10 replies to this topic

[alic]

I have a 1981 998cc mini to which i have fitted front disc brakes and a 2nd hand servo + master cylinder. I have bleed the brakes several times but still cannot get a firm pedal. All the brakes are operating,if the pedal is pumped a few times then the front brake pads are just gripping the discs. I have changed the brake regulatory valve but this made no difference. Can anyone suggest anything?

Thanks,

Alic

[Jordie]

nope.but i've done this conversion afew months ago. Gotta bleed em up today, so u've worried me now!

[Bungle]

You do have the engine running for the servo to work havent you

[Guess-Works.com]

Quick tip to make sure your servo is working...

engine off, pump the brakes, and then leave your foot on the pedal, start the engine, and the brake pedal should sink. This is the vacuum of the engine drawing the servo and hence you foot.. If there is no movement then your servo is ka-put.

[Boab]

Quick tip to make sure your servo is working...

engine off, pump the brakes, and then leave your foot on the pedal, start the engine, and the brake pedal should sink. This is the vacuum of the engine drawing the servo and hence you foot.. If there is no movement then your servo is ka-put.

Nice one. I will try this once I get the effing thing started

[Cir-clipalot]

Also you should feel the pedal getting firmer with every push of the pedal if you pump it after the engine is turned off (as you get rid of the vacuum over 4 or 5 pushes).
Correct me if I'm wrong, those in the know, but surely a servo only reduces the amount of pressure your foot needs to exert on the pedal, and unless you've got a weak leg wont actually make the car stop any better than the equivalent non-servo setup?
sounds like air still in the system to me with this problem, loadsa people seemto have trouble bleeding the brakes properly, also if youve done the conversion make sure the nipples are facing up and at the top and that when bleeding youre not pumping the pedal so hard that the pressure limiting valve (if fitted?) shuts of the rear brake lines.
good luck! I'm hoping to so this conversion on my clubman now its running as the drum brakes give me nightmares!

[Dan]

The servo does make the brakes more efficient for the same pedal pressure and so in theory you can put more line pressure on with the servo, but whether the servo works or not you should still get a firm pedal and functioning brakes.

Keep bleeding them, they can be really stubborn sometimes. Are you bleeding them in the right order? How exactly have you set up the system? Is the FAM7821 valve you fitted new or second hand?

[Guess-Works.com]

The servo only provides assistance, hence the term Servo assisted brakes. This makes for a lighter pedal, but the myth that it provides more stopping force than a non servo assisted brake system is unfounded.

The servo can only provide assistance up to the point where the valve to atmosphere is open enough to destroy the vacuum, ie under heavy braking, at that point the servo is providing no assistance, and it's all down to your right ( or left !! ) foot.

Actually, if you do practice left foot braking, if you have you foot on the gas while braking in a servo assisted car, then the servo's not doing anything anyway, as the vacuum being produced by the engine is now drawing air through the intake manifold, not the pipe to the servo.

ohh.. ps if you use a servo on drum brakes, make sure you keep the adjustments in good order, because of that lack of intial feel on the brake pedal which the servo provides, I found that drums would bite you, if not careful.

Also I have a nearly new single line remote servo in the garage, with bracket and pipes.

[alic]

Thanks everybody for the advice we are now back on the road with the brakes working good.

Cheers,

Alic

[TimS]

did u find the problem? did it just need bleeding more?

[gsms]

I'm curious about the actual problem too actually!