Brake pedal to the floor - no stop!
08-22-2010, 04:58 AM
#1
Brake pedal to the floor - no stop!
I had the master cylinder fail on me while driving home the other day. No real warning, just foot to the floor!
Luckily, I wasn't in bad traffic or driving aggressively and was able to get the car stopped without any incidents. What surprised me was the lack of symptoms before the failure.
Have many others seen a 'no warning' failure of the brake master cylinder?
Best,
John
'91 Turbo (56k miles)
Luckily, I wasn't in bad traffic or driving aggressively and was able to get the car stopped without any incidents. What surprised me was the lack of symptoms before the failure.
Have many others seen a 'no warning' failure of the brake master cylinder?
Best,
John
'91 Turbo (56k miles)
08-22-2010, 11:15 AM
#2
Addict
Rennlist Member
Rennlist Member
I am glad you got through this unscathed. I can think of times when that exact scenario would be fatal. Was there no prior warning? Great brakes and suddenly none?
It is a dual-circuit system, so a single hydraulic failure should leave you with brakes on two wheels. The only credible "pedal-to-the-floor, no brake action" I can think of is a mechanical failure of the linkage from the brake pedal, or a fracture of the brake pedal hinge pin. Please post what caused this, including pictures of the failed parts. I will be driving more carefully until I find out!
It is a dual-circuit system, so a single hydraulic failure should leave you with brakes on two wheels. The only credible "pedal-to-the-floor, no brake action" I can think of is a mechanical failure of the linkage from the brake pedal, or a fracture of the brake pedal hinge pin. Please post what caused this, including pictures of the failed parts. I will be driving more carefully until I find out!
08-22-2010, 11:25 AM
#3
Actually, now that you mention it, I may have just had failure on the front brakes. Mashing the pedal to the floor gave perhaps 5 or 10% of the systems normal stopping power. Not enough to stop the car at any significant speed, but sufficient to safely limp the car to a shop for diagnosis (ie. a 20mph crawl).
Sounds like I may have seen failure on the circuit controlling the front wheels.
I should have the car back from the shop tomorrow - will update on what the fix was.
Sounds like I may have seen failure on the circuit controlling the front wheels.
I should have the car back from the shop tomorrow - will update on what the fix was.
08-25-2010, 04:16 PM
#6
Picked up the car from the shop yesterday. New master cylinder fixed the issue.
Shop that did the repair supports 30 or so DE cars and several race cars. Owner tells me they've had customer cars have this failure out on the track - and recommend replacing the master cylinder every 3 years even if there haven't been any symptoms. That's for a track car.
Planning to disect the old master over the next couple days. If I find anything noteworthy, I'll share.
Shop that did the repair supports 30 or so DE cars and several race cars. Owner tells me they've had customer cars have this failure out on the track - and recommend replacing the master cylinder every 3 years even if there haven't been any symptoms. That's for a track car.
Planning to disect the old master over the next couple days. If I find anything noteworthy, I'll share.
08-25-2010, 07:06 PM
#7
Burgled
Rennlist Member
Rennlist Member
Picked up the car from the shop yesterday. New master cylinder fixed the issue.
Shop that did the repair supports 30 or so DE cars and several race cars. Owner tells me they've had customer cars have this failure out on the track - and recommend replacing the master cylinder every 3 years even if there haven't been any symptoms. That's for a track car.
Planning to disect the old master over the next couple days. If I find anything noteworthy, I'll share.
Shop that did the repair supports 30 or so DE cars and several race cars. Owner tells me they've had customer cars have this failure out on the track - and recommend replacing the master cylinder every 3 years even if there haven't been any symptoms. That's for a track car.
Planning to disect the old master over the next couple days. If I find anything noteworthy, I'll share.
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08-26-2010, 01:09 AM
#8
Yeah, at $700 for a new master cylinder, it's not the cheapest maintenace item on the car.
On a street car, mine was good for close to 20 years. Hope to get more than 20 out of this next one!
On a street car, mine was good for close to 20 years. Hope to get more than 20 out of this next one!
