Hello John,
"I'm not sure how much you know about brake bleeding in general, but for these bikes, a decent workshop manual is a must."
- Thank you very much for your very detailed response. I picked up the factory service manual today, 12/31/15 and indeed it is a must-have. I have bled a few brakes over the last forty years but this is definitely not something I have seen before. My experience has not involved anything beyond standard braking systems.
" The procedures for bleeding are different on the ABS bikes - particularly if they also have CBS - Honda's combined braking system. It isn't always the case that one bleed valve is fed only by the action of one lever or pedal. If you let air in when you open the bleed valve and don't have the proper procedures for getting rid of it, you will have no brakes."
- Yes, my bike is ABS/TCS/CBS. A quick skim through the pages of the manual quickly reviewed a very complicated system with multiple bleeding steps, all while using professional pneumatic brake bleeders.
"However - you will find one valve on each caliper which is in line with the centre piston. This valve opens up the fluid that feeds just this one piston - although it may be fed from more than one source. The other valve will be in line with one of the outer two pistons. These two are connected together and releasing the valve opens up the fluid to both of them. You will find that before opening a valve, if you push one in, the other will pop out."
- Thank you, this is very helpful info.
"I would think twice before opening the valves if you do not know the procedures for bleeding the entire system, in case you let air in and cannot get rid of it again.
If all you need is to put new pads in, then I would remove the old pads, move all of the pistons out a little bit (you can learn something from which control moves which piston) and thoroughly clean the surfaces of each piston. Use brake fluid and the hem of an old sheet to clean all the way round (like drying your back with a towel), getting rid of all of the crud that has gathered. Check that there is room in the brake fluid reservoir and gently push the pistons back as far as they will go. Keep checking the reservoir level - in theory there should be enough room for the fluid, but if someone has topped up the reservoir since the pads were changed last, you may need to remove some.
There is nothing wrong with doing this - if the brake mechanisms are working properly, the pistons will move back into place with thumb pressure. You will need to see-saw the outer pistons to prevent one from popping out while pushing in the other.
Did I say to keep checking the reservoirs ?"
- Great descriptions! Thank you. What about Brake Cleaner spray? Do you use it at all?
"Once fully retracted, the new pads can be put in and the pistons pushed out to meet the pads so that they are just touching the disks. Pop the pads back out again and smear rubber (silicon) grease for hydraulics around the exposed part of the pistons. Don't use any other sort. Replace the pads and calipers and the pad pins."
- I will look for the rubber silicon grease.
"Those allen key sockets in the pad pins are very soft metal and if they show any sign of rounding, replace them. The pad pins can get very tight and difficult to get out if the hex socket is even slightly worn."
- The pad pins looked intact. Considering the terrible condition of the pads, it made me think that perhaps they were original. I am just not sure that brake pads last 33k miles on one of these bikes. Do they?
"I have one concern about what you are suggesting - it may be that you omitted something, but it would be remiss of me not to point it out. IF you remove the fluid from the system by opening up a bleed valve as you push the pistons in, rather than pushing it back to the reservoir, then you are effectively throwing fluid away from the system. With new pads going in, the level in the reservoir will remain almost as it is now and all would be ok - initially. But as the pads wear down, more fluid will be required to fill the space left by the pistons - and there will not be enough in the reservoir. One day, half way through a ride, the reservoir will become empty, air will get into the system and the brakes will fail. There's an obvious answer to this, but I feel I need to point out the potential problem."
- Good reminder to keep an eye on that DOT4 fluid level. Thank you.
"Also - I don't know how long it is since the fluid was changed. Do you ? Brake fluid absorbs moisture. It gets into the system over time and the fluid goes cloudy. Apparently, as the fluid gets hot (from using the brakes, from the engine, from the exhaust) the moisture in the system can turn to little bubbles (of steam), resulting in brake failure. If it has been a while, then the system needs a complete flush through with new fluid and it needs to be bled properly."
- I'm also unaware of when or if the fluid was changed. According to the previous owner a "full-service" was done on the bike at 30k miles by "a guy who knows a lot about motorcycles." I am skeptical judging by the fact that this so called expert ignored most torque values of any nut or bolt he touched. The automotive oil-filter and the conversion to full synthetic 20W-50 motor oil were also alarming, to me anyway.
"Finally - does your bike have a secondary master cylinder ? I don't need the answer, but you do ! On my 2000ABS bike the SMC was behind the shroud on the left hand front fork. If it does have one (and it is quite likely on a 1999 ABS model), then you have to be aware of how that operates and how it affects the bleeding at the rear calliper. You will also need to know whether or not the brake pedal affects the front callipers. That is quite likely too.
After pushing in the pistons and seating the brakes, make sure that all of the pistons are in contact with the rear of the pads. You may need to operate the SMC (if you have one) to do this. Then check that the fluid level is not too high. If it is, take some fluid out before you turn on the ignition."
- Yes, the 99' also has a secondary master cylinder. Yet another very valuable piece of information. Thank you very much! With your response and with the factory service manual now on-hand I feel much better prepared to tackle the job.
Thanks again for your time on responding to me on this. It was very kind of you! Happy New Year!
d.
