I have some Hope hydraulic disk brakes. In the last week or so i've noticed a black oil on the disk (an it squeeks like crazy).
I've been told its probably the seals that have gone. Im not sure what model they are but i've bin looking on the net for seal kits (at www.chainreactioncycles.com) and have found a couple of sets at a third of the price my LBS charges.
Theres: closed2 and open2. I know that my brakes are two piston so i assume it will be one of these??

How do i work out which one??

Also how hard a job is it to change them (im told its easy, its re-filling the brakes thats the hard part!)??

To install seals on twin piston calipers you need air pressure. You will have to split the caliper and use air to pop the pistons out of the caliper halves.(Use eye protection and cover the caliper with a rag) then, with out scratching anything, remove the seal from the caliper body Check for any wear or damage(It is unusual for seals, even old ones to just leak). Clean and dry all the parts. Use the correct brake fluid (mineral or dot 3/4) to lube and install the seal in the caliper half. Reasemble the caliper. Install and bleed out the system. If this is unfamilar to you find a competent shop to do the job unless you like having no brakes.

I would check it's the seals that are leaking first. If it is brake fluid on the disk you may need new pads and the disk will need cleaning to remove the brake fluid.

The hope website has exploded diagrams and manuals that will help you identify your brake and tell you how to take it appart so you can change the seals.

Thanks
Ive had a look on the hope web and downloaded all the docs (Cheers d_D) And thanx for the tips Rev. Ill probly mess it up and end up at the bike shop as this is the first set of hydraulics i've had (or done anything with) but i believe in having a go myself before calling the experts in!!

I've talked to Hope in the past about problems and they've been helpful, so if you need more advise I'd ring them direct.

I've also heard of the calipers themselves leaking at the joint between the two halves. Might that be the problem before you split them? Don't know the torque setting for the caliper bolts but that might be worth checking as well