Rock Hard Brake Pedal ?

Hello Lunarboy,

When you remove the vacuum line from the booster and then depress the brake pedal, it feels very hard as there is now no pressure differential across the vacuum chamber,..ie both sides are at atmospheric pressure.

It is not a requirement for a hard brake pedal that there be a leak from the slave cylinder allowing brake fluid to enter the vacuum chamber, but there usually will be, especially in a unit that has seen some years of service.

The air control piston is the item which if stuck within its bore will prevent a vacuum from being formed on one side of the chamber, thus no pressure differential and no vacuum assist.

Ten years or 100,000 miles is typically the most you will ever get out of a booster.

Ron.
 
can you take a servo from a donor car and fit it without serious problems or do you have to have a new one?
servo that is !
i have a few servo's including one still on a car if anyone is interested,.
 
8866nk wrote,..
can you take a servo from a donor car and fit it without serious problems or do you have to have a new one?
servo that is !
Click to expand...

Of course you can take one from one Rover of the same type and fit it into another,..but why would you? Unless you know the history of the booster from the donor car, you could well be just waisting your time.

Ron.
 
If you knew it was working before you took it off , there's a better chance of it being OK after fitting an overhaul kit
 
not convinced that it was that great - i also appear to have lost some fluid - about 1cm - nothing at brake pedal (was checking master cylinder) and no obvious sign at calipers? Looks like servo then - does the one way valve fail and can it be replaced or would that involve stripping the unit anyway? :?
 
lunarboy wrote,..
i also appear to have lost some fluid - about 1cm - nothing at brake pedal (was checking master cylinder) and no obvious sign at calipers? Looks like servo then
Click to expand...

You only have one option then, and that is a complete removal and overhaul. I know that you are looking for any excuse not to do so, but the fact remains that the seals within the slave cylinder are worn in the same way that the seals in the master cylinder will wear. The problem won't go away, it will only get worse.

Ron.
 
Between the caliper body and the metal cover you'll see the rubber dust seal, carefully push a thin screwdriver in next to the caliper body next to the rubber and twist the screwdriver slightly, and see if you get drowned in fluid.......
 
Cheers - have now checked and yes fluid dribbled out of one side and I reckon i have punctured the one on the other side - not a lot of space in there :( So, what are the recommendations and would this alone account for the poor braking performance ie that the servo is prob ok? Are re seal kits reliable or should i go for re con - yes I have looked at the price :( If one isn't leaking albeit now with a slightly damaged cover seal should I leave it alone?

Cheers :?
 
Looks like you might have explained the fluid loss via the rear calipers, in which case you might get away with an air valve for the servo.

Chris
 
Hello lunarboy,

If one of your rear calipers is leaking, chances are that the other one is not far behind. So if I were you, I would be having both of them overhauled. Leaking rears however will not account for a hard brake pedal, quite the opposite in fact. A soft pedal is the usual pointer. Given the hard brake pedal, that takes us back to the booster again.

Have the booster and rear calipers all out and overhauled at the same time. On the subject of rear seals being reliable. Provided the cylinder bore in each caliper has been resleeved in stainless steel, then the new seal kit should last for 13 years or more. If they have not been resleeved, then your best bet is to go for an exchange pair, or have your existing ones resleeved.

Ron.
 
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