Post by bobh on Feb 9, 2015 19:01:47 GMT
After a few winters the front brakes on the MT-03 started to drag. The calipers are the same as those on the current XJ6 and the earlier FZ6, and are a similar design to those on the XJ600 and 900. So I thought it would be relevant to post this here - by all means re-home it in the technical area if you like, Martin.
I expected the worst, i.e. seized pistons and a full overhaul with new seals would be needed. I have another pair of calipers that I bought cheap on ebay, so I was all set to swap them over. But before disconnecting the hoses I decided to try pumping out the pistons of the old ones to make overhauling easier at a later date. To my surprise, all the pistons moved quite freely, and could even be rotated by hand after pumping them out about half-way. So I gave them a thorough clean-up, smeared them with red grease and pushed them back in. I should mention that I changed the fluid a few months back, so hopefully they'll be good for another year or two.
The sticking was, in fact, caused by some corrosion on, and under, the steel "shims" that bear on either end of the brake pads. So all it needed was a good clean-up and a smear of copper grease here and there, and I now have fully-functioning front stoppers again, without all the messing about with brake fluid and re-bleeding that I'd feared.
The rear caliper seems to be OK at the moment. That's good, as on the MT-03 it's by Brembo, who apparently don't believe in doing spare seal or piston kits (which is why I couldn't find one listed anywhere by the likes of Wemoto) - you have to get a whole new caliper. Perversely, the Owner's Manual, under Periodic Maintenance and Minor Repair, says "Every two years replace the internal components of the brake master cylinders and calipers, and change the brake fluid." In fact I think that's a standard clause that appears in all Yamaha manuals, though I'm not convinced that dealers actually stick to that when servicing customers' bikes.
According to Haynes, all the 660 singles have the same rear caliper, and worse still, the others (XT660X, R and Z) also have non-serviceable Brembo fronts. Nice little earner for Mr B, and if my experience is anything to go by, don't even think of wanting one in August because the factory is on a month's shutdown.
I expected the worst, i.e. seized pistons and a full overhaul with new seals would be needed. I have another pair of calipers that I bought cheap on ebay, so I was all set to swap them over. But before disconnecting the hoses I decided to try pumping out the pistons of the old ones to make overhauling easier at a later date. To my surprise, all the pistons moved quite freely, and could even be rotated by hand after pumping them out about half-way. So I gave them a thorough clean-up, smeared them with red grease and pushed them back in. I should mention that I changed the fluid a few months back, so hopefully they'll be good for another year or two.
The sticking was, in fact, caused by some corrosion on, and under, the steel "shims" that bear on either end of the brake pads. So all it needed was a good clean-up and a smear of copper grease here and there, and I now have fully-functioning front stoppers again, without all the messing about with brake fluid and re-bleeding that I'd feared.
The rear caliper seems to be OK at the moment. That's good, as on the MT-03 it's by Brembo, who apparently don't believe in doing spare seal or piston kits (which is why I couldn't find one listed anywhere by the likes of Wemoto) - you have to get a whole new caliper. Perversely, the Owner's Manual, under Periodic Maintenance and Minor Repair, says "Every two years replace the internal components of the brake master cylinders and calipers, and change the brake fluid." In fact I think that's a standard clause that appears in all Yamaha manuals, though I'm not convinced that dealers actually stick to that when servicing customers' bikes.
According to Haynes, all the 660 singles have the same rear caliper, and worse still, the others (XT660X, R and Z) also have non-serviceable Brembo fronts. Nice little earner for Mr B, and if my experience is anything to go by, don't even think of wanting one in August because the factory is on a month's shutdown.
