ahhhhh, body work. How I hate it

[T-Rex]

Latest from the SCCA Barber Motor Sports Park Labor day weekend.

Got a great start, but the rear brakes locked up again in the hairpin causing some problems. BMP is a small nimble car track, and the ZX's weight still it's achilles heel.

http://www.youtube.com/watch?v=eM6QWBxyj6U&feature=plcp

Having said that, we did pick up five seconds a lap from last year and gave the saturday race a good showing.

Now I will need to replace a door, bang out a fender and fix the rocker panel. I can't complain too much, it could have been worse, and I feel bad for the damage to I did to a competitor's car.

Never a quiet off season!!!

[Matt93SE]

Ouch. It coulda been worse though.
Why not dial back the rear brakes a touch? are you allowed bias lever/knob in ITR?

[T-Rex]

Yes, and that is a winter project.

I believe that the fronts are getting soft, but not so soft that I get a long pedal.

So I don't get a clear picture that there is an issue until the first time I brake hard at a corner.

Obviously bleeding the brakes before each session is going to have to become a standard procedure.

[Matt93SE]

that's no good. Are you running iron or aluminum calipers? 26 or 32mm rotors?
what pads and fluid?

[T-Rex]

The larger Aluminium Calipers and rotors, with Carbotech pads. Plus they have two brake ducts on each front wheel. It's a heavy car to slow down, and obviously generates a lot of heat.

[Matt93SE]

Hmm.. Might try the iron calipers. they weigh more, but I've heard from some of the Z guys that the iron ones had less flex and less tendency to fade.
also maybe a titanium pad shim or something to help keep heat out of the caliper.

[Def]

Yea, a Ti, or even stainless steel shim will help keep the heat transfer down. The stock shims actually help out quite a bit being SS.

[T-Rex]

Already have the Ti shims in. The iron caliper is an interesting idea, and may need to be looked into. But I just think bleeding more often, regardless of the pedal feel is going to be required, in addition to any other changes I make.

[Matt93SE]

Quite possibly so. But my brake fluid hasn'et been bled in probably a year and I don't have any of those sort of issues. always have good pedal feel until the end of the race, even at the hardest running track I run (Hallett), which has two 100+ downhill entries to a 25mph turn-in.
I even use cheap (Valvoline DOT3/4) $6/quart fluid.

But I'm running Wilwoods instead of Z calipers.. HT-10 or DTC-60 pads, and the caliper didn't care which pads.
I also have 2700lb to stop and only 150hp to push it. but still. Absolutely zero brake problems.....

[Def]

I'd run a small 2" duct to the caliper itself.

[Def]

Wait... so this is the rear that is locking due to some sort of hardware failure? Or the fronts are giving up causing the rears to lock (i.e. fluid boiling up front)?

How much power does your car make again? I ran quite a bit through my Z32 brakes, and they were obviously getting hot as pad wear was pretty high, but they never boiled fluid (I ran RBF600 due to how hot they got, had SPL brake duct deflectors which do a good job of cooling everything down). I had 30mm Aluminum calipers as well. They were good except for the dust boots constantly dying.

[T-Rex]

Yes it's my theory that the fronts are boiling. This is with two brake ducts per caliper, and the Ti shims. Remember guys my car is a lot heavier than your 240s.

[Def]

True, but on track it's mostly about weight. The only exception for short periods is for those really slow braking zones that are followed by inherently high speed sections. Over a full lap braking heat capacity is closely correlated to engine power output (otherwise a ALMS P1 car could use the brakes off a Civic and have more than enough heat capacity).

What kind of pads are you running?


I tracked my car for a while at very similar power levels to your Z32, and it was pushing it on Z32 brakes, but it worked (without shims) or much directed ducting.

Any pics of your ducting setup?

[T-Rex]

Well, got all the body work done and went off to the SCCA South Atlantic Road Racing Invitatational Championship Race (SIC).

Being that I showed up fourth in the points, and with one of the top three drivers (all tied in first place) not going, all I had to do was finish the race to get third in the Championship.

Despite picking up four seconds from the race in May, I was soundly beaten by the top two cars, but finished the race in fourth, and secured third overall.

Not bad considering how I have struggled with the car up to this year.

But with the progress we made, perhaps we'll get it a bit better next year as we continue to tweak.