12 replies to this topic

[mk=john]

Hi
I have just filled up my new braking system with silicon brake fluid. It is an early mini with drums all round, and a single line system.
It has the older type metal master cylinder. Someone mentioned that I need to bleed the master cylinder along with each line. The master cylinder has no bleed nipple.

So can anyone tell me the correct process?

Thanks
John

[Ethel]

The single line cylinder will bleed itself because the pipe is right at the top. Bleed starting with the nipple furthest from the cylinder,sucking with a syringe 'n short length of rubber hose makes it easier.

Is your silicon fluid recommended for your setup?

[il-barba]

just screw a bleed nipple in the master cylinder and bleed like you would bleed a wheel cylinder

[mk=john]

The single line cylinder will bleed itself because the pipe is right at the top. Bleed starting with the nipple furthest from the cylinder,sucking with a syringe 'n short length of rubber hose makes it easier.

Is your silicon fluid recommended for your setup?

I am not sure, I assumed it was. if not, is it safe to replace with with normal fluid?

[Ethel]

I'd have a read up on the manufacturers' websites. I've never really looked into it as I've always thought Dot4 was adequate for a road car.

I think there are issues with mixing fluids, but then we now have universal fluid where once you had different stuff for Lockheed 'n Girling plumbing.

[mk=john]

I'd have a read up on the manufacturers' websites. I've never really looked into it as I've always thought Dot4 was adequate for a road car.

I think there are issues with mixing fluids, but then we now have universal fluid where once you had different stuff for Lockheed 'n Girling plumbing.

But bleeding the master cylinder....another post says screw a bleed nipple into the master cylinder and bleed the same as a wheel cylinder

[il-barba]

hi, you should not need to bleed the master cylinder on the single line one (had missed that part), i would connect all the system and bleed as ethel told you.

[mk=john]

hi, you should not need to bleed the master cylinder on the single line one (had missed that part), i would connect all the system and bleed as ethel told you.

Well, i used the Gunson easibleed system, and it seemed all the air was out of the system. Then when that was done, i pressed the brake pedal and it felt really spongy.

I have checked for leaks, and there are none...dry as a bone.

[Ethel]

Drums can be a bit more tricky as they have pull off springs . Put the hand brake on and turn the front adjusters to lock the wheels, that may help. If you're unsure about the cylinder then replacing the pipe with a bleed nipple (bigger than the Mini's) or a union with a bit of crimped over pipe to seal it - if the pedal isn't solid the seals have gone.

[mk=john]

Drums can be a bit more tricky as they have pull off springs . Put the hand brake on and turn the front adjusters to lock the wheels, that may help. If you're unsure about the cylinder then replacing the pipe with a bleed nipple (bigger than the Mini's) or a union with a bit of crimped over pipe to seal it - if the pedal isn't solid the seals have gone.

Hi, Everything is new, master cylinder, slave cylinder and all of the brake lines

[Dan]

Sometimes master cylinders can indeed trap a bit of air, all you need to do to bleed it is slightly crack open the line while it is under a little pressure. If there is air in there, it will splutter a little fluid out on its way. It's more like bleeding a domestic radiator than brakes really.

I fail to see how fitting a bleed nipple to a master would ever help though, in order to hook it back up to the brakes you would have to remove the nipple and reconnect the lines, letting air straight back in.

Mixing fluids is not good. The problem with using silicone in a system not intended for it is that the seals and cylinders are lubricated with brake fluid on assembly. So there will always be a little to mix if the fluid used was mineral. How much of a problem this actually is has been debated more than once here, without a real answer.

[mk=john]

Sometimes master cylinders can indeed trap a bit of air, all you need to do to bleed it is slightly crack open the line while it is under a little pressure. If there is air in there, it will splutter a little fluid out on its way. It's more like bleeding a domestic radiator than brakes really.

I fail to see how fitting a bleed nipple to a master would ever help though, in order to hook it back up to the brakes you would have to remove the nipple and reconnect the lines, letting air straight back in.

Mixing fluids is not good. The problem with using silicone in a system not intended for it is that the seals and cylinders are lubricated with brake fluid on assembly. So there will always be a little to mix if the fluid used was mineral. How much of a problem this actually is has been debated more than once here, without a real answer.

Hi, I think it is now bled OK, I did another stint in the Garage today (After I saw our footy team lose misreably). Then only thing is there is quite a loot of pedal travel, but when it reaches half way down, it stops moving firmly.

I guess thats because the brakes front and rear need adjusting.

John

Edited by mk=john, 27 June 2010 - 07:05 PM.

[CaptainBland08]

the travel will most likely be the rear brakes... like you say just adjusting.... if there is good resistance but long pedal travel, the rear brakes are always the place to start...