11 replies to this topic

[stardude]

as title says realy, need a breif description of how to do it.


cheers

adam

[Ethel]

pump 'em out on the car - use a spanner or similar to block their travel so one doesn't shoot out before the other's barely moved.

Once they're on the point of popping out you can take the caliper off the car and have enough piston to grab hold of to pull 'em out.

Doubtless there'll be some disagreement but I think it's much easier if you split the caliper.

[stardude]

what about when you are putting the seals back in?

can you put all of the seals on and put the pistons in at a later date?

[Ethel]

The fluid seal just sits in a groove in the caliper, that's no problem.

The dust seals can be a right pain, held in with a metal retainer ring that bends sooo easily.

You need all the bits really - fit the pistons then fit the dust seals - or try to

[stardude]

ahh ok

thanks ethel

[dklawson]

As Ethel said, you really need the pistons in their bores before fitting the dust seal and their metal retainer.

Before fitting the fluid seals to the caliper, carefully clean the square groove the seal sits in. Make sure it's clear of all rust and build up before fitting the new seals. The walls of the piston (not the cylinder walls) need to be pristine. If you find pitting on the outer walls of the piston, replace them. The stainless ones are a nice replacement for the chrome plated steel ones.

by the way, I'm in the "don't" split the calipers to remove the pistons camp.

[Ethel]

As Ethel said, you really need the pistons in their bores before fitting the dust seal and their metal retainer.

Before fitting the fluid seals to the caliper, carefully clean the square groove the seal sits in. Make sure it's clear of all rust and build up before fitting the new seals. The walls of the piston (not the cylinder walls) need to be pristine. If you find pitting on the outer walls of the piston, replace them. The stainless ones are a nice replacement for the chrome plated steel ones.

by the way, I'm in the "don't" split the calipers to remove the pistons camp.

Ii think if you don't split the caliper you'd need the proper tool to get the dust seals in wouldn't you?

[dklawson]

Even if you split the calipers I don't see how you'd fit the dust seals without some form of proper tool... the retainers are very flimsy sheet metal as mentioned earlier.

I have a box of weird homemade tools for the Mini. I have one for the dust seals that is nothing more than a 1/4" thick metal ring bored out to have about 0.005" clearance to the brake piston. I fit the pistons to the caliper, then the dust seal components, followed finally by the tool I made. I put a flat plate over the opening in the ring and use a C-Clamp to pull the dust seal and retainer into position.

[busa1999]

does this mean you cant do the dust seals without the proper toll as i need to replace mine

[Ethel]

does this mean you cant do the dust seals without the proper toll as i need to replace mine

I've tried a variety of things, sockets etc - it can be done but I never managed more than a 1 in 4 success rate .

Making up a tool shouldn't be too hard especially with a lathe.

[redhotmini]

unless you have a full seal kit including the little square section o rings then splitting the caliper is ok. it can be a complete b****rd to seal again afterwards, but it does make rebuilding much easier.

[Brumski]

I always split the calipers and replace the o seal....

Here's my trick to successful replacement of the metal ring...

Split the caliper and clamp the oold piston in a vice... then wiggle the C**p out of the caliper half until it comes off. As above, thoroughly clean out the grooves from all debris and corrosion.

Insert the inner seal and lubricate well with fresh brake fluid. Insert the piston till its got about 5mm showing then slot over the outer seal and the metal ring.

The place wood over the lot and compress slowly in a vice.... there's a sickening crunch when it goes in but always goes in square and true...

But doing it this way, you MUST make sure that the mating faces of the 2 caliper halves are meticulously clean before reassembly and, as above, you use a new seal between the caliper halves.