Swing arm bushing failure

[egleaves_imp]

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.

[max]

Was it anything like this?
https://www.youtube.com/watch?v=CztY7oUtr74

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.

[GoldOxide_imp]

Huh, wow. Half inch does seem much, certainly seems more than normal wear 'n' tear due to use.

[egleaves_imp]

Was it anything like this?
https://www.youtube.com/watch?v=CztY7oUtr74

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.

Very interesting. Looks similar to my issue. I should pass this video along to the service department.

Huh, wow. Half inch does seem much, certainly seems more than normal wear 'n' tear due to use.

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.

https://www.dropbox.com/s/k3zbnaly85jg39...M.mov?dl=0

https://www.dropbox.com/s/m0caawqq1cydl5...M.mov?dl=0

https://www.dropbox.com/s/l6luj5qd5wm9fh...M.mov?dl=0

[dave]

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.

[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.

[dave]

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"?

[egleaves_imp]

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.

[the Ferret]

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?

[max]

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.