Discussion
I drove my car down to Wadebridge today (around 60miles). 50miles into the journey I overtook a couple of cars, dabbed on the brakes to scrub off a bit of excess speed and there were no brakes. The last 10miles were completed using the gears and handbrake to stop me. I'd got things to do down there so thought I'd worry about getting back once I'd finished.
Back to the car several hours later and the brakes are fine. Drove the 60miles back home (in pouring rain) and the old girl didn't miss a beat.
I'd been driving fairly conservatively on the way down with lots of nice roads that didn't need huge amounts of braking, so now I'm just worried that it'll happen again and next time it'll be at a time where I need to stop 'quickly'.
Anybody had a similar problem?
She's had some proper workouts in the 10years I've owned her and I've only ever lost the brakes once before, but that was down to a split hose.
Back to the car several hours later and the brakes are fine. Drove the 60miles back home (in pouring rain) and the old girl didn't miss a beat.
I'd been driving fairly conservatively on the way down with lots of nice roads that didn't need huge amounts of braking, so now I'm just worried that it'll happen again and next time it'll be at a time where I need to stop 'quickly'.
Anybody had a similar problem?
She's had some proper workouts in the 10years I've owned her and I've only ever lost the brakes once before, but that was down to a split hose.
Didn't feel like they were binding 
No nasty brake smells either, just one minute they worked and the next my foot went straight to the floor and there was nothing.
I used to be quite proud of the fact that I had a wedge with a fully functional handbrake. The handle now points to the sky to get any sort of purchase though just like everybody elses.
No brown trousers 'yet' as they decided to fail on a nice stretch of road. Next time however ..........
No nasty brake smells either, just one minute they worked and the next my foot went straight to the floor and there was nothing.
I used to be quite proud of the fact that I had a wedge with a fully functional handbrake. The handle now points to the sky to get any sort of purchase though just like everybody elses.
No brown trousers 'yet' as they decided to fail on a nice stretch of road. Next time however ..........
Has it lost any fluid? Any signs of fluid being expelled from the reservoir?
Carefull while you're dealing with any fluid spills, by the way. Even the slightest trace on your fingers will wreck everything you touch, and you'll have left fingerprint sized holes on stuff all over the house by the time you notice.
Carefull while you're dealing with any fluid spills, by the way. Even the slightest trace on your fingers will wreck everything you touch, and you'll have left fingerprint sized holes on stuff all over the house by the time you notice.
I had a similar problem (not in a wedge).
There is a valve that closes off the channel back into the reservoir before the actual main brake seals do anything, this is on a little spring to keep it slightly pre-tensioned, when you take your foot off the brakes it opens up the channel again to let the fluid get to and from the reservoir.
If this seal gets dodgy then it sometimes lets the fluid through under light pressure but if you firmly apply the brakes it clamps up properly and things work.
So if your breaks fail again like this try pushing hard to see if they start to work.
Otherwise if you aren't losing fluid anywhere then it is a fault with the master cylinder, make sure that you check both reservoirs if there are two internal for a split system.
Russ
There is a valve that closes off the channel back into the reservoir before the actual main brake seals do anything, this is on a little spring to keep it slightly pre-tensioned, when you take your foot off the brakes it opens up the channel again to let the fluid get to and from the reservoir.
If this seal gets dodgy then it sometimes lets the fluid through under light pressure but if you firmly apply the brakes it clamps up properly and things work.
So if your breaks fail again like this try pushing hard to see if they start to work.
Otherwise if you aren't losing fluid anywhere then it is a fault with the master cylinder, make sure that you check both reservoirs if there are two internal for a split system.
Russ
Would propose new seals in the brake master cylinder, and bleed the brakes. First as mentioned before (had this myself and cured the problem), second to be sure of no air and good brake fluid at the brakes (old brake fluid with water content will be have like that as well, but not after a brief, not full use of the brakes).
Another possibility is pad-out problems, but this only happens with large discs and especially when these are warping.
Rob
Another possibility is pad-out problems, but this only happens with large discs and especially when these are warping.
Rob
Somebody I know had some brakes that would fail randomly like this. The best theory we came up with was that the seals needed a small amount of pressure to deform them before they would seal. If you stamped the brakes, they would work. Press them gradually and they wouldn't. To make things more interesting, it had a mechanical balance bar and quite often the fronts would come in but the rears wouldn't - or vice versa. All quite scary until the M/C was rebuilt. This one also had the problem where the brakes didn't come back far enough to open the reservoir port if you came off the brakes too gradually, meaning the brakes would wedge themselves on if they got hot. It lead to a very unusual driving style ...
rev-erend said:
GreenV8S said:
It lead to a very unusual driving style ...
Is this a self confession
It wasn't my car, but basically the only way the brakes worked was if you slammed them on and off. Given that the car was very light and stupidly powerful, the whole thing was quite exciting!
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