Rebuilding entire braking system KZ1k

Yakimasy,

great work in putting up the parts book page. Shows the bits I was trying to describe in the MC. the plastic bit has a couple of lugs which fit into the MC body. Press these inwards and the whole piston assembly can be pulled out.

I just went through rebuilding a 81 kz 1000 brake system and there are few things that may help you a bit.
First, the only thing you can put to them old seals to clean them is isopropyl alcohol, anything else will swell them up and ruin them. You are probally going to need new pistons as the ones you have shown have pits in them and they will not seal and let air into the system...When you start to put everything back together fill all parts and lines with fluid as you go because I have never seen a more difficult system to bleed, its almost impossible to get a firm handle after the whole system has been emptied.
Kiwiz, I think you still have air in your brakes if you still have weak braking...

Hope this helps

1045

Thanks for all the tips and info guys.

I've got my 5 rebuild kits, am just going to clean up the insides and sealing / mating surfaces as best I can and reassemble what I've got. If I end up with leaks or the lever goes soft after it's setup down the road, then I'll look at replacing calipers, MC's or pistons then. I'm not afraid of a *little* rework. It's better than throwing good money after bad now I guess, gotta keep moving on to all sections of the bike, can't dump too much into any one area all at once!

You'll certainly hear back about how it all went. Later guys.

1045,

I have bled and bled it to no avail, and in desperation took it to a brake specialist who smiled smugly and said "these brakes were really hard to bleed" However after a day there including a reverse bleed they confessed there was no air in the system and they beleived the problem was the slider pins binding. The caliper were really difficult to remove off the sliders as plastic (anti rattle) sleeves on them had swelled and tended to pull the caliper back an excess distance from the disc, leading to excess clearance and large lever movement. Thats the theory anyway. After having rebuilt everything else, replaced all hoses only the calipers remain.

Gradually assembling the parts to do a complete caliper rebuid: still shy one piston

Check your master cylinder and see if smaller holer in the bottom of the reserviour is plugged up, its a very small hole... Take a strand of wire from say a 18 gauge stranded wire (like the wire you bike is wired with) and poke it through the hole to make sure it is clear, if it is not you will never be able to get firm brake lever.
Did you rebild the master cylinder??? If so, make sure it is put together properly, and the seals are not nicked or damaged..
Another way to ckeck to see if the master cylinder is working is to clamp the line a few inches away from the master cylinder (this will only work with rubber hoses, don't nip braided steel lines with anything!!!) with a pair of vise grips with something flat and smooth bteween the jaws and the line, so not to damage the line. If the lever is hard with the line clamped then the master cylinder is working.
If this is the case, then you still have air in the lines and/or the calipers beyond it..
Once had a bad caliper piston seal that didnt leak fluid but would suck air into the system and cause a soft lever, changed the seal, brakes were fine after

Oh yeah, if you have stainless braided lines installed at the master cylinder, disconnect from the it and plug the hole with a proper size bolt and washer (don't use too long of a bolt as it can go in to far and damage the inside of the cylinder) and see if that gives you a hard brake lever..

Hope this may help, let us know

1045

Post edited by: 1045, at: 2007/01/21 17:54