Cleaning up caliper bores

[Guest]

I've got lots of hardened old brake fluid in the grooves of my caliper bores. Been scraping it out w/ a jeweler's screwdriver and magnifying glass - it's getting old real quick . . . Anything I can soak these in to soften up the crud?

[GateKeeper]

grab a dremel and a brass wire brush on the end, will get it clean quick

[Steve]

grab a dremel and a brass wire brush on the end, will get it clean quick

You can use a steel-bristled wheel, too.

Either way, please use eye protection, those bristles fly very easily.

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[GateKeeper]

yes do wear eye protection....

I did not want to use the steel bristle ones as I was afraid of damaging the calipers, by gouging a groove or something

[chuck hahn]

NO WIRE BRUSHES ON ALUMINUM!!!!!! They can leave uneven bore width from them basically grinding the bore up. If your planning on repainting them or the finish is waxed, I suggest you throw it in a can of laquer thinner for a few hrs and that will soften the gunk up. Also you never want to wire wheel things like heads and engine case and covers to get the old gaskets off. This leaves low spots and grooves in them that almost always result in a leaky gasket thats a Biitch to get to seal.

[Steve]

NO WIRE BRUSHES ON ALUMINUM!!!!!! They can leave uneven bore width from them basically grinding the bore up.

If the piston needed to seal to the bore, I might agree with you, Chuck, but a light touch with ANY wheel, and limited to the area where the rubber seal rides in the groove, will remove any stubborn crud without damaging the caliper.

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[chuck hahn]

Thats why I asked about the finish and his intentions about repainting...the laquer thinner will soak it off without any worry of any bore damage at that point. IF , as a last resort, I would use something like a gun cleaning brush and do it by hand. High speed Dremels would scare me off because ( to me ) its just too easy to scrub a dimple in there and then yiour basically screwed. Dollar store near me has what look like tooth brushes but have brass and stainless bristles. Those would be ideal and more controllable.

[chuck hahn]

OR...How about an overnight soak in some vinegar or carb dip?? some penetrating oil and a green dish scrubby may also scrub the groove out well. That grey scaley craps a bugger..I am very aware!!!!

[chuck hahn]

Steve..By "bore" I was referring to the Bore of the groove the seal slips in. I wouldnt want to get it out of round for fear the seal wouldnt snug up perfectly around the piston..Does that make more sense??

[seano]

Thanks so much for all the input guys. I'll start w/ the vinegar soak and go from there.

[chuck hahn]

Vinegar will take a day or 2..overnight in some berrymans should get them real nice inside..regular tooth brush to spiffy them up and they will be good for another 30 years!!!

[Steve]

Steve..By "bore" I was referring to the Bore of the groove the seal slips in. I wouldnt want to get it out of round for fear the seal wouldnt snug up perfectly around the piston..Does that make more sense??

OK, that's fine. Some people are of the impression that the inside of the caliper needs to be spotlessly clean because it needs to seal against the piston. In fact, the piston only touches the rubber seal, so the rest of the cavity really does not matter, as long as it's nothing that will affect proper operation.

I still stay that a light touch with a wire wheel won't hurt the groove (bore) that the seal sits in.

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[chuck hahn]

Well, It kinda DOES matter in the sense that I wouldnt want any of the scale getting in between the seal and piston and causing a leak..or the stuff getting around and contaminating the brake fluid.

[Steve]

Well, It kinda DOES matter in the sense that I wouldnt want any of the scale getting in between the seal and piston and causing a leak..or the stuff getting around and contaminating the brake fluid.

I believe that falls into the "as long as it's nothing that will affect proper operation" category.

.

[spyug]

I've cleaned and rebuilt about 15 calipers in the last 5 years.Of those 6 had pitted, rusted or cracked/missing chroming on the pistons. Each of those 6 calipers also had concretions on the sides of the bores hard enough to require scraping. On the advice of my pro-wrench I used the dremel brush technique to clean them up.

I think, like plaque in a human artery, if any of that crud breaks off or remains in the bore it stands a good chance of plugging the "in" line or working its way passed the seal or possibly damaging it. The chances might be slim of this happening but I'm not keen on a possible problem so I'd rather clean it up when I find it.

Out of habit now I routinely dissassemble, clean and rebuild the calipers on any new to me bike and I'm doing that this weekend on the 550. I'm convinced that folks generally don't give a moments thought about their brakes unless there is an obvious issue. You can tell right away how well they've been looked afterwith a quick peek at the colour of the fluid. Everyone I've looked at has been brown to black. Call me paranoid, but an ounce of prevention is always better than a pound of cure.

Ride safely friends.
spyug