Bad Swing Arm bearings symptoms

Sidekick

Sidekick

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Joined
Apr 25, 2017
Messages
405
Location
Rhinebeck, NY
Bike
ST1300A '05
I'm experiencing significant instability on my 2005 ST13 with 80K miles, even after thoroughly checking the front end. I suspect the swing arm bearings might be the culprit. Is there a way to diagnose them without disassembly?
I am thinking of checking the torque on the pivot bolt & lock nut, is it something that should be done as a regular maintenance?
Any tips or advice would be greatly appreciated.
 
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I would be shocked if they are worn out. Mine have over 400,000 miles on them and looked like new the last time I had it apart for a Ujoint change last summer.

You can check for side play by putting the bike on the center stand and try to move the rear of the tire sideways. If it moves independent of the bike (swingarm moves sideways) it may be loose.

The way the bearings operate they are under very little movement or load and I doubt they could ever wear out but do the center stand check for sure.
 
Agree, would be shocked if it was the swingarm....... suggest check the rear shock remote preload adjuster is actually doing something, ie, may need to be re-filled and bled. Insufficient preload and rebound damping can cause instability.... also check the shock at the rear/bottom for significant oil leakage that might suggest the seal is worn/lost the damping..... after all it does have 80k....
 
Is the instability a new thing or an escalation of previous behavior?
 
My ST was reasonably stable in the turbulence behind tractor-trailer trucks until I 'improved' matters. I took a screw driver and lessened the damping in the rear shock. The bike was very unhappy and unstable in turbulent air. Reading the HSM and putting the damping back to the 'stock' position cured my 'improvements'.

I've read other posts which have said that damping of the rear shock is important to stability. This is a ridiculously easy thing to check. You insert a screw driver through a hole in the frame to engage a slotted screw on the shock. Back off the screw until it stops, counting the turns. Screw it in until it has gone the required number of turns. The spec is in the Service Manual.
 
dduelin said:
Is the instability a new thing or an escalation of previous behavior?
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I am fighting with this instability for years, I know that it obviously looking like a misaligned front wheel.
I have replaced the fork seals, springs, wheel bearings and fork bearings, tried to align the front wheel a thousand time, by the book and many other ways.
I also troubleshooted the problem with different tire brands, checked the front wheel bearing seating position and even compared them with another ST.
No luck.
The instability is still there and is recently becoming more concerning. The bike is under stirring on the left side and over stirring on the right side when leaning.
The transitions on leaning side to side are unpredictable, tar snakes are a challenge.
The thing I really can't figure out is why is it sometime worse and sometime lightly noticeable (at the same 42 PSI tire pressure).
To say frankly, I don't know where to look anymore beside the swing arm bearings?
I have the tools, the Honda maintenance manual, a decent experience working on engines and bikes and all the previous work on this bike has been done following the best practice.
I am lost and I would deeply appreciate any help giving me a hint for the solution.
Thank you for your time!
 
SMSW said:
My ST was reasonably stable in the turbulence behind tractor-trailer trucks until I 'improved' matters. I took a screw driver and lessened the damping in the rear shock. The bike was very unhappy and unstable in turbulent air. Reading the HSM and putting the damping back to the 'stock' position cured my 'improvements'.

I've read other posts which have said that damping of the rear shock is important to stability. This is a ridiculously easy thing to check. You insert a screw driver through a hole in the frame to engage a slotted screw on the shock. Back off the screw until it stops, counting the turns. Screw it in until it has gone the required number of turns. The spec is in the Service Manual.
Click to expand...
I have replaced the oil twice in 80K and rebuild the rear shock recently with good results. In my case, hardening the rear shock makes the bike more stable most of the time, but I also suspect that it's just making the problem less obvious. Same way as over-inflating tires could hide some geometry problems.
Thank you!
 
Do you have access to other motorcycles so you can compare characteristics?
 
dduelin said:
Do you have access to other motorcycles so you can compare characteristics?
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I've occasionally worked on my friend's ST, which I also ride. To troubleshoot my own instability issues, I've compared bearings, swapped wheels, and considered factors like tire wear and balancing.
Despite these efforts, the difference between my ST's handling and my friend's is significant. I've even inspected the frame for cracks and checked bolt torque.
There must be a straightforward explanation that I'm overlooking.
 
SMSW said:
What tires are on the bike, and how many miles on them?
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Checking the tires is definitely the first step. I've experienced instability with various brands, including Shinko Verge, Michelin PR4, Pirelli Angel, and Dunlop. The symptoms are less noticeable with new tires but worsen as they wear.
 
You mentioned replacing things up front... does that include the steering head bearings? Over tight bearings can cause hunting or inconsistent steering behavior as can dents in worn bearing races. Does the fork want to self center when the wheel is removed from the fork?
 
dduelin said:
You mentioned replacing things up front... does that include the steering head bearings? Over tight bearings can cause hunting or inconsistent steering behavior as can dents in worn bearing races. Does the fork want to self center when the wheel is removed from the fork?
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Yes, I have replaced the steering head bearings with tapered roller bearings. I thought that it was a reasonable diagnosis then. Finding the right torque for tapered bearing is not easy as you know, but they are not over tight, the self centering tendency is natural. It's really hard to be 100% certain as so many wires and brake hoses are involved in the movement.
As a matter of fact, I have replaced them as a way to troubleshoot the instability issue.
They have improved the handling of the bike but did not fix the pre-existing instability.
I will try to loosen them a bit to double check if it could improve anything.
Again, thank you for your help.
 
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Lots of things you've looked into, but you haven't said anything you've done with the rear shock.... look into it, where is the preload at and where is the damping set....
 
RaYzerman said:
Lots of things you've looked into, but you haven't said anything you've done with the rear shock.... look into it, where is the preload at and where is the damping set....
Click to expand...
The rear shock as been flushed and refilled and works well from the first click. Preload is set as 3 clicks/turns (solo) and rebound is 80% tight.
The fork preload is 25mm with Race Tech springs .90kg.
 
Willsmotorcycle said:
What do you weigh? Do you run a top box, carry anything in it? How much weight is in your side bags
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I am 164 pounds, my suspension settings may vary with loaded saddlebags or a top case or even windshield height.
40 years of motorcycling teach you a lot, I think that I have a fair understanding of suspension adjustment and how it affects handling.
My main question is about checking the swing arm bearings without disassembling everything.
Thank you.
 
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To your question.. how to inspect the play in the swingarm.. I'd raise the bike on center stand and check for side play in the swingarm and wheel assembly (grab the wheel and see if you feel any side play). There shouldn't be any. For the swingarm bolts torque, I witness mark with a paint dot the bolt position relative to the frame and check from time to time if it moved.
There's a bearing in the lower mount on the rear shock that may have some play so check swingarm up-down movement as well.
 
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