Rear brake issue

[Igofar]

Talking about installing the rear wheel, and using the word grease got my attention
You can use a very little amount of grease on the brake pad pin if you want, but I find that just collectings dirt etc.
Grease on the stopper plug will get squeezed out the first time you hit the brakes.
Grease on the axle won’t hurt anything, just don’t use paste on any of these parts other than the splines.
I find antiseize works better on the axle, and will remain there.
If you’ve ever pulled an axle out and found two rusty rings on it, that is where grease used to be, and is metal to metal wear from the bearing races.
When you use antiseize you will never find that.
It’s not in the service manual, but I use antiseize on the stopper plug to it’s a glancing blow every time it contacts it, and the steel plug does not damage the soft aluminum bracket as much.
YMMV.

 

[Chris09]

[edited after rechecking measurements] Here's a few pics and measurements of my Stopper Plug and Bracket. These measurements are a little rough, and I can slightly rock the plug in the middle of elongation. The flat part of the elongation is uniform and I can move the vernier caliper along with no [[edit - added] discernable change.
The chamfer edge is uniform in width so I would think that if the elongation is getting longer, I'd expect to see some narrowing of the chamfer at the end.
[edit - added] I've replaced the sketch photo after remeasuring. I've added the axle bore and revised the stopper bolt to 0.553 / 14.05 with no discernable variation between the flat marks and perpendicular to those.

 

[Igofar]

Your rear caliper mounting bracket is damaged and should be replaced!
I would love to see a couple pictures of the pad retaining clip from the right side as mounted, and facing straight on, to see how worn the bracket is at that point.
Can you wiggle or move the clip up and down at all?
The spiral flutes inside the caliper bracket hole where the plug sits indicate that the axle/stopper plug were either torqued in the wrong sequence, or the stopper plug got loose and danced around etc.
It’s also a sign that your SMC may have either been failing, or failed putting pressure on the stopper plug.
Has your SMC been replaced at any time?
If so, you should have replaced the rear caliper bracket as well.
I would suggest you not operate your bike with that bracket for safety reasons.

 

[Igofar]

Does your clip look like the first picture, or the 2nd two pictures?
There should be no gap/space/movement in the clip at all.
And if you can remove it, the bracket should be replaced.

 

[Chris09]

Rotating the stopper bolt back from fully threaded in, there is no visible change in the elongated hole fore and aft gaps, I don't have dial indicator but this observation along with holding a steel ruler tip against the inside of the swing arm, it looks like the stopper bolt flat section is straight.
Putting the stopper bolt backward into the bore at the same depth that would normally occur it can rock very slightly, I'd say there might be a thousandth or two clearance.
With the axle, bracket and stopper bolt assembled, the bracket can not be pivoted from the axle.
The original pads have worn very evenly but not quite perfectly; a little more so toward one end.

 

[Igofar]

Your reply sounds like your trying to convince yourself, or you already have convinced yourself, that all your parts are good, so I won't try to convince you otherwise. With that said however, I see a small gap on the top side of the silver clip, that would indicate that the clip is moving under pressure (which also causes the flutes in the bracket) I'm sure if you were to clean things up, you would probably see it also, maybe not.
You don't have to convince me that your parts are good enough, I'm not the one with brake issues.
And after replacing too many of these to count, I know damage when I see it.
Not trying to impose my will on anyone, so with that, I wish you good luck solving your bikes brake issues.
Ride safe.

 

[Al Gully]

Chris
I’m off my 12-15 hours a day 7 days a week shift for 1.5 months.
I can stop by and give you some moral support if you need me too.
I can bring my spare stopper bolt and support and caliper if you need me too.

 

[Chris09]

Actually that's not the case at all. No offence and not challenging the expertise of someone that has dealt with these issues probably hundreds of times and I appreciate all your help.
Just throwing it all out there, there's an elongated hole in my bracket. A new bracket is either round or elongated to some extent. That hole is glazed and looks knurled and bright at both ends which looks like the stopper bolt has pressed into it on both ends. So I need to know does a new bracket have a round hole or an elongated hole, and if it is elongated, how much worse is mine.
The red line I've drawn is the long axis of the oblong, the pic of stopper bolt in the oblong shows virtually a compliant fit perpendicular to that line, and the uniform oblong shaped chamfer suggest the hole might initially be oblong and the clearances might exist to enable contraction and expansion along that line. If the hole is initially round, I would expect the wear to reduce or at least slightly distort the chamfer at each end.
If the bracket is shifting fore and aft that much, and none of it is attributable to difference in temperature to the swing arm, where is the corresponding shift in the corresponding stopper bolt to swing arm end occuring; could the combined axle to swing arm bore clearance and bearing clearance take up that much slack, if so, have I already compromised other components.
Didn't want to clean the clips yet in case the grit and glaze might shed some light on anything.
I haven't checked either upper or end clip to see if they are tight.
No glazing or evidence or wear on the axle, bit of grey grease wasn't as much as I thought at first, maybe just what was applied to the seals somewhere along the line.
Both bearings roll smoothly, seem good.
Some small amount of clearance between the swing arm bore and the axle but seems round will have a harder look tomorrow [next month] see if there's any evidence that the axle could have been shifting or creeping.
Both the stopper bolt and the axle nut were probably torqued close to the correct values but the lesson there is use torque wrench when dismantling wouldn't hurt.
Prior to dismantling, I checked the rear caliper temperature by hand more than once during every ride and no excessive heat.
Did the SMC check periodically on the stand seemed to work correctly and release.
Everything seemed to be working perfectly before I took it apart, [edited - wrong, not perfectly] but maybe I'm only another millimeter from twisting the rear caliper.
[Added] Could never get the number of turns on the center stand upon releasing the rear brake since day one; maybe a half or slightly better turn at best but lay off the brakes for a while during a ride and zero heat.

 

[Igofar]

The last few words of your post would strongly suggest that your SMC is NOT working correctly.
Did you ever consider that your not getting heat because the pistons are not moving correctly?
They can not only drag the rear wheel, causing heat, but they can also prevent the pads from returning to the correct position etc.
The Flutes in your bracket clearly indicate that the SMC was causing issues.
You should be able to get 2-3 full rotations of the rear wheel, with one firm push downward with your foot on the rear wheel.
Alot of folks don't understand how to do the function test correctly, and just read online, or watch a video of what someone's opinion of how to do it is.
I've seen folks push the SMC bracket forward "to stop the rear wheel" hard enough to push the bike off the centerstand!
And just because the wheel slowed down, and then stopped, they felt it passed the test.
Its also possible that you can push a defective SMC hard enough to even cause the rear wheel to slow down and stop, and, release because the piston is stuck in the bore and not moving correctly etc.
Think of the SMC bracket like you would the brake lever. If you put your thumb against it and pushed, hydraulic pressure, when working correctly would INSTANTLY cause the brakes (wheel) to abruptly stop, and then when you barely release your thumb pressure, it should spin freely again (if the piston, or return port isn't clogged up, and working properly).
You should be able to place your thumb on the rearward (towards the engine) flat spot on the SMC and press with thumb pressure enough to cause everything to either work correctly, or not.
I can use my thumb and index finger to grasp the upper bolt head, and back of the SMC and PINCH it enough to lock up the brakes, and then release them when a system is working correctly.
You may want to re-think your SMC testing routine.
Bottom line, the flutes you see are damage, you must decide what caused it.
Your over thinking the "Hole" being round or elongated, they are cast, and that is the shape they are cast in, however, those flutes were not there, when it was new and working correctly, or as I like to think, before it showed damage.
Find the cause of failure, instead of throwing solutions at a problem.

 

[Chris09]

I still think that my SMC is okay, reason being is that it has no slack and returns to the initial position after compression.
I don't see any problem with my rear caliper bracket. It seems to me that the stopper bolt isn't a stopper bolt at all; it's a guide pin.
Earlier in the thread, I traced the caliper bracket elongated stopper pin major centre line incorrectly; on closer look it aligns exactly with the axle bore.
I checked the distance between the holes at 50 and used a heat gun to get the bracket up to about 160 and there was no significant difference, my opinion remains that the elongation is a guide and that the limits are never realized by the stopper bolt post; the only cause for concern would be the fit between the pin and bore, which doesn't vary very ___ much.
My opinion is that the knurled pattern at both ends of the elongation is achieved in manufacturing, and that the stopper bolt post never makes contact with either end, so I question your outright condemnation of my bracket. Not that you are, cause... you never are, trust me I've been reading... and paying attention...
The plate that the chicken ***** brake pad ends have to slide back and forth on I think is still pretty good; you didn't like the bond between the steel and the [call it] alloy, I think it's good.
My opinion is that, my left front caliper slide pins and possibly pistons are not as slick as they used to be, and that, consequently, fluid return through the [correction] SMC skinny ass port can get a bit lazy.

 

[jfheath]

It seems to me that the stopper bolt isn't a stopper bolt at all; it's a guide pin.

Just a comment on the above

The stopper bolt is a large chunk of metal that stops the caliper bracket from rotating around with the wheel when you brake. Think about it - you apply your brakes, the pads grip the brake disc which is rotating at 70mph and it is stopping a third of a ton motorcycle. That is going to put one heck of a force onto the caliper bracket which has to brace itself to stop the caliper rotating with the brake disk. Each time you apply the brakes it is one massive thump onto that stopper bolt. The fact that the other end of the bracket is clamped by the rear axle is irrelevant - that isn't going to stop the bracket trying to rotate under those braking forces.

If the bracket becomes twisted - eg due to non-parallel slide pins, brake pads wearing faster at one end than the other, incorrectly installed pads / spring / retainer - that hole and that stopper bolt are going to be at a slight angle in relation to each other. Think what happens if you strike a flat metal surface with a an angled hammer head . It's not a metal face to metal face. It is metal face to metal corner.

 

[Chris09]

Well that was a bit of a meander down the dumb dumb rabbit hole. Wrong again...
Yes I see your point, I was imagining that the force would be more toward parallel with the bracket holes, kind of stretching the bracket from the axle but when I set them together it's pretty clear that it would be closer to perpendicular against the stopper bolt. I wonder if that's how it got it's name...
So when I set the bolt where it would be in relation to the bracket, I can rock it a bit so I guess that's where the damage can start with some of the twisted calipers.

 

[jfheath]

So when I set the bolt where it would be in relation to the bracket, I can rock it a bit so I guess that's where the damage can start with some of the twisted calipers.

I think its the other way about. That stopper bolt isn't a tight fit through the hole. My bracket has 72,000 miles on it and it doesn't show any of those rifling marks (spiral marks). And I use the brakes a lot, living in the Yorkshire Dales where roads are narrow, hills are steep, bends are out to get the unwary and stray stones, cyclists, wall tops, sheep and pheasants abound.
I think that it is the twisted caliper brackets that cause the marking. I do change the stopper bolt, but not every time I remove the bracket. I always have one in stock -ready to replace if I think it is worth doing.

 

[Andrew Shadow]

I think that it is the twisted caliper brackets that cause the marking.

The contact area between the caliper bracket and the stopper bolt is very small. Many of the brackets that I have seen that exhibit these marks they seem to be present far outside of this contact zone, which seems illogical. While I have no doubt that a twisted caliper bracket is problematic, I wonder if these marks are the result of something else.

 

[Igofar]

I commonly find them on brackets that were assembled incorrectly, or the wrong sequence when removing and replacing the rear wheel.
But I always find them on bikes where the SMC failed, or was failing.
To prevent as much damage as possible, I go outside the service manual, and coat the stopper plug with a very light film of antiseize.
This slippery service then Becomes a glancing blow instead of the steel plug banging into the aluminum bracket as hard.

 

[jfheath]

Just musing - on that @Andrew Shadow - I can only imagine that pattern is caused by oscillations over a period of time. A slow cyclical wobble.

But I can't think how it can be anything other than contact between the bolt and the bracket. Something is moving.

Eg if the flange of the stopper bolt isn't clamped squarely against the boss, then the bolt is free to wobble on its threads.
That seems unlikely - unless perhaps the bolt has been reused without the thread locking compound being cleaned off.

The only other thing that could wobble is the caliper bracket itself. That would require the axle to move - which it cannot.

But what if the wheel bearings have not been installed correctly ? That left hand outer race should fit against the shoulder in the hub - if it was driven in first, as it should be. The other bearing is driven in until the inner race meets the distance collar. ie the distance collar cannot wobble about.

But what if it can ? To understand this next bit, it is necessary to appeciate that only one bearing sits on a shoulder in the hub. The second bearing outer race is prevented from meeting the shoulder on its side, because the inner race meets the distance collar first.
So what if the left hand bearing was incorrectly installed last and is not seated on the shoulder. If the other bearing does not clamp the distance collar, then that left hand bearing has room to move inwards. And that will result in the caliper bracket not being clamped at all.

That is a contrived 'what if' suggestion. I'm not sure I believe it - because tightening the axle bolt will probably clamp the distance collar ? Maybe not. In the past I've removed wheels where the distance collar was free to rattle around.

Does that explain Larry's link between the fluting and the SMC ? Possibly. The only time that marks like that can be created is when there is movement when there is force put on the stopper bolt. Ie when you are braking. And if the SMC isn't working properly, the rear brake is always dragging.

I don't know, I'm just imagineering. I've got better things to think about - like Larry's guitar tab notation. Goodness that Mr Paxton moves his fingers quicky.

 

[Mark H]

Hi all ! This is my first post on here although I’ve been “lurking” since 2020 when I bought my 2010 ST. First of all, I want to thank everyone for all of the help you have given me while working on this thing ! Now about the “fluting” in the caliper bracket slot…. this is a machined slot and the spiral marks are caused by tooling chatter at the factory, not wear in the field. Some brackets will have these marks in them and some will not because they can sometimes be caused by dull tooling, wrong combination of speed and feed of the tooling, improper coolant flow, chip buildup, etc . Many machinists call them
“chatter marks “ and are not proud of them when they occur ! ( Ask me how I know ). Thanks again for all of the help !

 

[Sadlsor]

Goodness that Mr Paxton moves his fingers quicky.

Because Larry has lots of time to plunk around while on the phone while training new SMC installers. <G>
I am one of the few who somehow stripped the stopper bolt before I learned how to replace my SMC.
Thought I was being so careful, even had antiseize on it. Of course, since I didn't know him at the time, I elected to argue with Larry. "It CAN'T be stripped! Something else is wrong somewhere!"
Silly me.
I learned, though.
Oddly enough, I rode it back from Atlanta where I bought it from my brother-in-law, and it worked great for about 3 weeks before the SMC started acting up, but when it gave up it was very obvious.
It had sat in his garage for 2 or 3 years with no exercise and no miles ridden.

 

[Igofar]

Hi all ! This is my first post on here although I’ve been “lurking” since 2020 when I bought my 2010 ST. First of all, I want to thank everyone for all of the help you have given me while working on this thing ! Now about the “fluting” in the caliper bracket slot…. this is a machined slot and the spiral marks are caused by tooling chatter at the factory, not wear in the field. Some brackets will have these marks in them and some will not because they can sometimes be caused by dull tooling, wrong combination of speed and feed of the tooling, improper coolant flow, chip buildup, etc . Many machinists call them
“chatter marks “ and are not proud of them when they occur ! ( Ask me how I know ). Thanks again for all of the help !

While I understand what chatter marks are, we will have to strongly disagree in this case, as I have seen many new, undamaged, smooth brackets become damaged after the SMC goes south, or the wheel installation process was not followed correctly etc.
I have opened, examined, and installed hundreds of these over the years, and have never found one “fluted” or damaged when new.
I have personally installed new undamaged ones to correct brake issues, then had members neglect their bikes for a few years and not clean or service the brakes, or install the wheel in the wrong sequence only to have the damage start again.

Just a guess, but they are probably caused when the rear brakes start dragging and locking up and the force of the engine/drivetrain keep struggling to overpower the brakes etc.
Again, just a guess.

 

[Andrew Shadow]

I have wondered about these marks as I don't have an explanation for their presence. If none of what JF Health mentioned is present, and none of what Larry mentioned is present, i.e. There are no assembly or brake deficiencies, what else could be the reason for the presence of these marks? This is the question I ask.

My Brother in-law had a 2007 ST1300 that he bought at 60,000 or so. We noticed these marks the first time that we had the rear wheel off. We didn't find any anomalies other than those marks so we never replaced the bracket. When he sold his ST1300 at about 150,000 it still had the same SMC and bracket and exhibited no brake problems.

I bought my ST1300 new with 0 on the odometer. I removed the rear wheel at around 3,000 KM, or about 1,800 miles. Those spiral marks were present. There were no brake problems- The motorcycle was still new. I am now closing in on 150,000. Those marks are still there and don't look any different than the first time that I saw them. Everytime that I am in there I carefully check everything on the caliper bracket based on information gleaned from JF Heath and IGOFAR looking for a developing problem that would explain these marks. I have not found one. I am still riding with the same caliper bracket and the original SMC from the factory. I have no brake deficiencies, no hot rotors, the SMC passes the functional tests with flying colours, the rear wheel spins easily for several rotations, I routinely get 55 MPG.

I will state again that I concur 100% with Larry that a deformed caliper bracket is a problem, and that dragging brakes due to an SMC may cause that. What I am questioning is if these marks are the result of a deformed caliper bracket, or are they coincedental and can be present as a result of something else unrelated even when the bracket is not deformed.
i.e.
Are all brackets that have these marks deformed? I know the answer to that is no.
Do all deformed brackets have these marks? I don't know.