Rear brake problem
- Thread starter Fishermark
- Start date
OP
OP
Group #11 is what I ended up ordering. Will report my findings. 
I’m thinking and hoping that you’re on the right track. I’ll admit that I’ve never been inside the NT master cylinder, but your description of an “all or nothing” condition suggests to me that there is some sort of valve (bypass or back flow) that is sticky. Or master cylinder seal with an intermittent failure. Good luck.
I suspect the NT's still out there are aging to the point where various problems like this will start to crop up, even though it is a reliable bike, things age and wear out. Just like me 
Keep us posted on what fixes it.
Keep us posted on what fixes it.
The master cyl repair may very well fix the issue, hope so. Keep us posted.
The only other thing that has entered my twisted mind is that it only fails when the bike is moving and the wheel (and rotor) are turning. So is there still something back at the caliper? Maybe new brake pad not square and sticking/moving in it's mounts, some dirt messing with caliper seals? Maybe a bit of a stretch but it is an uncommon thing going on and this started with pad maintenance.
Arknt
The only other thing that has entered my twisted mind is that it only fails when the bike is moving and the wheel (and rotor) are turning. So is there still something back at the caliper? Maybe new brake pad not square and sticking/moving in it's mounts, some dirt messing with caliper seals? Maybe a bit of a stretch but it is an uncommon thing going on and this started with pad maintenance.
Arknt
ST1100Y
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Possible that the fluid replacement knocked some crystallization loose which are now randomly clogging the bores in the MC? 
I was thinking but rejected the senario of stuck brakes that heat of the fluid till it boils....doesnt make sense here. I will say that I took my VFR for a ride in the semi spring yesterday and the rear brake works about as well as dragging my foot......just like my Vstrom. I dont get it.....
OP
OP
UPDATE.
Well, I received my master cylinder rebuild kit. While I was at the Honda dealer, I spoke with the mechanic there regarding the problem. He suggested looking again at the rear caliper and the pads. He said if I didn't clean the pistons real good before pressing them in the chances are good that one is sticking and causing a bind and thus the problem. SO... before rebuilding the master, (and adding another layer of uncertainty to the equation), I took off the rear pads again and looked at the pistons on the caliper. (Truth be told, I did not clean them before pressing them in originally as they looked reasonably clean). I cleaned them good and pressed them in - and carefully pressed the brake pedal to ensure they moved. Did that a couple of times and then reinstalled everything.
Just got back from a test drive and everything is working perfectly. I will keep the rebuild kit handy and that will be the next step if it happens again.
As an aside for anyone looking to do the rear brakes: I know it can be done without removing the various components in the way. But the job is MUCH easier if you remove the side pannier and the muffler. I have removed my muffler several times in the past couple of years for various reasons so it is easy to remove. And the side pannier takes maybe ten minutes tops to remove.
Well, I received my master cylinder rebuild kit. While I was at the Honda dealer, I spoke with the mechanic there regarding the problem. He suggested looking again at the rear caliper and the pads. He said if I didn't clean the pistons real good before pressing them in the chances are good that one is sticking and causing a bind and thus the problem. SO... before rebuilding the master, (and adding another layer of uncertainty to the equation), I took off the rear pads again and looked at the pistons on the caliper. (Truth be told, I did not clean them before pressing them in originally as they looked reasonably clean). I cleaned them good and pressed them in - and carefully pressed the brake pedal to ensure they moved. Did that a couple of times and then reinstalled everything.
Just got back from a test drive and everything is working perfectly. I will keep the rebuild kit handy and that will be the next step if it happens again.
As an aside for anyone looking to do the rear brakes: I know it can be done without removing the various components in the way. But the job is MUCH easier if you remove the side pannier and the muffler. I have removed my muffler several times in the past couple of years for various reasons so it is easy to remove. And the side pannier takes maybe ten minutes tops to remove.
OP
OP
So yes - it appears Arknt hit the nail on the head. I too do not believe in coincidences, and had a hard time believing it was the master cylinder. I just couldn't wrap my head around how a sticking caliper piston, or misaligned pads could cause these symptoms. Of course it is a little early to confirm it is finally fixed. But everything is working good so far.
"....But the job is MUCH easier if you remove the side pannier and the muffler. I have removed my muffler several times in the past couple of years for various reasons so it is easy to remove. And the side pannier takes maybe ten minutes tops to remove..."
I do the same when I'm removing/reinstalling the rear wheel during a tire change. It's amazing how easy things go when you have visibility!
I do the same when I'm removing/reinstalling the rear wheel during a tire change. It's amazing how easy things go when you have visibility!
Glad that Fishermark found the problem. I removed the right pannier as well, for rear wheel and brake service, because I didn't have a lift. But I never removed the muffler, didn't see a need to disturb the exhaust system.
I also plan my rear brake pad changes when I change rear tires. That seems to happen every 7 or 8 thousand miles so if pads look worn enough, I just put a new set on at the same time. I keep a set of pads on hand.
OP
OP
On a different subject - I am surprised at how hard it was to find a set of tires to fit my bike. I guess many American manufacturers don't make the tire size for the rear tire anymore.
Fishermark... glad you got it resolved. That was an odd one.
Yes, the rear tire is also an odd one (150). A lot of manufacturers make the 160, but not a lot make a 150. I just got a set of Pirelli Angel GTs, and I've also put the Dunlop Roadsmart 3 on the bike (since I couldn't find the Dunlops in stock anywhere).
Yes, the rear tire is also an odd one (150). A lot of manufacturers make the 160, but not a lot make a 150. I just got a set of Pirelli Angel GTs, and I've also put the Dunlop Roadsmart 3 on the bike (since I couldn't find the Dunlops in stock anywhere).
OP
OP
That's exactly what I just had put on my bike.
i put a Conti Motion on the rear of my NT last year. It seems to be wearing as well as the Bridgestone T-31 I took off. I have these on 2 other bikes and am very happy with them.
I am currently running a 160 Roadsmart in the rear without a problem. There is ~1% speedo/odo error but handling is not affected and there are no clearance issues.
Mike
OK, I must be tired and its late....so for old people, what is the theory here by the mechanic? If a Piston sticks in either the actuated position or the relaxed position, the brake pedal still wont go "to the floor"?????? What am I missing? If a piston sticks and causes a bind, yes, the pads wont work but the peddle will still feel resistance?
Yes, if the pad sticks, the pedal will feel resistance since the fluid is non-compressable.
Mike