I just came back from Laguna Seca. Had 3 great session and then my brake pedal went all the way to the floor. I thought that I had boiled the fluid but noticed I lost ~8 ounces of fluid. I bleed the brakes at the track with brand new motul but the pedal keeps going all the way to the floor. I drove back home with very little brakes (brakes lightly after you pump 3-4 times). Once home I had lost ~ another 8 ounces. I pumped the pedal at home but still can't find any leaks! For background, I went to the track with fresh motul 600 and pagid yellows. It's a tough track on brakes but I can't understand what is happening. Planning to take it to the shop on Monday but would appreciate any thoughts.

 

It doesn't take a big leak to make a good pedal become that long. I'd advise you to check the bleeder screws at each corner and the fittings where the soft brake line attaches to the hard line. Re-torque each bleeder to 17-20 Nm and then check again.

If this doesn't fix it, then you've likely got air in your ABS controller valves. Any dealer can run a special bleeding procedure to fix that.

If that's not it, then check your calipers for leaks at the pistons. You may have damaged a seal or blown one out.

 

I checked all the bleeder screws when I bleed the system (all was tight) and changed the pads when I got home and found no leaks. What is strange is that brake fluid tends to be easy to spot since it is so greasy but I couldn't find any traces in anywhere. Even when I pumped the pedal in my garage, I was expecting to see a pool of fluid underneath but there's nothing. I will drive around the neighborhood tomorrow am and see if the fluid level keeps dropping. Any other ideas welcome.

 

16 Ounces is a lot of fluid, I'd be looking in my front trunk to see if that's where it's going. If it's not on the ground and you put enough fluid in the system, I can't think of where else it would go.

 

Yep - you were right; it is all there in my front trunk. All the black covers are soaked in fluid. I believe there must be leak in the reservoir or maybe an issue in the master cylinder? Any ideas?

I am happy to be alive and rethinking driving schools. I may not be writing this note if this had happened yesterday at 130mph on the front straight with no brakes....

 

So it would have been better if it happened on some off ramp, or some side street; or while pulling up to your kids school with children around!!!!

Mechanical failures happen no matter what; just be glad it did not end in an accident as we can not control the outcome of all events in life, this one just ended with some dirty carpet not a blood soaked exterior or interior.

You almost did it to yourself, your car looses that much brake fluid and you think so little of it that you just add more and then keep trying to fail.

BTW I am really glad you are OK and that nothing happened.

 

Oh, you should have mentioned that sooner. You got the brakes so hot that you didn't just locally boil the fluid at the wheel ends, you actually boiled ALL the fluid. That means that the fluid expanded so much that it overfilled your reservoir and spilled out the top.

 

To be clear, once I noticed I was loosing fluid, I packed my stuff and did not get back on the track. It may not have been the best idea to drive back home on the car but I felt that I had "enough" brakes and it was all freeway driving. I made it home fine but can't defend that this was smart....

I guess ALL the fluid would explain the initial loss/expandion of fluid, but somehow I seemed to have damaged something else in the system. Otherwise it would be working find with new fluid but my brakes aren't working well yet and I am still loosing fluid. Any other ideas on what might have happened to the rest of the system?

 

I mean to write....

 

Hey were all human, we all do dumb things, I was not really questioning that.

But what I would say is we do not stop doing everything because bad things could happen.

It is way smarter to do the dumb things, like driving way to fast, at the track than it is to do them on the road.

 

How much fluid are you losing now? Is it still several oz, or has it slowed down?

 

I decided not to take the car out today but I have no reason to believe that anything has changed. My guess is that I was lossing ~1oz for every 3-4 pumps of the brakes. My mechanic is only ~4 miles away so should be no problem to get there. Hope it is not a major expense.

 

My shop found that the issue is that the ABS pump is leaking. The bad news is that the part from the dealer is $3600. This is an independent shop so they will look around to see if possible to find a remanufactured unit or a repair kit given the high cost of the part. I will keep you posted. Man, this is getting expensive.