Looks like I'm going to rebuild the calipers and dust boots on my '90 legacy front brakes. Is it recommended to address the piston seal and piston dust boot at the same time? Or can I consider them separate sytems and leave the piston alone? It looks fine to me so I didn't want to mess with it.

You have a 15 year old calipers, seals, dust boots and pistons. I'd surely be popping out the pistons, inspecting the pistons for rust and scoring, replacing the seals and dustboots, and checking the condition of the piston bores in the caliper. If the pistons and bores can't be cleaned up easily with very fine steel wool, cleaned and flushed out with fresh brake fluid, then I'd be trading them in for newly remanufactured calipers with new seals and dust boots.

I usually go with rebuilt calipers, not much more $, complete rebuild, much time saved. Good time to flush the brake lines.

Just go get some loaded calipers that have everything you need. It's probably not much more expensive than ordering all those parts individually, and takes a whole lot less time.

 

If you really want to rebuild the calipers yourself, definitely pop out the pistons and inspect them while replacing the seals.

rebuilt calipers are a pretty good way to go. If you rebuild your own, use the brake pedal or air to eject the pistons from the bores. The pistons will be chrome plated steel with a satin finish. This surface gives the rubber seal traction so the pistons will retract when you release the pedal. As long as the chrome plating has not broken down, the pistons are reusable. If they are starting to go, the chrome will be starting to flake off, this is usually from fluid that hasn't been replaced that contains a lot of moisture.

if you're mechanically inclined at all, definitely rebuild the calipers. i got rebuild kits online for like 7.35 (that includes BOTH sides) and it was very simple. for your first time, just tear one caliper down at a time, so you can look at the other one to see how the boot and seal sets in there. great deal, two rebuilt calipers for under 8 dollars.

 

very easy job, there's a piston seal and dust boot and not much else to it. clean everything up real good and put it back together. the only tricky part is screwing the piston back in if it's on a threaded spindle (like the XT6 front calipers). but with the right tools, it goes right in, they are tough to turn by hand without a good brake caliper piston tool and the finely threaded spindle takes forever to get anywhere. just keep turning and turnning. i spent a ton of time screwing the pistons back in my first time, but with the right tool this job is super easy. don't forget to grease the seal and boot as you install them. (the rebuild kit came with grease).

The rebuilts are the way to go. A lot less swearing and screwing around. I've rebuilt calipers many years ago and usually needed to buy an expensive new piston and seals. Bought a hone to try and get a good finish on the bore too. Almost cost what the rebuilt would have been, but I can see not wanting to put a lot into a '90.

Add up all the parts (seals, pins, etc) and see what you think, I may be wrong depending on the condition of the caliper, but you don't know 'till you pull it apart.