Replacing rear brake pads, can't compress caliper pistons

[Joss]

Replacing the rear  brake pads (1999 1500CT)  for 1st time but cant move caliper pistons enough to drop in new pads. Close quarters...  Perhaps taking off pin #11 for better caliper access??
Do I have to remove rear axle to get at the caliper? Is there a better way?

Any help is really appreciated!


Best,

Joss

[revks]

There is a good chance that you have corrosion in the caliper. I have found it will often show up behind the seals causing the pistons to seize up.

[98valk]

pop out the pistons and clean with 0000 steel wool. clean with fluid and then install.

[sandy]

Remove the caliper; place something between the pads that is a bit thinner that the rotor. Press the brake pedal which will push the pistons out. Clean the pistons well. Old shoe laces soaked in a degreaser will help get behind the piston. I use 2 small C clamps and press them back in. That should do it.

[Joss]

Thanks everyone for replies. Is there a way to remove the caliper without removing the axle so I can press in the caliper pistons to remove from bike?

[Hook#3287]

If you have the pads out, the caliper should move back and forth somewhat easily on the pins.

If not, you should remove the caliper and clean everything up.

If it moves good, you could use a wood wedge between the cylinders and the rotor, but you have to move both close to the same amount.  You don't want to move them any more than needed to get the new pads in.

You can remove the caliper w/o pulling the rear axle or wheel.

Remove the calipers front pin/bolt with a 14mm socket, then using a 10mm open end , remove the rear pin/bolt.

[Jess from VA]

Or you can pull the axle out just enough to slide out the caliper and spacer, then push the axle back through to carry the wheel/pumpkin weight, until you've serviced the caliper and are ready to put them back in.  When out, do not just let the caliper hang on the (aging) brake line; use a bent up coat hanger or something.

I have had very good luck cleaning my calipers and pistons and everything (not the pads) with firearm bore cleaner and a collection of my old beater brass and stainless bore brushes on a pistol rod, and dental pics.  If you are going to use aerosol brake cleaner to blow stuff off, wear full eye protection, and not just ordinary eye glasses either.  Nitrile gloves are your friends.

After everything is all shiny clean, if you have trouble getting the pistons back down enough to reinstall you can use something across both pistons and a big C-clamp to push them back down.  Taking the top off the rear master cylinder will ease up pressure in the system, but you don't want brake fluid running all over the bike, and you don't want to let air in either, so keep an eye on fluid level while working.

[..]

Once the new pads are fitted I use a piece of flat timber. Place it between the pads and twist it. This pushes both pads back at the same time.

[Colin]

No need to remove the axle just remove the pin as you suggested and the caliper comes off. It is easier to remove the pin if you lube it first around the rubber boot to prevent that grabbing the pin. It is the way I always replace the rear pads so that it is easy to clean the pistons properly before putting back with new pads.

[indybobm]

You can remove the caliper by removing Item#11 and #12. You need to use an open ended wrench on #12 to screw it out of the caliper mount. Be careful not to round off the corners of #12. After that, the caliper will come off. #12 will come off with the caliper.
When putting the caliper back on, slide #12 into the caliper before putting the caliper in place.  Be careful not to cross thread #12 when starting the threads into the caliper mounting plate.

https://www.partzilla.com/catalog/honda/motorcycle/1998/gl1500ct-a-valkyrie-tourer/rear-brake-caliper

[Earl43P]

Seems to me that if the pistons are too hard to press back into the bore, even after driving them out a bit to clean the crud off, as previously advised (brake fluid and a shoestring)....Your rear master cylinder has a blocked spooge hole, which won't allow fluid to "return" the the reservoir.

Easy way to verify that is to install the clamp against an old pad and put pressure against the pistons. Then crack open the bleeder. If it becomes easy to retract the pistons with the bleeder cracked, your Master Cylinder spooge hole is blocked. You can either clear it with a good cleaning and some stiff guitar string or wire of the appropriate diameter, or replace it. Spooge is the TINY hole, not the big one (front MC has it under a shroud).

Failure to do so, will rapidly wear your new pads along with overheating the rotor.
Easy way to verify that is to apply the rear brake several times, then release and try to roll the bike around. A dragging rear brake makes it really hard to roll the bike around the garage. Alternately, you should be able to rotate the rear wheel while it is still on the jack. Yes, you'll have resistance from the new pads not bedded in to the rotor, but you should still be able to rotate the wheel.

I'm not real strong, but I can always push newly cleaned pistons in (with one pad) squeezing with two gloved hands. If they won't move by hand, something like I described is amiss. I do use a clamp to fully retract them into the bore, but again, if you can't move them in by hand at all = problem.

Typically, if your MC spooge hole is blocked, that old brake fluid was in service too long. It absorbed water and this blockage is a corrosion result. If you are this far into a problematic rear brake job, flushing out old brake fluid is prudent. I do that with the pistons fully retracted and clamped, with the bleeder oriented straight up and a hose on the bleeder looped up high and terminating into a partially filled jar of new brake fluid. That keeps air from getting sucked back in every time you pump/release the brake pedal. I also suck the NEW fluid out of the reservoir several times while flushing, then refill. If you notice, old dirty fluid mixes with the new fluid upon pedal release (unless you use a fancy MightyVac or similar tool). It's much easier to see that occur with a front MC, since the rear hides that by having a hose and more remote mounted reservoir.

Good luck!

[Jess from VA]

Thanks for that Earl,  Now I get it.   

[Joss]

Thanks to all for your comments and advice. Rears all cleaned and buttoned up. Great suggestions Now the fronts.......My first time using the 1500 Tech board and it truly reminded me of the caliber and willingness to help all that I encountered at each Inzane I have been to (Billings & Spearfish).

Be well my Brothers of the Valkyrie!

Joss