What kind of times are you running at VIR and Summit? Summit is pretty hard on brakes. VIR a lot less so due to the long straights. Are you running ducts? Ducting in cool weather can lead to cracking or pads not reaching temp.

They said it appears normal…even after only four track days and 1,200-,1500 miles. This was their response:

“Hello,

This appears to be a disc that has seen many track days and heat cycles. This looks normal for a disc that has been used for track use and also street use with DS1.11. We do not recommend street driving with the DS1.11 because it is designed to operate under track temperatures so in street use it can be very hard on the rotor surface.”

2:13s at VIR, 1:33s at Dominion, and 1:43s at Shenandoah (not Main). It was wet all day at Shenandoah…I only did 1:43s in the last session as the track started to dry. I heard Max4 86s and BRZs were doing 1:37s to 39s yesterday with sunny skies and ambient temps in the low 60s, so my 1:43s on Saturday didn’t even come close.

I only did one day at Dominion, two at VIR (one rainy all day and one dry), and one mostly wet at Shenandoah total on those brakes. The pads still look new.

I do not have ducts.

Tell us what your warm up and cool down procedures are.
Also, what does the other front rotor look like?
And what about the inside surfaces of the front rotors?

I usually take it easy on the first and last lap as soon as I see the checkered flag, and usually though not always drive around the paddock for a few minutes after.

I haven’t engaged ABS but once in the rain, my lap times aren’t braking any records, and I’m running RS4s which aren’t the stickiest tires in the world. Based on everything I’m reading, however, it would appear I’m somehow braking harder than the average Joe. I have yet to put a single tire off track or have a spin/off of any kind even in the rain—but of course now that I say it, it’ll be the first thing to happen next time I’m on track. I don’t baby it on track, but I’m also not 10/10 out there.

It seems I need a real BBK. I may need a few days to accept this was the costliest decision of my build so far as I may need to buy new wheels and tires because my 17x9s likely won’t fit anymore.

On a separate note, I have a kidney for sale. Make an offer.

You are 1. getting the rotors very hot and 2. thermal shocking the braking system.

Based on the amount of heat you are generating, I recommend you look for a much heavier BBK, rather than the weight-reduction based BBK you are currently using.

Check out this thread, for example.

https://www.ft86club.com/forums/showthread.php?t=147978

Keep in mind that it is VERY easy to inadvertently get into ABS on a modern car without even realizing it. You may not even feel the ABS engaging, as modern ABS pulses very quickly, and you only really get the crunchy feel when you're DEEP into ABS.

Weight reduction wasn’t my goal. I was looking for something better than stock but not overkill…erroneously thinking that anything bigger would be overkill.

I had a Miata before with stock brakes and $80 pads. Used it and drove it the same way as the 86. Never had a brake issue. 12-14 track days after, the pads still had more than 50% left and the rotors were perfectly fine.

When asked if I’m engaging ABS when braking, I can say I’ve only felt it once in the rain. I can’t say it has never happened otherwise, but certainly not enough to notice it.

I’m sure thermal shocking is directly related to the premature damage to the rotors, I just don’t know what I did.

Not that I’m policing every person on track, but I haven’t noticed doing anything drastically different than anyone else as far as picking up speed on the first/second lap and cooling down on the last lap and on the paddock.

I’ll take whatever advice I can get to help prevent this in the future because at $700 per rotors every three track days, I’ll have to quit the sport. What am I doing to thermal shock the system?

Have you talked with other owners in your area about what they are running? That is usually where I start when I have questions.

These are $299 per rotor from Essex, if I’m thinking these are what you are referring to.

AP Racing J Hook Competition Disc Replacement Ring (11.75" x1.25" / 299x32mm)- Right Hand, 60 vane
Part #: 13.05.10084
Brand: AP Racing

AP Racing J Hook Competition Disc Replacement Ring (11.75" x1.25" / 299x32mm)- Left Hand, 60 vane
Part #: 13.05.10085
Brand: AP Racing

Most folks will warm up their mind, as well as their engine and transmission on the outlap, but often times forget about their brakes. Ideally, you want to gently accelerate, and brake, repeatedly, on the outlap, to input small amounts of heat into your braking system to bring them up to temp, rather than just taking it easy on the outlap, and then suddenly going full threshold at the first braking zone of your first lap.

So, the discs were thermal shocked, overheated, abs was going off constantly causing excessive heat or they were driven on the street with a pad that was too aggressive, according to the supplier.

:iono:

A too aggressive street pad will cause increased rotor wear, but not cause the cracking. The cracking is is pretty much all thermal shock.

Agreed 100% yet the OP was told the aggressive pads could cause the cracking, unless there was a miscommunication.


I can't get my head wrapped around how a 32mm wide rotor, after just 3 track days, could overheat and crack like this. It's hard to imagine that these discs couldn't take anything thrown at them. Short of being tossed in water after a hot run, I just can't comprehend how this happened.

I don't get it either.