a diff that responds consistently (even if it's a truly open diff) before you can really start tuning.

Re: Suspension mods for autocross?
 

Not one mention of shocks either.

Next to tires, shocks are the most important item on any car-why? because it controls the chassis and wheel movements. Even if you run stock shocks, they should be in the best condition possible.

You don;t need SFC's to run properly in autox. SFC's are good for about a 2-3 mm drop in rear swaybar size when added. THe chassis now does not flex as much so keeping the same rear swaybar will cause the car to go loose with SFC's. Again, not needed until you are alot more extreme into modifications on the car and everything is then pointing to the weakest link in keeping the tire footprints flat- Chassis flex is not anywhere near critical when you are on normal street tires and hadly any suspension modifications.

Consider my comparison-

Take a car that is completely stock:

1) put good tires on it (and nothing else) and run a lap time

Compare that to

2) put old tires back on and just put shocks on it (and nothing else) and run a lap time

Compare that to

3) merely keep the stock shocks and tires and JUStT weld SFC's intot he car...and run a lap time

Conclusion-
1) is best by far because it will promote grip no matter how bad the suspension movement or chassis movement was on the lesser tire.

2) is second best by a small margin becasue it will contrrol chassis movement and not get the articulation as far out of wack in suspension movement keeping the tire footprint in better contact on all four corners

3) vitrually does nothing to a crappy stock susension car other than promoting more *** end looseness coming off a corner. It takes out the rattles, and gives a more soild feel, but will not translate into better lap times when the crappy tires and crappy shocks are still allowing the chassis to bobble all over and cause unwanted tire lift, roll, and scuff from improper chassis control and poor traction.

Re: Suspension mods for autocross?
 

Pablo, I just checked your Youtube link. Those two short video's of you on Adams on Aug 27th were with you and I both out there prerunning the course. You have any more footage of that? I can hear my truck. (I can hear my NASCAR West boomtube exhaust- very distinct sound)

Dean

http://www.youtube.com/watch?v=KMme9...1&feature=plcp

Re: Suspension mods for autocross?
 

I can't speak for all, but I know I didn't talk shocks because he mentioned Koni Yellows in the first post, and I didn't want to broach the topic of rebound settings until he got the differential and tire situation sorted...

I do agree with you completely though Dean, that shocks are incredibly critical, especially on high transient situations like autocross.

Re: Suspension mods for autocross?
 

I ran Sumitomo's treadwear is 160. The course really chewed them up. I know I need to improve my driving but more grip would really help. My runs were described as "Entertaining" due to all the tire squeal and smoke! What do you think about the BFG Comp 2's? Or lowering the car? Thanks to all, Good information!

Re: Suspension mods for autocross?
 

Sounds to me like you need tires and a limited slip. Until you do those two I wouldn't touch anything else.

Look at the Torsen T2R or Auburn racer for limited slip. Will not work in your 9 bolt. But you are going to have to swap that out if you are serious about times.

Re: Suspension mods for autocross?
 

If you're going to be competitive in ESP, you'll need race tires. I'd look to your local roadrace or hillclimb guys and see if you can pick up their cast-offs cheaply. Do you know Mike Ancas or Mark Andy?

Re: Suspension mods for autocross?
 

Sorry Dean,
The only footage I have from that day is of my car. I wish the people taking pictures would have posted them at least :(

As for the original post, he did mention he had koni yellows. LSD and tires sound like they will make the biggest difference next to seat time.

I have been spoiled by the adams time attack and karting. I forget that for most, seat time is limited to whatever runs you get at your local autox. To me that is sadly far less than adequate.

I think you need to get enough seat time to where you start feeling the balance of the car and tune it accordingly. You should right away say "oh this car is loose" or "it's too tight" or "I need an LSD".

I think making those kinds of observations is a lot harder if you only have a few seconds of driving "in anger" once a month.

Re: Suspension mods for autocross?
 

OMG he said hillclimb im getting a semi .... lol

Re: Suspension mods for autocross?
 

Well, this is off-topic, and not F-body, but here's hillclimbing for you.

This is my FWD car. I don't have any of my Camaro-piloting runs uploaded (the car owner still has them...).

http://vimeo.com/40698968

Re: Suspension mods for autocross?
 

right on that hill looks fun. only two hill climbs here that i go to. not having a truck and trailer sucks...lol

Re: Suspension mods for autocross?
 

'I might be mistaken but that looks like a Loa T212 from behind as you pull up and park. Nice run- that kind of racing is a blast. I used to love hill climbing on dirt bikes in my younger days, anything uphill is fun and a fighting challange when you have the HP

Re: Suspension mods for autocross?
 

Good info Gentlemen, well I'm rebuilding my 9 bolt, for now, with a 3.27 gearset and a decent set of used cones. And I'm looking at the Nitto road racing radials to put on my spare set of IROC rims. I probly won't have it done by the next autocross but it's a start. Thanks again.

Re: Suspension mods for autocross?
 

I had similar issues with my L98 GTA when I got to autocross it for the first time last August. Mods are listed below, but the one thing I learned that helped me the most is to squeeze the throttle. This meant not only changes in driving habits but also pedal and throttle cable adjustments. The harder the pedal feel the more I was able to control my inputs and keep the car doing what I wanted.

Another must is to firm up the steering response. These cars are old and when we race them, we are at an immediate disadvantage if everything on the car is loose and squishy feeling.



88 GTA L98 700R4:

3.70 9 bolt
Koni yellows
Eibach pro-kit
LS1 aluminum driveshaft
UMI adj. panhard bar
BFG Super Sport A/S 245/50/R16
Spohn spherical strut mounts
3000rpm stall
shift-kit

Re: Suspension mods for autocross?
 

All my bushings are polyurethane. The car responds nice and tight. My biggest problem is the diff. I'm building a new one but can't decide on new cones or not. I know I need them, just need the wife to allow me to fund them. I spend alot of money on my cars as it is. (I have 2 IROCS and a Corvette). I also want to try new tires, I can't really say the tires suck. I really can't tell at this time without the diff locking up. The tires are holding up incredibly well for what I put them through. I really want to try the BFG Sport Comp 2's though. They appear to have a tighter tread block pattern.

Re: Suspension mods for autocross?
 

I put an extra washer (I think 3/8" grade 8) under the preload springs in my 9-bolt when I last went through it, helped a lot with wheel spin. You can machine your old cones down if they're bottoming out.

Get some more negative camber up front up too. A stock spec alignment is going to push badly almost no matter what.

Re: Suspension mods for autocross?
 

I forgot about this thread. I have put in a 10 bolt with a Zexel and 3.23 gears and changed the tires to 17" CTWs with BFG Sport Comp 2s. I should have been racing today but the ignition relay gave up. It will take 2 to 4 days to get one in. Oh, and the Sumis suck compared to the BFGs. Does anyone have an alignment recommendation for this setup? Thanks.

Re: Suspension mods for autocross?
 

I believe that you need camber plates so you can run a performance spec alignment.