rear caliper question

jfheath said:

It sounds like you need this !

Have you checked that you have not overfilled the reservoir by pushing the pistons in ? If the rear fluid has been topped up since the last pad change, that is quite likely. Having too much fluid in the system will cause problems.

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Nice article. Will be very helpful. The reservoir has not been topped off since last pad change.

When you have multiple pistons and apply pressure to the brake fluid, the piston that moves most easily will be the one to relieve pressure in the system and move. The other's will stay usually stay put (but not always). I've not had to work much on my ST's brake calipers, but this has been true for other bikes and cars that I've had apart.

If you can get that second piston to move with finger pressure on the first, it sounds good to me.

Something I learned rebuilding Calipers/brakes on the old V4's, when you rebuild, remove the seals, and using a dental pick, scrape out the groove the seal sits in, it's amazing how much stuff can get in there behind the seal itself. I've had some pistons stuck so tight that I had to plug the banjo bolt fitting with a bolt, and use the bleeder screw as a grease fitting, pumping in grease at 1500 PSI usually pops the pistons out. Cleaning out that groove allows the seal to sit back where it's supposed to. Basic theory behind how calipers work is this: The seal is square cut, when the piston moves outwards while applying the brake, the seal "rolls". When you release the brake the seal tries to go back to square, this retracts the piston slightly. This action, combined with the fact that no rotor is actually "true", stops the pad from dragging during normal use. Now, if you get a situation where the fluid pressure cannot be released, or the seal itself is binding on the piston, or a slider pin is jammed, and you start to get a dragging caliper. Yes, a sticking guide pin can also cause a caliper to bind. When servicing, remove the guide pins, clean out all the gunk(using non petroleum based cleaner-actual brake cleaner works well-carb cleaner? No-so-much) And lube with a silicone base lubricant(Sil-glide was my go to for years-but most auto parts stores carry something branded as Brake grease) Regular grease is a no no, the grease attacks the rubber boots and components and causes them to swell and start to disintegrate, which of course, negates all the work you just did. Personally, when bleeding I use a Vacula brand air powered bleeder tool, but, I have one.... This tool allows me to completely drain and fill the system with no issues. While working on the calipers themselves, you can clamp the rubber hoses closed(so the system doesn't drain dry). I, obviously, have special nylon clamping pliers designed to do this also, they don't damage the hose or liner, Vice grips can be used, but gently, you don't want to crush the hoses inner liner. I haven't had need to service any of the master cylinders on a 13 yet, sort of looking forward to it....
We should do a webinar at my garage one day....who needs brakes done? Bring the parts, bring the beer...:tools1:

dduelin said:

The service manual shows the pad retaining pins installed dry and that's all I've ever done. The pins are exposed to road grit and grease collects crud on the pins then grinding a flat spot. The pins themselves will wear over time even dry, why coat them with grinding paste?

With the new pads in place how easy was it to insert the retaining pin?

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Running the hanger pins dry is probably ok for the folks who live in the south and the roads haven't been coated with brine/salt/gravel, etc. A thin film to help keep the corrosives at bay certainly won't hurt. The Illinois bike I just serviced, had a rusty hanger pin because of the caustic road treatments. This was a contributing factor to his brake problems.

I think I'm good to go. Bought some of that fancy brake grease. Are the hangar pins made out of different material? The longer one I was able to clean up on the wire wheel nice and smooth. The shorter one looks like old corroded cast iron pipes look. It is pitted pretty bad, should probably order a new one. For now, I lubed it up and put it back together. The rear wheel spins much better, kind of hard to tell because there is always some kind of minimal drag. The other issue I think I may be having is my rear rotor is pretty worn. In fact the backer plates come in contact with the rotor prior to the pads being totally worn out. So, it seems I would have a contact point at the top and bottom of the pads as they actually fit "into" my rotors. Does that make sense? Anyway, hope to do a shake down ride on Wednesday to see if she's worthy of a 4K mile roadtrip in a few weeks.

You may be alright if the rotor is not worn past minimum thickness or grooved deep or have metal transfer from the backer plates. If there is some slight grooving, then the pads will take longer to seat to the rotor. Mother Honda is very proud of their rotors, so if the damage is much, it would be easier to have a machine shop resurface the rotor if the thickness will allow. Not sure, but I think the thickness of the rotor doesn't allow much room for wear.

Ken, Vinny U can NOT turn, clean up those rotors for MC. There is not enough beef. I replace my rear rotor (OEM) on the ST last year just below MIN. spec. Thinking 6MM.

I'll have to keep my eyes open for a low mileage used one. I seem to recall they were >$300 new. My bike is barely worth that, LOL

kendoo said:

I'll have to keep my eyes open for a low mileage used one. I seem to recall they were >$300 new. My bike is barely worth that, LOL

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Ken, I called & left a message on your phone. Have Honda brake pins & tiny white o-rings. My rear rotor still has miles on it. It is at 6mm But I would want U to see it. If U like U can have it. I'm real fussy about my braking system on my MC. That is why it was changed out. Like U travel by my self try to keep ahead of repairs/replacement or PM.
Those brake hold on pins for me get replaced every other brake pad change. OEM parts for my HONDA brake system.

acedantinne said:

Ken, I called & left a message on your phone. Have Honda brake pins & tiny white o-rings. My rear rotor still has miles on it. It is at 6mm But I would want U to see it. If U like U can have it. I'm real fussy about my braking system on my MC. That is why it was changed out. Like U travel by my self try to keep ahead of repairs/replacement or PM.
Those brake hold on pins for me get replaced every other brake pad change. OEM parts for my HONDA brake system.

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Thanks Bob. No cell reception in the building at work. I will measure my rotor to see what I have left. I suspect its quite thin because when I start to hear metal, its the backer plate hitting the lip on the rotor and not the pads being totally worn out. BTW, what's the function of that little white o-ring? I ask because mine is no longer there, LOL

3= pin quiet, keep dirt out, hold center wear on caliper side pin.

kendoo said:

I think I'm good to go. Bought some of that fancy brake grease. Are the hangar pins made out of different material? The longer one I was able to clean up on the wire wheel nice and smooth. The shorter one looks like old corroded cast iron pipes look. It is pitted pretty bad, should probably order a new one. For now, I lubed it up and put it back together. The rear wheel spins much better, kind of hard to tell because there is always some kind of minimal drag. The other issue I think I may be having is my rear rotor is pretty worn. In fact the backer plates come in contact with the rotor prior to the pads being totally worn out. So, it seems I would have a contact point at the top and bottom of the pads as they actually fit "into" my rotors. Does that make sense? Anyway, hope to do a shake down ride on Wednesday to see if she's worthy of a 4K mile roadtrip in a few weeks.

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Ken, I had one of the two rear caliper hanger pins do the same as yours. (the pins the entire caliper slides on) The front one as I recall. It cleaned up good and shiny but the surface was pitted. I found it like that at 125,000 miles when I had the caliper start dragging and I know yours has a lot more miles than mine. I just did a caliper cleaning/greasing job at 158,000 and that hanger pin had not deteriorated any more.

I check the thickness of my disks on a regular basis. I think the fronts will last forever! The rear was down from new 7 mm to something like 6.2 mm (min spec 6 mm) when the high spot on the extreme edge of the rotor started rubbing on the metal backing plate of the pad. Like you said there was maybe 25% of pad left but the high spots where the disk is unworn and original thickness would contact the metal backing of the pads. I sent it to Highrider on this forum and he resurfaced it and made it all flat and true but it is barely 6 mm after grinding. I keep it for a emergency spare and found a good used one with a claimed 8,000 miles on it (eBay) which I put in use.

acedantinne said:

Ken, Vinny U can NOT turn, clean up those rotors for MC. There is not enough beef. I replace my rear rotor (OEM) on the ST last year just below MIN. spec. Thinking 6MM.

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You just proved what I was thinking in the above post! I thought they were designed slightly over minimum specs.

acedantinne said:

Ken, Vinny U can NOT turn, clean up those rotors for MC. There is not enough beef. I replace my rear rotor (OEM) on the ST last year just below MIN. spec. Thinking 6MM.

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If the rotor is thick enough prior to resurfacing they easily can be cleaned up and still be in excess of the Honda-specified minimum 6 mm thickness. They start at 7 mm I think. Of course if they are at the minimum 6 mm to start with they can't be turned and refinished as the finished rotor will be less than 6 mm. I have one in the garage that was ground down to refinish it and it is slightly thicker than 6 mm. I only keep it as an emergency spare for myself or a RAN list member that might need one to get home.

dduelin said:

Ken, I had one of the two rear caliper hanger pins do the same as yours. (the pins the entire caliper slides on) The front one as I recall. It cleaned up good and shiny but the surface was pitted. I found it like that at 125,000 miles when I had the caliper start dragging and I know yours has a lot more miles than mine. I just did a caliper cleaning/greasing job at 158,000 and that hanger pin had not deteriorated any more.

I check the thickness of my disks on a regular basis. I think the fronts will last forever! The rear was down from new 7 mm to something like 6.2 mm (min spec 6 mm) when the high spot on the extreme edge of the rotor started rubbing on the metal backing plate of the pad. Like you said there was maybe 25% of pad left but the high spots where the disk is unworn and original thickness would contact the metal backing of the pads. I sent it to Highrider on this forum and he resurfaced it and made it all flat and true but it is barely 6 mm after grinding. I keep it for a emergency spare and found a good used one with a claimed 8,000 miles on it (eBay) which I put in use.

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Good info Dave. I bet I will be real close to that 6.2mm based on the fact that I too have close to 25% pad left when the backer plate starts rubbing. I think I will be fine once I get a few miles on these new pads. I'll be needing a new rear tire in another 25K, so I have a few months to try to locate a low miles rotor...or a whole new bike. LOL