If the transmission heat is a problem you can run a transmission cooler. Like the Z51 has.

I still think that a transmission tune is going to help the most. It makes it shift faster so thats less slipping and less heat generated. I could be wrong on this tho.

Plus you can adjust the settings so that it only shifts hard when your at WOT or 3/4 throttle so on the streets the car drives like stock, and this only when in S mode. Its really the best of both worlds.

I understand that if you go with a full coilover and Ptfd sways and all the goodies is going to make a faster car no doubt, but this is up to how important auto-crossing is to you.

But if you just need to beat up on the Z51's then lowering and a tune is the cheapest- easiest way.

 

Are you running your courses in second gear except for the start?

 

I have to agree that body roll and dive were very noticeable on the autocross and there were times I waited for the car to "settle" down before hitting the accelerator. The Z06 front bar was a big help, but dive is still there. I agree I should be considering coilovers. Thanks much.

 

Another tech you could try is left foot braking. One of our fastest guys is a pro at it and that is with a manual. he keeps the rpm's up and gets out of the corners quicker than most of us.

 

I've got to agree that the C5 Z06 is a high water car. They do perform remarkably well. The C6 I have looks like it will go back to totally stock (off with the Z06 bar and back on with the stock brakes to eliminate the Hawk squeel), as my wife was very upset when we parted with our '66 427 Coupe, which was experiencing lot rot from sitting too much. I promised the next Corvette wold be driven daily, so she's done just that logging over 70,000 miles. To set the F55 for full on racing would be too expensive and compromising for daily use. I just hoped someone might have come up with a silver bullet that permitted the F55 to be used. Not so; even the Z06 sway bar on the front had changed the daily driver feel. So what's my solution for competitive driving? Well, I recently bought an '88 C4 and, now knowing that the C6 can't be set up without too many compromises to daily use, will set up the C4 up for competition. I know they can be very competitive, right up there with the C5 and C6 Z06's. Should be fun. Oh, and my '88 does have a 6 speed (not a 4 +3). Thanks to you and all those who commented. Jeff

 

You're right, I'm sure, but that Auto is such a gain of time that I think I'd always be chasing my tail. Plus, having ridden in a stock Z51, I concluded the F55 I bought for road trips is just that, a good road car and not a competitive autocrosser. Thanks much.

 

I've done some trail braking on the road courses to good success, but haven't with autocrossing. Got to crawl before I walk, I guess.

 

I am getting so good at swapping suspension components that I may just just swap everything for race days and put it back stock for the rest of the time. I need purchase a tech 2 but I think I can make it work. What I am doing for this winter is basically putting the base suspension under it, still have poly bushing to see what it feels like. Coil overs back on in the spring. Get a set of Pfadts camber plates and I should be able to dial it in for whatever suspension I put under it.

 

I'm kind of surprised by what you guys are saying about the F55 setup. I would have thought the damping would have been the silver bullet to driving nirvana if you were willing to swap the roll bars and springs to your own taste.

The obvious mod would be coil overs but they are not dynamically adjustable; have to stop the car to make changes and you have to iterate to get the right setup per road course, parking lot, whatever. I figured F55 would avoid all that.

Or are we splitting 10/10ths hairs?

FWIW, I'm at the researching a car stage. I recently sold my moderately built S2000 and have settled on a Vette for the replacement. Leaning GS or Z06 but haven't decided yet. In our local club classing system the sky is the limit for mods in the class I'd be running so I have a blank slate to work with.

 

The F55 shocks are probably superior to anything on the market today. But the springs rates they use with them is the problem. You can fix the lean in the corner with sways but you will not eliminate the brake dive or weight transfer on throttle pickup. I am talking here about the coupe, not the Z06 or ZR1. I do not know what spring rate they use in there F55 equiped cars.

I did not really latch on to the brake dive issue until last year when I got on the big track. The first time I hit the braking zone, 145mph to 35mph I thought I was doing an hand stand in the car, it was that bad. I also blew the front right shock this day but did not find out until months later.

Everyday roads and streets it is hard to beat the F55. Even occasional track use it is more than capable. Want to be competitive it is not the way to go. Now if someone could just break the code in the controller and develop F55 type coil overs I think that would be the best possible solution for everyone. I would shudder at the price though.

 

If you are doing NCCC AX, the classes are divided by model. All base C6 coupes/verts run in the same class, a GS runs against the Z06 and that's a disadvantage.

A F55 coupe with Z51 sways and Z51 front spring should be a very nice combination street/AX car. With good tires...

 

I don't Auto X anymore....a wee bit older.....lost my motivation. I was very good though & spent a lot of time with suspension & setup. Here was part of my process when I set up a car up.

The first hard lesson for me was power is the last thing on the list, generally when you added more first.....you went slower.

The second very hard lesson was the "ego" combined with driving Technic, very good books on that. The best part is some of those Technics you can practice every time you drive the car. Such as shuffling the steering wheel.

The suspension schools are soft springs & large sways or stiff springs & smaller bars. For me I like big power & the stickiest tires possible in the class. Tires "First"!

I found big springs to control not only the dive mentioned in this thread already but equally is "squat" . Big springs act like adding big bars without adding big bars. You can now run deeper into the corner & exit sooner. The car stays settled & balanced, easier to throttle steer.

To the OP I would keep the F55 & run & find the biggest springs your class will allow.....such as C5 Z06 rates.

 

Having spent this winter considering the situation, including comments made by TMyers, Gearhead Jim, CTD and others, I've reconsidered and decided to run my C6 with the F55 suspension (will be selling the ’88…… don’t need to have 6 vehicles for two drivers). Several things resonated and influenced my decision: (1) I’m going to put another set of tires on the car; I’m sure the 5 year old Kumhos in the rear weren’t helping They were hard as rocks compared to the year old front ones. (2) In looking at some autocross photos of my car, it’s true that there is considerable weight transfer on braking. I know that affected my ability to adequately get back on balance and power. (3) Will seek to replace the front spring with something more stiff, to offset the dive. I did learn from the C4 that the bigger the spring, the better the handling. Hopefully, that will apply to a C6, too. (4) Will put the Z06 front sway bar back on, as that really helped last season….. not sure about using the rear Z06 bar. Will experiment with that. (5) May drop the height….. even purchased lowering bolts, but will not go whole hog; will just set with the equivalent of lowering with stock bolts. (6) Will replace the front rotors, as between autocrossing and four track days, they’re ready. Any suggestions, if not stock? Will use Hawk High Performance pads which worked great last season…….. even at Buttonwillow and Thunderhill there was no fade. (7) Will investigate how to gain control over the automatics shifting points. The time between hitting the shift paddle and when it shifted got me in trouble at some autocrosses. Nothing more fascinating than going thru a slaloms and have the car bag a shift while the car is turning. (8) Since I’m 69 next month, I think the testosterone level has moderated some, so I hope I’m using my head more than my hormones.

I DO HAVE THREE MORE QUESTIONS: (1) Steering rack. I believe the Z51 and mine are different ratios. Having driven a Z51, it felt better (I know there were many differences between my car and the Z51, but the steering felt better). Any comments on whether there is a significant benefit in switching? (Wish we could make a change like on the C2 and C3’s by just selecting the quick steering hole.) (2) Camber/Caster and Toe-in? Front was -2 degrees, +5 ½ degrees (max’d out at that) and zero toe; rear was -1 ½ degrees and 1/8” Toe. (3) Any recommendations on tires. I liked the Kumho Ecsta XS (save for the age of the rears) and have run Toyo Proxes R888 on a C4 which worked well.

Many thanks for all of the comments. Jeff