Hey guys, I'm in the middle of a brake rebuild on my zxr250A. I am gonna repaint them black also except I have a problem. I wire wheeled and paint stripped the calipers, but now they have black spots all over them and I can't seem to remove them without heavy sanding. Anyone have any ideas how to tackle this? Cheers!
It's like some kind of oxide or rust, it comes off with the wire brush but comes back again. A friend suggested an acetone bath to get it completely off then paint immediately
Probably pitting corrosion. Not much you can do about it without removing material around it. Sand/media blasting might improve it a bit, but you(or a shop) are going to have just chemically treat it and paint it.
Depends on what the material is. I dare say it'll be a steel alloy. Products off the top of my head are Presto Black and Deoxit. Not too sure how easy it is to get presto black as we use it at work(industrial) But basically it's an acid that eats away at the corroded metal. Leave it too long and it'll start eating into the non-corroded parts. These are just general instructions but basically you saturate the part in the chemical (once the correct amount of time has lapsed or colour has changed) rinse off with water to neutralise and dry the part. Paint as soon as possible after treating with acid solutions (usually within the hour).
Cheers for the info! Ill look into it, wonder where I can get the acid or similar products from. And yeah, best to paint asap, learnt hat from when I did the headers. Hopefully get stuck into it tomorrow, maybe get some before and afters. Thanks again!
So I got the calipers finished and put on with new fluid, they looked good pictures to come. But, I pulled in the lever and there was no pressure whatsoever. I tried standard bleeding, syringing it from the bleed nipples back to the mc, tied the lever back to the bar overnight (worked a treat last time, not so this time) and cracking the bleed nipple and letting it drain continuously. Aaaand nothing worked ha. So I bit the bullet and bought a vacuum pump. And boy, it worked so well! Sucked a bottle of fluid through both calipers which pulled a heap of air out tied the lever back for a while and saw bubbles come out at the reservoir and the brakes got pressure. New brakes feel a lot better, except a slight problem that has persisted through the rebuild. Brakes feel spongy for the first pull but go harder after 2 pulls on the lever. Might be the slave cylinders taking up slack, or air in the system or maybe the mc is shot. I cannot for the life of me source a mc rebuild kit anywhere. Anyway, I'll take this as a successful attempt, not bad for a first time!
