Brake master cylinder

[djb222]

Just in the process of finishing off my car after a very lengthy build ( 10 years or so, on and off) anyway the end is in sight. I moved the car into my garage, a 50m drive and the brake pedal went very spongy and I had to pump the brakes to get pressure. So, I found some bubbles in the fluid reservoir and decided to bleed the brakes. The front bled ok and on topping up the reservoir found a few drops of fluid around the said reservoir. Trying to bleed the rear brakes I found the brake pedal hard, on looking at the reservoir again there was a lot of fluid on the floor pan. As I was doing this job solo I called my wife as a second pair of eyes. With all bleed nipples tight I depressed the pedal several times and even from the car I could see a jet of fluid shoot from the reservoir.

My thoughts are because the car has been standing for a good while the fluid control valve in the master cylinder has failed resulting in fluid being forced back into the reservoir or could it be seals? Has anyone come across this before or any other ideas?

Has anyone got any photos or comments on securing or protecting the brake lines front and rear please. I've looked at the spiral wrap but feel they need additional fixing.

Regards

David

[Steve_D]

Fluid coming back into the res. is classic seal failure.
Could well be just that you have had them a long time with no fluid in the system and they have perished.
You can get replacement seal kits which I would normally never use but in this case where the piston and cylinder have done no work a seal kit will be fine.

Spiral wrap works fine. Just wrap the whole exposed length then there is nowhere for it to move too.

[djb222]

Thanks Steve,

the master cylinders were probably sitting around for about 18 months before brake fluid was put into the system, so I would hope the seals wouldn't have perished. Perhaps they are just faulty, I'll take the cylinder off the car and have a good look to see if I can just replace the seals or the cylinder.

Regards David

[Steve_D]

The cylinders are pretty standard so are readily available and not expensive.

Steve

[845ste]

I'm looking at the braking system: ok I don't have the brake servo, but trying other racing cars, the pedal of my gtr is too hard!
I have to put a lot of pressure on the pedal, too much.

I thought of installing a pump with the smallest diameter:

is correct?

here you, what kind of pump do you fit? Girling? diameter?
very thanks

[UltimaCH]

845ste said:

I'm looking at the braking system: ok I don't have the brake servo, but trying other racing cars, the pedal of my gtr is too hard!
I have to put a lot of pressure on the pedal, too much.

I thought of installing a pump with the smallest diameter:

is correct?

here you, what kind of pump do you fit? Girling? diameter?
very thanks

Stefano, I think others have upgraded to bigger brakes and this solved the hard brake pedal without reverting to a servo

[845ste]

Danel, iI already have bigger brakes: kit brembo gt3 6pots ant and 4pots rear........

I have read here and in fb that the system is poorly sized:
here many own have problems with the hardness of the pedal.
before switching to the servo,I wanted to try with a smaller diameter pump master, but apparently no one has tried.

i run on the track with race cars ,but none has the pedal so hard and not very modular!

[V8Dom]

UltimaCH said:

Stefano, I think others have upgraded to bigger brakes and this solved the hard brake pedal without reverting to a servo

Sorry to say Rog and I discovered the brake master cylinders are the wrong size... theres plenty of discussions about it previously but basically the rear cylinder should be the front.. and the front a size inbetween... swapping them makes a huge difference

[845ste]

ciao Dom,
in fact I want to try to install the same dimension behind, in front of it.
I hope to solve