Master cylinder

[Dan5]

New poster! (less than 10 posts)

I've recently fitted some big 4 pot brake on my car but now my brake pedal goes right to the floor i've spent ages bleeding them and they're still the same.

I think my master cylinder has had it so i'm going to replace it but should i replace it with a larger bored one to suit the bigger calliper and where would i get one from?

Thanks

[adscan]

Were your brakes working ok before you fitted the new brake parts? Unlikely that the master cylinder would suddenly fail.

[Dan5]

yeah they were fine before i change them. I did have problems bleeding the driver side though.

[adscan]

bit suspect that the problems start after you change the brakes. looking at the master cylinder, does it show any signs of leaks? worth bleeding the whole system again.

[Dan5]

I've look over the whole brake system and found no leaks.

I've bled the system a few times now hoping it would help but the pedal still travels to the floor. I'll try bleeding them again tomorrow

[Alastair]

Your m/c will have gone. The seals are 20 years old now! Ideally you can fit a 21mm one from a r11 or a reacement standard 19 mm one. Make sure you add the fluid, then leave it for a half hour before you bleed the new one to ensure the seals are lubricated and when you first depress the new m/c do it v slowly and carefully. I went through 2 new ones doing my 4pots... The 2 man method is far far better that even the best vacuum 1 man kits. Get a mate to help you...!

[Dan5]

Is the r11 master cylinder a direct fit?