Found one of my brake caliper seals were leaky last week in a very unfortunate way. Overnight, the calipers would leak and pool up on the backside of the wheel. Upon driving, the brake fluid would spin out of the wheel and leak out of the rim and onto the face of the rims. Thinking it was just a little bit of wheel grime, I went to clean the wheels, only to find that the brake fluid had etched its way past the clear coat of the wheels

So after investing a couple of hours to find the leaky piston (4 pot metro turbo vented discs) and getting a set of pistons and seals from Minispares, I start fitting the new parts.... you will not believe how incredibly fragile and difficult it is to replace the dust seal retainer ring

After bending 3 rings (almost enough to do a whole caliper)... I'm just about ready to throw in the towel on this one...

two things here:
1) If you're planning on rebuilding your own calipers, buy a couple more sets of seal kits... you will likely bend the hell out of a few rings before (if) you get it right. The work is not laborious, but getting the ring to fit is a nightmare...
2) Anybody with some nifty tricks to making the retainer ring fit? I read on a couple of Land Rover forums (same type of brake setup with a PITA retainer ring) where owners opt to not fit the metal ring back in and hope for the best.......

 

I know a guy who rebuilt his recently so I shot him this question....

here's what he said:

I'm not sure how different those 4 pot calipers are from the 7.5" cooper calipers, but the seal is easy if you have the right tool. Unfortunately, the one I had available was home made. I think I have a pic on my other computer, but it was essentially a pipe machined down to just the right diameter to push the seal into place. Sorta like something you might use to put in a bearing.

Those 4 pot brakes may be different -don't know.

The 'tool' is the piece of metal in the top right corner of this pic.