[NLZN21]

Thurs night I installed pre-bedded xp10/8's to new rotors (did the material transfer process, much quicker with the prebed pads) and with a fresh swap to RBF 600.
Event started Saturday, scca regional time trial @ NCM. For some added info I'm a solid intermediate track driver and avid autox'r. Car is a 19 Ltg 1LE, stock on 265 re71s.
I noticed towards the end of the day Saturday that I was getting increased pedal travel, decreased braking performance and decreased pedal resistance. I did a quick 4 corner caliper bleed Sunday am before the first session, rear was clean, front was darker and I did get a bubble or two out of the fronts. Topped off with some fresh rbf600 and went back out.
Needless to say it didn't get much better, might have gotten a bit worse. With the car on, I can apply pressure to the pedal and eventually it will get almost to the floor. I'm assuming I may have boiled up some fluid?
Thoughts on the 10s getting overly hot? Should I swap to running xp12s square vs 10/8? That brake fluid is DARK, check the pic.

[olblue75]

Looks low too.

[Stephen12ZL1]

pads are streaking and leaving deposits...my suggestion is to go straight to a more track appropriate pad like a Hawk DTC 70 front and DTC 60 rear. Also, try a better brake fluid like Endless instead of RBF 600. When the car is running there is engine vacuum providing assist and the pedal will slowly go to nearly to the floor. Try it with the car is not running and see if you have a harder pedal then.

[SCCAForums]

The soft pedal is due to the additional heat the XP10/8’s are doing. Any good brake pad will do this, as they create more friction than stock, which in turn creates more heat.

WhileI also run 8’s due to mixed events with Autox and Time Trial (G-Loc, same as Carbotech) I also switched to Endless 650, and carbon fiber brake lines along with titanium shims and SS1LE front brake deflectors.

That cured everything for my ZLE. We just completed one lap of America, traveling 3800 miles, racing at 10 different tracks in 8 days and never even so much as needed to bleed the brakes.

Best Regards,
Dave

[weemus]

Yep, boiled the fluid. I would recommend switching to Castrol SRF.

Also I did the SS brake deflectors, SRF, Z06 vented pistons (Ti shims are much simpler) on stock pads. That cured my issues.

[Osbornsm]

Originally Posted by weemus

Yep, boiled the fluid. I would recommend switching to Castrol SRF.

Also I did the SS brake deflectors, SRF, Z06 vented pistons (Ti shims are much simpler) on stock pads. That cured my issues.

BUY THESE, or continue to boil fluid.


https://knsbrakes.com/c/car-item/496...+Shims+-+Front

[MatthewAMEL]

Originally Posted by Osbornsm

BUY THESE, or continue to boil fluid.


https://knsbrakes.com/c/car-item/496...+Shims+-+Front

Full disclosure, I have these for my car and I have used them.


However, there is something I would keep in mind regarding their use.


They only partially will solve your braking issues.


Yes, they will reflect a lot of heat away from the pistons, but that heat has to go somewhere, the shims aren't heat sinks. They reflect the heat back to the pad.


I found that I can keep from boiling the fluid, but it's much easier to reach maximum temp on the pad itself. Pad fade and boiling the fluid both lead to the same result...no/poor braking performance.


If you often find yourself at the edge of braking performance, consider moving up to a more track oriented pad in conjunction with the shims.

[Trackpack]

You likely need a pad that takes a higher temp. XP12 or higher are appropriate for this weight of car. https://ctbrakes.com/choosingcompounds/

[weemus]

MatthewAmel that is exactly why I went with the vented pistons. Didn’t want to cook the pads. We are just moving heat at some point.

[Og Neon]

I would also ask "how do you brake?" I see a lot of causes of boiled brakes from people over braking or braking too early and then progressively getting on them harder.
Also on your quick 4 corner bleed, did you do the inside bleeder? If not that is why your pedal is still mushy...you have air trapped on that side as well.
Just a thought as well.

[NLZN21]

Appreciate all the responses.

In direct reply, I don't think I really over-brake, or if I am, it's not that much.

Here's a good reference lap (unfortunately my OBD data isnt that great, you can't see my pedal inputs): https://youtu.be/JCVEWf9LRRg?t=302

Car is bone stock outside of pads, fluid, forgestars and 265 re71's. Definitely not the fastest car on the track (I bought to campaign in AX DS), has a lot of trouble going anywhere in 4th over 100. And of course I'm not the best driver in the world.

Fwiw, I actually called Carbotech and spoke with them before ordering those XP10's. I asked them if the car weighed too much or if I needed 12's. After doing some inspection, there is zero airflow from the front to the J55's on the LT 1LE. Not really what I'd call "track-ready" from the showroom, especially with lesser pads, fluid and a much less grippy compound tire.

[Alpha1BC]

Originally Posted by NLZN21

After doing some inspection, there is zero airflow from the front to the J55's on the LT 1LE. Not really what I'd call "track-ready" from the showroom, especially with lesser pads, fluid and a much less grippy compound tire.

Did your car not come with the brake deflectors that go on the leading suspension links? I thought the LT 1LEs did at least, but if not you should definitely get a set of them. ~$20 shipped in quite a few places, GM part number 84433357.

[NLZN21]

Just the little deflectors on the front LCA's, fender liners are buttoned up and front bumper cover inlets for the ducts have block inserts.
I'm pretty sure the SS+ 1LE's have ducting through the fender liners in the area boxed, may be able to get the ducting kit here working, i could just cut mine or order up some SS fenders perhaps?

[wilbur_xmas]

Originally Posted by NLZN21

Just the little deflectors on the front LCA's, fender liners are buttoned up and front bumper cover inlets for the ducts have block inserts.
I'm pretty sure the SS+ 1LE's have ducting through the fender liners in the area boxed, may be able to get the ducting kit here working, i could just cut mine or order up some SS fenders perhaps?

Even my LGX 1LE has the brake ducts so it's surprising the left that off on the Turbo 4 package. If you don't want to go full brake duct hacking I would invest the ~$30 in GM Part #: 84433357 which will get you smaller front dust shields for brake cooling and larger plastic deflectors that scoop air from under the car (and look like big plastic vampire fangs in track pictures). You may need to trim the deflectors a bit to not rub your abs sensor wires at full lock, and be very very careful with the screws that hold the deflector to your control arm they are easy to crossthread/strip/break.