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I just bought a 99 FRC a couple weeks ago and have had it on the track twice. The brake pedal has been very long (compared to previous Corvettes) since the first time out. Here's what has been done to try to resolve:
- new master cylinder last year (previous owner)
- new pads
- bled entire system
- checked wheel bearings
- checked for leaks, other obvious things
I don't see any smoking gun. I'm no stranger to the car or the track, and this one is baffling me. When the car is first started, the pedal will go almost to the floor and will pump up slightly. On the track, the pedal is consistent, but long (no piston knock back). With the car off, it will pump up better, but not as good as previous cars.
I've rented a C5 track car and it had a very similar issue. The owner said it's always done that and it's normal. I'm throwing the BS flag. There's gotta be something causing this...
Maybe air in the ABS unit? I know that you can't make this go away in the garage because you need to activate the ABS unit while bleeding using the Chevy tech tool.
Any similar occurrences or other thoughts? This is making me brake early, thus losing lap times. It's probably costing me 1+ second per lap until I'm completely confident...
I did everything you did and also didn't do the Tech 2 bleed and I've never solved it and simply learned to drive with it. I actually like it now. I have wilwood calipers and I did get better pedal feel after I couldn't get the 3 pistons lined up and brake fluid leaked out around the pistons as I was trying to get the pads in.
I am relatively new to corvettes, but I haven't noticed that the pedal in the corvettes I've driven is any longer than any other car. You say you've replaced the master cylinder and have NOT bleed the ABS? I really don't think it is any more complicated then that. How can you track down the problem with that left unresolved?
Sean,
Had a buddy have a similar problem (more of a soft pedal IIRC) after building his frc track car. After having everything apart i guess air found its way to the abs unit. He had to have the abs bled w/ the tech 2 and it solved it.
Sean,
Had a buddy have a similar problem (more of a soft pedal IIRC) after building his frc track car. After having everything apart i guess air found its way to the abs unit. He had to have the abs bled w/ the tech 2 and it solved it.
Had this happen several times over the years. Tech 2 fixes it.
ANDO,
The brakes have been bled numerous times and then the car driven to activate the abs and then rebleed. Poor man's method of brake bleeding. The tech 2 we are referring to cost about 2k dollars. So for those of us that would have to trailer the car to a dealership, unload, pay dealer prices, wait, reload car and then hope it is the problem, well cost to benefit ratio has never induced me to do that. Like I said, I've gotten to the point that I like the longer pedal.
Sean,
Had a buddy have a similar problem (more of a soft pedal IIRC) after building his frc track car. After having everything apart i guess air found its way to the abs unit. He had to have the abs bled w/ the tech 2 and it solved it.
Thanks for the insight. It's the only thing I could think of that hasn't been addressed yet. I guess it's time to slap it up on a trailer and haul it to the nearest dealer to bleed. That's a lot of Castrol SRF $$$ to play a hunch...
Anybody know of a non-Chevy deals in the south Miami area who has a Tech 2?
he did the same thing. drove the crap out of it/exercised the abs. The tech2 fixed it. and yes he had to exactly that...trailer it someone with a tech 2. IMO id do that in a heart beat....ur talking about the BRAKES.
If u have a problem you are not gonna notice the showing signs b/c you are already starting with a compromised system. Ull notice but it might be a total failure by the time u do.
If the abs is shut off from the rest of the hydraulic system (by valves) during normal brake operation (no need for abs activation) how would air in the abs block cause a long pedal?
I did have a friend who was getting air into the total system, which he would bleed out a caliper & it would come back. Turned out he had an air leak at one of the (many) abs brake line connections.
If the abs is shut off from the rest of the hydraulic system (by valves) during normal brake operation (no need for abs activation) how would air in the abs block cause a long pedal?
I did have a friend who was getting air into the total system, which he would bleed out a caliper & it would come back. Turned out he had an air leak at one of the (many) abs brake line connections.
Fixed the leak fixed the issue.
Froggy, how did he have an air leak and not a fluid leak? Upstream of the ABS unit? That would still be pressurized when the brake pedal is presses, no?
he did the same thing. drove the crap out of it/exercised the abs. The tech2 fixed it. and yes he had to exactly that...trailer it someone with a tech 2. IMO id do that in a heart beat....ur talking about the BRAKES.
If u have a problem you are not gonna notice the showing signs b/c you are already starting with a compromised system. Ull notice but it might be a total failure by the time u do.
You make a good point, I just wanna make sure my hunch is right. At $70 per quart and the hassle of trailering to the dealer (or somebody else with a tech 2), I wanted the opinions of you guys before chasing this.
If the abs is shut off from the rest of the hydraulic system (by valves) during normal brake operation (no need for abs activation) how would air in the abs block cause a long pedal?
I did have a friend who was getting air into the total system, which he would bleed out a caliper & it would come back. Turned out he had an air leak at one of the (many) abs brake line connections.
Fixed the leak fixed the issue.
I think I had something similar happen where one of the lines running into the ABS unit loosened, probably when I R&R'd the EBCM. But the brake fluid loss became pretty obvious.
Take every wheel off and have someone with a strong leg push the hell out of the pedal, look for any flex at all (caliper or spindle). I have never found a Tech2 necessary to bleed the brakes. Besides the extra effort of loading up a racecar and taking it to a dealership, I had my local dealership flash a new BCM for cheap and then kindly asked me not to bring the car back to them; the liability was something that scared them.
Soft pedal is due to air in the system. Long pedal is due to other things such as pad kick back or tapered pads. Soft pedal makes the brake pedal feel spongy while long pedal makes it feel like there is no brake at all until the pedal travels some distance and then you hit a firm point.
If your brake pads look like this you have tapered pads and you will get a long pedal.
The calipers are floating calipers and will tend to move around on their guide pins when you apply the brakes. This causes some twisting of the caliper on its mount resulting in the taper seen above. When you take your foot off the brake the pad retracts and may actually get knocked back if there is some looseness in the wheel bearing or some other runout. Then the caliper settles in its normal position. The next time you apply the brake the system has to fill the empty space between the pad and the rotor and you get a long pedal. You can bleed forever with all of the best fluids while doing the ABS Automated bleed and still not improve anything. All C5s have this issue with the stock brakes. My 97 had it the first time I took the car to a track when I had 2700 miles on it. By the end of the second session of the first day I had to pump the pedal like hell to get any brakes. When I took it to the dealer a couple of days later they said the pads (not the rotors) were warped and replaced all of the brake pads under warranty (this was when the only pads available were OEM pads).
To limit the impact of the taper you should flip the pads from one side of the car to the other at the end of each track day. This will compensate for the taper and cause the pad wear to even out (also extends pad life). When you first get on the brakes apply the pedal a little easier until the pads are against the rotors and then push harder. On old C5s make sure the brake hardware (pins, caliper brackets, etc) isn't worn/loose. Check your wheel hubs for play as that can cause excessive kick back.
One thing I learned from one of the guys who wrote the StopTech tech paper on rotor warping is as you approach a turn while your right foot is on the floor, take your left foot to tap the brake pedal a couple of times before you hit the brake to slow the car. This gets the caliper and pads back in place with the pads touching the rotor so when you go to hit the brake you have a firm pedal right then instead of halfway to the floor.
I always thought that using more aggressive pads reduced the tapering some small amount since I didn't have to press on the brake pedal as hard to get the car to slow the way I wanted it to slow.
Do all of these things and the car becomes easier to drive. Install a LG Motorsports G Stop kit as I did and the problem goes away. I installed the G Stop kit after I started having issues with the pedal going so low I couldn't heel/toe downshift because the brake pedal was so far below the gas pedal.
Bill
Last edited by Bill Dearborn; 07-13-2014 at 04:23 PM.
On my '04 Z I kept getting caliper spread and boiling my fluid on the stock calipers. I would have to double tap the brakes going into every corner in order to get any kind of pedal feel as Bill describes. I now no longer have to do that. Here is what I purchased to get a firm pedal every time.
-AP T1 front brake kit
-SKF front hubs
-Castrol SRF brake fluid (this helped a lot)
Now, the pedal is firm every time I go into a corner at Sebring and that track is very tough on brakes.
On my '04 Z I kept getting caliper spread and boiling my fluid on the stock calipers. I would have to double tap the brakes going into every corner in order to get any kind of pedal feel as Bill describes. I now no longer have to do that. Here is what I purchased to get a firm pedal every time.
-AP T1 front brake kit
-SKF front hubs
-Castrol SRF brake fluid (this helped a lot)
Now, the pedal is firm every time I go into a corner at Sebring and that track is very tough on brakes.
Great thoughts... I should have mentioned in the orignal post that I have Wilwood SL6 setup with thermlock pistons and SKF at all four corners.
Bill, your explainations are always top notch. Thanks for your contribution. As mentioned in the post above, I forgot to mention that I already have the Wilwood SL-6 setup with thermlock pistons. Not the best out there, but my last racecar had the same setup and didn't feel as soft.
You also mention soft/long differences. Based on your description, it feels soft. Long to me because it takes a whole lot more pedal travel and effort to stop, but you describe it well. It never feels firm... Just long/soft but consistent. Car still runs like a bat out of h3ll, but I know she has more in it.
Caliper spread
pad taper
wheel bearings
rubber brake lines
90% of problem and be solved by fixing above. When we raced C5's in SCCA T1 in the stock brake era we put new calipers in annually and used skf wheel bearings.
You can cycle out the abs without tech2 by threshold braking into abs on the track. Then bleed the brakes and all the air and stale fluid in the abs is gone.
07-13-2014, 10:26 AM
Long brake pedal - can't figure it out
Had this happen several times over the years. Tech 2 fixes it. 
