caliper rebuild parts question

[78xs11]

Hi all, Ive decided to rebuild all 3 calipers and both masters, due to crud. Ive been looking for good prices on all the kits. My question is for 28.00$ (old bike barn) for the caliper rebuild kit, is that price for one caliper only? I called them and the dude wasnt sure it was. Also, who has a killer price for the caliper pistons? I dont have paypal and want to buy over the phone.....
What company will be a good one to deal with?? Thanks again DG

[prometheus578]

I've never had to replace caliper pistons. Yes, it's a close tolerance fit, but a little fine grit sandpaper on the piston and bore should smooth out everything real nice. It's the square sided O ring that controls the sealing and you can just scrape that clean using your thumb nail and brake fluid. But, if you still wish to throw your money away... toss a little over here at me.
( the only time you'd need a kit is if the outer dust seal rubber is torn and you'd like new ones)

[pathfinder]

MIKESXS.COM has all the parts you could need including the pistons. I think it all web order now, you'll have to check. If you do talk to them just don't tell them it's for an XS1100. Something about his agreement with partsnmore.com they have them to bu more expensive.

[pggg]

Proms right. Just strip and clean. Master cylinders come out by prying out the rusty circlip and C-clip. Get the pistons out of the calipers and clean and polish with fine paper. Swish gunk out all the passages. Give yourself a whole day to do it all proper. Costs not a red cent.

[78xs11]

well the dust boot on the frt master was tore, so I need that. How pitted is too pitted on the caliper piston?? There is some towards the top ( pad side ). Also the right side caliper dust boot is swelled and dosent fin in the groove good........DG

[John]

Buying the caliper kits is simply cheap insurance in my book. The pistons can rust and pit and if it is near the top, that may be in the area that is contact with the seal. I have had to have some pistons for a Special front caliper custom machined because they are not available from anybody. The pistons for Standards are available from Mikesxs, as the xs11 Standard uses the same calipers as the xs 650. The same piston fits both front and rear calipers. Keep the wire dust boot retaining ring...they do not come in the kit.

[prometheus578]

Agree with John. Pitting near the top is no biggie as that's the part exposed, anyway; not in contact with the caliper bore. As for the torn dust covers... if it were me, I'd try using the liquid rubber stuff recommended for carb vacuum diaphram repairs. And for the dust cover that doesn't fit well... I'd seal it with the same stuff.
Dust covers do have a purpose... but considering the low yearly mileage that bikes actually see... I really wouldn't have a prob doing it that way. Dust covers on forks are far more critical due to the tubes constantly riding up and down through them. Dust covers on caliper pistons... well... when brakes are applied, the piston barely moves out with the pad, and then retracts the same small distance. It's imporatant to keep the area clean, but I wouldn't have a seizure over it. And as for brake piston seizures... they're caused by crap on the inside of the caliper, not the outside.
I'm sure other's might disagree... but I'd try a home repair before shelling out $30 for a kit when all I needed was a dust cover.

[78xs11]

Great points made, The dust boot on the rt frt caliper is too swollen to use. So I think I have to pony up for the kit. The rubber sleeve on the frt master is torn, but in half. The lower lip tore from the upper part. Unfortunately Im thinkin I have to spend a few $ for the piece of mind it will give me while on the road. Man, those pistons are pricey,,,,Maybe santa will be good to me this year,,,, Thanks for the great info though, I for one am always looking to save some $$!!!

Thanks again D...

[TopCatGr58]

Hey 78XS11,

The pistons can be severely pitted, and still seal just fine, cause it's the O-ring that does the sealing. As long as there isn't any pitting right around the groove where the O-ring fits, then you shouldn't need to worry about replacing them. Just take a drill fitted wire brush, or emory cloth and sand them down smooth. I had a fair amount of corrosion around the O-ring and the groove, but just scraped out the groove, and the cleaned up O-ring fit very nicely back into the groove and into the caliper! Save your $$, spend it on the seal kit if you must, but not the pistons!!
T.C.

[Winterhawk]

I've had some K@L caliper kits with the square O-ring stick. The square O-ring looks the same size but isn't. It will make it hangup a little which isn't good. I just gently scrape the O-ring with a single edge razor blade and reuse it. Clean the grove out really good being careful not to scratch it.

I've probably did 100's of calipers like this with great results.

[Erik the Red]

add'l questions...

I've been doing some old thread research, and this thread seemed to be the one to revive for my question. Here goes...

I'm in the middle of a brake caliper rebuild (read: calipers all in pieces on the garage floor) and my caliper pistons have some rust pits. My local mechanic is of the opinion that no pits should be on the piston for anywhere it could possibly touch that square-cut (O-ring) seal. ...which, if it's sitting at the back wall of the bore, is nearly the whole piston.

Q1: How much room is there between the bottom of the piston and the back wall of the bore with new brake pads installed?

Q2: How much material can be taken off the piston (sanding the pits off) to make it smooth and have it still work how it's supposed to?

Q3: In the opinion of the collective great XSive mind, is $24/piston (PN 29-0516) and $19/caliper rebuild kit (PN 29-0016)worth the ~$86 + S&H from MikesXS?

Q4: I'm not made of money, but brakes is NOT the area in which to cut corners. Would using the old stuff actually be cutting corners??

Any input is, as always, greatly appreciated. TIA all.

[randy]

As long as the pits aren't large enough to span the width of the seal, you should be OK. More leaks develop from the gunk in the seal groove than pitted pistons. Clean out the seal groove, too!

Clean pistons with crocus cloth, won't take off too much, should be good to go.


That being said, yes Mike's XS pistons are a good deal, have them on Swamp Thing.

[TopCatGr58]

Hey Erik,

Are you saying that the pits are only near the bottom recessed section of the piston, a good 1/2" or more away from the pad contact area?? IF they are just near the bottom or only a little bit on the sides from the bottom, then they'll be just fine. They will sit essentially all the way into the caliper body with new pads and the thickness of the rotor. You can look at how thick the pads are to see how much travel you will have, it ain't much!

Many of us have reused the square O-ring, works just fine, seals well even under the pressure of stainless steel lines!

There's frugal, and there's pennywise and poundfoolish, as long as the square O-ring looks good, nice square edges, you should be good to go.
T.C.

[Erik the Red]

The pits are mostly within a 1/2 to 3/4 inch of the groove where the dust seal sits. One of the pistons actually has a 5 mm wide ring of good steel bordered by rusty pits on either side. One of them is pretty good, with only minor pitting, and I'll try the crocus cloth on it. The other I may just pony up the cash.

Any idea of what grit of crocus cloth? I went to Auto Value last night and they can get the tape anywhere between 80 and 400 grit. I think I even saw some 800-1000 range on the web too. Thanks.

[randy]

I would use 1200 grit, it's the same I've used for polishing crank pins. Apply a little oil to the abrasive surface.