Help please guys, brake problem!

[chris862]

Hey chaps, did the offside wheel bearing yesterday, dropped the caliper and it stretched the hose but didn't think anything of it, went for a test run, wheel bearing grumbling solved but its not braking well, pedals going further down than usual, suspected a split brake hose from the drop, but it wasnt leaking anyway fitted new hose this morning just to make sure, bleed the brakes, now the pedal goes all the way down and no brakes?

now suspect the master cylinder has let go or is it something else?
just to make it more annoying,have got a spare master cylinder, but it has bigger and smaller fittings for the pipes and the one on the car has fittings which are all the same!
a bit baffled, any help would be great cheers :)

[kent14sr]

It could be any number of things. Has the fluid level dropped?

It is probably the master cylinder but could be a seal elsewhere - can you see any leaks? Is all the air definately out of the system?

From memory all the master cylinder connections are the same - although two of the four outlets have pressure reducing valves for the rear, but the union on the brake pipe should still be the same size?

I have a spare master cylinder somewhere - ill try and look

[paul james]

Yeah the master cylinder can have two different sized connectors, M10 and M12 , both 1mm pitch thread. No idea why, perhaps just to help identify which was which when building the car in the factory.

[chris862]

Well in the end Dad transferred the innards from the spare master cylinder to the one on the car, when he dismantled the one on the car it seemed to be stuck?

anyway innards transferred, and still no brakes?

Chris, we're not loosing any fluid, and the levels not going up or down when the brakes are applied!

Also noticed the engine nearly stops when the brakes are applied, pointing towards a knackered servo again! perhaps the stuck master cylinder has killed the servo?

Bloody thing ! need the car for monday aswell :( in desperate need of a servo in cambrigeshire guys!

[jimbob-mcgrew]

might sound silly, but somethings not up with the pedal side of it is it ?
dodgy linkage from the pedal hinge along the bar up to the servo ?

you said the innerds were stuck, how so ?

i had a similar problem on mine some years back, and was scratching my head for a long while, in the end i removed all 4 bleed nipples, and pumped the pedal for about a minute, eventually brake fluid went all over the fcuking place, made a right mess, but got it back on track after that, quite a bit more bleeding from all 4 corners after that and it was back to good. not sure why it did it, possibly a blockage in the system or maybe just a huge clump of air ?

[silk violet]

my car is a gsi and mine has different unions on master cylinder 12mm on drivers and 10mm on passenger..... :thumb:

[chris862]

Cheers paul and silk, thats the one with the different unions, but we've got round this by transferring the innards from the spare one to the one fitted on the car.

and yea the spring and two pistons in the master cylinder were stuck, but we swapped em over so thats ok now.

Cheers Jimbob, might try removing all bleed nipples and doing as you say, but at the moment the pedal is operating the rod into the servo fine, but the servo doesn't seem to be operating the master cylinder?

[kent14sr]

I cant see the servo would make any difference - it only assists pedal pressure, it is not part of the hydraulic circuit so cant account for lack of pedal.

More like engine tries to stall as the master cylinder is travelling through the full cycle resulting in more servo trying to apply using more vacuum.

I think you need to check the calipers and connections - then if not take off back drums and check wheel cylinders.

Have you used a pressure bleeder to bleed the system? You may just have a air lock that needs pushing through!

I have servos,calipers, master cylinders if you get stuck

[jimbob-mcgrew]

might be worth checking the front brake hose bolts too. the ones on the caliper with 2 copper washers.
theres a hole thru their cores, and out one side. sometimes they can block up inside with rust or crap and cut the fluid flow quite alot

[chris862]

Many thanks Chris and Jimbob, plus rep :)

Kept bleeding the offside front at the union and finally got fluid though and then at the brake, must have been an airlock in the end! thanks for pointing us in the right direction chaps! well pleased :thumb:

[jimbob-mcgrew]

cool, so the old girls ready for monday :thumb:

[chris862]

Sure is! I think 200miles a week for the last 8 months is taking it toll on her lol

[paul burney]

Did you mange to sort this chris I am having the same problem at the moment if u sorted it could you let me no how u did it pal

Thanks
Paul

[joff-turbo-nova]

Use a pressure brake bleeding kit - solves lots of problems with airlocks when bleeding brakes.

Cheers

Joff