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Brake failure at Watkins Glen race - cause is ABS control unit
I can't remember if I posted this, but my brakes had lots of issues throughout the event and the brakes finally failed during the second sprint race. My pedal went to the floor braking for the bus stop. Normally, I would go straight into the runoff, but I was passing 2 cars and we were 3 wide with me on the inside . Code brown, but got through it with some controlled off-roading and a little drifting
We tried everything we could at the track, including replacing the master cylinder. Pedal stayed hard for about an hour, but then went soft again. No 90 minute enduro for me...
The car has been with Spencer at FarnbacherLoles since the race. The problem has now been diagnosed as a failed ABS control unit. Despite that my ABS is disabled, the control unit is "in the plumbing" of the brake system. It appears to be a blown seal, but it is difficult to tell.
Just wanted to put this out there in case anyone else is having braking issues. A good way to tell is with the car off - pump the brakes a few times until the pedal is hard and then keep pressure on the pedal. If the pedal slowly goes down, you have an issue. Most mechanics would initially point to the master cylinder (which it could very well be - and you should start with since is it much cheaper...), but if not it may be a broken ABS unit.
That's a scary place to lose the brakes! Not much run off on the right if you couldn't go straight. Sounds like a real pucker moment!!
yeah, no kidding. essentially no runoff on the right, unless you want to get sucked into the quicksand. i knew i had that option, so i decided to try to get through on the pavement. it worked out that time...
its quite nasty for the ABS to completely fail the brakes, one would think any failure of the ABS would just means you no longer have antilock brakes, but for it to lead to the inability to brake is really scarey.
braking should be a completely mechanical process, but its good that you've manage to sort out this very sticky situation.
Joel, I had the ABS control unit go on my 993 track car, blew an internal seal. Had it replace, and still had problems. My left front wheel would lock up!!! After repeated testing on the street, track and in the shop, we had a failure of the front left caliper, while having it on the Porsche tester, it blew a nickel size hole out of the caliper. What had happened is a part of the broken seal from the ABS unit got trappped in the caliper. Watch out for for lockup, if you experience this, replace the caliper.
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Joel, thanks for the heads-up on the brake issue. Glad you escaped unscathed.
BTW, I thought Spencer went to Deman -- has he returned to F/L?
Andy
Andy - Spencer recently left DeMan and has opened up his "own shop" - FarnbacherLoles Clubsport. His show and focused on DE and Club racing. Perfect!
Quote:
Originally Posted by Morefun
Joel,
Just out curiousity, what upgrades have you made to your brakes other than usual brake fluid, pads, rotors and front GT3 brake ducts?
Glad to hear that you got through unscathed! A true big moment.....
No other upgrades than you mention. But I do have 7,000 hard track miles on the car...
These ABS units are NOT meant for racing. They are for street cars. DE's seem to be fine, but for a dedicated track/race car Porsche is finding that the units are not bullet proof. This is apparently a know isse with 997's as well (essentially the same unit). I will be replacing mine with a Porsche Motorsport unit - intended for racing....
Cayman was designed around GT/touring street use...it is poorly prepared for aggressive track use. Porsche just wants you to spend a small fortune on racing parts rather than give you a solid car from the factory.
I don't know if that is quite fair. It is as much a track-worth car as the 911 (with perhaps a few items that were not tested thoroughly enough prior to release). This ABS issue is the same as experienced on raced 997's. My Cayman has been largely trouble free after 7000 very tough track miles.
I will be replacing mine with a Porsche Motorsport unit - intended for racing....
Joel - please keep us posted with your braking system changes, including part numbers, etc. As you know, there is another thread (Brake issues at track) about braking issues at the track, and it would be great to identify fundamental, complete, and effective solutions to all of these braking system problems.
Until 
