calipers on gsxr1000 k2

[markw]

hi all,

bike is in peices for winter rebuild, how difficult is it to change seals etc on calipers...?

also what is the best paint to spray them gold again or sould i go for black.........

thanks mark

[markw]

does any one how to do it...............

[rureadyboots]

Its not difficult to do but the seals are incredibly expensive. As in stupidly ridiculously expensive for tiny little bits of rubber.

[szrdave]

hi all,

bike is in peices for winter rebuild, how difficult is it to change seals etc on calipers...?

also what is the best paint to spray them gold again or sould i go for black.........

thanks mark

It's not too difficult a job, just fiddly. It's a fairly common topic, a quick google showed this which is for a Bros, but the general principle is the same.

If you don't have compressed air available I'd advise freeing the pistons up and getting them as far out of their bores as you can before disconnecting the caliper.

[kja.busa]

You can get the caliper halves powder coated, obviously by someone who knows what they are doing, they look awesome too when they're done. Try these.....

http://www.triple-s.co.uk/

Not the cheapest, but their work is excellent.

[lorenzo]

OK, proper bit of a guide:

Take your caliper off the bike but leave the hose attached. Get something tough but slim and stick it in the middle, where the disc'd usually go. I'd suggest a screwdriver. Squeeze the brake lever a bit and watch the pistons come out. If one starts coming much further out then the others, get something and hold it back a bit, so the others come out to catch up with it, then go again. What you're trying to acheive is all the pistons meeting in the middle at exactly the same time. This is the tricky bit, you'll often find one zooms out and another stays sat deep in the caliper body. Unless you stop the freely moving piston, you're going to have that one pop out and leave you with brake fluid everywhere and all the other pistons stuck in the caliper. This is a bit crap when this happens, you'll have to then bleed the caliper again justto pump the others out, and that's a bummer. I've actually kept some off-cuts of 3mm aluminium sheet that are really good for this sort of thing, I can just stack them inside the caliper where I need to slow a piston down a bit.

Finally, you should have all the pistons touching your screwdriver or whatever you used, and they're all more or less in the middle. Take your screwdriver out, without pressing the pistons back in much if you can help it, then gently give your lever another squeeze, making sure that one's not coming out too soon again. You're walking a tightrope now, all of your pistons are going to be coming to the end of their travel and one's going to just leap out when you least expect it. They're sneaky like that, these pistons, especially in those nasty cheapo tokico calipers, the dust seals always snag and slow one piston down.

Anyway, in an ideal world you'll have them all meeting exactly in the middle, but probably, 1's dropped out and the other 3 are all close to the middle, and there's brake fluid everywhere. If so, mop up this fluid, or if you were lucky and they're all in still, but they're out as far as they can go, then drain your caliper and dispose of the fluid in a thoughtful manner, it's my planet too, you know. Then sit the caliper down on your workbench thing and undo the bolts that hold the two halves of your caliper together. Be careful not to damage the little O rings that go between the two halves. They're probably stuck inside one of the halves anyway, but I thought I'd warn you just the same. Then you can either take an expensive piston tool and hold the pistons from the middle (the best option), pull the piston out by hand (dry the brake fluid off first, it's proper slippy stuff) or if one's really stuck and you don't have the posh tool, you can get a set of long nose molegrips and some rubber hose, cut the hose so it goes over the grippy bit of the grips and then get the pistons out. Key to all of this is to be gentle with the pistons. You don't want to mark them, score the chrome surface, anything. They need to be pristine when you're done. Clean the pistons off, and remove any minor imperfections with nothing stronger than 1200 grit wet and dry. If you've any real corrosion on there, you're going to want to replace the piston itself. Be careful which piston you order, often pistons are one size on the leading edge of the caliper and another on the trailing edge, so measure carefully first.

Get a little pokedey thing and try and scoop the piston seals out of the caliper now. I use a little watchmakers screwdriver, but there's probably a specific tool for this job, I just don't have one. Be carefull here, your caliper's aluminium, your tool's probably steel and steel wins. Give the caliper a wash out with hot water, this'll get a good bit of the grot off, and scrape it away with something gentle and preferably plastic, so it doesn't damage the aluminium. Get all of that powdery aluminium corrosion off there, in the slots that held the seals, that's better. Push your new seals into the freshly cleaned slots and marvel at how good they look compared to when you took them out. Then, using some rubber grease ideally, or some brake fluid, get them wet and place the piston on top of the upper seal, making sure it's sitting squarely. Then push it home. It should glide back in, after initial resitance, and be smooth as it goes in. See the back door loving thread for other actions similar to this. once you've put all the pistons back, reassemble both halves of your caliper. If you're really good, you'll have nice new stainless banjo bolts and bleed nipples (or titanium if you're posh) sat there waiting, alongside new copper washers. Refit your pads, using a bit of copper grease on the sides of them and where the pins go in, but not on the backs of them; you don't want copper grease on the pistons, this'll cause the seals to swell and you'll be back to square one again in a few months time. Refit the brakes, ideally using fresh dot 5.1 fluid (or dot 4, but not dot 5), and make sure you get all the bubbles out and that the fluid you're pumping out comes out as clear as the stuff you're putting in, so you make sure that all of the old stuff is flushed out, as this too can contain water which'll corrode your brakes from the inside.

Finally, as you've got new pads on, clean the discs as well as you can, especially around the floating bobbins, perhaps put a dab of wd40 on them, but then clean the excess off the discs themselves with a squirt of brake cleaner.

You will now have awesome brakes.

[buster]

With mine, if the brake pad retaining pins are free (most of the time they are as I keep on top of it), I drop the pads out, then press the brake lever until all 6 of my pistons are out and nearly touching the disc, give them a good clean like that, then remove caliper from fork leg for a better shufty at the job, if all's well, push pistons back in and reassemble.

[matt_the_blat]

As long as the pistons aren't really badly seized, a set of brake piston pliers makes a very easy job of pulling out the pistons one by one.

[gurninman]

As long as the pistons aren't really badly seized, a set of brake piston pliers makes a very easy job of pulling out the pistons one by one.

+1.. although 9 times out of 10 the pistons in the Tokico 6 pots will be too seized.

I remove the dust seals from the 6 pots - I clean them on a weekly basis anyway.