Brake master cylinder...

[TT Tim]

...what's involved in changing it? The brake master cylinder that is.

I haven't looked at the car yet, but how do you get to the bugger, is it via the footwell?

Also, has anyone sourced a master cylinder from a motor factors? It's listed in the equivalent parts thread as:

Ford Fiesta XR2 or 1.6i Ghia - check the bore diameter as there were two types used. The one you need for the 4.2 Cerbera is the larger, which is 22mm.

What year should I be looking for?

I've been to my, helpful as ever, motor factors and we've looked through the books and found what looks like it's correct, 22.2 mm bore. But it doesn't look like the ones on Clevor Trevor or Racing Green web sites, but rather an alloy item.

Does that sound right?

Any help appreciated, before I roll up my sleeves and get on.

Tim

PS: If it is the one I've found, it should at least half the cost of those offered by the TVR suppliers.

I'm seriously thinking about setting up an on-line shop for all these bits.

Edited by TT Tim on Thursday 13th March 08:18

[julian64]

No idea but quite like the idea of comming and seeing you do the brake master cylinder as it seems to be a common replacement thing and I've never done one.

P.S. does this mean Jules wasn't impressed at the way you put your car back together

[trackcar]

Tim put his car back together just fine but the brakes are not good. We thought it was just too hard a pad compound at first, seems not though on further investigation Tim ?

The master cyl is a right royal PITA to get out .. comes out on the complete pedal box from inside the footwell .. putting it back in against gravity is a pig of a job, I don't envy you. Fortuntely I've had to do very few, usually accident damaged cars where the insurance compan has insisted on a complete new pedal box if the brakes have taken a real hammering in a crash. Never had to replace one through wear and tear. You're very unlucky if it is a M/cyl fault.

[TT Tim]

julian64 said:

No idea but quite like the idea of comming and seeing you do the brake master cylinder as it seems to be a common replacement thing and I've never done one.

P.S. does this mean Jules wasn't impressed at the way you put your car back together

Cheeky man, I may bring the car to you and we can do it in the comfort of your garage!

Everything back together fine, but have an oddity on the brakes.

Have dreadful pedal feel, I've put a litre of fluid through it, so did Joolz and it's still not right. I know everything else is okay as I changed and cleaned it all.

I've ordered new pads to eliminate the possibility of me having contaminated the pads when they were cleaned. That leaved the master cylinder.

Hense, my train of thought.

Tim

[TT Tim]

Morning Joolz.

Did you get my mail?

Car feels great - thanks very much.

Tim

[julian64]

Do you have a way of measuring the brake pressure in the system to identify where its being lost.

If your master cylinder isn't leaking then you only really have two posibilities I can think of.

1) Air in the system from a poor bleed causing spongy poorly acting brakes.

2) fluid escaping past the master cylinder primary seal causing brake fade the longer you have your foot on the brake.

I assume your number 2 if you're hell bent on the master cylinder removal? But it would be nice to quantify a before and after with some sort of pressure gauge.

Oh BTW, comfy garage always available for learning wrt Cerb.

[billy no brakes]

I have changed mine and it is a bugger to do but not impossible. to get to it you will have to tkae off the black cover near the wing you can,t miss it, it has got a mastic seal around it and you will need to take that off first to find the screws that hold it down, once the cover is off you will see the clyinder thats when it gets awkward firstly take off the brake pipe conected to the cylinder this enbales you to get a spanner on the bolts holding the clyinder in place, you will then need a contortionist in the foot to hold a spanner on the nuts and someone to undo bolts from inside the now removed cover. Inside the footwell the clyinder is held onto the pedal by a nut and bolt which is easy to undo. once all the nuts and bolts are off bobs ya uncle and out she comes. getting it back is fun trying to put the bolts back took me nearly an hour kpet dropping the bloody things. I can,t remember wher I got the clyinder but it was from someone on here, hope that is of help and good luck have plenty of plasters ready for the cuts.

Billy No Brakes

[trackcar]

TT Tim said:

Morning Joolz.

Did you get my mail?

Car feels great - thanks very much.

Tim

yeh it went to vicky's laptop instead of mine. i didnt measure the ride height, it's about level so didn't want to raise the rear as i would for a road car as that is just going to exagerrate any back-end looseness you already have, as i didnt touch it i forgot to measure it! doh! never got around to the scales either, time ran out on that one.

[TT Tim]

julian64 said:

Do you have a way of measuring the brake pressure in the system to identify where its being lost.

If your master cylinder isn't leaking then you only really have two posibilities I can think of.

1) Air in the system from a poor bleed causing spongy poorly acting brakes.

2) fluid escaping past the master cylinder primary seal causing brake fade the longer you have your foot on the brake.

I assume your number 2 if you're hell bent on the master cylinder removal? But it would be nice to quantify a before and after with some sort of pressure gauge.

Oh BTW, comfy garage always available for learning wrt Cerb.

I agree, but neither of the above seems likely, as has been said both Joolz and I have bled the brakes, so i'm confident we're air free.

The pedal doesn't go to the floor regardless of how hard you press the pedal, but the feel isn't right, it's hard but doesn't lock the brakes, other than the front n/s. So this leads me to the possibility of knackered pads.

It's a service item anyway, so worth eliminating, before pulling the car apart to change the master cylinder.

The only other thing is that the master cylinder is a 2 piston set up, and there seems to be little feel on the pedal at the top of travel, so maybe, just maybe, I've broken a spring in the cylinder?

Tim

[julian64]

TT Tim said:

julian64 said:

Do you have a way of measuring the brake pressure in the system to identify where its being lost.

If your master cylinder isn't leaking then you only really have two posibilities I can think of.

1) Air in the system from a poor bleed causing spongy poorly acting brakes.

2) fluid escaping past the master cylinder primary seal causing brake fade the longer you have your foot on the brake.

I assume your number 2 if you're hell bent on the master cylinder removal? But it would be nice to quantify a before and after with some sort of pressure gauge.

Oh BTW, comfy garage always available for learning wrt Cerb.

I agree, but neither of the above seems likely, as has been said both Joolz and I have bled the brakes, so i'm confident we're air free.

The pedal doesn't go to the floor regardless of how hard you press the pedal, but the feel isn't right, it's hard but doesn't lock the brakes, other than the front n/s. So this leads me to the possibility of knackered pads.

It's a service item anyway, so worth eliminating, before pulling the car apart to change the master cylinder.

The only other thing is that the master cylinder is a 2 piston set up, and there seems to be little feel on the pedal at the top of travel, so maybe, just maybe, I've broken a spring in the cylinder?

Tim

And of course the system is a two ring, so there will be at least three seals in the cylinder. Is it worth going to the local MOT garage and having a quick rolling road brake test?

[TT Tim]

julian64 said:

And of course the system is a two ring, so there will be at least three seals in the cylinder. Is it worth going to the local MOT garage and having a quick rolling road brake test?

Yep. It's going for an MoT next week, fingers crossed, so will know what's what then.

Tim

[Allandwf]

Just a thought, but, doesn't it have a brake balancer valve somewhere in the cicuit ?

[shpub]

It could well be a problem with the callipers. I have had an internal seal go so it blocked the transfer pipe that equalises both sides. Restricted the piston movment and gave very lopsided braking. I have also had pistons corroded into the callipers so that they don't move. Callipers bleed correctly but obviously little to no braking. If it is a piston calliper issue and the callipers are the early ones (no TVR logo), then it is cheaper to get a later pair from someone like Bell Hill.

The other point about the brake master cylinder to look out for:

1. The pipe fittings. They do vary and the last thing you want to do is is change the brake pipes.
2. The mounting bolt hole size and orientation.

[shpub]

Allandwf said:

Just a thought, but, doesn't it have a brake balancer valve somewhere in the cicuit ?

No. Balance is achieved through the different calliper sizes.

[julian64]

shpub said:

It could well be a problem with the callipers. I have had an internal seal go so it blocked the transfer pipe that equalises both sides. Restricted the piston movment and gave very lopsided braking. I have also had pistons corroded into the callipers so that they don't move. Callipers bleed correctly but obviously little to no braking. If it is a piston calliper issue and the callipers are the early ones (no TVR logo), then it is cheaper to get a later pair from someone like Bell Hill.

The other point about the brake master cylinder to look out for:

1. The pipe fittings. They do vary and the last thing you want to do is is change the brake pipes.
2. The mounting bolt hole size and orientation.

Considering he recently beadblasted his calipers to make them look shiny, the comment about blocking the transfer pipe, is now about to give him nightmares

[johnbear]

I've done this job and it took 14 hours!

I know some have mentioned getting at the brake master from the clutch fluid cover, but it was impossible for me.

I had to remove:

drivers seat
ALL CARPETS AND FOAM IN FOOTWELL AND BEHIND SEAT - the fluid just eats the carpets
universal steering joint by front wheel.
disconnect the electric to steering coloums,
remove plate in footwell around bearing in firewall for steering column. Screws were covered in sealant and had to drill 1 off.
remove steering column.
disconnect brake light cables
There are 4 or so bolts in bulkhead above pedal assembly by the windscreen. Remove from outside. One is really had to get at as it's covered by the wiper assembly cover.
Place towels in drivers footwell - lots of.
Drain all clutch and brake fluids
disconnect acclerator cable
Remove the bolts at bottom of pedal assembly
remove bolts clutch and brake pipes into aluminum block in drivers footwell.
break the sealent bonding around the brake fluid res.
Remove whole pedal assembly.
change brake master cylinder - the easy bit

The real difficulty was reconnecting the fluid pipes into the alloy junction block. The thread wouldn't catch. I had to use a pair of mole grips to carefully clamp the top of connecting flange nut to the bottom of the connect block whilst turning the flange nut.

Refit and reseal around brake res

Get some latex gloves as brake fluid kills your hands.

[TT Tim]

shpub said:

It could well be a problem with the callipers. I have had an internal seal go so it blocked the transfer pipe that equalises both sides. Restricted the piston movment and gave very lopsided braking. I have also had pistons corroded into the callipers so that they don't move. Callipers bleed correctly but obviously little to no braking. If it is a piston calliper issue and the callipers are the early ones (no TVR logo), then it is cheaper to get a later pair from someone like Bell Hill.

The other point about the brake master cylinder to look out for:

1. The pipe fittings. They do vary and the last thing you want to do is is change the brake pipes.
2. The mounting bolt hole size and orientation.

Thanks Steve, but I can rule those out.

The calipers have been completely cleaned and refirbed with new seals all round.

New braided hoses fitted okay.

All calipers fitted back as original.

Tim

[TT Tim]

julian64 said:

shpub said:

It could well be a problem with the callipers. I have had an internal seal go so it blocked the transfer pipe that equalises both sides. Restricted the piston movment and gave very lopsided braking. I have also had pistons corroded into the callipers so that they don't move. Callipers bleed correctly but obviously little to no braking. If it is a piston calliper issue and the callipers are the early ones (no TVR logo), then it is cheaper to get a later pair from someone like Bell Hill.

The other point about the brake master cylinder to look out for:

1. The pipe fittings. They do vary and the last thing you want to do is is change the brake pipes.
2. The mounting bolt hole size and orientation.

Considering he recently beadblasted his calipers to make them look shiny, the comment about blocking the transfer pipe, is now about to give him nightmares

LOL, No, it's okay, they were all blown through with an airline

Tim

[Extra 300 Driver]

billy no brakes said:

I have changed mine and it is a bugger to do but not impossible. to get to it you will have to tkae off the black cover near the wing you can,t miss it, it has got a mastic seal around it and you will need to take that off first to find the screws that hold it down, once the cover is off you will see the clyinder thats when it gets awkward firstly take off the brake pipe conected to the cylinder this enbales you to get a spanner on the bolts holding the clyinder in place, you will then need a contortionist in the foot to hold a spanner on the nuts and someone to undo bolts from inside the now removed cover. Inside the footwell the clyinder is held onto the pedal by a nut and bolt which is easy to undo. once all the nuts and bolts are off bobs ya uncle and out she comes. getting it back is fun trying to put the bolts back took me nearly an hour kpet dropping the bloody things. I can,t remember wher I got the clyinder but it was from someone on here, hope that is of help and good luck have plenty of plasters ready for the cuts.

Billy No Brakes

Was that the clutch master or brake? Sounds like clutch to me.

[BLUETHUNDER]

The most frustrating part of this job for me,was trying to line the pipe back up to the cylinder.took me over an hour,as the thread wouldnt catch.took f**king ages.