69autoXr

NCCC Michigan region is running several High Speed autocrosses this year at Waterford, Gingerman, and Grattan. We did the Waterford events Monday, and I didn't feel particularly confident in my brakes (factory power assisted). I'm not using performance pads, and I'm using Valvoline SynPower (?, gold bottle) fluid. Does anyone have suggestions for pads and fluid? Would I have to do anything to my rotors, or could I just put the performance pads in without turning them? Fronts and rears, or just fronts? Will it change my pedal feel? Right now the car stops ok for parking lots, but the brake pedal goes down past the gas pedal making heel and toe at the track difficult (but possible).


Thanks in advance.


[Modified by 69autoXr, 8:58 AM 6/4/2004]

Richin Chicago

Other than adding some stailess steel brake lines and bleeding your system I'm not sure that a higher heat pad would help. If you are running the typical high speed autocross (one lap on the track?) you really don't have the time to get pads or tires up to much temperature. Maybe you are getting enough practice laps so the pads are going past their heat range? You could go to PFC Z pads and change to Superblue brake fluid but I'm not sure how much difference you would see. Maybe some others can give you more specific advice.

Jim 47

The thing that got my attention was "the brake pedal goes down past the gas pedal"

This is NOT GOOD. It could be caused by, tapering pads, bad/expanding flexable brake lines, or air in your brake system. Whatever it is FIX IT.

If it were me, I would: install SS brakes lines, install new rotors and pads, install some good high temp brake fluid, bleading the brakes to get all the air out, and burnish and bed in the rotors and pads before the event.

The information you have provided is too sketchy to know the condition of your pads, rotors, calipers, lines, or fluid, so if some of these things are new, then just replace the old stuff. But make sure you get good dry air-free fluid into your system.

The Brake Pedal should NOT be going below your gas pedal if your brake system is in good working order.

Jim Helm

VetteDrmr

There's something basically wrong with your system. If possible, get a friend to step on the brake pedal (with the engine running, if possible) while the car's suspended in the air with the wheels off. That way you can look for leaks, expanding flex lines, etc.

One thing: once you got a firm pedal, did the brakes work as expected? Or were they still weak and you just bottomed out the pedal itself?

HTH, and have a good one,
Mike

69autoXr

Thanks for the replies. To address some of the questions, the pads are in good shape, ie not tapered nor flexing, I have stainless braided lines, new power booster and the rotors are in good shape, and the calipers are new VBP "extreme duty" O-ring calipers. It's not that the car doesn't stop, the pedal is just too low to make heel and toe easy. It doesn't go all the way to the floor though. The pedal firms up after two pumps when the engine is off. However like I said the brake pedal is not confidence inspiring on the high speed autocrosses, when I need to haul it down from 100 mph, rather than 50 like in a parking lot. It's possible that this is just how the old car's brakes are, but putting in aggressive pads might help at the tracks. And it is one run at a time, so I would need a performance pad that works without having to build alot of heat like in a lapping situation.

Richin Chicago

Sounds like air somewhere. It's particularly telling that the pedal comes up with a couple of pumps.

I also had a thought on pads. I used to run EBC green pads. They were great cold and could even stand my early track days of running until I really stayed out for longer sessions and drove harder. It could be a really good pad for what you are doing. take a look at: http://www.tirerack.com

Also you might want to think about joining our Gingerman track day on June 28th. You'll all kinds of combinations and drivng skill levels.
http://www.northshorecorvetteclub.or...gingerman.html




[Modified by Richin Chicago, 12:41 PM 6/3/2004]

VetteDrmr

Could you have some rotor runout that's introducing air into the calipers? I've read (never lived with, or worked on directly) that the 4-piston calipers on the C3s were really sensitive to rotor runout, and that they could actually get air pumped back into the system. Again, I'm speaking from a fair amount of ignorance, but it's something to think about.

HTH, and have a good one,
Mike

BrianCunningham

I've been running Performance Friction Pads and FORD ( yes he said Ford ) motorsport brake fluid. I boiled them at Gingerman though the convinced me to install brake ducts.

Hawk Pads are better, but they're rough on rotors. Most road racers consider them a "consumable item".

Nice to hear they're stepping up the high speed events there!


[Modified by BrianCunningham, 5:39 PM 6/3/2004]

Solid LT1

You should talk with Red Vette Racer about your O-ring calipers. The people answering here are C4/5 guys who are not familiar with our cars. Red Vette and I have both expressed our problems with O-ring calipers in the C3 forum. The J-56 heat insulated pistons were once carried by Vette Brakes and perhaps they still have them avaliable. Stainless Steel Brake Corp also once carried J-56 parts for our cars. I use Hawk HPS pads in my LT-1, they work very well! The Performance Friction pads were very inconsistent for me at lower speed autocross racing but, may be ok for high speed if there are multiple laps involved in your runs. Vette Brakes sells the HPS Hawk pads and you can modify your calipers to the dual pin J-56 type to get better performance by reducing backing plate deflection of the stock pads. I have covered the subject before and I will do it again, you are wasting your time if you do not remove the old friction material embeded into the rotor surfaces when you try to change pads. You can buy a $20-40 right angle die grinder and use 3M prep pads to remove the old pad material and prep the rotors for break-in with the new pads (they WILL require a break-in session and Hawk Brakes gives a very specific detail of the type of break-in proceedure they want followed with their pads in every box.) I use Ford brake fliud just like I have with every Vette I have ever raced, including a SCCA/IMSA Trans Am/GTO Corvette that regularly approached speeds in excess of 180MPH at Riverside Int'l Race Track in the late 70's early 80's (with Ford brake fluid, trick rotors, and "stock" J-56 brake calipers, they work WELL!) One of the best sources for pads for your Vette would be Andy Porterfield in Los Angeles (he has raced c1/2/3/4&5 Corvettes.) porterfield has pads and rotors for your car you may want to ask him for the best set-up. Here is the link: http://www.porterfield-brakes.com/
DO YOURSELF A BIG FAVOR, check and minimize your rotor runout, can those O-ring brakes and put some Ford fluid in your brake system, break in your pads correctly and go and stop like He**!

James G

1. Performance Friction pads.
2. Motul fluid or Red Line fluid
3. Titanium heat shields for the pads
4. front brake ducts ( to the rotors )
5. Just say NO to drilled rotors
Good to go


[Modified by James G, 1:19 PM 6/4/2004]

Red Guts

(me, too)