Sticking brakes

[MrIan]

Yet another little issue with ole Boris.
Car has servo discs front, standard minor rear.
When the brakes are applied they (9 times out of 10) stick on for between a couple of seconds to sometimes 10 maybe 20 seconds (which is a complete pain). I can get the brakes to release if I press the brake pedal hard and release it then the brakes will be instantly ok which is ok if you're coming to a stop but a complete pain slowing for a roundabout as you end up going round the roundabout with the brakes partially on.
I was thinking master cylinder seal not been removed but then why would pressing the brakes hard release them?
So i'm thinking maybe a sticking air valve on the remote servo and maybe the hard press I give to release the brakes pushes the air valve a bit more increasing the pressure on the return spring ??
I'm thinking if I remove the vacuum hose from the manifold and plug both manifold and hose i'll then have disconnected the servo assistance thus if I then have no braking problem the problem lies with the servo and not the master cylinder !
Anyone got any views on yet another job on my 'To Do List'

[Trickydicky]

Sounds to me as though it is most likely a sticking brake cylinder, possibly a rear one.
If you don't know when the fluid was last changed it would be wise to change it.

[martin418]

i would start with the servo , i have had the same problem on my friends mgb , we by passed the hydraulic pipes and problem was solved so an exchange unit was fitted , up on further investigation i found the hydraulic piston to be sticking in the bore and just as you have found a ' hard brake ' will free it

[Jaywhy]

Did you have this problem before the disc brakes were fitted?. My reason for asking is that there is a top hat seal in the master cylinder that needs to be removed once disc brakes are fitted

[MrIan]

I bought the car with it all fitted. I was thinking about the seal in the MC but if that's the problem then the previous 2 owners have suffered with it and not done anything, also why would pressing the brakes hard instantly release them? So I'm not sure the MC is the problem hence the thought of servo problem.

[bmcecosse]

Just clamp the servo vac pipe....

[MrIan]

Just clamp the servo vac pipe....

What an ace idea for a quick test!!! 10 out of 10 for that one Bmc

[bmcecosse]

Never used them, or had any problems with uneven wear.....