Swing arm bushing failure

E

egleaves_imp

Running like a top
Thread starter
It’s time for new tires, so I went to the dealership today for a routine, out-patient procedure. Halfway through, the tech summons me and says “come look at this”. Bike is on the lift and he grabs the rear tire and wiggles it from left to right demonstrating something around a half inch of lateral slack in the swing arm. OS! I had three wide-eyed techs standing there saying they’ve never seen a swing arm bushing that far gone.

The bike is now in for surgery and won’t be home for at least a week. Hopefully it’s just the bearings and the damage hasn’t spread to the swing arm itself.

Seems like premature failure as far as I know. Crossing my fingers that my extended warranty will cover some of the cost.
 
Was it anything like this?

My bearings were fine but the swingarm had to be "locked in" i used a shim but others just tightened the big bolt up, look at the wear on the bolt, it had been functioning as a bearing, the "bushing" is actually two needle bearings on the chain side and one on the brake side, standard honda big bike swingarm setup.
Hope this helps.
 
Thread starter
max_imp said:
Was it anything like this?

My bearings were fine but the swingarm had to be "locked in" i used a shim but others just tightened the big bolt up, look at the wear on the bolt, it had been functioning as a bearing, the "bushing" is actually two needle bearings on the chain side and one on the brake side, standard honda big bike swingarm setup.
Hope this helps.
Click to expand...
Very interesting. Looks similar to my issue. I should pass this video along to the service department.
GoldOxide_imp said:
Huh, wow. Half inch does seem much, certainly seems more than normal wear 'n' tear due to use.
Click to expand...
Right? 42K miles, 70% of them straight line on the freeway. How could I possibly have worn this bearing to death?
I reviewed some footage and my videos are useful. Stand by while I remember how to post them.
Quick video clips. Hope the links work.

Dropbox

Dropbox

Dropbox
 
My bearings were fine but the swingarm had to be "locked in"

Max, can you please clarify what you mean by "locked in"? Was your swing arm sliding back and forth along the axis of the bolt, between the LH side and RH side frame members? I understand your shim cured the problem for you, but what was the root cause? Was the frame out of tolerance? Were the bearings installed incorrectly into the swing arm? Was the torque on the bolt correct?

Thanks Max.
 
Hello Dave, There is a tolerance when the swingarm is assembled to facilitate quick installation.

I'm doing this from memory so there could be mistakes in what i say, the installation includes a dustcover on the lefthand side of the swingarm, this also affects clearance, so if the design has a thicker dustcover than the one at hand at the time of assembly that would affect the clearance.

The needle bearings don't run on the bolt ( or should not ), they ride on the compressed hollow shaft.

in my case the long bolt was done up tight but there was just a little clearance left ( yes, sliding back and forth along the bolt but by a minute amount, say 0.1 mm ) that probably got bigger over time ( at 7000 km ), enough to keep the frame from compressing the bearing shaft ( the hollow part where the bearings run on), when the long bolt was undone the gap was 0.7 mm. measured with a feeler gauge, i had some 0.6 mm material and produced a shim ( washer ) that just fitted in the gap and when the bolt was done up loosely it already eliminated all sideways play.
So when the long bolt was tightened up properly it had "locked" the hollow pipe in place so it could now act as an inner race for the bearings to run on as it was designed.

Exactly as with the front wheel bearing where the hollow shaft compresses the inner race of the bearings, the spacer in between the inner bearing races and both spacers on the outside of the shaft where the dust seals ride on is compressed by the bolt on the right hand side of the front wheel.

As you can see in the video the long bolt had been acting as the bearing judging by the wear marks on it.

To my knowledge wisedrum has had the same issue but he just torqued up the long bolt until the play had disappeared, same thing but i had a look at the frame and decided that a shim would also do the job so that's what happened.

It did not affect the ride and i only noticed it when i had a close look at all the mechanical parts after i got the bike, like a pilot's pre flight checks, as some might affirm; new does not mean good.:(
 
Hi Max. Thank you for your reply. I am not for one second questioning your mechanical skills (I'm sure they exceed mine), but your "fix" seems to be directed to eliminating movement of the swing arm in the axial direction (with respect to the attachment bolt) only. In the second video, there is definite movement of the swing arm in the radial direction, along with what appears to be an excessive gap between the frame and the RH side of the swing arm. I really want to understand this issue better - can we discuss this using the "private messages"?
 
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Word from the dealership is that the bolt broke on the RH side, near the nut. Not sure what came first....the bolt breaking, or the bearing/bushing being destroyed. Still trying to ascertain if my extended warranty will cover any of the costs.
 
Chain adjuster bolt? One would have to think that little bolt would break before a bearing went out. I'm thinking broken bolt (although who know's why) followed by misalignment and bearing wear, How do the chain & sprockets look?
 
Ferret i think he means the big bolt that is the support for the swingarm, it's about 5/8 of an inch and has a tensile strength ( normally ) of several tonnes before it breaks, it'l be very interesting to see any pictures of the fracture if that is what happened, thanks Egleaves for the update and that means that the nut and what's left of the bolt was sitting loose inside the chrome plastic cover, interesting.
 
Thread starter
The ferret_imp said:
Chain adjuster bolt? One would have to think that little bolt would break before a bearing went out. I'm thinking broken bolt (although who know's why) followed by misalignment and bearing wear, How do the chain & sprockets look?
Click to expand...
The break was on the right side....opposite the chain & sprocket. I haven't laid my eyes on the front sprocket yet, but the rear looks ok.
max_imp said:
Ferret i think he means the big bolt that is the support for the swingarm, it's about 5/8 of an inch and has a tensile strength ( normally ) of several tonnes before it breaks, it'l be very interesting to see any pictures of the fracture if that is what happened, thanks Egleaves for the update and that means that the nut and what's left of the bolt was sitting loose inside the chrome plastic cover, interesting.
Click to expand...
Correct. It's the long bolt that holds the swing arm on the frame.
 
this is kinda terrifying. and you didn't feel any play when riding it? I just went outside to put my cb on the center stand and try to wiggle the swingarm out of paranoia.
 
Thread starter
misterprofessionality_imp said:
this is kinda terrifying. and you didn't feel any play when riding it? I just went outside to put my cb on the center stand and try to wiggle the swingarm out of paranoia.
Click to expand...
If I applied throttle going around a corner, sometimes I felt a what I though was my rear tire slipping just a bit (already knew I needed tires) and a couple of times I heard/felt what I though was my chain slapping (already figured it was on the loose side). I normally adjust my own chain, but since I was about to take it in for new tires I thought I'd let the dealership adjust it for me this time.
Lord Popgun_imp said:
Here it is from the parts fiche. Item 7 https://www.partsfish.com/oemparts/a/hon/52f28c08f870021404ec5a4a/swingarm
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#7 broke at or near the threads for #15. #17 was destroyed.

I haven't seen the broken parts for myself yet, but I talked to someone today and they're saving everything for me.
 
egleaves_imp said:
The ferret_imp said:
Chain adjuster bolt? One would have to think that little bolt would break before a bearing went out. I'm thinking broken bolt (although who know's why) followed by misalignment and bearing wear, How do the chain & sprockets look?
Click to expand...
The break was on the right side....opposite the chain & sprocket. I haven't laid my eyes on the front sprocket yet, but the rear looks ok.
max_imp said:
Ferret i think he means the big bolt that is the support for the swingarm, it's about 5/8 of an inch and has a tensile strength ( normally ) of several tonnes before it breaks, it'l be very interesting to see any pictures of the fracture if that is what happened, thanks Egleaves for the update and that means that the nut and what's left of the bolt was sitting loose inside the chrome plastic cover, interesting.
Click to expand...
Correct. It's the long bolt that holds the swing arm on the frame.
Click to expand...
The break was on the right side....opposite the chain & sprocket. I haven't laid my eyes on the front sprocket yet, but the rear looks ok.
max_imp said:
Ferret i think he means the big bolt that is the support for the swingarm, it's about 5/8 of an inch and has a tensile strength ( normally ) of several tonnes before it breaks, it'l be very interesting to see any pictures of the fracture if that is what happened, thanks Egleaves for the update and that means that the nut and what's left of the bolt was sitting loose inside the chrome plastic cover, interesting.
Click to expand...
Correct. It's the long bolt that holds the swing arm on the frame.
Holy smokes :s
 
The ferret_imp said:
egleaves_imp said:
The ferret_imp said:
Chain adjuster bolt? One would have to think that little bolt would break before a bearing went out. I'm thinking broken bolt (although who know's why) followed by misalignment and bearing wear, How do the chain & sprockets look?
Click to expand...
The break was on the right side....opposite the chain & sprocket. I haven't laid my eyes on the front sprocket yet, but the rear looks ok.
max_imp said:
Ferret i think he means the big bolt that is the support for the swingarm, it's about 5/8 of an inch and has a tensile strength ( normally ) of several tonnes before it breaks, it'l be very interesting to see any pictures of the fracture if that is what happened, thanks Egleaves for the update and that means that the nut and what's left of the bolt was sitting loose inside the chrome plastic cover, interesting.
Click to expand...
Correct. It's the long bolt that holds the swing arm on the frame.
Click to expand...
The break was on the right side....opposite the chain & sprocket. I haven't laid my eyes on the front sprocket yet, but the rear looks ok.
max_imp said:
Ferret i think he means the big bolt that is the support for the swingarm, it's about 5/8 of an inch and has a tensile strength ( normally ) of several tonnes before it breaks, it'l be very interesting to see any pictures of the fracture if that is what happened, thanks Egleaves for the update and that means that the nut and what's left of the bolt was sitting loose inside the chrome plastic cover, interesting.
Click to expand...
Correct. It's the long bolt that holds the swing arm on the frame.
Holy smokes :s
Click to expand...
The break was on the right side....opposite the chain & sprocket. I haven't laid my eyes on the front sprocket yet, but the rear looks ok.
max_imp said:
Ferret i think he means the big bolt that is the support for the swingarm, it's about 5/8 of an inch and has a tensile strength ( normally ) of several tonnes before it breaks, it'l be very interesting to see any pictures of the fracture if that is what happened, thanks Egleaves for the update and that means that the nut and what's left of the bolt was sitting loose inside the chrome plastic cover, interesting.
Click to expand...
Correct. It's the long bolt that holds the swing arm on the frame.
Holy smokes :s
I might be wrong, but if any bearing or long bolt/pivot #7 were seized up,
it could act as a torsion bar and got badly damaged due to too much stress??
Strange.
 
It's hard to understand how that bolt could have broken without a mighty force being applied to it.
 
Same here Cormanus, something interesting going on here and thanks Egleaves and Popgun for the input, even when the bolt is over-tightened the threads would just strip and the nut would be hard to remove.

Since the bolt broke close to the nut it was still captive in the frame on both sides and the only thing preventing it from exiting to the left is the plastic cap that clips into the cavity where the head of the bolt resides, good thing that cap is held in tight eh?

Overall a good find from the dealership:worship:
 
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