Hi,

 first time posting here but hopefully some of you fine people can help!

having problems with the wife's mk1.5 focus 1.8 petrol, basically the brakes are bad with the feeling of no stopping power. so had a look around and found a weepy rear cylinder so replaced the cylinders and shoes on the rear. didn't sort the problem, so with the pedal feeling bad i decided to try a master cylinder on it but again no difference, still  can't get any stopping power, so master cylinder was then replaced with another one and still no difference, so far i've replaced the master cylinder twice the rear brake valves, the servo unit, rear cylinders and shoes and all the brake hoses.also tested the servo and it holds a vacuum without any bother,even went to the extreme of fitting the calipers of my focus but again nothing changed.

if anyone has experienced this before or has any ideas please feel free to post as iam completely out of ideas 

thanks

please clarify some points.

is the pedal pressure feel good and firm, not spongey.

If you (without engine running ) put your foot on the brake pedal holding it down moderately, whilst keeping your foot there, start the engine. Do you feel the brake pedal move down further as the servo takes effect?

now with the engine running, hold you foot on brake pedal hard, turn engine off, start pumping brake pedal, do you feel it harden up as the servo loses its effect.

if you remove the vaccuum pipe from the servo with engine running is there some good suck from the vaccuum pipe

did it suddenly go like this one day or was this a gradual thing

Thanks for replying 

Yes would be the answer to your questions on the servo, if acts completely normal like any other servo, I don't really know if it was a gradual thing as it could be bad for ages before the wife noticed, pedal is firm when not running, drops when started a bit and comes hard again when switched off, also good suction when you stick your finger over the end

no sorry, I am out of ideas also.

@iantt  any ideas on this?

Personally I would take it to an MOT testing station and get them to check braking efficiency on there rollers, this could point in which area to look at( rear or front) . Also does your car have abs? 

Thanks for trying anyway, fresh thoughts can sometimes help

No abs on the car, yeah was thinking of taking it with me on Monday to work and sticking it on the rollers at dinner time, see if it shows anything

Silly question, but have you checked/replaced the pads themselves (I'm thinking contamination)? Also, do the non ABS MK1.5s have a load limiting valve for the rear brakes?

They don't have a load valve on the rear but they do have the pressure reducing valves up at the master cylinder, I've swapped them with a different set already. Pads and discs in the front aren't that old and tbh the pads and discs on my focus are much worse and still work well

Very strange indeed. So to recap the pedal feel's good, its just the brakes don't seem to provide the sharp stopping power you're expecting? The only other thing I can think of is that there's something wrong with the pedal and/or its mechanical linkages meaning that its providing enough movement/force for you to bleed everything up but when you're going to step on the pedal its somehow not transferring the force through to the master cylinder somehow.

Tbh I thought this too, but When you open the bleed nipple there's plenty of fluid coming out and going a good distance, I'll see how it gets on with the rollers, also noticed the clutch master cylinder is a bit damp but I wouldn't think it would affect the brakes as its a different circuit 

could be collapsing rubber flexi brake pipe restricting flow under pressure. seen that before. 

he does say in first post that all hoses have been replaced

1 hour ago, isetta said:

he does say in first post that all hoses have been replaced

oh yeh, forgot that. 

Didnt get near the car today so nothing to report back hopefully I'll have done info tomorrow

so got the car onto the brake tester at work and it showed up a slightly low reading on the offside rear wheel, still braking over 1kn though the other side was more like 1.3kn. car still made 62% efficently so even as bad as bad as the pedal feels it would still pass a mot, going to drive it about for a couple of days and then re adjust the rear brakes and see if things then improve on the rollers 

It might be worth giving the rear adjusters a full stripdown, clean and rebuild with a bit of grease.