i have metro turbo 4 pots on my race car, which are giving me serious grief.. when we bleed them the ring that holds the piston seals in is coming loose and popping out its really stressing me out, weve been through two sets of seals and had the brakes rebuild by a proffesional.. is there anything i can do before i throw the whole lot away...

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Potato

put some lubricant like the pbr brake lube (rubber grease) or similar on the dust seal prior to installing the pistons, they must be dragging.

Regards

Daniel

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Videos - Turbocharged A-Series on Dyno & at Wakefield
Mafs waz not my strong subgeckt at skkol

What were the brakes assembled with as a lubricant?
I use PBR rubber grease, as I found brake fluid too thin to get the
parts together with.

If the seals are the problem, change them. You've spent this much, $30 for new
seals is nothing.

Is the problem with all the seals or just some of them?

Have you ever found the rubber grease to react with anything? I wouldn't usually chance mixing oils,greases and brake fluid?

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I found the dust seals on S brakes I bought swelled up when degreaser was used to clean calipers down, I had to change a set.
I uses Dow Corning silicone grease.
Don't ever use ordinary grease!!!
<edit> mineral oils and grease are incompatible with the rubber.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

The PBR stuff is made for brake calipers. If it reacts with brake fluid, the product
is useless.

Oh well there you go. I've got PBR rubber grease here, but it's just normal crappy rubber grease. I had a brickie mate with a smooth top 63 van who topped his brake fluid up with engine oil...

It swelled the hoses up and stuffed everything.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

rubber grease is OK for assembly, won't hurt but it doesn't last- is not as good for dust seal lube as the silicone grease is.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

as i said it was assembled by a brake specialist the second time so it has been greased up fine, i was fiddling with them today and i may have fixed the problem, only bleeding the system will tell...

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Potato

well ive bled the system and i have brakes, but the pedal travel is way too much for my liking, meeni u can stand on the brakes and the pedal barely moves, this one you have too much movement.. anyone know why? there is absolutely no air in the system

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Potato

Just as a complete paranoia check , what discs do you have , are the 4 pots meant to go on vented discs and you have solid ? By rights you should be in buisiness by now but something doesn't seem right , did you have this combo working before or is it new components ?

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its a complete metro turbo setup so it shouldnt be wrong... ive not used the setup before no if i had id know what was wrong.. the pedal is just super spongey, my grandad reckons its the master cylinder rubbers not holding the fluid properly but why spend 260 bucks when it might not be that..

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Potato

The seals on the master cylinder are the most likely culprit for spongy brakes.

Something else to consider is how the original car (the metro) was set up.
Did it have a booster or larger or smaller master cylinders to compensate for the
difference in piston area?

i dunno but many mini people have had these brakes and ive not seen anyone complain and have problems like i have

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Potato

It is maths.
More pistons = More surface area = More fluid displaced = Lower pedal.
I have heard a few complaints about 4 spots and lower pedal but check everything first.
You can work out the surface area of the 4 small pistons and see if it is larger than the 2 larger (Cooper S) pistons. This can give you a guide as to how much extra movement you may expect at the pedal.

Check the master cylinder.
If you can, take the pipe out of the master cylinder and replace it with a bleed nipple. Bleed the master cylinder and see how much slack there is in the system. If everything is OK there should be very little pedal movement. If something is wrong you could find a bit of movement.