I need to replace the brake caliper piston seal not ordered any yet.  What's the best way to fit new ones?  I noticed two seals, one on the inside and one on the brake piston itself. If that makes sense?  

Yeah the inner one is the actual piston seal, the outer one is a dust cover, best place to get the seal kits is Bigg red I've always had fantastic service from them.

 

As to replacing them, put a block of wood between the piston and the frame of the caliper then with compressed air into the bleed screw hole pop the piston out, with the piston out you can then pick the seal & dust cover out, cover the new inner seal in fresh brake fluid & fit it into the groove in the casting, the dust seal dry fit the bottom into the top groove of the casting, then cover the piston in fresh fluid and insert it through the dust cover and then press it into the casting and when it's about 50% in hook the top of the dust cover into the groove in the piston, then push the piston all the way home, I think there might be a video of how to do it on the Bigg Red site

Thank you will check it out now

Theres a trick i came across as it can be diffcult if you only have two hands and no mates like me lol.

I found a plastic aerosol tin lid just slightly larger dia than the piston then cut top off it with sissors dident take long.

I then put the inner seal in then put the dust cover in the caliper.

Then i put the plastic ring i made out of the cap inside the dust seal by folding it in half. When relseased the plastic ring spings out and opens the dust seal up so you can drop  the piston righ in dead easy. With no risk of damageing any new seals ive used this way a few times now and on few didfferent vehicles at work too.

Be carful if you use picks ect to stretch the dust seal, they damage very easyliy have seen it done and many times my self before i started using the above method.

Have not brought the seal kit yet but both great ways to do the job. I shall try both I think thanks.

My order came today from bigg red quality looks good.