brake caliper rebuilds

Hey folks,

Restoring a '82 kz750e. most of it in working order except carbs, tank and brakes. Cleaned carbs, got another tank, she runs. Brakes were going good until the rear caliper. I can't get the piston out. Tried air pressure - wouldn't budge even after penetrating oil soak and heat. Tried grease - grease gun did not mate well with m7 bleeder and just poured out all over the exterior of the caliper.
Do you guys have any other suggestions? Did I miss something with the grease technique? Do I need to put an actual grease valve in the caliper. M7 grease fittings hard to find. Help! Thanks.

Thomas

What about brake fluid? Hook it up to the master and pump until the piston pops out...and makes a mess.

I have this and like it a bunch. It is especially helpful on multi-piston calipers.

www.kwickstand.net/Hyper-Formance.com/KWICK_Kaliper_Pliers.html

It is possible that there is so much corrosion than nothing short of the nuclear option will work.

boil the caliper in water. works great.

Thanks for the advice guys. I tried a combo. I boiled it in hot water tried the air again, still nothing. But found a m10 grease fitting and screwed that into the banjo bolt threads and greased it out of there. On a side note, I would have just pumped it out with brake fluid but the reason I had to get at it in the first place is because the lines were crystallized and the pedal seized up. Was registered up until 2016 in MA but must have been sitting well before that given the condition.

Tvag06 wrote: Thanks for the advice guys. I tried a combo. I boiled it in hot water tried the air again, still nothing. But found a m10 grease fitting and screwed that into the banjo bolt threads and greased it out of there. On a side note, I would have just pumped it out with brake fluid but the reason I had to get at it in the first place is because the lines were crystallized and the pedal seized up. Was registered up until 2016 in MA but must have been sitting well before that given the condition.

Be careful using petroleum products around brake components, because it will eat the brake rubber components and turn them to mush. Just sayin.

I use a spare front master cylinder or two, that I last used to push out a caliper piston from a stuck rear truck caliper.

Good call on the spare master cylinder. This is my only bike at the moment so no spare parts around. I got a '78 cb550 back on the road a few years ago but have long since sold it and all it's parts. I'm a budget builder so, the solutions I employ are typically the cheapest. If I get a spare MC i'll be sure to keep it around tho. Thanks for the tip.

OR, wait until you get the back one working, OR use the front brake master cylinder, but under no circumstances should petroleum products be used on brake parts. You don't necesarily need to own a "spare", there are two on most bikes.

My rear brake pedal was seized on my LTD too, when I first got it. And my 81 CSR had sat so long, I had to remove the calipers to move it from the spot , and get it to roll n my trailer.. There were rust stains in the concrete under my CSR when I bought it.

Note the rust stains in the concrete. It sat for a bit.


Take special note on the bent over Kansas License Plate. This bike was purchased in St. Louis, sitting outside for many years dead, behind a brick duplex row house type apartment building. Rather than taking that clean title and registering it after writing down ALL of his info on the back of the title AND a lien release from a bank in Kansas, THIS hoosier just bent over the expired plate so that police could not tell it was expired. No sense in spending ALL of that ~35 bucks to title it. duh.
Also note no air box, or air cleaner of any sort. Whatddya need that for? Another nut and bolt rescue.

The pistons were seized tight on my 750 calipers as well but eventually I managed to free them up. Unfortunately, two of the three caliper pistons were pitted and had to be replaced, at a fairly high price. Kawasaki isn't doing us any favors in that regard. I just checked the availability and it seems the pistons are no longer available from Kawasaki but there are a few kicking around on ebay. Fortunately, the piston seals and dust boots are still available. I strongly advise purchasing OEM parts, not aftermarket like K&L. I've had bad experiences with K&L brake system parts on three different occasions so use at your own risk. You can clean the calipers in solvent just as long as you keep any rubber parts you plan to reuse out of the sauce.

No eBay APP ID and/or Cert ID defined in Kunena configurationI wonder if any of the stainless steel brake caliper pistons are good? (Example below). Ed

Stainless pistons are common in the UK, and many people report good success. Given the limited options, I'd give them a go. My first choice would be for the OEM parts though. Hard chrome plating makes the ideal surface for brake piston seals to rub against. And hard chrome is harder than stainless so durability should be better, although I can't imagine wearing out a caliper piston.

Calipers are all cleaned up, gaskets and all. I soaked them in a Pinesol solution (50/50) and scrubbed. Reassembled and waiting for install on the bike. I had to order a new seal for one of the calipers tho. It was a great deal enlarged and hanging off the piston when I got the bike. Maybe absorbed some solvent, unknown. Purchased all new copper crush washers. I noticed they aren't entirely flat. One side of the washers has a minor arc. Does it matter what mating surface the arc is facing?