kedvesh

BLUF: Rebuild my calipers or not?

DISCUSSION:

HPDEs and track days are a great hobby. I am a race crew and driver of one who drives to and from the track with my tools and tires in tow. I’ve never done more than 5 weekends a year of HPDE or track day time. Two to three weekends a year is more normal and is what I usually plan for. It seems that of the tracks I've driven (incl., VIR, Road Atlanta, Barber, Summit Point), the hardest ones on my car have been Sebring and Road America.

I recently returned from another very fun weekend at Road America...played around with some ACR Vipers and the like...pretty good weather…could hang with the normal Viper crowd on the track, but not with those race-prep’d ACR types.

Unfortunately, I let my front brake pads (Carbotech XP12s) get too thin and as a result, ended up putting way too much heat into both of the front stock-style C5Z06 calipers, so much so that I turned the piston dust boots to ash—I didn’t melt them off, I burned them off of both calipers. Even the lower end of the middle outside tab of one of the calipers turned from red to ash white. Looks like the rubber boots around the caliper pins were also affected. Plus, the right caliper was leaking fluid from somewhere. I think I may have killed my calipers.

For the future, I could just use a new set of front pads every day when at Road America, which I am finding to be a much more brake-intensive place than VIR (my previous “home” track). At $200+ a set, that kind of plan can make it an expensive weekend. (I thought I got away from new pads each day when I made the switch to purpose track pads vice HP street! BTW, I use ATE Typ 200 or ATE Superblue brake fluid.)

Whatever I do WRT pad and/or fluid usage, I definitely need to do something with the existing calipers. I want to keep use of my stock C5 coupe wheels for the street and my stock C5Z06 wheels for the track, both 17”-F, 18”-R, as well as the use of “cheap” stock blanks for rotors. Here are some options on the table:

- Rebuild calipers with SS pistons
- Have someone else rebuild calipers with SS pistons
- Buy already rebuilt calipers with SS pistons
- Rebuild calipers w/stock components
- Buy new stock C5 calipers (no SS pistons)
- Buy new stock C6 calipers (non-Z06) (no SS pistons)
- Buy new stock C6 calipers and rebuild, have someone rebuild them with or buy them already rebuilt with SS pistons.
- Buy an upgraded system that will still work with 17” front stock wheels (both coupe and Z06) (Wilwood Superlite?)
- Get someone to sponsor me and go whole hog on brakes! ;-) (just joking…this option will never happen for me)

So, what say ye to the options I’ve listed? Thanks in advance for the constructive comments!

sperkins

It's not uncomon to turn the dust boots to ash. They really are as they're called - just dusts boots. Mine have been burned through for many events and though I really need to swap them, it's not a big deal. Some guys remove the dust boots completely, but I like the fact that they protect the o-ring/seal inside the piston - especially when pushing the pistons back in their bores to put in new pads (pad material can stick to the sides of the piston and tear the seal when pushed back in).

What's not good is the leaking fluid you described. You need to get to the bottom of that immediately. Rebuilding the stock calipers is a breeze and it doesn't take any more time or work to upgrade to SS pistons from DRM.

Contact me if you're interested in upgrading to Wilwood four or six piston calipers that fit under the stock C5Z wheels (both 17" and 18") and use stock rotors.

CHJ In Virginia

I had the same problem and finally went with the LG Gstop Wilwood kit. 6 piston calipers that will fit under your stock Z06 17" wheels and use stock rotors. You will save much of the cost of the kit in the first year in pad costs. Wilwood H race pads are MUCH cheaper than Carbotek and last 3 times as long. They are over twice as thick as stock configuration pads. Bonus extra - no soft pedal from pad taper !!

John Shiels

Dust boots what are they?

Get some SS pistons from DRM, rebuild kit, and some brake ducting if you don't have it. You can also add spacers and thermal shields for whent he pads wear down. Wilwood kit is great also.

RX-Ben

Are you sure you were leaking brake fluid? From where? Did your pedal feel like garbage?

You can get great pads for $163/set (Raybestos ST-43 or whatever flavor you want).

Dust boots are optional and short-lived.

Use SS pistons.

Make sure you still have grease in the slide pins and use is high temp stuff.

davidfarmer

if you really think you damaged the calipers, you need to inspect the pistons to make sure they are still true (I've melted/deformed them in a single day at CMP) and make sure the caliper is still square. They tend to "open up" over time, since they have to real structure (like a monoblock does). If those two things are OK, I'd rebuild them. If not, obviously replace them. You can get Ti or SS shims to put behind your inner pads, or run SS pistons. Either will work at protecting your fluid slightly, but will not protect against caliper deformation. You need a LOT of cooling to protect the OEM calipers if you are running long sessions at a high braking track.

Han Solo

Sounds like lack of cooling. I have used up a set of pads in 7 sessions once but the reason was running with no cooling ducts. I had a problem with one duct and just tore them both off and kept playing. Once I got new brakes and put my ducts back on I had no more trouble.

RX-Ben

Hmm. I have run with battered hose or none at all and have not noticed a difference in wear or performance.

John Shiels

not going fast enough

rfn026

I've started using temp strips (instead of rotor paint) recently and I love them.


You'll notice I wasn't going too fast that day. I promise to do better in the future.

I also had my caliper pistons modified for extra cooling. I'll post those soon

Richard Newton
Brake Fluid Column

rfn026

Here are my modified caliper pistons.



Richard Newton

darguy

I have essentially the same setup as you do - C5 stock calipers, Carbotech XP12's Quantum/DRM cooling ducts, ss lines & ATE Dot 4 fluid under stock C5Z wheels. This last weekend I wore my front brakes down to nothing after 5 track sessions (3x 20 min each) on a notorious hard-on-brakes track. My dust boots are long gone & my slider pin covers are pretty much toast as well. By the end of each day the pedal would get pretty long & I'd bleed the brakes.

I'm looking at the AP Racing T1 system from Hardbar, but would also consider the Wilwood SL6R Superlites. Ideally, I'd like to be able to swap pads at the track without having to remove the calipers - and would like to be able to get through a whole day without having the pedal go long. I'm guessing you're looking for the same.

RX-Ben

What tires are you using and what hp?

kedvesh

Yep; r-side caliper was leaking fluid from someplace; was all gunked up with fluid and grime by the end of Sunday. Don't think it was from around the pistons...probably from the bleed screw I just had replaced on the caliper (serviced by a local race shop). No evidence of my SS brake lines having busted. May replace them nonetheless. Pedal did feel like garbage...lots of travel by the end of Day #2. I had worn the front pads to virtually nothing, which put a lot of heat into the system. Think I had boiled the otherwise capable ATE fluid because of it.

Have never tried Raybestos ST-43 pads. How do they compare to Carbotech XP-12s?

Yep; SS pistons are in my future!

Def will regrease slide pins with high temp stuff.

kedvesh

Thanks for the contact.info offer!

RX-Ben

I have not used the Carbotechs, but ST-45s are excellent, as are the ST-41s (popular NASCAR pad).

kedvesh

Thanks for the advice!

kedvesh

Thanks for the advice!

kedvesh

I'm concerned about the calipers because I put so much heat into the system by allowing my pads to go to almost nothing that I also discolored the red paint of the OEM C5Z06 calipers in several areas. So your concern over caliper deformation definitely is noteworthy. Thus, also the reason I am thinking about rebuilding them with SS pistons, if only to see if there is any damage (other than the dust boots turning to ash ).


I do have front brake ducting to both front assemblies, and that has definitely helped with braking on the track. Maybe one or both ducts are blocked. I'll have to check.

No pun intended (or maybe yes, I do!), but all of this boils down to my primary dependence on one set of front track-caliber brake pads to last me the entire weekend at Road America, as they have in the past. Of course, I wasn't trying to play with a slew of ACR vipers in the past at RA. And, it never got above 60 deg F in the past when I was out there. (It was in the upper 60s and 70s and sunny last weekend!) I probably was more agressive because of it. After resolving my caliper health, the easiest (not necessarily the most cost effective) thing to do would be to run new pads each day. But, as mentioned in my OP, that can get expensive.

kedvesh

Thanks for the diagnostic ideas! Can't see the pics right now...connectivity issues...will check later.