Foot Brake pressure fade.

[Johnh]

Hi all you technical guys.
My Stag has until recently stopped nicely when required and I could slow down comfortably.
Now if I stomp on the brakes it works well and rubs its nose on the ground!!!!
If I press gently on the brakes to slow down slowly the pressure goes steadily until the pedal is nearly on the floor.
I do not seem to be loosing fluid.
Is this the fluid flowing back to the main cylinder or is it the Brake servo giving up the job and a new one beckons.
I have read that replacing the servo is a bit of a challenge and I do not do brakes generally and definitely not bleeding them.
Advice and guidance appreciated.
John H

[StagManiac]

It sounds to me as though your brakes simply need a proper bleed.

Paul

[Stagnant]

Hi John.
It sounds to me like the master cylinder is letting by. They are not as easy to refurbish as some other makes - I went for a new one.
Cheers, Mark.

[tonyh]

If the brake pedal sinks slowly, take your foot off the pedal and re apply the brakes and the pedal feels normal again it the brake master cylinder, brake fluid is seeping past the seals, when you take your foot off the brake fluid goes back past the seals.

Tony.

[Ian F]

John

Exactly how mine failed a couple of years ago........New Master cylinder I'm afraid!

Ian F

[Seaking]

Replaced the seals on mine a bit fiddly but all went well

Cheers Glenn

[Johnh]

Thanks all, sounds like a new master cylinder, at least it is not a servo.

Have to make a visit to the spares suppliers.

then have it done.

John.

PS. just ordered new master cylinder, almost as much as a new servo!!! The car is costing me a fortune at the moment, mind you when have they ever not.

[Donkey]

Excuse me "piggy backing" your thread John but I've experienced a similar problem and have couple of questions for the lads.

If I press gently on the brakes to slow down slowly the pressure goes steadily until the pedal is nearly on the floor.
I do not seem to be loosing fluid.
As John has said there but it happens only rarely to me.
So the questions are:

Is this a prelude to a catastrophic failure and if so how long is it likely to last? It might sound like a silly question but can it be left as a winter job?

Is the job of replacing the Master Cylinder fairly straight forward? The WM doesn't really give you a clue as to this, it suggests it's very straight forward.
I'm long enough in the tooth to know that often is not the case.

Regards,

Brian

[tonyh]

I would replace the master cylinder NOW, you can never tell when it will fail completely and end up having a large accident, if you did have an accident and the insurance company found out you knew there was a problem with your brakes they could refuse the claim.

Never mess with brakes, it's your life, your passengers and could be other road users.

Tony.

[Danny]

Replaced the master cylinder on mine but still have the original and I will replace the seals on that when I have more time.

Danny

[Johnh]

I hope that one day you find the time, I have got rid of a lot of "roundtuits" recently, I think a few of them may have been a decade or longer old!!!!
John H