Rebuilding my Calipers

I'll be rebuilding my calipers in the next couple days. VERY noticeable grinding metal on metal sound when i ride. Goes away when brake is applied. I smoothed the edges of brand new brake pads and still so help. So Calipers are my next task.
The manual says I need an air compresser to complete this rebuild, to remove the pistons. Is there a way to do it without? I dont have parts yet and havent removed the calipers but I was curious to know how this could be done. Luckily I have access to a brake bleeder so I can remove the caliper completely. Just plug the line when you remove the brake line from the caliper right?
(First time btw )

-Chris

 

Rebuilding the calipers might help, especally if they are sticking. Did you give the pads time to seat in ? They do make some noise when not seated on the rotor.
Compressed air would help to get the piston out, there is really no other way. Don't use pliers to grab the piston you will ruin it. If the piston is stuck a grease gun can be used to push the piston out. Its a little messy but works great. Maybe one of your friends has a compressor , or try a local auto shop.
Its not easy to plug the brake line to keep it from dripping, I put a pan under it and catch the fluid. You have to bleed anyway so I start with fresh fluid.
Consider rebuilding the master cylinder at the same time, its cheap insurance.

 

I've never had any luck with air to remove stuck caliper pistons. The grease trick works every time, and although a bit messy is not dangerous.

 

When I have a stuck one (air won't remove it), I hook it back up to the line, bleed it, and use the brake lever to pump it out.

I've never had one fly apart but it's a good idea to wrap it in a rag and have a basin under it just in case.

 

It's trickier to use the grease gun trick on the XJ700/900 calipers, since there are pistons on both sides of the caliper "halves". A liberal application of some penetrating oil to the pistons ("Kroil") and then an attempt to force them out via pumping the brake lever (using brake fluid pressure) is the best way, and then you migt have to use compressed air.

The fluid transfer passage between the caliper halves is rather small, and although grease will go through it, it's an awful lot of grease that gotta be put into those calipers.........

 

Cool! Thanks guys. I'll just have to try using the brake pressure to pop em out and clean em up. She needs this bad. If I cant pop it out with pressure Then i'll have to take the caliper to a shop or somethin. Livin in an apartment complex sucks.. I miss my house in the country
-Chris

 

If you've got a multiple piston caliper you're going to need to get creative with some clamps and scraps of wood. Otherwise the loosest one will come out and you'll lose pressure.

 

I always pump them out with the master cylinder

 

Well by using c-clamps and the brake lever, and some wood I managed to pop out the pistons one by one. I needs 2 more c-clamps to make the process faster. Cleaned out allll the GUNK that was in there. I couldnt get every scrap with my toothbrush and peice of wire but i got a whole lot out. Put the seals in, and the left side seems fine.
She wont hold pressure, which makes me think there is an airleak... Soo I listened and theres a little suckng noise coming from the right Caliper. Tightened all the bolts.. No effect. So I guess i tore a seal or something putting the piston back in?? Just on one piston im guessing..
I used a c-clamp and wood to push the psiton back in. Is there a better way?
-Chris

 

I hate trying to get a piston to go back into the bore.

I've worked out a procedure that often makes a rebuild unnecessary.

As with my carb suggestion, do what you want with it. I'm just throwing it out there.

I pump the piston out with the lever or pedal, as far as I think I can get away with. Sometimes a look at the parts fiche helps, gives you an idea of how deep the piston sits.

Then I carefully peel the dust boot back and expose the piston. Clean up what you can see with crocus cloth or something similar, nothing that will really scratch it though. If it's pitted real bad, this is the time to decide a rebuild is in order.

But if you can dress it up smooth, do so, then flush with a cleaner/lube like WD-40, reseat the dust boot, and push it straight back into the caliper, with the bleeder open to purge the dirty fluid from it, and prevent it from backing up through the system.

Once it's back on the bike, pump it back into position, filling the master cylinder as you do, it's gonna go down quick as the piston seats the pads again. Don't wanna suck air in there, obviously.

Many times they work fine after this.

 

If the channels the seals sit in (and you did use NEW seals, right?) are not 100% completely clean, the seals won't seat properly. That crud builds up BEHIND the seal; the new seals won't work right if there is still crud in the channels. Jamming new seals in on top of still-gunked up channels will not work.

What condition were the pistons themselves in? Any pitting?

Once the calipers are right, it still takes a lot of doing to refill the system with brake fluid. A vacuum pump can be a great help.

 

I cleaned channels best i could and put NEW seals in it. What I didnt do was pump the brakes until they slide right up on the rotor, thus, giving me my "pressure" in the lever. Wish I woulda thought of that first... X.x Prob solved at least
-Chris