Xj550 brake piston issues

So after taking out the stuck brake piston and cleaning my caliper it seems as though my piston will not slide into the caliper. With no seals it is supposed to slide in and out fairly easily correct? Right now with no seals it only slides in 15mm and stops. And it doesn't seem like it slowly gets stuck it feels like it is hitting something. I'll go to drop the piston in and it slides right down for the 15mm then it sounds like it dropped onto mental and stops. The caliper is clean and so is the piston. What's going on here? A warped piston or caliper maybe? Thanks for any help.

 

Look closely for a little ding, burr, etc.... On BOTH the piston, AND in the bore. Or, is a washer stuck to the wall of the bore....., or a bolt-that-is-to-long stuck in the brake line hole, or bleeder screw hole? Did you remove the brake one then run the bolt all the way down into the caliper so you wouldn't forget where it is? Well, now you'd know---

 

Saw a slight ridge that looked like a weld or maybe a line of hardened brake fluid if that's possible? Couldn't file it away. Should I try sand paper or steel wool?

 

How much of the piston is sitting proud of the caliper? Are you certain it's not bottoming out?

Gary H.

 

21mm sticking out. I'm pretty sure it's not in all the way, I dont think the disk and both pads would fit in the gap as is.

 

I agree.

Gary H.

 

Check the groves in the caliper bore where the seal sit in. Look for debris. It can be removed with a dental type pick.

 

seal the brake hose hole with a bolt and fill the cylinder with carb dip or cleanerto soak. I used small brass rotary brushes for cleaning the grooves out you can use them to remove the crud.
you can also use a brake hone to clean the walls
chacal sells the brushesand hone click his logo upper right
go to brake section his email is at the bottom of his first post
one for each groove
HCP15924 Aftermarket RADIAL BRASS BRISTLE-WIRE BRUSH is a properly sized, miniature brass brush $4.95
HCP15536 Aftermarket RADIAL BRASS BRISTLE-WIRE BRUSH is a properly sized, miniature brass brush that is both small enough, gentle enough, yet abrasive enough to remove the rubber debris that builds up in the caliper fluid seal groove. Failure to remove such build up leaves an uneven surface for the new fluid seal to seat against......sure to cause either immediate or longer-term performance problems. 1/8" shank fits into most standard dremel tool collets and allows you to make quick work of the polishing of this area before the installation of your new rubber seals.
$ 4.95

CYLINDER BORE HONE
Replacement shoe sets are available in both medium (240) and fine-grit (400) finishes. IT IS RECOMMENDED THAT YOU PURCHASE A SET OF 400-GRIT STONES WHEN YOU BUY THE HONE, so that you can make two passes on your caliper bore when rebuilding your caliper: first with the "clean-up" 240-grit stones, and then change the shoes to the "polishing" 400-grit stones for a truly professional job.
HCP9955 Aftermarket 3-shoe brake CALIPER CYLINDER HONE, comes with a set of 240-grit stones. Works on all XJ-series front or rear brake calipers.
$ 24.95
HCP9958 Aftermarket replacement set of three brake caliper cylinder HONE SHOES, 400-grit. Includes a set of retaining cotter pins.
$ 12.95