Stopper Bolt Came Loose

I just bought a 2007 St1300 with 12k miles and was experiencing a very troubling riding experience as I was riding around the neighborhood trying to get used to this new machine. When pulling in the clutch the bike was nose diving and the rpms were immediately decreasing. The back brake eventually went mushy and I took her home to do some research. I came on the forum and searched “brakes locking upâ€.

I found a wealth of information! I am not someone that does a great deal of wrenching on my motorcycles and felt a bit unsure about trying to diagnose and fix the brakes so I reached out to Igofar and Larry got back to me the next day. Within 5 minutes I had a full page of notes to troubleshoot the issue. With my notes in hand I had the muffler loose, the axle loose and access to the back caliper where I found this:



The stopper bolt had backed itself out and the caliper was pinching down on the SMC cable against the swingarm. I sent the pic to Larry and he advised me to go and get a lottery ticket!

I felt nauseous.

This is where Larry called me several times to assure me that we are going to fix this problem together. He offered to walk me through the entire process of replacing the cable and flushing the brake lines – gave me the part number and a long heartwarming discussion about life and motorcycles.

Larry is a true gentleman. I cannot emphasize enough how humbling it was to have a complete stranger call me and quickly become a confidant and someone I could trust to get me going again. I am awaiting the part now and will soon embark on getting to know the braking system on this bike. Thank you Larry! Thank you to all the great forum members that add to this community! I am looking to the day when I can pay this forward.

-Marc

:22yikes:

Yeah, that's not a good thing to come across on a low mileage bike, or any bike for that matter.

Glad to hear Larry (igofar) is there on the :call: to help!

We've seen pinched hoses before, but I think you'd be the first to have one sever like that. Bummer of a way to start your time with a new bike, but nobody got hurt, and that's the important part.

You're in good hands with Larry. He knows the brakes on this bike inside and out and has a fierce case of OCD. None of the work you're going to be doing is rocket science, so take your time and follow the directions carefully.

While you're ordering parts, order a replacement stopper bolt (P/N 90158-MZ0-000). The one you'll get will have appropriate thread lock pre-applied. I'm sure Larry will tell you this, but that bolt must be torqued properly for it to stay in place. If you don't have torque wrenches to cover that and the other fasteners you'll be replacing, get them.

Let us know how things go with your repairs and after you get the bike back on the road.

--Mark

Thanks for the reply! The stopper bolt looks fine and I have thread lock and all the tools - the courtesy phone has me properly prepped for when the part arrives.

Glad you got it sorted before anything serious happened.

A thought about the stopper bolt. The manual says to replace it with a new one every time. It says it is an ALOC bolt, whatever that means, but all of the ALOC bolts I have seen have thread locking compound on them.

But - yours seems to have been working its way out of the thread, and in that loosely fitted condition, I assume that it has been stopping the rear calliper bracket from rotating around the rear axle - which is what it is intended to do. At some point it has worked loose enough to allow the hose to be trapped. So for some time, all of that force has been applied to a bolt that is 'slopping around' on the threads. Who knows what damage might have been done ? The new bolt costs about the same as half a tank of fuel.

Odd that your stopper bolt shows no sign of thread locking compound.

Whatever - you are safe. It helps to know your way around the braking system - even if you never intend to do the work yourself. That way you can check that work has been done properly when you get it back.

IMO, the previous owner probably replaced the rear tire recently and forgot to tighten that bolt. I'd contact him, and try to get the $ for all the parts.
The shop I bought from replaced the rear pads and installed them wrong (not hooked in). Didn't realize this till I got home 480mi later... Called, and they sent me a new set of pads at least.

Perhaps someone can clue me in. I still don't see why the stopper bolt is such critical piece. The bolt only has a lateral load on it, not longitudinal. It seems to me the caliper could just as easily be kept from moving forward (and is) by a member of the frame or swingarm. It seems one could just as easily use a cotter pin.

docw1 said:

Perhaps someone can clue me in. I still don't see why the stopper bolt is such critical piece.

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I hate to get into these discussions myself, but I agree with your opinion. I've had my 1100 for 20 years and 107k miles, which means I've changed the rear tire at least 12 times, perhaps 2-3 more. I've never used thread lock, or a new bolt, I just snugged the old one back in place and moved on. Never used a torque wrench, just a 14mm open end, as that's what fits in the available space (unless you want to move the exhaust). I know I'm a heretic for saying so, but I think the obsession with loctite and torque wrenches on incidental bolts is overly conservative, but to each his own. Agree with your cotter pin comment, if the bolt is there at all it keeps the caliper assembly from rotating, which is all that matters.

There sure seems to be a rash of these stopper bolt issues lately.
I wonder if folks are following the rear wheel sequence down correctly? The stopper bolt should be tightened first, then the axle nut second.
I have seen two other cut/damaged rear brake lines in the past few months.

docw1 said:

Perhaps someone can clue me in. I still don't see why the stopper bolt is such critical piece.

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As soon as the brakes are applied, the pads grab hold of a rapidly rotating brake disc, and the bracket will be forced to rotate in the same direction that the wheel is spinning. The force is considerable - equal to the braking force itself. No matter how much the axle is tightened, it isn't going to be able to stop the calliper from rotating. So the stopper bolt is there to make sure that the calliper cannot rotate, and it has to be meaty enough to withstand the same force that would be required to lock a wheel on a bike travelling fully loaded at a silly speed. Many bikes have a long arm that connects the calliper bracket to a fixed point further forward on the swinging arm instead of a stopper bolt. It does the same job.

The consequences of this stopper bolt working loose or shearing could very well be fatal.

dwalby said:

I know I'm a heretic for saying so, but I think the obsession with loctite and torque wrenches on incidental bolts is overly conservative, but to each his own. Agree with your cotter pin comment, if the bolt is there at all it keeps the caliper assembly from rotating, which is all that matters.

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Respectfully, I have to disagree. The stopper bolt is a safety critical component, not just an 'incidental bolt'. It has to be capable of resisting quite large forces as mentioned above.

I use a torque wrench to get it absolutely right - although I have a pretty good 'feel' for what is right, it isn't as accurate as a torque wrench. Not enough, the bolt could come loose. Too much, the threads could be damaged, or more commonly the bolt could be stretched and rendered ineffective.

I've seen this a few times on front calliper bolts - the bolts would not tighten as I expected and closer inspection revealed that they had been stretched by overtightening - there was a slight pinch point in the middle of the threaded section. Winding the torque wrench down and experimenting on the work bench, I found that the bolt would click at about 26Nm, but set any higher, the torque wrench wouldn't click at all. Instead, the bolt was stretching further. Eventually, further tightening caused the bolt to snap - without ever reaching its full torque value.

These bolts must have been put in by someone who thought that they had tightened them properly. Instead, they had stretched the bolt and rendered it incapable of supporting the load for which the bolt was originally designed.

docw1 said:

Perhaps someone can clue me in. I still don't see why the stopper bolt is such critical piece. The bolt only has a lateral load on it, not longitudinal. It seems to me the caliper could just as easily be kept from moving forward (and is) by a member of the frame or swingarm. It seems one could just as easily use a cotter pin.

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dwalby said:

Agree with your cotter pin comment, if the bolt is there at all it keeps the caliper assembly from rotating, which is all that matters.

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As mentioned above, considerable shear force being applied to the bolt. Also, the stopper bolt is cantilevered, considerable weight would be needed to put in a second side for a pin to cross across too, and it'd need to be a lynch pin, never believe a cotter pin could hold that. And that would be one more thing we have to maneuver around while putting the back end back together.

dwalby said:

I've never used thread lock, or a new bolt, I just snugged the old one back in place and moved on. Never used a torque wrench, just a 14mm open end, as that's what fits in the available space (unless you want to move the exhaust). I know I'm a heretic for saying so, but I think the obsession with loctite and torque wrenches on incidental bolts is overly conservative, but to each his own.

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That's not heresy, it's gambling. "I've never done recommended thing X and bad thing Y hasn't happened" doesn't mean Y won't happen; it just means it hasn't.

I will add to Jon's excellent comments that pretty much everything outside the drivetrain that calls for thread locker is a part that has to withstand braking forces. Every last one of them is unsprung, which means they get to contend with more vibration than anything on the soft side of the suspension.

Having seen firsthand what happens to fasteners that are under- or over-torqued, some in applications where there a second chance to get it right is very expensive, you can bet your bottom dollar that anything safety-critical gets properly wrenched. I don't replace my stopper bolt when I remove it, but I do clean the threads, check its condition, apply what would have been on a fresh one and torque it correctly. I don't put a torque wrench to the fairing fasteners and am, in fact, missing one because I forgot to snug it down last time I put it back on. If here's anything that's the definition of an incidental fastener, that's it. The stopper bolt? Not so much, and a few minutes of hard braking with enough safety wire to approximate a cotter pin in its place should bear that out.

Marc should, IMHO, replace his stopper bolt with a new one because he doesn't have a good bead on its condition. $20 is cheap insurance against a repeat of what he experienced.

--Mark

Blrfl said:

That's not heresy, it's gambling. "I've never done recommended thing X and bad thing Y hasn't happened" doesn't mean Y won't happen; it just means it hasn't.

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agree with the gambling analogy, but its not much of a gamble really. In the same category as the car commercial "professional driver, closed course" warnings at the bottom of the screen while you see the car being driven at 35 MPH down a regular road. Lawyers will take any opportunity to extract money for blame, so companies like Honda take the extra step of safe-proofing everything that might be potentially dangerous. In 40 years of wrenching on bikes and cars I've never had any issue with bolts vibrating loose because they didn't have thread lock on them or weren't torqued to some exact spec value. I'll keep taking my chances.

I've been wrenching on my stuff for 50 years and think I have a pretty good feel for tightening fasteners but that stopper bolt has virtually no "snug up" to it. It's turning loosely in until the shoulder bottoms against the swing arm then the torque wrench clicks almost immediately. It's not one to gamble with and at 51 ft/lbs it takes a fair amount of torque to spec. I do not replace it every time but always clean the bolt threads well and chase the threads in the swing arm clean before putting a drop of LocTite Blue on the bolt threads.

What's the difference between an ALOC bolt and TTY bolts that I'm familiar with (VWs are loaded with these type) and use no thread lock to keep tight? No "stretch" to ALOC type?
Forgive my simple ignorance as I probably answered my own question(s).

jettawreck said:

What's the difference between an ALOC bolt and TTY bolts that I'm familiar with (VWs are loaded with these type) and use no thread lock to keep tight? No "stretch" to ALOC type?
Forgive my simple ignorance as I probably answered my own question(s).

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Yes, you did. One deforms to create resistance to loosening under load/vibration and the other uses adhesive to resist loosening.

jettawreck said:

What's the difference between an ALOC bolt and TTY bolts that I'm familiar with (VWs are loaded with these type) and use no thread lock to keep tight? No "stretch" to ALOC type?

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Metals go through three states as you stretch them: elastic, plastic and broken.

Most fasteners have their torque specifications based on elasticity, where there's springiness to hold the threads together but the applied torque doesn't exert so much pull that the bolt won't go back to its original shape when removed. As long as they're not torqued beyond elasticity, you can re-use these fasteners practically forever, just like the spring in a ball-point pen will always retract the point when released.

If you stretch the metal far enough, it becomes plastic and retains its new, stretched shape. This is what torque-to-yield (TTY) fasteners are designed to do. As I understand it, a fastener in this state can handle a lot more stress along its axis because it's not constantly under the same kind of pull as one that's still elastic, which makes them a good choice for holding things like cylinder heads in place. The trade-off is that you can only use them once because you'd have to stretch them again to get the same effect. Trying to use one of these fasteners again would either result in it being so deformed that it will no longer fit properly or the metal will fail.

The joke goes that ALOC stands for "add Loc-tite Or Crash." Best I can tell, there's nothing special about them other than having thread locker applied at the factory. None of the parts that take these fasteners would be good candidates for torque-to-yield fasteners because they're not subject to a lot of axial stress. They do take a lot of radial (side-to-side) stress, but bolts are naturally good at that. The torque values aren't particularly high, which makes me think they're being used in their elastic state.

My suspicion is that the thread locker on critical fasteners is more a hedge against improper installation than anything else. If somebody re-uses the brake rotor bolts without cleaning the threads (or buys new ones) and doesn't torque them correctly, there's at least something in the threads to keep them from being shaken loose, falling out, causing an accident followed by injury, damage and the ever-present lawsuit. (I did, at one point, have a theory that it's less labor and less error-prone to just replace the parts than it is to depend on someone who wants to maintain a high bikes-through-the-shop rate to work carefully.)

--Mark

Blrfl said:

there's at least something in the threads to keep them from being shaken loose, falling out, causing an accident followed by injury, damage and the ever-present lawsuit.

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If you don't use the thread locking goop, the lawyers will immediately ask why you didn't, since it was available, so you must be negligent.

I have over 300K miles on the ST1100s (3 separate bikes). To the best of my knowledge, the factory original stopper bolt is still in use on the '96 after over 200K miles. I never replaced it, cleaned threads, torque wrenched or used any kind of thread lock on it. Never had a problem. I guess I'm living on borrowed time.

I torque nuts and bolts at work all day every day including using a torque checker to verify the wrench is correct. All this according to a blue print. One of the silliest torques was 35 inch pounds on a 1/4-28 grade 8 screw with 3/4" of thread engagement. My co worker torqued it. I put a wrench on it and tightened it another half turn using just my little pinky finer. Not my hand, wrist, or arm, just my little finger. Yes, we removed it and did it to the print.