tony@cvi

I'm new to the forum and realize what a great resource this will be. I have '07 stock coupe and am looking for alternative tire, wheel and suspension modifications to be more competitive for local AutoX events. I have AutoX last season and feel I am starting to become one with the car but have a lot more to learn. Can I, should I, consider increasing wheel size to 9.5" front and 11" rear or stay with the stock size of 8.5" front and 10" rear? I have a stock Coupe no suspension or brake brake options . What about tire manufacture and tire size? This car will be driven daily during the summer months [around 3,000 miles/season]. Any recommendations on front and rear sway bar packages? Any modifications I make need to keep me in a stock autox class in my local Corvette club autox rules. Any help? Thanks T

ipuig

Read this:

http://forums.corvetteforum.com/auto...k-in-here.html

I would not worry about modifications until your times drop to the point that you are running almost as fast as the more experinced individuals runnig similar equipment.

napacruzerc5

I would recommend installing a 5-pt (at least) harness asap. I find it surprisingly difficult to hold yourself in your seat while taking the sharp corners typical of most autocross courses. And once you start suspension mods which will raise your cornering speeds and g-forces you need the harness even more. Even a simple chest strap, seatbelt type material with velcro fasterners to go around your chest and your seat back, can help although may be illegal by some event sanctioning bodies.

gkmccready

Stay as close to stock as you can while you get used to things. A second set of stock wheels with "better" tires would be a nice addition. If you're a base coupe you might enjoy a C6 Z06 _front_ swaybar. Otherwise spend your mod money getting a performance alignment and if you really want to spend some money get the car corner weighted. I certainly wish I'd listened to the people telling me this when I bought my car... :-)

383

I am new to C6s and will be autocrossing this season. Any suggestions on an A/X allignment and cross weight #s with a 210lb driver in an all stock 07 Z51? How badly does lowering these cars on the stock bolts effect suspention geometry?

mr.beachcomber

It's not clear from your post if you are new to auto-xing or just the C6. Either way, I would recommend sticking with a stock car for the first season just to learn the car's handling characteristics and adjust your driving style to compliment the car. That being said up front...

Stick with the stock alignment if (1) you drive on the street and (2) don't want to prematurely wear out your tires. Otherwise a modicum of toe out in the front will allow you a quicker turn-in on course. Make sure that you rear wheels are either straight or slight toe in for stability.

You're basically stuck with what the factory gave you in the stock classes so cross-weighting a stock car isn't going to do anything for auto-xing unless you change over to adjustable coil overs which bumps you out of the stock class. It just adds another variable to a new car during the first season.

Changing to a lowered suspension is going to bump you out of the stock class. Counter productive if this is your first season with the car. Bumping usually places you in an uncompetitive position with more experienced drivers with higher levels of prepped cars.

Save your money for seat. Let more experienced drivers help you out with ride-alongs with you both as the driver and the passenger. The best money you can spend at this point in time is a professional driving school such as SoloPro Driving School or Evolution Performance Driving School.

Good luck and have fun!

Solofast

We don't usually see terrible advice here, but this post is so full of it that I had to comment....

Absoultey wrong advice here. If you are serious enough to want to autocross the car you are a performance oriented driver in the first place. The car will handle better and you will give up a bit of tire wear on the street, but a performance alignment is an inexpensive way to get the most out of your car. We'll talk about setting the toe later on, but you absolutely will want to get the car aligned. Toe out on the street is the fastest way to burn down a set of tires, so for street use toe out is a

Sorry, but this statement is simply

In SCCA or NCCC there are allowances in terms of alignment and lowering and setup and you absolutely should take advantage of them. These cars are C6's and you can cornerweight and lower the car legally in the stock class. You will go faster, have more fun and your car and tires will last longer and work better. You will learn more, and you won't get as discouraged and that's what it's all about. Cornerweighting the car will make sure it turns the same going left and right and you want your car to do that! You do it once and you are done. Don't mess with it any more than that and you won't introduce any other variables.

You should absolutely keep the car in the stock classes, but with any stock car you want to make it as good as it will be and handle properly from the start. If you don't properly prep the car you will develop bad habits trying to drive around the things the car doesn't do right in the first place. This doesn't cost much to do and the payoff is huge.

I can't tell you how many cars I have driven at drivers schools that were miserable handling things and the student drivers were just wasting time trying to learn to drive the POS car.

Yes all true, but we aren't talking about changing to coilovers, we are just setting the car up properly in stock form. That means lowering the car properly on the stock bolts, aligning the car and doing the cornerweights. This is absolutely the cheapest and biggest bang for the buck improvement that you can do.

Lower the car 3/4 of an inch with the stock bolts, corner weight it, set in a serious alignment based on how many events you are going to run each year, and enjoy the car and learn as much as you can.

If you are going to run more than 4 or 5 events a year, crank in 2 degrees of negative camber in the front and 1/2 a degree less in the back, set the toe at 1/8 of an inch in all around and get as much caster in the front as you can get. The negative camber won't kill your tires as much as toe out will, and if you are running the same tires on the track your wear will be pretty even. If you are running fewer events, use -1.5 degrees in the front and -1 in the back. If you find you are wearing out tires too fast flip them on the rims when they get to half tread on the inside. If you want to mess with toe, put a paint mark on your tie rods and start with 1/8 of an inch of toe in and crank in one full turn towards toe out when you are on the track. Keep it toe'd in for daily driving and you won't eat tires.

A drivers school is absolutely a great idea, but if you take the car to one with a stock alignment you will eat the outside edges of the tires because you will get a lot of track time and the roll over and poor alignment will kill them. The amount you pay to set up your car in the first place will save you that much or more in tire wear at your first drivers school. You will learn more and progress faster in a properly set up car.

vettehardt

What group do you run with. You mention a local Corvette club, but are they part of NCCC? Or, do they have their own series they run? If we know the rulse you can go by, it would help us better give advice as to what you can do. For instance, in NCCC stock class you are not allowed to change sway bars, so that would nullify one of your questions. Also do you plan on running a street tire or a "race" tire?

383

Thanks for the great post that was just what I was looking for! I am new to both C6s and A/X but expect them both to be very fun. I like to do lots of street driving so the -1.5/-1.0 might be the way to go for me. When I bring her in for an align. what amount of caster do I ask for , max? They also need to corner weight the car with me in it correct?

gkmccready

I've been doing more HPDE than autocross lately, but my current alignment is -1.75deg camber, 1/32" total toe-in, ~7deg caster. Rear is -1.25deg, 1/16" total toe-in. I'd lower the car to around 4.5" or 4.25" measured to the frame just in front of the front jacking puck hole, and set the rear maybe 1/2" higher (measured just behind the rear jacking puck hole) -- rake recommendations will be all over the map so you'll need to figure what works for you... if you like the lowered look run no rake.

I also use the car to get back and forth to work and end up putting on several thousand street miles every year. Tire wear is not bad with this alignment, but you could knock off the 0.25deg camber and be even happier.

And, yeah, they should both align and corner-weight with you (or your equivalent weight) in the drivers seat.

FWIW, my car showed up stock measuring right around 5" to the jacking puck holes front and rear...

383

I thought HPDE was an autoX event. Is that like an open track day event?
When they cornerweight the car dont they use the height adjustment bolts? so how do you keep the ride height where you want it?

Solofast

What you do is lower the car to about where you want it and then look at the cross weights. By lowering say the left front and right rear, and jacking up the right front and left rear, it takes very little twisting of the bolts to dial it in.

Also a small trick is to turn the front bolts in even one turn increments and do the final adjusting in the back. That way the pads on the front screws are already deformed and there isn't going to be any settling to screw up your adjustment.