gkull

My track days have come to a halt because of lack of brakes. Today I exceeded the heat limitation during my second 30 minute run group which potentially could have cost me my whole car.

Back when I had smaller motors this never happened to me. I have a lightened 79 Vette equipped with all new stainless O-ring calipers, metalic ceramic pads, and HD rotors. Dot 4 higher temp fluid with all stainless braided lines.

Right at nearly the last lap my brakes started going to the floor and required a few quick pumps to get slowed. I thought we are near the end and i have some low brake turns and a straight to get them cooler. What a mistake.

I going about 90 mph into a sharp left turn with two Porsches behind me..........The petal goes to the floor. I know that pitching a car sideways really scrubs off speed. I did about 600 degrees of blue smoking rotations before I went off the track kind of backwards into the gravel traps. I still had the motor running and waited for other cars to go by before pulled back out and I limped down and pulled into the pits.

I have tomorrow as another full race day and I had to buy another set of Kumo's just an hour ago. I have to buy big brakes and air cooling before I can really ever compete again. Now the first sign of mush and I have to limp back to pits.

My 434 has exceeded the present car. I don't have a quick fix to this problem

Godfathers Ghost

There's a CF vender, Corvette enginering, I belive that has willwood kits with better rotors. Or I also know that Baer is developing a high end kit for C2&3. It is part of their Track Plus lineup. I also spoke with them about bigger setups (6 piston monoblock calipers, 14" two piece rotors) and one guy said they're not doing that but, I spoke with someone else there, higher up, and he said if there is enough demand, they will. Also said, it's not a strech to make them anyway once the other kit is done (duh, they allredy have almost every thing needed) so even if they don't do an actual kit, it won't cost much more to custom build one if I wanted. Not much more than the other, similier, 6 piston, 14" kits, obviously.

RobRace10

How much taper wear are you getting on the pads? We flip our pads every session on track, inside pad to the outside and outside pad to the inside on our race cars because of the wear. If the pads get tapered they will drag causing friction, heat and brake fade. Hook up some brake ducts as I would doubt any brake without proper cooling will boil the fluid on a closed wheel car.

Yellow73SB

I still think my insulated o-ring calipers with brake ducts will be fine.

0Corvette Engineering

Man george, that was close!
So they wouldn't even pump up again?

Now you know why I started this whole brake thing. I never got that that bad but I did spend a lot of time bleeding brakes
When I started there was no other option, now there are a few options. All pretty dang good.

no one makes a big piston 6 piston caliper, they are all pretty small pistons and would require a new master clyinder and rear caliper. The 4 piston calipers are really the optimum.

Take a pair of these with brake fluid recirculators and you will not have that problem again. The recirculators pump fluid through the caliper so every time you use the brake you pump cool fluid into the caliper and hot fluid out of the caliper.

I really believe in recirculators for performance applications. they are incredible, no more bleeding, ever again!

You can put them on any of the superlight calipers. expensive but worth it.

http://store.corvettengineering.com/...od&productId=4


This is my car, 13" rotors on VBP aluminum hubs.

Note the return lines where the bleeder screws should be.


Plumbing the valves and return lines.


But Brake ducts will probably help more than I want to admidt!

Keith

Restorod '79

Sorry to hear that man! It sounds like you were well prepped for some track time. I've made the same preps, along with ducts(primitive) but haven't run it hard yet. I'm going with Hawk HP plus. I'm always looking for that first sign of fade- it sucks! Keep us posted. Good luck and good job getting off without a wreck!

Keith- How does the circuit hold pressure in the caliper during braking?? Solenoid?

birdsmith

Any attempt at running a heavy car like a C3 Vette on a racetrack at sustained high speeds without some kind of substantial ducting to cool the brakes REGARDLESS of pad material is as you discovered an invitation to disaster. Presumably you were running at Reno/Fernley, a new track with lots of smooth runoff. Do that in turns one, three, five, or nine at Willow Springs and you'll be on your roof. Even with killer carbon pads you will encounter the fluid boiling/ pedal to floor situation unless you get enough cooling to the front brakes to keep the temperature below the boiling point- good pads work best at high temperatures but once you've passed the fluid's boiling point it's all moot. And a properly-maintained set of C3 brakes aren't that bad (they're actually just about the best feature of an otherwise positively antiquated chassis design)- Roger Penske and Mark Donohue won two consecutive Trans-Am titles in 1968 and '69 by bolting them onto Camaros.

rihwoods

There was a guy on the forum here who ran a Motown block roadracing a 72....he ran Wildwoods on the front lap after lap with no brake issues to speak of...
To bad he and other guys have left the forum....knowledge/experience lost...

Rich

Bangkok Dean

As others have said good thing you did not crash out. You will solve the problem and still get your race time in the season is young.

2000FRCZ19

have you thought about setting up a duct system. you could cut a few holes or mount them at the bottom of the nose and route them back. you can get the ones they use on the c5's or you can make some out of fiberglass and then attach a flex hose before the next track day.

TimAT

George, I'm surprised that you were able to get off the seat! I'd be puckered so tight I'd be carrying that seat with me for a week- and never have to use my hands!.

Great Save!

TheSkunkWorks

If you're using a stock master cylinder, have you considered adapting a 1 1/4" piston unit per Chevy Power Book recommendations for progressive loss of pedal height?

VegasJen

george, when i first read the title, i was getting ready to come yell at someone. then i found out it was you and you were talking about 30 minutes into the session.
for the normal driving schmoes, our brakes are plenty good enough but start really stretching them out on a track and you do find the weak spot quickly. and as you found out, it is overheating.
i did pretty much the exact same thing about 20 minutes into a session at SOWS a couple years ago. very unpleasant to hear the bottom of a vette hitting raw desert... again and again and again! since then i contrived a makeshift ducting system with some old pool hose and a couple funnels. it's better than nothing but it's way too small and they still get hot by the end of a session.
unfortunately, i will never be convinced the solution is anything other than a light, throwaway track car like an old datsun or MR2. making a c3 into a good track car is the epitome of throwing good money after bad.

hensen1954

I thought racers used brake pedal activated water spray to stay cool ??

Guru_4_hire

You could send a bunch of brake pads to swaintech and have them ceramic coated.......

http://www.swaintech.com/store.asp?pid=10971

Its a thought.

Guru_4_hire

I have been thinking about this as I would like to get into racing of some kind.

I am thinking an 84-90 AE86 toyota corolla with the 4AGE motor, and you can find them for a reasonable amount of money.

2200lbs and 115hp.

bb69

I had a similar incident on Monday at Gingerman. I started getting longer and longer pedal travel. I finally brought the car in to the pits. I still had brakes, but a long pedal. I let the car cool down, and when I went to pull it to a spot to bleed the brakes, pedal again went to the floor and the only brakes I had were on the rear. I had bled the system just before the event, but I don't think I ran enough fluid through it. When I bled them, I got some bubbles at all 4 corners. After that, the brakes were fine for the rest of the day. Now, I have a better understanding for why people use different colored fluids. For reference, I am using Hawk HP Plus pads and Valvoline synthetic fluid. This was the first time I had ever experienced a problem using this setup. Of course, my sessions are only about 15-20 minutes at the most.

Ken

gkull

I'm in a rush to get my new 255/45/17 Kumo's mounted. I will answer each of you. My front KDW's are shredded with cords showing. The real problem is I have never gon this fast ever before and the brakes are not up to the test. The air temp was only in the low 50's. That is why they could last about 30 minutes. then of course each lap I was learning and being progressively harder on the car.

zwede

I had the same problem with my 96 Z28. Pedal to floor followed by bad noises as I went offroading.

Next time I switched to performance friction pads and Castrol LMA fluid. The pedal got a little mushy at the end of the session but I never lost the brakes. So pads+fluid makes a big difference, but I think ducting would help even more.

69autoXr

Track days = brake cooling

Ken, Gingerman is very hard on brakes. A cooling duct setup should help you. I don't even have a setup with a duct going to the center of the rotors, just a simple duct pointing at the caliper made a big difference.