OK, I admit it. I can put fuel in and lube the chain. Not much else. But in changing my pads recently and cleaning the front caliper it became apparent that one piston is slow to come out, and won't retract as far as the other at all. A mate reckons it's time for new seals. My local Yam dealer is booked up for 3 weeks so it's time for muggins to dive in and service the caliper!

Armed with a new set of seals from Motorworks, a Haynes manual, a big hammer and a dunce's hat, I'm ready to dive in.

This thread is for me to ask stupid questions.

Stupid question no.1. I need to remove the caliper completely. What's the normal thing to do with the brake hose? Clamp it? Just let the whole thing drain out into an old bottle? Or is there some other way to not waste all the brake fluid and avoid the faff of a complete refill and bleed.

Thanks and apologies in advance.

Just spray wd 40 around the piston behind the dust seal work a few times,pushing it back and pumping it out.DONT BLOW THE PISTON OUT.

Nip down to your local bike shop and ask for rubber grease, normally red in colour. take the caliper off, put a wedge or stick into the brake after you've taken the pads out. give the pistons a good clean with hot soapy water. after pushing them in and out a few times then apply a good spread of grease, push the pistons in and out again, job done.

if you really want your best using the bleed nipple at the rear of the caliper. find a small tube that fits on the nipple then open and drain into a jar, pull the brake several times to drain the system. if you do get brake fluid on anything wash it off as it's nasty stuff. you'll need new stuff to refill the brakes

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Plough on

Cheers Maxwell. I already have red rubber grease from when I cleaned up and re-greased the slider pins.

I'm really nor sure what's normal or abnormal with the pistons. When I pump the brake with the pads out, one piston comes out before the other, and the "dragging" piston only really comes out easily once the first piston is blocked. This could indicate a problem with the seal, but it might also be normal with the fluid routing? I don't know.

In addition, the pistons are super shiny and look as new, as much as I can see pumping them out as much as I dare. But they really hard to push back in. Also, when they both push back, they stop with 2-3mm of piston still out. Again maybe this is normal? Or maybe it suggests too much brake fluid? But it means that when refitting the caliper with new pads, there's always a little contact with the rotor even before I pump the lever to bring the calipers out. Once the lever is pumped and the pistons come out, they're binding. Period.

I've already bled the brakes a little in case they were overfilled and stopping the pistons retracting fully but to no avail. I guess I could pump the pistons out, open the bleed nipple and push the pistons back and see if it's much easier when the brake fluid is not compressing but coming out the bleed nipple instead?

I have the replacement seal kit here, and am just trying to figure out whether there's something else obvious I should be checking or whether my symptoms to really suggest a complete drain, new seal kit and then refill and bleed.

OK, so I've tried pushing the pistons flush with a clamp and even with the bleed nipple open, they're not budging. I think that's as far as they go.

Here's a pic. https://lh3.googleusercontent.com/-U...o/IMAG0329.jpg

Strangely, my pistons seems to have inserts which make them sit even further out. Is that normal?

So I'm stuck. With the pistons retracted as much as is physically possible, with the pads installed, it's not easy sliding the caliper over the disc. The pads are already rubbing signficantly. Rotation isn't free even with the caliper just pushed on and held - there's physical contact. Once the caliper bolts are tightened up and the lever pumped, that's it. Proper binding.

I'm getting stuck here. It's like there's not really enough space around the pads even with the pistons fully retracted for them to completely clear the disc.