BRAKES STUCK ON

P

pdcharlie

New Member
Hi guys
Not a very frequent poster on here but always read with interest , had a very strange thing happen today . My rear brakes stuck on .
I parked up on a very steep slope to an underground car park whilst the electronic door opened , the handbrake held fine . I switched off the engine and then , when the door opened i coasted down the hill a little and used the foot brake until the servo assistance was no more , re applied the handbrake and started the engine , then tried to move off and the car was stuck firm , handbrake totally off and no foot on brake pedal and still on a very steep gradient .

No way could i block this doorway so i had to rev like crazy and managed to stagger the car forward to a parking bay . I left her for around an hour and a half then returned to find the brakes had eased off somewhat so that i was able to start driving home , some 9 miles or so . The rear brakes were still pretty much on and i struggled to reach 30 mph after around 2 miles and a horrible smell they suddenly freed off completely and were then totally normal . I probably should not have driven the car at all but was in the middle of the countryside and had no option .

The discs and pads all round and rear calipers and servo have all been renewed in the last 4 years, the rears last year. She was MOT'd last month . Fluid is all good and no leaks . Do u think its possible that i caused the rear calipers to seize on by coasting until servo pressure was out and then restarting with my foot on the brake pedal ? Its the only thing i can think of , will put her on the wheel ramps tomorrow and take a look at the calipers .

Sorry about war and peace ! any theories/ suggestions welcome ! The car is a '67 2000 SC and i have owned her for 19 years ( 2nd owner ) 56000 miles

All the best

Paul
 
Hey Paul,
sounds like your servo has stuck on. The air valve one the servo if your car is a four cylinder or on the master cylinder in it's a V8 can sometimes stick open. If that happens it will constantly hold the brakes on. Easy way to fix for the way home is to remove the vacuum hose from the servo, plug it so the engine doesn't stall. If the brakes release there's your problem. If your lucky the air valve just had a bit dirt in it and it failed to seat properly. If not somethings wrong with servo or M/C and that's more expensive.

Just my thoughts,

Steven
 
Difficult to know but could you tell if the rear brakes were stuck on, or all four. Did the car dig in at the front when you tried to drive off?

If it was just the rear brakes, then I suggest it could be the hand brake linkage just jamming on. If it was all four then go with what sdibbers suggests, although personally i've not heard of that happening.
 
Given the surface area of the rear pads and the pressure that can be exerted by just one very small piston per pad, I doubt that your rear brakes alone were jammed on.

I would be inclined to side with Steven and point the finger at the air control piston within the booster slave cylinder. The front brakes will also be applied when such happens, and they apply significant pressure which will make their pressence felt when you attempt to drive as you experienced.

Ron.
 
Thanks guys i have been under her all morning greasing and inspecting , although to be honest everything looked in excellent condition as i try to keep on top of stuff . I am thinking the servo is the problem and am starting with the vacuum hose as this looks to be collapsing in on itself . Will keep you posted !

Paul
 
I would look at the air valve on the servo. I had a problem when I rebuilt my servo where I have refitted the valve wrong. When I operated the brakes with the engine running the car was anchored until the effects wore off.

Colin
 
Hi, i had a similar problem with my rear brakes last year. Firstly the N/s rear brake had a habit of sticking on, and then it got to the stage where the N/s/r brake wouldn,t work and nothing would come out of the bleed nipple.
After much head scratching i removed the rear flexi brake hoses (the chassis to O/s caliper AND the hose which joins both calipers. To my amazement, the hose which joined both the rear calipers was blocked. I couldn't even blow 120psi of air through it.
I replaced both hoses & the difference was amazing. The pedal feels positive & the brake response is improved. Therefore i would check your hoses first!!
I hope i have been of some help. :twisted:
 
Could be the caliper swinging pivots are seized ? However if the hose is blocked , that would give the same impression.Release the bleed nipple to see if fluid spurts out and then if the caliper is more free
Onre more idea ,is the piston in the master cylinder sticking ? I'm thinking whether , when you were pumping the pedal , the piston went further down the bore than normal and got stuck ?
 
Hi All

Ordered a new servo hose from Wins at 4 pm it was delivered the next morning ! Great service . Fitted it and am surprised to say the brakes feel much more responsive , I am definately getting more servo assistance so i am hoping the problem is sorted , time and driving will tell !

Thanks for the replies , all much appreciated :)
 
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