Topic: Best way to clean inside of caliper?

[Tugboat]

FINALLY got the piston unstuck and pushed out of the caliper. Inside isn't too bad but there is some rust, and I'm wary of scratching it. I figure I can use a dremel & wire brush on the "lip" where the pad goes, but what's the best way to get that little bit of rust out of the bottom?

Also, how does this piston look? OK, or replace?

[Toxic]

Looks fine and I don't see any severe pitting.  I would use some 0000 steel wool and brake cleaner. Lightly rub it without making scratches to it.

A brass wire wheel on  a dremel is best for getting all the crud out of the rubber ring's groove.  The brass won't scratch.

[Patrick]

That piston is cleaner than any I have ever pulled out of one of these old bikes. Toxic is right. Brass brush on a Dremel will do the job. The cylinder already looks pretty darn clean. And you say that piston was stuck?

Patrick

[Tugboat]

Well, turns out that it wasn't so much "stuck" as the fluid resevoir behind the piston - as well as the bleeder itself - were both so full of old gunk that I couldn't get any fluid in there. Once I cleaned that out and was able to push some fluid through it popped right out.

Also meant to ask: How do you get the rubber ring out without marring the groove?

[Patrick]

I usually just snag it with a mechanics pick. Hook it is a few places to loosen it up and it should pop right out. Be careful not to force it or you can damage the ring and, therefore, the seal.

[Duke McDukiedook]

Mechanic or dental pick, I think both can be had at HF for cheap.

[CoachDoc]

Mechanic or dental pick, I think both can be had at HF for cheap.

The dental pick is cheap, easy, and effective in the groove. Will do a better job than the dremel where the floor of the groove meets the walls,a frequent target of brake fluid crud.

[chewbacca5000]

You need to deglaze the inside of your caliper with a small brake hone.  You can get one for a few dollars at Harbor Freight, or online.  I have done several brake calipers and delglazing them makes a big difference.  Just use the hone with a cordless drill to get the crystallized brake fluid out of the inside of the caliper.  Soda blasters clean the outside and ultrasonic cleaners do wonders to clean these up as well.  Pay attention to the inside of the caliper cylinder to make sure you don't have any white rust and that no material is missing.  You'll be glad you used a hone when you go for a ride and forgot your toolkit and your brake does not lock up.  It has happened to me usually on calipers that have had a long sit.

[Kemp]

It is really important to clean out the grove where the O ring sits. It must be perfect or the piston will not return properly. The only tool I've found that works is a dremel with a little brass wire wheel. Picks, steel wool and chemicals don't do a good enough job only the dremel wire wheel can get all that white powder out and get the grove spotless. It makes all the difference in a rebuild as you'll have a brake calipher that doesn't drag, the motorcycle will be able to be pushed like a bicycle, no effort, no drag.

[RAFster122s]

Like Toxic has said, brake cleaner and a little 0000 steel wool can clean the piston right up. You might want to break out some polish and polish it if you have some compound and a buff, it won't hurt. Just make it shine like a mirror...

All the white you see in the photo, not a tremendous amount is aluminum oxidation, you'll want the brass brush or dremel and brass brush to clean those up so you have bare aluminum. Others have said everything else that needs said I think.
Post some pics, please, of your work before putting back together so we have before and after shots... They make nice contrast.

David

[Hondawggie]

IPA, aka "Isopropyl Alcohol", aka 'rubbing alcohol' evaporates quickly and leaves little if any residue.  As someone else suggested, using the 'ultra fine' steel wool and IPA on the bore and the piston are great.   

I used to work on extremely high-vacuum (cryogenic vacuum pump) semiconductor manufacturing equipment - these machines were called 'sputters' as they melted very pure gold and platinum onto computer chips under very very high vacuum.

These machines used rubber o-rings and cleaning them was extremely controlled as any contamination would adversely affect the cryogenic vacuum pump.

IPA and a brass o-ring removal tool (same shape as a dental pick but thicker so as not to puncture the o-rings on these machines) were all we used to remove and clean o-ring grooves.

You will find some factory shop manuals specify using IPA to clean brake caliper innards.  Cool thing is, you can buy rubbing alcohol (IPA) for very little at any drugstore.

I use the IPA and ultra-fine steel wool on the bore and piston, then use a Q-tip and IPA and the brass o-ring pick to clean the o-ring groove.

- rubbing alcohol
- Q-tips
- ultra-fine steel wool

Your well under $10 on this.  The condition of your parts there is decent, have a go with it.  Make sure to clean that groove as was mentioned -- good luck.

[wedoo2]

I have a stuck piston.  Been soaking in PB.  It will tap in, but it can only go so far.  Haven't been able to blow it out yet.  How did you get yours loose?

[Toxic]

If you can't blow it out, then attach a grease gun to the bleeder hole and it will come out.  You will only get a couple of threads from the gun to engage so don't force it.

When you are done clean multiple times until all grease is removed.  It's got to be spotless.

90psi couldn't budge mine but the grease gun method worked real well.

[Patrick]

Or reattach it to the brake line, bleed it, and let the brake lever push it out for you. Put a bucket under it to catch the piston and the gush of brake fluid that will come out with it.

Patrick

[grcamna2]

Wouldn't it be Great if more folks would flush out the brake fluid in bikes...after years of sitting outside in the sun? along w/ stabilized fuel?...but, I suppose if they did, not many of us would get such great deals on these nice vintage motorcycles.