Bad Swing Arm bearings symptoms

[jfheath]

Thanks for the kind comments. Although I reckon it fell a long way short of advice. Just observations and related experiences that I had stowed away at various times.

I sometimes prattle on about stuff - like my answer to your post. Sometimes the silence that follows is very clearly due to everyone NOT saying: 'what the hell is he going on about' . But I really don't care about that - because I've been an educator all my life, and my job was to help people to understand. It's difficult to break the habits of a lifetime. Sometimes it helps, sometimes it needs a different input - or somebody else.

I find things like the bicycle analogy can trigger a different thought process. Usually overnight when your brain is filing information away, and it rifles through other related information. You dream quite vividly and from nowhere out pops an answer.

My favourite anecdote about this sort of thing:

I can't do that myself. I'm not as clever as other people. My brother is really clever. He can do anything.
So when I have a problem that I can't solve, I think about what my brother would do.
And then I do that.

 

[Sidekick]

Thanks for the kind comments. Although I reckon it fell a long way short of advice. Just observations and related experiences that I had stowed away at various times.

I sometimes prattle on about stuff - like my answer to your post. Sometimes the silence that follows is very clearly due to everyone NOT saying: 'what the hell is he going on about' . But I really don't care about that - because I've been an educator all my life, and my job was to help people to understand. It's difficult to break the habits of a lifetime.

I find things like the bicycle analogy can trigger a different thought process. Usually overnight when your brain is filing information away, and it rifles through other related information. You dream quite vividly and from nowhere out pops an answer.

My favourite anecdote about this sort of thing:

I can't do that myself. I'm not as clever as other people. My brother is really clever. He can do anything.
So when I have a problem that I can't solve, I think about what my brother would do.
And then I do that.

I got a lot of insight from this place and I brought very little.
I believe that sharing our knowledge and experiences can be incredibly beneficial. Even if it doesn't directly solve a problem, it can broaden our understanding and inspire new approaches.
Your contributions are much appreciated by everybody here.

 

[motornut]

Try checking the alignment between the front and rear tire rims to see if that has any variables, I am hoping that there are ways that are recommended and accurate. I have used many different ways.
I am sure there are a lot of ideas on how to do this, I have done this the string method on my bikes with chains, and used a square to draw lines on the floor from the rims. But there is probably more accurate ways. Might try something off the axle centers on rear and the rims on the front
Doing this several times might show a variance that can zero in on problem.

 

[Sidekick]

Try checking the alignment between the front and rear tire rims to see if that has any variables, I am hoping that there are ways that are recommended and accurate. I have used many different ways.
I am sure there are a lot of ideas on how to do this, I have done this the string method on my bikes with chains, and used a square to draw lines on the floor from the rims. But there is probably more accurate ways. Might try something off the axle centers on rear and the rims on the front
Doing this several times might show a variance that can zero in on problem.

You're pointing out something I've been wondering about for a while: how to check the alignment between the front and back wheels?
Like you, I've tried several methods and concluded that none are 100% reliable or accurate. It took me time to admit that there's no way to adjust the front wheel's alignment other than following the installation protocol precisely.
I wondered if the back wheel might be misaligned and asked about it on this board. The shared answer was "no," and I believe it.
Even if there were a misalignment between the front and back wheels, I concluded there's no way to correct it or adjust any variables. I wish I were wrong.

Since buying my ST 10 years ago, the fluctuating feeling of misalignment has been a constant issue. I've experimented with different tire brands, pressures, tapered or OEM fork bearings, fork springs, suspension presets, and installation procedures, but while I've been able to mitigate the problem, I've never completely solved it.
I would love if somebody could come with a smart way to check the geometry!

 

[motornut]

The only way I can think of is to place a straight edge on both sides of the rear wheel extending forward to the front axle and see if the front wheel is equal between them. I would think that the more it is tried the more confident the results. I have not tried it though, I did not have reason to, but will play around with it.

 

[Andrew Shadow]

I would love if somebody could come with a smart way to check the geometry!

Note: It is not always easy to measure in-line with the axle because of fenders, mufflers, etc.. This is not neccessay if the rims are vertical. If they aren't, the measurements need to be taken in-line with the axle to negate the influence the lean has on the measurements or you need to take much more precise and complex measurements and compensate for this.

Motorcycle on centre-stand with the wheels vertical.
Magnetic self-levelling laser level designed to mount on a vertical surface.
Straight piece of two or three inch flat steel of a length equal to the rim's diameter plus another twelve inches.

Sit the steel flat bar on something solid so that the laser beam will be at the same height as where you will be measuring to on the rim. The flat bar is held upright by the magnetic laser level mounted at the end closest the the rear of the rear rim with the laser beam projecting forwards. The more vertical the flat bar the better so you don't exceed the limitations of the self leveling function of the laser.

Measure horizontally from two points as close to 180° apart as possible in the horizontal plane from the rim centre-line to the laser line. Adjust the steel bar, or rotate the head of the level if it has this function, until these two measurements are the same, indicating that the projected laser line is parallel to the rear rim.

Measure from the laser line to two points on the front rim as close to 180° apart as possible in the horizontal plane. Rotate the forks until these two measurements are the same indicating that the front wheel is parallel to the laser line.

If the distance from the laser line to the two rim centre-lines is the same both wheels are in line. If the measurements are different they are not in-line.

 

[W0QNX]

I believe that sharing our knowledge and experiences can be incredibly beneficial.


I wondered if the back wheel might be misaligned and asked about it on this board. The shared answer was "no," and I believe it.
Even if there were a misalignment between the front and back wheels, I concluded there's no way to correct it or adjust any variables. I wish I were wrong.

We want to think the wheels must be "perfectly in line" in order to ride down the road the best. Most also want to think the wheels might not be "inline" in the fore aft line only. The front steering stem up there is welded on more "vertically" so any variation from perfect causes a left right position change down at the road contact. It might be a parallel track with the rear wheel but not necessarily on the same exactly rolling track line (over to the left 5mm but still parallel). I'm sure the best aligned handle best but by how much?

Perfect may indeed be the best but in reality all things cast in metal and welded (our bike frames) on an assembly line have "tolerances" which allows for some variance. Results that vary can still be "good" and therefore give us a tolerance range. And as you state some of how our wheels end up are just NOT adjustable very much if any but likely still work and are in tolerances. One degree of variance at the steering stem vertical angle projects down to the road point at quite an error to where the front rim centerline will fall. (someone else can do the math)

Common knowledge: You might have a 120 mm wide tire with a strong curved exterior form (not flat) on the front and a 180 tire on the rear with a less curved form (flatter tread). Now NOT moving the handlebars, if you lean over the tires are no longer on the same tracking centerline. 180-120=60 but only half so 60/2=30. You changed the centerline track up to 30mm (over an inch) if you full lean the bike. Can you tell the centerline track changed? Usually not. Now at a slow speed "steer" a little, move the handlebars. It became way off centerline track as the front doesn't track in the same line as the rear. It's made to change.

Knowledge from my own experiences: With my rear tire moved over exactly .250" over from the final drive mount surface (off centerline .250" relative to the front) by use of a spacer has no or unnoticeable affect on the tracking. Like I said, my actual experience but not on an ST1300.

Give the huckleberry above a call and get the front end "in tolerance" as best as possible and see if that helps. Just my own wild guess as to your problems but I think worn front tires make most people think their bike must be changing in handling or have "bad bearings".

Good luck getting comfortable on the handling.

 

[Sidekick]

We want to think the wheels must be "perfectly in line" in order to ride down the road the best. Most also want to think the wheels might not be "inline" in the fore aft line only. The front steering stem up there is welded on more "vertically" so any variation from perfect causes a left right position change down at the road contact. It might be a parallel track with the rear wheel but not necessarily on the same exactly rolling track line (over to the left 5mm but still parallel). I'm sure the best aligned handle best but by how much?

Perfect may indeed be the best but in reality all things cast in metal and welded (our bike frames) on an assembly line have "tolerances" which allows for some variance. Results that vary can still be "good" and therefore give us a tolerance range. And as you state some of how our wheels end up are just NOT adjustable very much if any but likely still work and are in tolerances. One degree of variance at the steering stem vertical angle projects down to the road point at quite an error to where the front rim centerline will fall. (someone else can do the math)

Common knowledge: You might have a 120 mm wide tire with a strong curved exterior form (not flat) on the front and a 180 tire on the rear with a less curved form (flatter tread). Now NOT moving the handlebars, if you lean over the tires are no longer on the same tracking centerline. 180-120=60 but only half so 60/2=30. You changed the centerline track up to 30mm (over an inch) if you full lean the bike. Can you tell the centerline track changed? Usually not. Now at a slow speed "steer" a little, move the handlebars. It became way off centerline track as the front doesn't track in the same line as the rear. It's made to change.

Knowledge from my own experiences: With my rear tire moved over exactly .250" over from the final drive mount surface (off centerline .250" relative to the front) by use of a spacer has no or unnoticeable affect on the tracking. Like I said, my actual experience but not on an ST1300.

Give the huckleberry above a call and get the front end "in tolerance" as best as possible and see if that helps. Just my own wild guess as to your problems but I think worn front tires make most people think their bike must be changing in handling or have "bad bearings".

Good luck getting comfortable on the handling.

Your insights are spot on, and I truly appreciate your measured approach. I share your perspective and that's why I abandoned DIY solutions for measuring wheel alignment. Like you, I firmly believe that many other factors contribute to the perception of poor handling.
Honestly, I can say I've explored most of the parameters you mentioned, which has mitigated the issue but not entirely solved it.
What sets the ST apart from my previous GTs is its aluminum frame. Aluminum frames are known for being more rigid than trellis frames, but they can also transmit more feedback and harshness from the road. Perhaps that's why I'm chasing a phantom. I've never experienced this same sensation on my other heavy bikes, but none of them were as sharp or "light" as the ST.
Considering everything I've done, the handling is a satisfying compromise. While it's not perfect, it's definitely good enough to keep me smiling on the road.
I'm embarking on a few thousand-mile trip next week. I hope this smile stays on my face the entire time!

 

[draser]

Perfect may indeed be the best but in reality all things cast in metal and welded (our bike frames) on an assembly line have "tolerances" which allows for some variance.

That is indeed what's happening... motorcycle components are manufactured to specifications/tolerances, which are tighter or looser depending on the component role (safety, general assembly, engine, etc.). There's also a "tolerance stack" which appears when several components (part of an assembly) add their own tolerance to the assembly tolerance, which may result in a unacceptable tolerance for the assembly.

For us/users that means we can remove a component (for cleaning/repair for example) and reinstall it (following a "work instruction" - in our case the repair manual) and not worry further (that the component needs alignment or other action). Basically, we mimic the manufacturing/assembly process.

So, unless the bike was in an accident, or has a poor state of repair, or has high mileage/high wear, the wheels are aligned because they will fall in the accepted tolerance range agreed upon at design time.

As I've been riding vintage bikes for a while now, I basically strip down any new (to me) bike I buy and do a comprehensive maintenance "catch-up" so I can trust the bike from a safety and mechanical standpoint. Edited - at your mileage, I'd replace wheel bearings even though they may "feel" good, check the flange bearings, check wheel balance, check wheel trueness, check forks spring length and side wear, damper wear, replace bushings, rear shock bearing, swingarm bearings, etc.

 

[Andrew Shadow]

We want to think the wheels must be "perfectly in line" in order to ride down the road the best. Most also want to think the wheels might not be "inline" in the fore aft line only. The front steering stem up there is welded on more "vertically" so any variation from perfect causes a left right position change down at the road contact. It might be a parallel track with the rear wheel but not necessarily on the same exactly rolling track line (over to the left 5mm but still parallel). I'm sure the best aligned handle best but by how much?

My thoughts exactly- How much off of true is how much? I have no idea. I have never looked in the manual for this so I don't know if there is a specification listed for this or not.

He asked for a way to measure it and what I listed is one of the things that I saw a restorer checking when he was checking for a bent frame after an accident. He had a more elaborate set-up but the same basic principle. It would provide a measurement between the two wheels but without having specifications of how much deviation is acceptable, or without knowing how much is to much, I'm not sure how useful the measurements would be. Then there is the question what to do about it if you can determine that it is out of specification. Assuming that all of the mechanical components are as they should be, which is the starting point, that pretty much leaves a bent frame or something that was not welded in the proper position at the factory. I'm not sure what can be done about that but I can certainly appreciate wanting to know the answer and the cause.