When applying the brakes sometimes the brakes are slow to release.
could it be a servo problem? Advice please.
It could be lots of things.
It could be one or more sticking slave cylinders, or a sticking master cylinder.
It could be the flexible brake pipes that go to the front wheels and the back axle - they can swell internally and block the flow.
On the Jaguar it could be the anti-creep device.
And it could be the servo.
Try to find out which wheel is the culprit - if it’s just one of the fronts it’s probably the slave cylinder sticking or the flexible hose, if it’s one of the rears then it’ll be the slave cylinder sticking but if it’s both it’ll be either the anti-creep device or the flexible hose.
If it’s all four wheels it’ll be the master cylinder or the servo.
On my Daimler I’ve eliminated everything else so for me it’s either the master cylinder or the servo.
Hi Robert,
Thanks for replying, the fault seems to have gone now, a bit of a puzzle.
The car had been standing for a couple of weeks. They do like constant use so hopefully
it should not recure.
Colin.
| bobtills Robert Hughes
August 1 |
- | - |
It could be lots of things.
It could be one or more sticking slave cylinders, or a sticking master cylinder.
It could be the flexible brake pipes that go to the front wheels and the back axle - they can swell internally and block the flow.
On the Jaguar it could be the anti-creep device.
And it could be the servo.
Try to find out which wheel is the culprit - if it’s just one of the fronts it’s probably the slave cylinder sticking or the flexible hose, if it’s one of the rears then it’ll be the slave cylinder sticking but if it’s both it’ll be either the anti-creep device or the flexible hose.
If it’s all four wheels it’ll be the master cylinder or the servo.
On my Daimler I’ve eliminated everything else so for me it’s either the master cylinder or the servo.
The rear brakes on mine could not be bled and the culprit was the rear flexible hose - it had completely swelled up internally. Now I have the right front not gripping as much as the left, despite new flexibles. More forensics needed.
I read a few years ago that silicone brake fluid causes brake seals to swell considerably, sometimes to the extent of seizure. I assume the rubber formula has been changed to prevent this.
Hi Peter, Thanks for replying, it seems that it could have been a temporary fault with either the master cylinder or the servo. The brakes are working normally now. Very odd!
Colin.
Last set of new brake pads I fitted , I had to take a grinder too them , the metal backing was a tight fit in the caliper , they need to be a little lose .
Maybe you not using the car , the calipers rusted up a little !
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my mgc used to do that first time i use it after winter lay up. first dab of the brakes then ok after that.
Hi Robert, thanks for replying, it it one of those mysteries!
Jag chum Colin.
Agree about silicone brake fluid. i could not blead after sitting for 30 years, popped the slaves off and found them full of a green brown Jelly?. a clean and reassemble and she’s all good
What a coincidence, yesterday my Daimler V8 250 was pulling up with rear brakes sticking on, they got very hot. It appears to be the rear flexible hose allowing pressure to the brakes but not return on release. The hose is off and indeed appears restricted.
The inner walls do collapse with time , then the pipe acts like a one way valve .
I have fitted braded lines , not sure if it happens on them too 
My '65 S suffered similarly. The rear flexible had swelled up internally but looked good externally and could have been an original. This deterioration is due to extreme age. It is worth renewing all flexibles - cheap insurance for safety.
The reason there is a slow return is the great difference with the force/pressure applied at the foot pedal versus the minimal return force.
I had a similar problem with my rear brakes, particularly in hot weather, sticking after stopping at a traffic light. A tap on the brake pedal while waiting for the traffic light to turn green would solve the problem. Last week, I tried an experiment. In the garage, before even turning the key to start up the engine, I pressed and released the brake pedal repeatedly at least 20 times before starting up the motor. I then proceeded to take a 20 mile drive during which time there was no brake drag and all items worked as they should. Hopefully, the problem has been cured.
Mine does this, but only when thoroughly warmed up. I’ve replaced the flexible hose for the rear brakes and none of the wheel cylinders are sticking. A previous owner replaced the front flexible hoses.
Especially as it only happens once warmed up, I’m suspecting the servo, which I will replace when the engine comes out this winter as it’ll be easier to get to. I’ll replace the master cylinder as well, because they aren’t expensive and although it doesn’t leak it looks very tired.