brake problem

[cyphrsbird]

on the way back from Wales last weekend I realised that I had been drivng with the handbrake on (ok, its easy done ), rectified this immediately but when I went to brake for a roundabout the pedal just hit the floor - no brakes - pumped the pedal = brakes. This happened a couple of times so I stopped for break fluid thinking maybe it was low. Got the fluid, took the instrument panel off the dash but the fluid was fine.

Tried the brakes again...no problem....since then, absolutely no problem.. Was thinking maybe air in the system but surely if that was the case it would happen frequently not just a couple of times. And would still be happening?

Could this have just been linked to the fact that I was a numpty that forgot to take my handbreak off (wondered why van was so sluggish ) or is it likely to happen again and I should take it in to have brakes checked as matter of urgency?

[CycloneMike]

Was the handbrake on for some time? Like long enough for the brakes to get so hot that any moisture in the fluid could boil and cause vapour lock? That's what it sounds like. You've probably also glazed the friction material on the shoes so they'll never work quite as well as they did and be more prone to fade. New brake fluid and a close inspection of the rear brakes is required in my opinion.

[andisnewsyncro]

As I understand it, you've boiled the fluid and temporarily lost braking efficiency. It lets small bubbles for in the fluid which compress rather than taking up the pressure from the pedal, hence the spongy or no brakes feeling. This will probably clear as the fluid cools and braking will improve again, but it would be wise to drain, refill & the bleed the system with fresh brake fluid and to check the wear on the shoes / drums.
There is a chance the heat could have warped some components so have a good check over of everything.

(speaking from experience, I managed the same trick a few years back if it's any consolation )

E D I T beat me to it but pretty much the same info, change the fluid and check everything carefuly

[kevtherev]

I bet the drums were cherry red

And BIG brake fade

[Red Westie]

Technically called vapourlock, as others have explained, where the brake fluid boils (fluid does not compress but when boiling the bubbles DO!) hence foot to the floor.
I would certainly strip the rears and check for damage, you may be lucky, in the respect that everything is OK and it might be that your brake fluid was contaminated with water. FYI (brake fluid is hygroscopic....it atracts moisture from the surrounding air) even if you take care to tighten caps etc, brake fluid must be changed every two years.
To put this in perspective, just 3% water contamination lowers the fluids boiling point by 25% and a sealed system can absorb as much as 2% in one year under worst conditions.
Martin

[kevtherev]

... and two liquids of different densities will compress.

[cyphrsbird]

thanks guys, I think it is exactly what you described....the hand brake needs a tweek anyway (and prob even more so now lol) so am going to book her in for a once over next week cos I dont fancy driving to the cotswolds worrying about major league brake failure. The brake fade was extremely scary though I managed to hide my adrenaline rush from Richard really well LOL

And yes, Kev, I am sure they were cherry red as I had done about 5 or 6 miles before I noticed .....and all the way bitching that the van was being gutless and unresponsive all the way Now I have guilt.

[Red Westie]

Brake fade as you put it, is something different again...where brake lining/pad friction suface get so hot it lowers the materials coefficient of friction. Rather than loosing the pedal altogether, brake fade just means you end up pressing harder and harder to get the same braking effort.
Martin

[kevtherev]

.....and all the way bitching that the van was being gutless and unresponsive all the way Now I have guilt.

you are absolved brother, tis a human failing.

[cyphrsbird]

.....and all the way bitching that the van was being gutless and unresponsive all the way Now I have guilt.

you are absolved brother, tis a human failing.

Thanks...its great having a real life reverend to make you feel better

[kevtherev]

*snigger*

it is, I agree.
go in peace