ZR1 Track Day update (road course) - didn't go well :(

[cbaclawski]

My track day got rescheduled from Sat to Sun(yesterday) due to weather. That part worked out great as the weather was beautiful...


I had big plans of coming back here, sharing some video, data screen caps, etc., but alas, it's not to be.


Being my first time out in the car I was taking the first session easy at first, braking early and not pushing it in the corners. Around lap 4 as I was slowly picking up speed, I was heading in to a high speed corner (Turn 8 @CMP for those familiar), went to brake, and the pedal went straight to the floor. I tried to make the corner way too hot but couldn't hold it and spun right off the track.


Getting to the pits, it was suggested that by going so easy I'd been dragging the brakes and the pads (hawk HP+) had overheated. Sounded reasonable, but just in case I let it cool and bled all 4 corners. The fluid was clear, obviously not boiled, and no bubbling at all.


Thinking all was well I went back out, this time braking harder and shorter to avoid what I thought was the issue in session one, brakes seemed better but sill very inconsistent. Around Lap 4 again, in the same spot, I spun off track. Once I pulled back on track, the pedal was completely gone and I limped back to the pits. Consulting with some other drivers, they said it could be caliper piston lash and I should try to give it a pump before the braking zone. (apparently this happens a lot in spec miata racing)


After a brief time in the pits, and with no frame of reference on how the brakes were *supposed* to feel, I assumed the brakes on the z just sucked by design. I headed back out for the third and final time. This time I was going to keep it on the track for sure. Unfortunately, on lap 2, while I was really still warming up, I couldn't get slowed for turn 4, lifted and spun again, this time in to a tire wall, ending my day.(and the pristine condition of my front end)

With a day to replay the days events in my head, I'm 99% sure I have a failing master cylinder, which led to brakes that ranged from wildly inconsistent to non-existent. Thinking back to the bleed, the person I had pumping the pedal for me mentioned that the pedal was sometimes slowly going to the floor before I even opened the valve, and when I did crack the valve I didn't always get that much fluid, sometimes more than others. Shame on me for not recognizing the problem sooner and calling it a day before crashing out.


The good news is the damage is superficial and can/will be fixed, also when the brakes did work, the car was better than expected in the corners. virtually no body roll, good grip, and it was easy to hit my marks. I did have to be more careful with the throttle than I am used to in my lower hp cars, but overall very manageable and predictable.


Can't wait to get the repairs done and get back out there...


Curt