Braking myths
Blue Spot brake calipers from the YZF-R1, R6 and Fazer series are a classic upgrade – but how do you service them? Our Ralph has the answers.
A few years ago a customer, who soon became a friend, bought a 1999 R6 in blue. It had a few issues, including leaking fork seals, which I fixed. He had paid buttons for it and I rapidly fell head-over-heels in lust with it. It was pretty original save for a few imperfections, but it came with all the original parts. I did say to the chap that if he ever got bored with it, to let me know. At the end of last year when I rang him up to invite him to a liver-damaging event with fellow bikers, he asked if I knew anyone who wanted his R6. Of course I did; but I had to consult the management. Eventually, the wife got fed up with my unremitting sales pitch and sanctioned the investment. As soon as I collected it, winter came so I didn’t get a chance to ride my new toy for months and had to just drool over its beauty in the lock-up. When spring came, despite three months or so of inactivity, she started easily on the button. Being shod with Blue Spots on the front, I was expecting a big handful of front brake to propel my eye balls forward out of their sockets. While they worked (just) they were far from up to
committing stoppies. They used to be back in the day… The other problem I discovered on my test ride was that the engine was well lumpy at tick over and so clearly the carbs wanted balancing. I decided safety first, so I’d kick off with sorting the stoppers. The first job was to determine if there was any water in the brake fluid. The cap on the master cylinder has a special locking device, I removed the screw and locking device and once the paintwork was protected from brake fluid by a hastily taped on bin liner, I unscrewed the cap. The fluid didn’t look great and when I tested the water content, the tester had a full complement of lit LEDS informing me that it had at least 4%, and by the look of it much more than that. I decided to suck the master cylinder reservoir out with my vacuum brake fluid bleeder, effectively using it as a little wet vac, but given the brake fluid had turned into a primordial soup, it actually blocked up the pipe, which was a nightmare to clear again! I then attached the vacuum bleeder to the brake nipples on the calipers and sucked out as much of the swamp juice as would pass through the bleed nipples, which wasn’t much. I then undid the banjo bolt to remove the line, unbolted the caliper from the fork leg and clamped it in the soft jaws of my bench vice. I did contact Yamaha technical services, who take the view that they are supplied their legendary Blue Spot calipers by Sumitomo as a sealed unit and they are not to be taken apart. They say that the pistons can be removed using the plier style piston removal tools or hydraulically pumped out. Different motorcycle manufacturers take different views. Old Hinckley Triumphs use re-branded Nissin calipers and the manual tells the reader they must not be split, whereas Suzuki has used the same four-pot stoppers on its bikes and even sells the seal that goes between the two halves. I have to say I take the view that the seal groove on bikes used in all but the driest of conditions will suffer corrosion, which in turn forces the seal against the piston, impeding its ability to slide as intended, thereby wasting energy moving the piston that should be used to stop the bike. This inefficiency could be the difference between avoiding a collision or not. It is my belief that even if you manage to get the pistons out (and
I have never managed to get them out of a corroded Blue Spot caliper using this method) you still can’t get at the seal grooves to properly to remove all corrosion. I think they take the view that if there is that amount of corrosion then the caliper is scrap. The cynic in me thinks that is a perfect viewpoint for someone selling calipers. There is however an alternative; there is a tool available to remove the strangely shaped nut. Even though the tool is made from aluminium, it may very slightly mark or bruise the nut, as happened with this one, but considering a new caliper costs £255.95 (priced at time of writing) or £511.90 for a pair, this is something I’m prepared to live with, so read on! Before getting down to the nitty gritty The R-clip securing the pad pin was pulled out with needle nose pliers, followed by the pin releasing the anti-chatter spring plate and the pads. Although the existing pads had plenty of meat on them they were only organic compound, so I decided to skip them and fit some sintered ones. My account manager at the trade sister company of Wemoto, was keen for me to try their Brenta pads and gave me a set for nowt. I can say that they did perform well and given their keen pricing, I shall be using them again in the future. He knows I’m way too tight to pay money to try new products! Using a 22mm spanner and the special tool, I removed the Blue Spot nut. It looked as though a cider drinker had tossed his (or her) cookies into my braking system. Considering the state of the muck inside, it’s a credit to Sumitomo that these brakes worked at all! The outer pistons were very tight and I ended up using a G-clamp to force them out. I put something soft under the fixed end of the clamp to prevent it marking the anodised black finish and used the special tool as a soft anvil for the moving end to push against the errant piston. To remove the inner pistons, I used my trusty Laser Tools brake piston removal kit which was not entirely inexpensive when I bought it years ago, but is the canine genitalia when faced with corroded calipers like these. Biker’s Toolbox does sell a cheaper copy of this set as well, which looks very similar and will wipe the floor with plier type tools for tight pistons. I cleaned up all the pistons and carefully examined them. The pistons are made from mild steel and are polished and chrome plated. If the chrome has any holes in it the piston is only fit for the scrap bin, like the one in the photo. The edges of the hole in the plating are sharp and will cut the delicate dust and hydraulic seals running the risk of fluid leaking out which will inevitably leak on to the discs and pads having a life-threatening effect on braking performance. A genuine piston and seal kit from Mr Yamaha isn’t too expensive, though there are plenty of pattern items available from the likes of Wemoto. Considering this bike is visually in
excellent condition and is exceptionally low mileage for the year, these brakes were in a shocking condition. This is simply down to the fluid not being changed when it should have been. Fluid should be changed at least every other year, but one should always check the water content annually, electronic brake fluid testers are not a king’s ransom. I removed all the hydraulic and dust seals carefully using a 90º pick tool. As the dust seals were very ropey I bought complete seal kits for all the calipers and replaced the pistons that were past their best. I removed the rear caliper in the same fashion as the fronts, though it’s worth noting that you can’t take the top off the rear reservoir without unbolting it from the bike for some inexplicable reason,
enhancing your chances of spilling the paint destroying fluids therein. The rear brakes must have seen some more recent love than the fronts as I was able to remove the pistons with a plier-type piston removal tool. I initially gave all the caliper bodies a thorough scrub with a toothbrush and brake cleaner. As there was white powdery corrosion inside the seal groves, I cleaned these out with a small wire wheel, like a miniature chimney brush, in my Dremel. This is the only way I have ever found to get the seal grooves properly clean and free of nasty oxides. Given my intention to spank the arse off this little crutch rocket around Castle Combe in the near future, I decided to give the calipers an invigorating swim in the ultrasonic bath. This removed all the last vestiges of crap from all the drillings. For a bit of extra long-term protection, I painted the inside of the seal groves using a budget small artistic paintbrush with Corrosion Block (ACF50) grease. You’ll notice in the photo that I bent the end over so it’s easy to get the bristles in the groove. This is not usual motorcycle workshop practice, rather an idea I had some years ago, which I tried on my own winter hack (FJ1200) and found that it made a massive difference to the condition of the calipers at service time. As is standard practice, I lubricated the new seals with red rubber grease before wriggling them back into their respective grooves. I also very lightly smeared the pistons with red rubber grease before returning them to their bores. When refitting the pistons it’s of paramount importance to ensure that they are properly straight as you push them in. They should slide smoothly in and out. With the Blue Spot calipers you should fit the pistons from the middle of the caliper where the disc runs. I usually leave the covers off until I have all the pistons installed. I fitted the inner pistons first as it is easier, because you can push them in with your finger through the outer bore hole. The outer pistons are slightly trickier and you may find it easier to use a plier type piston removal tool, though I did fit these ones without. Before refitting the covers, I checked that the O-rings were in good shape; if they have any imperfections they must be replaced. Do NOT use regular O-rings found in normal O-ring sets, as they must be suitable for use with brake fluid and few seals fit the bill. I next fitted the covers, being uber careful not to cross the threads. I applied a small amount of grade 243 thread lock and seal to the threads. Sadly (as Yamaha don’t not want you to take these apart) there is no official torque setting and one has to use experience. I would not recommend anyone stripping these calipers who hasn’t got a fair bit of experience and knowledge of working on motorcycle braking systems, as the result from anything going wrong with brakes can be extremely messy. Next month, I will refit these calipers to the bike, fit a set of braided lines and give the motor a service. cmm