I've got a problem with my front brakes locking on, the car is a 98 Escort Gti Estate

When the car is cold they are fine, they start to stick on once it's been driven a few miles, getting gradually worse the more you're using the brakes, once everything cools down again, they release again

New calipers have been fitted, slight improvement but it hasn't solved it

What else could be causing it?

I'm guessing the master cylinder is a likely cause and I've read you can get a service kit for these, new seals etc


Incidentally, the engine has recently been changed and it's only since then I've started noticing the problem

 

Seen this a few times, next time brakes lock on, release the vacuum pipe from the servo, and see if that releases them, if so duff one way valve.
tabetha

 

Not really sure exactly where the servo is or what it looks like, but I'll give it a go

 

Pulling the valve out of the servo does release the brakes

I'm not sure that is the valve though, haynes manual says if you can blow through it both ways (or blow and suck from the one side) it indicates the valve is knackered

I can only blow through it the one way, could it still be the valve?

If not, what else would it be, the servo itself?

 

The valve is duff, not allowing correct passage of air upon release, next visit scrappies for a new one.
tabetha

 

I don't tend to use scrappies very often on account of having mates working at a motor factors, get most things close on half price

But ... they don't flamin sell the non-return valve/pipe

Popped round to the local ford's place and it's less than twenty quid for a new one direct from ford anyway, ordered one and it's coming in tomorrow morning, I'll fit it straight away and let ya know if that's solved it

 

Fitted the new pipe and valve and the brakes do seem better though I've not given it much of a drive yet

Trouble is ... the car doesn't tick over properly now

Also 'judders' when you're driving along and the revs drop below around 1500, prior to fitting the pipe I could let the revs drop to a thousand in fifth and it would handle that comfortably

I'm thinking I must have disturbed something when fitting the pipe but I can't see anything that looks like it's been pulled out of where it should be

Flamin cars!

 

It was obviously "breathing" through the servo last time, so now the air/fuel mix is out by a little bit, caused by another existing fault in the first place, the extra air it could get was just helping the engine.
I would clean the maf, and check the co.
tabetha

 

What do you mean by 'co' ?

There is a small hole in the bottom of the filter box, one of the lugs is broken off and I've not had chance to change it yet

Also when I changed the pipe I noticed the filter intake wasn't fitted into place on the front grill quite right, so I put that into place properly, don't see how putting that right would cause a problem though

 

The pipe hadn't been fitted to the manifold at the back of the engine properly, putting that right sorted the idling problem

But I've taken it for a drive now and the brakes are sticking as bad as ever, if not a little bit worse, so it doesn't look like it was the valve after all

I've ordered some carb cleaner for the maf so I wil do that

What would be the next thing to try?

 

Could it be the vehicle speed sensor?

Earlier I disconnected that and took it for a short drive, seems to be an improvement

I have to go out on a job that's around a thirty mile trip tomorrow, should give me a better picture


Are there any possible consequences to driving it with the sensor disconnected?


Obviously I'll replace it if it does prove to be causing the problem but that won't be until next week