1981 XJ650H brake caliper help

Hello! I've taken the front caliper off my Xj650 in an attempt to clean em up, and have run into a few challenges along the way. First of which was the piston was completely seized, I used the grease gun method which worked very handily and it is now free. Here are the 2 pieces after removal:





I soaked both the piston and the caliper in mineral spirits after liberal rinsing to try and get all the remaining grease out and I think I have, but I've noticed the plastic ring inside the caliper bore is out of alignment with the rest of the bore. This little misalignment prevents the piston from settling into the bore. Is there anyway to replace this plastic ring or is this caliper just need to be replaced?

Pictures to demonstrate:








It's more obvious in some areas, but I think you get the idea. It is extending out of the bore.


Some pictures of the piston, it looks heavily corroded in the area where it would have been in contact with that plastic ring, Im thinking its probably the reason it was seized.



Inside of the piston, seems fairly impossible to clean, I'll likely replace the piston.





IF you folks think this caliper is able to be saved, what do you recommend I clean all that gunk out with? I hit the inside of the caliper bore with some super fine steel wool and a wire brush for longer than I care to admit with little to no progress. Soaking in the mineral spirits didnt seem to do be any good in the corrosion department. And any tips for cleaning up in the seal groove? the front side is easy but the back has walls on either side and its impossible for me to slip my brush in.


For the sake of it, heres a picture of the bike as she stands, new mirrors looking snazzy!




Thanks for any response!

 

That plastic ring isn't plastic. It's a (formerly) rubber seal that will need to be replaced.
The piston looks a bit rough. You might be able to polish it out with 600 wet-and-dry paper, but if there are pits that contact the seal you'll need a new piston, or a used caliper to rebuild.
The inside of the piston doesn't need to be clean.

This link is for a different caliper but the rebuild process is essentially the same.
1985-86-xj700-caliper-rebuild.118121

 

Ah, I feel a bit silly thinking it was plastic now, but it really is pretty rigid!
Do you think I could just buy a replacement piston and seals, and clean this caliper up for use?

 

It is essentially plastic now. All of the elastic compounds have aged/cooked out of the seal.

I would not hesitate to rebuild the caliper with new components. The working portion of the bore looks very good.

 

info@xj4ever.com
Our resident parts supplier, Len Chacal, has everything you need. Talk with him

 

Bin that piston, it's had it. A wet rub down with some 500 wet and dry paper, new piston and a set of seals will sort that calliper. Once its all back together I would paint it, but don't spill fluid all over your new paint.