gkull

I'm not sure what HPDE means.

Cornering speed really comes down to the weight of the car and the tires.

If our cars were the same weight and the alignment setting were using the whole face of the tire. Things like springs and shocks are just a minor detail. What it would really come down to is tires.

I had 255/17 KDW fronts and 315/17's dunlop's out back. Quite often I was using the whole width of the track. Using late apex or early apex depending on the turn doing a 4 wheel drift and exiting on the outside edge. I was driving hard enough to destroy my front tires and the rears are about gone.

After the off road excursion the chief steward came strolling through the pits and talked to the Porsche guys about my driving. You can be banned for aggressive driving. Not even for a wreck with another car. Just you alone driving like an idiot and your gone for a year. these guys are out there in cars that some of them are more than a million dollars.

That steward never came and talked to me or the race team that I was there with. So the Porsche must have said that I was doing a good job of driving. Another thing - C-5's are very slow in the straights. I blow by them. That is why C-3 brakes and wimpy Wilwoods do not last.

VegasJen

HPDE=high performance driving event, i.e. non-competition (supposedly)
i still think guru has the right idea. just because it's cheap to buy, mod and replace doesn't mean it's junk. there's more than one reason that toyota et al produce 1,000,000+ cars a year.
george, i'm not telling you what to do with your car but i think i'd be right if i guessed you would be heartbroken if you wadded it up. as would everyone else on the forum.
the fact is that any time you put tires on a road course and actually drive at 100% of either you or your car's ability, that is a very real possibility.
one other thought, i just recently read an article in C&D that compared six high performance cars, two of which were the new Z06 and a kit car called an atom. the atom weighed half of what the Z weighed and had half the power. some would reason that it's performance should be pretty close given it was half the car but the track performance swung heavily in favor of the little atom, by 3 seconds at buttonwillow.
don't get me wrong folks, i still love our antique cars but they will never be more than a good GT car now without modifying it to the point that it is no longer a c3.

gkull

I've also thought the same thing. I've been looking for older real race cars. Not street cars converted into race cars. Every once in awhile you hear about these retired different class cars. Some of those 2000 cc open wheel things look like fun. You could really do some good lap times in an older Formula Atlantic.

For a few years the track record at Sears Point was held by a nut in a death machine unlimited Gokart.

The Speed channel was filming the whole 4 day Historic Motor sports Association event. I was only allowed to run on thursday and friday in the Red run group with the faster cars who were doing their test and tune getting ready for qualifying and full race event on Sat and Sunday

bb69

At our event last Monday we had a guy come out with an old ASA car. It's basically a lower level Nextel Cup car. He said he paid $5000 for it. Of course, he had to rebuild the whole front end so it would turn right as well as left, but the total investment was pretty low. The car sounded mean, looked like a blast to drive, and with the serious hardware it had, it could run forever on the track. It had coolers for everything, 6 piston calipers, full floating hubs, etc. It may be a little more expensive than some of the imports, but it sure was cool.

Ken

68427

I've had pretty good luck with stock brakes, good fluid & pads and cooling. I was running events with ATE super blue fluid, street tires and Porterfield R4 race compound pads (which are terrible until warm) and loosing my brakes after about 15 min.

Then, based on the recommendations from Porterfield I bought Raybestos newest race compound, 3" cooling ducts and Khumo 710 tires. What a difference, braking performance with the new tires was amazing and the new pads with cooling ducts last an entire 20 min session w/o problems. Strangly enough, the pads also grabbed great when cold (!?!), but the iron dust stained my driveway orange so they are not too practical for the street unless you have an unlimited supply of rotors.

Unfortunately (or maybe not), this was not in my C3, but in my transaxle equiped Alfa Milano which would run mid-pack with the C5s at our HDPEs. I mentioned transaxle because the rear brakes were mounted inboard and with the pads, sticky rubber and aggressive driving I found I could outbrake most other street cars. That is until the right side rear hub failed under heavy braking, putting me immediately off-road into a ditch which collapsed the right front suspension ruining the car. So there is something to be said for tracking inexpensive, sorta-disposable cars - as opposed to tracking hugely expensive appreciating classics.

Anyway, I put Willwood billet superlights on the front of the Vette with 13" rotors and am using the GM light truck mc with the slightly larger bore per the GM chassis book and have a rock hard pedal all the time.

Guru_4_hire

One of the formula atlantic motor is a race prepped version of the 4AG motor in the toyota. Toyota replaced cosworth as motor supplier.

turtlevette

Are we talking about beater toyota race cars or C3 brakes?

Guru_4_hire

It seems Gkull wants something a step up from willwoods. That is a pretty small group of products, when you get above their higher end stuff.

45ACP

Lucky? No, absolutely not. Having a plan B is the difference between a guy out bombing around the track and a fellow that is driving the car. Pitching that bitch sideways was a nice piece of work.

In case you aren't aware of it, blue colored oxidation from heat on cast iron = about 600 degrees.

DaveL82

I went with Wilwoods (4 piston superlites) up front on my car to reduce unsprung weight and provide the lastest in capliper sealing technology. My next step is adding cooling to the brakes since extreme heat is the real killer during a track day.

Can you make the standard corvette calipers work? Yes you can but you still are left with a heavy caliper and seal technology not on par with the latest caliper designs. Stock calipers and rotors do need forced cooling during track events if pushed hard as do any brake system. Or don't be wimp and stay off the brakes

There is always a solution to the problem even using stock brakes.

72 RAY

gkull,
I have the wilwood GNIII 6-pistons with thermlock cups up front. I went to a 12.2 rotor & hat. I was using 15" wheels and could not go bigger. And believe it or not stock calipers in the rear. I also have the 434 sbc. This setup did work OK with some (home dicky bubba brake duct) blowing on the rotor.
I quit tracking the vette for now and have since bought a dedicated race car and am competing using a custom designed brake system from The Brake Man. If I where you I would give them a call and talk to Bobby. They will spell out exactly what you need for your current car. Meaning they tell you the pedal ratio, master cylinder size, caliper front & rear, and pads for your aplication. This is all based on your car's Weight ratios. Meaning front to rear weight. Very heavy duty and no messing around. Consistent pedal every single time.
Worth a Phone call.
Later!

enkeivette

This is probably a stupid question, but is there any way to use the front C3 calipers in the rear?

69427

Yes, but I'll confess no personal experience doing it. I know some guys who did it while running in the IMSA series years ago. With the reduced front weight of their car, and the BIG rear tires under the Greenwood type flairs, the change of bias ratio seemed to work. (I'm assuming they also added an adjustable proportioning valve to tweak things.)

Van Steel

Must have been quit the scare.... Glad to hear no damage...

Reviewing the posts to your wild ride, you may want to consider these ideas. We have worked with several vintage racers, who have had the same issues. A progressive brake pedal, tall early, long late...

Calipers:
The VBP ceramic insulator, O Ring seal, Stainless Steel Sleeved Calipers work quite well. The insulators reduce the heat transferred from the pads to the piston to the fluid. Rebuild able, original in appearance, direct bolt on. We have measured 1300 degrees of spike temps and our mean temps were in the 800 degree range.

Brake Pads:
We are fond of the Hawk brand of friction material. We found in the older Corvettes, the Hawk HT10 material delivers great stopping power, works very well in temperatures up to 1300 degrees. The down side, because of the aggressive torque, rotor life is reduced. The Hawk 9012 Blue is the most popular SCCA pad, work wells, is friendly to the rotor, plus they are reasonablely priced. The 9012 Blue’s effective temperature range is up to 1000 degrees.

I would encourage a DOT 5 fluid based on your description. You may consider spot bleeding between sessions to assure of good fluid, no vapors in the calipers and a tall pedal.

Air Ducts:
Certainly would help. Feed the rotors from the inside (center) and force the air out works the best.
Hope this helps.

Yellow73SB

Thats basically what I am running

Bimmervet

I am glad I read your post, my car is set up like yours, VBP brakes set up for auto cross. Class winner every auto cross entered. My concern is high speed track. Went to Elkhart Lake with my sons modified 3 series BMW. He ran 3- 45 min sessions in 2 days. No problems, brakes never failed. Wants me to take the Vett and I was concerned how my brakes would work. (Vette has a built automatic which does not help for high speed events. )No problem, I will stick to the auto cross and drive my sons car at Elkhardt.
Glad I read this, when I am done paying for weddings and college maybe I will change the brakes. I have had the car for 18 years. Every couple years I buy a treat for the Vett, I just bought 17" wheels with 275x40x17 and Hooker Sidemount Hedders.
Putting it all on this weekend.
Thanks!!

69autoXr

Who do you autocross with? SCCA, NCCC, etc?

Bimmervet

Tri State, Windy City BMW, Non-NCCC Corvette Club, some N.C.C.C.
I do not care for the Multi Events in NCCC.
I was the past competition director for N.R.L. Corvette Club. Former Tri State Director.

gkull

So far the plan is to buy air ducts and 3 inch hose from www.colemanracing.com my existing calipers are going to be modified to use ceramic end piston pucks as a thermal barrier. I’m buying 600 degree racing brake fluid for just over cost which is nearly $20 per pint. The whole system is going to be flushed and cleaned.

This is part of an article about Dot 3,4,&5 brake fluid. This 600 degree racing stuff alone would cure most peoples problems. I managed to boil Dot 4

DOT 4 glycol based fluid has a higher boiling point (446F) than DOT 3 (401F), and both fluids will exhibit a reduced boiling point as water content increases. DOT 5 in its pure state offers a higher boiling point (500F) however if water got into the system, and a big globule found its way into a caliper, the water would start to boil at 212F causing a vapor lock condition [possible brake failure -ed.]. By contrast, DOT 3 fluid with 3% water content would still exhibit a boiling point of 300F. Silicone fluids also exhibit a 3 times greater propensity to dissolve air and other gasses which can lead to a "spongy pedal" and reduced braking at high altitudes.

DOT 3 and DOT 4 fluids are mutually compatible, the major disadvantage of such a mix being a lowered boiling point. In an emergency, it'll do. Silicone fluid will not mix, but will float on top. From a lubricity standpoint, neither fluids are outstanding, though silicones will exhibit a more stable viscosity index in extreme temperatures, which is why the US Army likes silicone fluids. Since few of us ride at temperatures very much below freezing, let alone at 40 below zero, silicone's low temperature advantage won't be apparent. Neither fluids will reduce stopping distances.

gkull

Thank you for the time to write all this out. I've got the 3 inch ducting on order