8 replies to this topic

[Nelson92]

1992 mayfair with standard AP brakes.

Hi all;
Quick question regarding brakes. I’ve refurbed my callipers using all new parts and everything’s gone back in except one of the metal rings. Referred to in the Haynes as a dust seal. is this simply to hold the rubber underneath in place or is it a functioning part that will cause problems if left out?
From looking at the design the piston shouldn't get any dust due to the two rubber seals. [as the metal seal has gaps around it so it doesn't touch the piston.]
I’ve just got another better condition set of brakes off an MPI to refurb slowly over winter so this current set isn't going to have to serve more then 4 months of driving.

thanks.

[Ethel]

They'll work fine, the dust seal just keeps the grot from corroding the surface of the piston which won't have any effect until you've worn out at least the current set of pads and ned to push the pistons back in to fit new ones.

[Sherlock]

They serve little purpose, & on my old Rally Cooper 'S', they fell out! Nothing bad happened after that, & the calipers did over 200,000 miles between two Minis. so I wouldn't worry too much.

[Nelson92]

thanks very much guys.

[Cooperman]

On the 7.5" calipers they ae an absolute b****r to fit, even when the two caliper halves are already apart.

[Nelson92]

one went in with barely any effort at all. the other one was a full on two hour labour that resulted in it being bent out of shape and useless.
my caliper is in 2 halves and i later tried it back together, no luck either way. i'm not sure if its the kit or the caliper being old and maybe a little out of shape.
are 7.5 calipers also made by AP?

[Cooperman]

I just had exactly the same problem (again). I had the two calipers both split. 3 of the new seals went straight in with the aid of a bit of Aeroshell aircraft control grease, but the other just bent to hell. I even tried an old seal carrier off another pair of calipers, but this went the same. In the end, I put the rubber seal in with a bit of RTV, for what that is worth and left it. It will be fine, although I shall get some more spare seals some time before the pads wear too much. Fitting those dust seals is one of the worst jobs on the Mini and ranks alongside the brake/clutch pedal box clevis pins as a real PITA.

[Nelson92]

I'm glad to hear i'm not the only one. But I have another THREE calipers to do; as i've got another set from an MPI plus my passenger side one.
The haynes said only to use brake fluid as a lube but i wondered if i could use anything else.
I also wonder if gasket sealant would hold the dust seal in place? A really small amount of the black loktite one? i may try it now actualy.

[Cooperman]

Gasket sealant is the same as RTV. I just thought that it would keep a bit of the DGS out (that's dirt, grit & *melon*).
I thought that the calipers for the 8.4" discs were a bit easier than the 7.5" calipers in terms of dust seal fitting.
You must use either brake fluid or hydraulic system rubber grease on all seals which are in contact with brake fluid or which are pressure seals. For the dust seals, however, I use Aeroshell aircraft control cable grease as it's just such a good quality and safe lubricant to use.