well rear brake locked up

Kevcules said:
This SMC linked braking system is a definite negative for the St1300 beast. I try to be proactive and do all kinds of preventative maintenance but it seems this locking brake phenomenon can just appear out of the blue. Not something I want to deal with on a long ride.
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I'd wager that those doing their own maintenance and preflights have nothing to worry about. I know I don't.

Sorry to hear of Ferret's misfortune though.
 
Kevcules said:
it seems this locking brake phenomenon can just appear out of the blue.
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The result may be unexpected but there's always a cause. I'd bet it's rare that a something breaks because of a defect such as metal fatigue or a crack from a flawed casting defect.

From just about every single failure mentioned in the short time I've been here they're due to corrosion of some sort at some level. None of it seems non-preventable. The SMC has benefits but it also demands regular thorough preventative maintenance. Like the rest of the bike. It's not a matter of 'sooner or later...' It's a matter of good maintenance.

That said I'll take the advice of carrying an 8mm wrench and a short piece of hose. I have a MP bleeder and could throw that in as well. and I think a wedge with hole drilled for a tie-wrap or something might be good idea as well.

I don't think there's any reason to fear the SMC. Spiders and robots— heck yeah.
 
My fluid gets bled more than every 2 years. I had read reports here of this happening and tried to be proactive. My mechanic also recently cleaned my SMC throughly. Just 9000 miles ago I had all new wheel seals and bearings, fork seals and fluid, new brake pads complete bleed to all systems, radiator coolant flush, clean and repack head bearings, new air cleaner and spark plugs. Mine is not a neglected motorcycle. I ride it a lot, but it is well maintained.
 
I guess there's a first time for everything. Here's hoping an SMC autopsy reveals the COD (assuming it's the problem).
 
MidLife said:
You can jam a spacer by the SMC piston to prevent it to engage.
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:eek:
I don't think I'd want to JAM anything in my brake system in an attempt to alter it.
If the SMC does not work, you only have (1) piston working on the rear wheel.
 
Soontobeone said:
I think I have to disagree with this, unless my understanding is in error. As I am looking at the service manual and how the front brake works I see this: The front brake lever applies pressure to the outer pistons of both front calipers, then the SMC activates the proportional control valve and applies pressure to the rear outer brake pistons. So, if you open the bleeder valves of the rear caliper there should not be any pressure applied to the rear caliper from the front linked system, when the front brakes are applied.
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Search and check out John Heaths write up on the brake system, it will make more sense to you.
I believe your understanding of the system may be an error.
 
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Kevcules said:
Dave........what type of maintenance do you do to keep your SMC working well?
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I'm meticulous about replacing the brake and clutch fluid at or before 12,000 miles. I ride enough that I'm changing it on mileage rather than time period. Since my bike has attained high mileage I have replaced certain rubber items to keep excess moisture out of problem areas - the master cylinder reservoir diaphragms several times and the rubber boots over the caliper slide pins. About every other fluid change I remove the caliper and clean the caliper slide pins and the swab out the holes the pins slide back and forth in. I lightly grease the pins and wipe off all but a light layer. The front left caliper is always removed and tilted and the lower pivot needle bearing is lightly greased with boat trailer water resistant grease. I replaced this bearing and it's press-fit collar once. Contrary to popular opinion I don't pay much attention to cleaning or polishing the caliper pistons.

I inspect and observe SMC operation often by giving the rear wheel a shove with my foot. I park on the centerstand at home and always check it when I park the bike at home. It should easily rotate two turns or more and every now and then I operate the SMC by hand to observe it's free action and the distance it takes to apply pressure to the rear caliper. (It's not much!) I used to carefully pry up the boot over the SMC clevis/push rod so I could look underneath it for rust or corrosion but I was afraid of tearing or puncturing the boot so I leave it dry and alone.
 
Let me ask a question. What would be the downside to bypassing the smc? Reduced braking? Front? Rear? both?
 
the Ferret said:
Let me ask a question. What would be the downside to bypassing the smc? Reduced braking? Front? Rear? both?
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Again, search and find John Heaths write up on the brake system, it is very detailed and well written and will explain how the brakes work in fine detail.
In a nutshell, the front brake lever only operates the upper and lower piston(s) in the front calipers. The foot pedal only operates the center piston(1) in all three calipers.
The only way to get the upper and lower piston(s) to work on the rear end is through the SMC and PCV.
So if you hit your hand brake only, your activating 6 pistons, if you hit your foot pedal only, your activating 5 pistons.
If you use both your brake levers at the same time (and everything is working correctly) your using 9 pistons.
 
Soontobeone said:
I think I have to disagree with this, unless my understanding is in error. As I am looking at the service manual and how the front brake works I see this: The front brake lever applies pressure to the outer pistons of both front calipers, then the SMC activates the proportional control valve and applies pressure to the rear outer brake pistons. So, if you open the bleeder valves of the rear caliper there should not be any pressure applied to the rear caliper from the front linked system, when the front brakes are applied.
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So your saying you would leave the bleeder valves OPEN to prevent pressure from being applied to the rear caliper from the linked system....one problem with that....you would be spraying the entire :butt1: end of your bike, including your rear wheel, with brake fluid as you tried to ride it :rolleyes: I would also venture to guess, that if you bleed out all the fluid from the rear section, that you would have a whole bunch of air in the system, and that might affect the operation of the front brakes as well (linked system).
I have rescued folks that had this happen to their bikes, and simply bled off some of the pressure by cracking open the rear bleeders (then closing them) and CAREFULLY riding home using engine braking, timing, and a whole lot of luck, and I would NOT recommend ANYONE try riding their bike with the brakes not working. :well1:
 
does this SMC make my rotor look hot? lol

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Something does not seem to make sense here. Most everyone uses the front brake most everytime they stop the bike meaning that the SMC is exercised many times on most every ride. It just does not seem reasonable that suddenly the SMC would be activated and not release at all. Is there some other component of the braking system that would cause a hydraulic lock?
 
Thunderchief said:
Something does not seem to make sense here. Most everyone uses the front brake most everytime they stop the bike meaning that the SMC is exercised many times on most every ride. It just does not seem reasonable that suddenly the SMC would be activated and not release at all. Is there some other component of the braking system that would cause a hydraulic lock?
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Think of debris as a wedge. You activate the front brake that activates the SMC piston. Now debris that has built up over time wedges itself between the piston and the bore. Since the piston doesn't fully release it keeps pressure on the rear disc and eventually locks it up. Does it make sense now?
 
You know,,, as someone who has been through what Ferret is dealing with,, and there are more and more of us every day who are at the same risk. I wonder if it is a good idea,,, in light of the potential severity of an sms failure,,, to come up with a general rule of thumb/guideline,,, based on our collective experiences. Something like,,, eg:"any sms in service for X- or more years/miles/conditions, without receiving regular appropriate PM, should be replaced". Of course,,, we should also define appropriate PM (preventive maintenance). This is the type of thing that Honda should do,,, but won't,,, due to financial and legal liabilities. So maybe it falls to us,,, and maybe we are better qualified to make membership recommendations anyway. Thoughts ?? Cat'
 
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