should i rebuild the brake calipers?

[Hepcat]

Speaking from experience here, if you have pistons that are scored (by Vice-Grips, etc...) there is hope! The good news is that you can salvage the piston, if it's not too deeply scored. The bad news is, you really should use a diamond hone/sharpener to get the high spots off. The chrome is really hard and will just dull a file. Sandpaper or emery cloth will take off the soft metal exposed by the scoring, the layer under the chrome, but it still leaves higher ridges of chrome.

I have access to a lathe so I just put the piston on there and honed it a little bit. Your fingers are a pretty decent judge of smoothness, so are the noises made by the hone passing over the material. You should start out hearing a clicking noise that decreases over time. When that noise is absent, or almost absent, you should be finished. Don't get too carried away, and use a fine diamond sharpener/hone so you won't take off too much material.

FWIW, my vote for removing the piston is the M/C method, just be sure to keep the brake fluid reservoir topped off or else you could end up with air in the lines. Chances are it wouldn't go too far, but why take the chance. Oh yeah, the mess...if you're using this method, just keep a thumb pressed on the inside of the piston. You can put quite a bit of pressure there and never be able to push the piston back in with your thumb. You shouldn't need much pressure though, it's just there to keep the piston from falling out before you're ready to catch the fluid. If it's making a decent seal, you should get just a little dribble of fluid before you realize that the piston's not moving. Once it stops moving, it should fall right out when you release the pressure from your thumb. Just put a rag underneath. Have an old oil bottle, or 20 oz pop bottle and a funnel handy to catch the rest of the fluid.

Good luck!

[John]

My grease gun method of removing the pistons is worry free. No brake fluid to spill/splash, make a mess. The grease just forces the piston out, and doesn't make a god awful mess when the piston pops out. I hate brake fluid. The grease can just be removed with your fingers, and a rag, along with some brake clean.

[mason79]

Originally posted by DiverRay
Mason,
I would have a rebuild kit for the MC BEFORE I started. That way, you can remove, clean, and replace WITHOUT forgetting what part went in the hole first.

Ray

do i really need to "rebuild" the mc can't i just clean it real good likt the calipers?

my ss lines came in today and the irony is i can't wait to stop when this place is all about go...figure

[prometheus578]

I've only once had to resort to a rebuild kit. Most of the probs with MC's is a plugged relief hole(splooge), or crud and corrosion in the bore, neither of which a rebuild kit will cure.
Clean the bore, but take care not to gouge the walls. If it looks a little loopy, wrap fine sandpaper around a pencil or something, and use that to smooth the walls. You'd want to sand it by spinning it, not doing the old in/out, in/out.

[mason79]

can of worms

okay, i got every thing off exept the mc, does anyone know how to disconnect the brake light switch at the mc?

pistons look good no rust, but the mc has major sluge/gunk/vomit under the resevoir...

help and thanks in advance!!

[mason79]

i found the tread to remove switch, i tried the bottom once before i guess i din't push hard enough... thanks anyways

[Ken Talbot]

Gee, Mason, you're making this way too easy when you answer your own questions...

[mason79]

it ain't over yet, i don't hear anybody clearing their throat...

Originally posted by Ken Talbot
Gee, Mason, you're making this way too easy when you answer your own questions...

1/ is it important to keep right side piston and caliper and other parts separated? right with right and left with left?

2/there is pitting on the right piston, it is 7/16 in from the bottom of dust boot groove, with pistion placed on table like a shot glass, my assessment is, it is safe from leaking as long as the pads are thick any comments?

3/ how the heck do i take apart the mc guts? i do have a snap ring plier but the rubber boot won't come out...

there is damage from channel locks on one of the pistions leading edge, i guess the po didn't bother to hold the hole for the other side to pump fluid instead opted to pinch it with pliers... thanks in advance....

[mason79]

okay i see the snap ring... thanks folks!

[Ken Talbot]

Now there you go again!

It is usually good practice to keep parts separated so you can put them back where they came from. In this case, I'm pretty sure the clearances are not so fine that it would make any difference if you mixed things up. I've replaced badly pitted pistons with used pistons from another caliper and not had any trouble.

If you pitting is so far down it is never going to contact the seal, you could go ahead and re-use the piston. Have a real good look at how rough or smooth the pitting is, and keep that in mind for a few years down the road when it might come into play.

[mason79]

no... the other left...

need confirmation

1/ these brake pad gliders, have cushion on one end, they are dried and chip on one of the two, is it important at this point to place them on the leading edge? and what's the down side to these hardening?

2/ support bolt sleeve and rubber bushing is in good condition, which direction does the covex end of the rubber point towards the disc or away...

thanks

[mason79]

one more thing what knd of lube should i use for the sleeves a little vasonline? no body get any ideas...

[Ken Talbot]

None of my gliders have any cushion left in them and they work fine. If they get a bit loose, you can bend the tabs a bit so they grip onto the caliper and don't rattle.

The sleeve and rubber bushing look to be in the correct orientation in the photo, and should be installed so the smaller diameter end of the bushing sticks out towards the bolt head - i.e. away from the disc.

Only lube these parts with silicone disk brake lubricant. You know what happens when you get vaseline on rubber....

[mason79]

all show and no go

okay, i buttoned everything up south of the mc, ss lines are on the bike , minimal binding, right lengths, a neat, i can't wait to slam on the brakes.

the dust cover for the m c piston has a rip and i have yet to remove the snap ring, no vise...

if all else in good can i leave the dust cover off or return the ripped item, the cavity where the boot is was full of crud maybe it's old dot 3 seeping out...

comments? thanks in advance

btw ken what is that thing as your avatar?

[Ken Talbot]

If you're going to keep up with regular maintenance and tender loving care for your XS, you could probably get by without the dut cover. The amount of stuff you see inside of there is usually many years worth of accumulation and neglect. Put it together without and get riding, and go ahead and order the part to put in at the end of the season.

BTW - dod you have to do any filing on your brake pads to ensure hey moved freely on the gliders we talked about a note or two ago? As often as not, the corresponding slot on a new set of pads will be a hair too small to move freely. A quick touch with a file will ensure you don't get any binding there.

The avatar, now that's a different matter. Once you've seen one in real life it is prettry obvious. I could just tell you but that would be no fun. Consider this to be a good excuse to practice with the search tool available at the top of the page and you'll discover ecactly what it is.