EMERGENCY!!! - Brake problem - MOT Tomorrow!!!

[darkcat]

AAAHH!!! ok so just thought is test all systems whre functioning etc before tomorrow's MOT (been off the road for 6 months)

My dad fitted new brake disks all round a few weeks ago.

come to try and stop, and discover nothing much happening in the brake dept!

a little investigation later and it seems the rear brakes are ok, but the front's arent budging at all, and the peddle is rock hard.

SO.. opened the bleed nipple on the rear's, and pumped some juice through OK. tried on the front and not a drop would come out.

Now there is definately vacuum, and the servo is definately holding a vacuum too (popped the one way valve out and it hissed.


so seems to me like theres either some sort of issue feeding the front, as a whole..!

Ideas??

Thanks in advance, and beer on stand-by if anyone can nip over to help :-)

[bobfather]

Did he clamp the brake flexi pipes? If so, have the clamps been removed. Were the pistons pushed hard into the cylinders for access to remove the callipers and discs? if so then the pistons could be seized in now. Should never push the pistons all the way back in.

I can't believe this work was done without testing afterwards. Bedding the pads to the discs is a fundamental part of the job. Don't let your dad do any other jobs on your car.

[darkcat]

no clamps where needed, just a simple disk change. the pistons where only screwed in far enough to get the pads in, not all the way. the fact that with the front bleed nipples open, pressing hard on the (rock hard, non-moving) peddle, nothing comes out at all suggests something before the calipers. (though with a rear-nipple open, i canb fully depress the peddle)

weve not been able to bed them in because the car is SORN.

Edited by darkcat on Thursday 12th May 15:08

[dbv8]

I may have a similar problem. Ive not had any fluid run through my fronts as yet but my pedal is pushable albeit quite heavy even with a nipple open. I will be trying again tomorrow otherwise it wll be up to TrackvRoad to sort out next week. The cars going there on a trailer this weekend.

[M@H]

Perhaps have the calipers been given a 360 degree spin during the re-fit so that the hoses are crimped ?

(unlikely I know)

If the car is on sorn do we know the calipers were actually moving before the brake work ??

[SMB]

darkcat said:

no clamps where needed, just a simple disk change. the pistons where only screwed in far enough to get the pads in, not all the way. the fact that with the front bleed nipples open, pressing hard on the (rock hard, non-moving) peddle, nothing comes out at all suggests something before the calipers.

weve not been able to bed them in because the car is SORN.

If nothing comes out with the nipple open then it is probably the master cylinder end , or damaged pipework, even a seized caliper piston would allow fluid past to the nipple I would have thought. As the car has different fluid circuits back to front it could explain it.
Does the pedal move when you bleed the rears or did you use a pressure system to bleed it? A non moving pedal could suggest master cylinder seized.

[darkcat]

M@H said:

Perhaps have the calipers been given a 360 degree spin during the re-fit so that the hoses are crimped ?

(unlikely I know)

No, checked, looked fine

M@H said:

If the car is on sorn do we know the calipers were actually moving before the brake work ??

yes they where fine.

[bobfather]

darkcat said:

weve not been able to bed them in because the car is SORN.

Yes I thought that. By 'bedding to the discs I didn't mean bedding in the pads. This is a procedure you need to do on completion of each calliper and before you start the next. You need to ensure that the calliper has pushed the pads onto the disc so that the shared hydraulic system is ready for the next calliper.

You don't screw the front calliper pistons, that is only required for the rears. That rotation may have caused them to jam in the cylinder. Of course that doesn't answer why no fluid at the nipple, possibly blocked, though I doubt it. Did he remove the callipers? Could that have caused damage to the flexi's or to the copper pipes they feed from. If the flexi's are old you may have dislodged some of the inner surface and that could be causing a blockage.

Disconnect the system bit by bit backwards from the callipers and test for flow. Once you get oil flow you will know that you have just disconnected the faulty component

[darkcat]

bobfather said:

Yes I thought that. By 'bedding to the discs I didn't mean bedding in the pads. This is a procedure you need to do on completion of each calliper and before you start the next. You need to ensure that the calliper has pushed the pads onto the disc so that the shared hydraulic system is ready for the next calliper.

You don't screw the front calliper pistons, that is only required for the rears. That rotation may have caused them to jam in the cylinder. Of course that doesn't answer why no fluid at the nipple, possibly blocked, though I doubt it. Did he remove the callipers? Could that have caused damage to the flexi's or to the copper pipes they feed from. If the flexi's are old you may have dislodged some of the inner surface and that could be causing a blockage.

Disconnect the system bit by bit backwards from the callipers and test for flow. Once you get oil flow you will know that you have just disconnected the faulty component

Yes im going to work my way back through the system this evening, must get it on the road this weekend!

no, the calipers where not removed from the flexi pipes, no need.

[M@H]

I can't remember, does the Chim have a proportioning valve to set the brake balance - it could be stuck !?

EDIT: it does, doesn't it - Brake balance adjuster... something makes me think its in the middle of the car under the armrest, but I could be totally wrong

Edited by M@H on Thursday 12th May 15:43

[Pink_Floyd]

M@H said:

I can't remember, does the Chim have a proportioning valve to set the brake balance - it could be stuck !?
EDIT: it does, doesn't it - Brake balance adjuster... something makes me think its in the middle of the car under the armrest, but I could be totally wrong

Edited by M@H on Thursday 12th May 15:43

No nothing like that to the fronts. I am supprised that both the fronts don't work at all and that no fluid comes out, Suggest that it is the master cylinder that is at fault.

[Tyre Tread]

collapsed flkexi pipes or he's crushed a copper pipe when jacking it up?

[darkcat]

Tyre Tread said:

or he's crushed a copper pipe when jacking it up?

I thought that, but they run on the side of the chassis rails...

[darkcat]

well.... ive tracked it back to the master cylinder itself.
Very odd, basically it feels like theres a stuck valve or something in there, as i said i can pump fluid all day through to the back, bit there seems to be no output what so ever to the two front pipes that come out of the end of the cylinder...

MOT at 2:30 today! im propperly annoyed about this! wanted a weekend blatt

[dbv8]

Bab luck, not the easiest of jobs to change. I am about to go look at mine.
If its the same diagnosis then TrackvRoad can fit me a new cylinder next week!

[M@H]

If you get a seal kit you should be able to re-furb it yourself in a couple of hours

[dbv8]

M@H said:

If you get a seal kit you should be able to re-furb it yourself in a couple of hours

Surely that 2 hours doesnt include removal and refit does it?

[M@H]

I reckon - from another thread:

AirconAde said:

Hi there.

I have just changed my brake master cylinder as it was leaking from the main seal.

I managed to do it without removing the pedal box the only thing I had to do was remove the reservoir and the clutch master cylinder cover so that I could get a spanner onto the pipes. It was a bit of a fiddle but was done in under an hour including bleeding the brakes.

Ade

But who knoews with a TVR of course

Edited by M@H on Friday 13th May 11:29

[darkcat]

All sorted - MOT'ed just this afternoon just in time for summer :-D

no advisories either :-D

[M@H]

Jolly good - so how long did it take to do the cylinder ?