Brake Pedal Fade

[mrmacca]

Hey Guys,


My Astra stops well. The brakes are all good, EXCEPT after stopping I can keep pressure on the brake and it fades / slowly travels to the floor. Is this normal with the astra as I've never noticed it before.

I've had a look, bought a Second hand Master Cylinder of Fleabay, fitted and bled and its still the same.

Perhaps I'm just being too heavy on the pedal? I got three different cars and one has no servo so perhaps I'm simply asking too much of it to stay rock hard.

The servo seems to be working, eg hard pedal with engine off, engine on and the brake becomes lighter.

Just wondered what you people would think of looking at next?



Thanks for any replies I get.

 

[Lefthooker]

Well, no this is not really normal. At least, it doesn't happen to me.
If the master cylinder has been replaced and it is still doing it, you might want to start looking elsewhere.
The brake cylinders in the rear drums like to get drippy after a while. Sometimes it takes a while for anything to become visuall, but I know these can break their seals quite often. Might want to check this.

 

[tabetha]

It's a simple system, pressure is or should be generated at the master cylinder and pushed to the brakes, so you have a seal problem, I'd put my money on the s/h master cylinder myself, but as said the rear wheel cylinders do shag out ever so quickly, I replace mine every two years.
tabetha

 

[Astraguy09]

You have a leak!

only thing that could cause pedal leak! If you have rear drums, do they lock up easily? If so crack them open see if theyre full of fluid! TEchnically you will need to change the drums but when i had this problem they just got cleaned out with petrol & they were perfect!

If you dont have drums get a torch and look over every inch of the brake piping & system to make sure that there are no leaks anywhere. Remebering that Brake fluid eats paint and is very acidic!

 

[mrmacca]

All good advice thank you.

I was sure it was the master cylinder but the guy I bought it from assures me it was a good one.

So I think the rear brake cylinders are next. I changed them about 4 years ago probably.

Stoopid Car


I'll keep you posted. Cheers Alasdair

 

[Rusty]

My money's on you buying a shagged master cylinder to be honest.

 

[Andy_Mk3]

I changed a rear wheel cylinder on mine a few weeks ago because the bleed nipple was seized. But it made a huge difference to the feel of the brakes. Wheel cylinders are quite a common thing to go on all cars with drums after some time.

 

[mrmacca]

I confess there was a little possible seal wetness on one of thethe rear cylinders so it could be that. I tried just clamping the flexi pipe to see if the system went hard again but didn't so you could be right about being sold a pup on Fleabay !

 

[tabetha]

Simple truth is vaux brakes are ****, they eat wheel cylinders, that's why I'm going disc, never seen the problem vaux have with certain brake parts, on any other make of car in 25+ years.
tabetha

 

[yam yam]

My astra sports tourer has had the brake servo and master cylinder changed about 4 months ago, the reason they were changed was brake fade, its now come back, any idea why.

 

[DavebGsi]

hmm seems strange, what do u mean by fade?

 

[81sguy]

It's a relative simple system. Mine has a vacuum pipe from the engine, it's brittle plastic after years, when it has a crack you loose pressure/vacuum and the brakes doesn't to the job anymore... Also air in the brake hoses or bad brake fluid can cause issues... If it's not the cylinder...

 

[Joycey]

Holy thread revival lol