sothpaw2

Hi Everyone,

Had some issues w/the C5Z brakes at my 1st event for this year at Summit last week. Even though I completely flushed the system (used 1.5 liter of Castrol SRF), by session #2 of the 1st day the pedal started to get low. My set up, mind you, is stock C5Z pads and stock otherwise. I was running Nitto R-II tires on all 4 corners for the 1st time but keeping my braking zones long to keep heat out of the brakes as much as possible. The day wasn't hot--only 70ish for a high.

The funny thing is that I didn't feel any fade and it didn't get any worse during session and the brakes always grabbed great--pedal just low for my liking & compared to when I started out.

For day 2, I bought some new fluid (? in my mind about the SRF since container said it was made in 2007--told this shouldn't be an issue). Flushing just 2 fronts helped a lot & I got 2 good sessions. Then, when I went to start session #3 of day 2, the pedal was low again.

It seems like the heat from the rotors in the paddock is just too much even for SRF and is cooking the fluid while I wait!! I'm just really surprised that stock C5Z pads would do this--I'd think they'd fade before overheating the fluid & that a pad upgrade would pump even more heat into the system. BTW, I did a good cool down lap every session w/ zero braking plus moved the car a few inches back after initial cool to put the pads on a diff. rotor spot.

Had a good 'vette mechanic who helps others w/HPDE stuff look over the brakes and he sees nothing wrong with it and even thought the pedal position was not so terrible (but admits it's a little low). He did say that the pads were close to or just overheated but not bad at all--has seen some turn color and these did not; wear was bad though since these are done after just 2 events (4 days).

Question for the forum: I ordered brake cooling ducts & will upgrade to Carbo XP8 all around to fix this problem. On a budget, should I be just doing SS caliper pistons & ss brake lines instead??? I figured the cooling will help wheel bearing life & rotor life too.

Appreciate any opinions,

Andy

VetteDrmr

My guess: there's nothing wrong with the fluid; you're experiencing pad taper. Brakes work fine, pedal just gets a bit lower. If you leave the pads on the car and drive it on the street the pedal will come back up over a few hundred street miles.

HTH, and have a good one,
Mike

02impactblue

Andy,

I was at Summit Mon & Tues with PCA driving the blue c5z06. Your problem is most likely pad taper. The stock pads will over heat and taper very quickly causing a long pedal. Did you try double pumping the pedal? This usually produces a very hard and high pedal on the second pump and is a good indication of tapered pads. I always do a very quick double pump before most long brake zones to provide the confidence needed to go deep in the brake zone. This is a very common issue with the stock brakes. If double pumping does not produce a high hard pedal then you could have other issues such as boiled fluid or air in the system.

I would recommend the xp10 front xp8 rear for starters and upgrade as you get faster. Since your running r-comps, the xp12/10 combo would be suitable as well. Good Luck!

Rob

Bill Dearborn

I agree on the pad tapering. Pull the front pads and check to see if they are tapered. You can flip them from driver side to passenger side to counter the wear.

Bill

sothpaw2

Rob,

I think we went to the same 'vette mechanic. Saw you in one of my sessions; my brake issues really just ate at my confidence; really want to be sure the thing's going to stop at these speeds.

If I switch to Carbo's will they taper too? I see the XP10/8 as a proven combo but will the 10 eat front rotors and last not as long as XP8? I'm just looking to fix this blasted pedal issue, not improve the brake performance. I thought the stock pads grabbed amazingly well and don't need any more stopping power for now--just a high pedal & confidence that the pedal will not go away at a bad time!!

Thanks guys!

sothpaw2

Bill--Sounds like a good idea but more work if every other session! Do you think Carbo's will help or will I need to swap them back & forth also??

Thanks

longdaddy

carbotechs will taper just as much as anything else in my experience. the only fix is real calipers or backing way off (no fun) by the way, get ready for your rotors to crack once you go to harder pads... make a habit of bringing at least one spare front rotor with you to the track... I wish someone had told me that before I blew up a rotor 300 miles away from home...

Last C5

Yes, the XP10/8 combo is the way to go and yes they will taper too.
As long as you are running stock calipers you can expect tapering from any pad you run. Carbotechs are fairly easy on rotors. I went the stainless pistons and lines route, but didn't stop the tapering until I switched to SSBC Tri Power calipers.

CHJ In Virginia

I will add my $0.02 worth here. The cooling ducts will do more than about anything else other than a high temp fluid change to improve your brake performance. If you are experiencing unacceptable pad taper, there is only one way to fix it - new calipers. Once they are spread they are junk ! You can buy new or find a set of takeoffs here on the forum. You will eventually be back at the same place requiring new calipers to get acceptable pad life. The best long term solution is to upgrade to something like the LG G Stop kit. It has Wilwood calipers, much thicker pads that cost a lot less than the Carbotek. More $ up front but a much better solution long term.

AU N EGL

pad taper from caliper spread.

Time to buy new calipers

sothpaw2

?? So the cooling ducts while helping w/rotor life etc. will not help at all w/this problem? Let's assume I don't care about more braking performance than I have now & just want a solid pedal & pads that last more than 2 events.

I'll pull a front wheel & pull the pads. If they are tapered, will new carbo pads taper (thus ruining pedal feel) in 2 sessions or can I at least get a clean event out of them? How long do they take to taper?

I could also order new calipers from GM (pre-bankruptcy ) but how common is this--I thought many used the stock calipers even w/ extreme pads? I'd rather invest in a better caliper that used the same sized rotor & was just a bolt-in fix.

Thanks guys--I do bring extra rotors although not rears yet. The stock Z06 pads don't eat rotors so it's not so much an issue.

argonaut

Sothpaw - what do you mean "keeping my braking zones long to keep heat out of the brakes as much as possible"?

I have always been instructed to make fast, hard brakes and that keeping pressure on the brake pedal for more than just a few moments ends up putting more heat into the system.

I have 4 track days on Nitto R2s with Carbotech 10/8, SS lines, ATE blue, DRM ducts, stock calipers and centric rotors. I'm a fairly aggressive intermediate and have had no brake issues thus far. I flipped the pads after day 2 (they were slightly tapered) and pulled them off after day 4 and they are nearly flat (very little taper). So it seems if I keep flipping them the pad life should be decent.

One more thought - I wouldn't worry about the pads 'eating' the rotors, you will crack them long before wearing them out.

AU N EGL

I put on new calipers each winter or about each 15 events.

A StopTech front set up with stock C5 front calipers on the rear is a viable option

sothpaw2

I mean I started braking long before the first marker in T1 when coming down from 130mph to 45-50 mph. I kept on the brakes all the way to turn point. For T5 & T10 there really isn't a landmark for where to start braking so I just started where I normally would regardless of brake issues--speeds here not nearly so high. But I didn't try to wait until the last second and really challenge the brakes. I wanted to know the pedal was not going to the floor before I got too close to the corner.

sothpaw2

I haven't even done 1/2 that many events on this car yet. I'll have to look into the StopTech offerings and see what they have for stock size rotors. Not interested in bigger rotors just want pedal higher or at least to know it's not going away on me.

0Vector Vette

I sell an AP Racing brake kit for the C5 but it requires a 14" rotor. I am pretty sure that Stoptech and Brembo will also. If you don't want to change rotor size, and therefore wheels as well, I think your options are limited. I would say buy new GM calipers, add cooling ducts, SS brake lines, and upgrade pads to Cobalt Friction. Give me a call if interested in a better pad.
Robert Finlayson
Performance AFX Motorsports
630-844-0089

tracjunkie914

does stoptech offer a front ST40 kit for the C5 with a 13" rotor for 17"wheels?

Adam@Amp'dAutosport.com

Andy,you should go xp10 and xp8.

Jason

You get used to it after awhile.

sothpaw2

Are the XP10's done after day4?? Wear on those seems to very a lot.
Your combo is the proven one I've seen on here but because of budget, I thought I'd do the SS line & associated flush later. I just finished flushing/bleeding the thing so figured do the lines at the next flush.

I wonder though if your calipers are good & mine are shot & should be replaced instead of doing the brake cooling now. What doesn't fit in my mind is that the brakes (pedal) did get better as soon as I put in new fluid in the fronts. If this was just a pad issue I don't see how that's possible. That's why I thought cooling & pads that will not be borderline overheating are the priority.

Thanks for all your responses, I'm listening!