My front wheel wanted a trial separation...

[jharvey]

Season's Greetings All,

More a wheels/axle than tires/suspension question, but I guess this is the closest forum topic, geographically speaking, so, here’s the scoop.

A couple of weekends ago, I was getting some riding in, and noticed a ‘rattling’ (something like putting a hockey card in bicycle spokes) coming from the front end. I only heard it at low speeds - but didn’t know if that was just because wind and engine noise drowned it out at higher speeds. I had also noticed it intermittently on a ride the weekend before as well, but less regular and less pronounced, but this time, it got bad enough that I started feeling occasional corresponding -very light- ‘clicks’ through the handlebars, and called the ride short.

Expecting that it was a front wheel or axle issue and not wanting to risk riding it again, I was calculating the costs of having the bike picked up and sent over to the mechanic, and then thought perhaps I could just unmount the front wheel and send it and the axle over for inspection. So I had a look at the manual, seemed pretty straightforward, went to look at the bike and found that one of the nuts securing the axle holder was … gone, doubtless having gradually rattled itself loose and eventually off at some point. And of course the other nut was finger loose now that there wasn’t any tension from the other side. (In 42 years, I’ve had blown fuses, fouled plugs, dead batteries, and even a clutch lifter cable that snapped at a stop light, but this was the first time the bike was actually unsafe to ride.) This comes about 10 hours of riding time after I had both tires replaced, so it MAY have been that the nuts weren't sufficiently tightened upon replacement - but if so, it took a while for that one to rotate completely off the thread.

Here's a link to a video of first the noise, and then the fork and axle holder.

https://www.youtube.com/watch?v=Z4Y4aEvQaIw

So now my two questions are,

1) When I replace the nut (and lock washer and washer), is this something I’ll have to buy a torque wrench to fasten to a specific force (can’t find any settings for these nuts in the shop manual - the mechanic gave a general guideline of 8-10 lfb on a 6mm thread, but these are 8mm, and I haven't heard back since I asked about the larger diameter (I'm thinking early departure for Christmas)). I was hoping to be able to avoid buying a torque wrench for about 5 minutes of tightening 2 nuts, but I'm guessing it's not enough to simply make the two nuts equally and very tight. (Regardless, I think I’ll be adding some thread lock fluid as well … and use those ‘locking nuts’ with nylon in the thread, to try to control the paranoia I’ll have about the front end for a while).

and

2) The clicking you’ll hear in the video seems to be regular but at a faster rate than simply the rotation speed of the wheel at the axle, but if anyone's been through a similar situation, are you hearing anything there that might indicate that damage had been done to the axle or any bearings inside there, or should things be alright once the holder is secure again. (Again, asked mechanic in follow-up email but no response yet.)


As always, thanks for your input,
Jim

[Rich82GS750TZ]

What bike? please create a signature w/ at least your bike year and model in it. From the video, I believe it may be a twin?

That's crazy dangerous. Did YOU un-mount and re-mount your wheels from your bike when you had the the tires replace 10 riding hours prior to the event? Or was it your mechanic who tried to kill you?

There certainly are torque specs for every nut and bolt on your bike. Should be in your manual. Look harder. could be in the section detailing re-installation of the front wheel. On my bike, the torque specs for the Front axle holder nut in 15-25 N-m / 1.5-2.5 kg-m / 11.0-18.0 lb-ft. - Yours may be different.

Or you can use this general guide.



If you're doing any amount of wrenching on the critical components of your 40 year old motorcycle, you should have at least a 1/2" drive lb.-ft torque wrench and a 1/4" drive in-lb. one. IMHO


I don't believe the manual calls for thread lock. I would not use any. Just the required lock washer and nut - Torqued to spec.

Yes, I would certainly have your wheel bearings inspected by a competent mechanic.

[jharvey]

Rich, thanks (1980 GS400ET (GSX400ET in UK and Europe)),

No, the tires were replaced professionally. Been going there for years without incident, specializes in vintage bikes (found after having to go through almost every bike shop in my area over the last decade or so (after my regular shop went out of business), none of which seemed to know what to do with bikes that had exotic things like carburetors and points-based ignition systems - including the place I bought it 40 years before, but I guess people rotate out and old skills are lost over time), but I suppose anyone can make a mistake - assuming that was the origin of the problem. Where I have to park in the summer (very tight quarters - gravel yard), I'll do basic things like adjust my chain, check my plugs etc., but that's it - hence the lack of tools like a torque wrench. So whether it was a delayed consequence of the tire change or just a coincidence, at least I know I didn't do it to myself.

And right you are on the torque settings - I was looking it on pages related to the front wheel, but it was part of a table of torque specs for the chassis.

Thanks again

[Rob S.]

Buy a torque wrench. They're not very expensive, and they should be used for just about any work you do on your bike.

[Brendan W]

We forget to tighten wheel nuts. At least, I managed it once, never to be repeated.
At this point I would assume damage to the threads in the fork and have them checked out carefully before replacing the screws with new.
Then check the bearing surface on the fork and cap for hammer damage. More than likely there is some and high spots will have to be removed before fastening back up.
Check the other side as well. It may not have taken kindly to bending forces.

[Cipher]

Are those nuts assembled with threadlock and split washers from the factory?
Whoever did this to your bike needs a kick in the balls with a frozen boot.

[Brendan W]

Yes, well, a metaphorical one at least.
Probably best to bring it back to the shop and let them sort it out.
If they value their reputation they should and the likelihood that this loosening is pure coincidence is so low, it's effectively zero, and they will know that.

[jharvey]

Thanks again for the input folks. In order...

Rob - Yeah, I know I should (and it appears, I will) get a torque wrench. It's just that since I don't have maneuvering room around the bike to really do anything more than the most basic adjustments where I live - I expect this may well be the first and only time I use it before either the bike or myself 'ages out.' (Money not abundant in my world - one of the reasons I've kept this bike running all these years, there will never be an option to buy a new one.)

Brendan - what I'm hearing is, I'm going to have the bike picked up and trucked back to the shop - you wouldn't even trust if for a ride back (about a 30 min ride, street speeds) before having all that examined? I live in Canada, and although there hasn't been a need to put salt on the roads yet in my neck of the woods YET, it could happen any day now, which would mean having it trucked both ways (lots of chrome, between the fender and exhausts, and no way to give it a thorough wash off (ie. no garden hose tap on my building) if I ride it home caked). And not many people who transport bikes in my neck of the woods anymore -some of whom had me fearing for the bike's safety in the past- and the last time it cost me $175 one way.

Cipher - split washers yes (see https://images.cmsnl.com/img/partsli...fig35_e868.gif), but thread lock was an idea of my own just for the sake of some little extra peace of mind after reinstallation. It never crossed my mind in the 42 years of having this bike, but the thought that these things are downward facing threads that are getting shaken and jostled thousands of times per ride has me amazed this sort of thing isn't happening all the time. In fact, I think, if not threadlock, once the nuts are back as they should be, I might put a second pair of the nylon-in-thread lock nuts just kissing up against them (and perhaps put a dab of paint on one side so I'll immediately know if they're rotating, so I won't be constantly worrying about them working loose again.

[rphillips]

Wouldn't doubt your concern, jharvey, considering it happened to you. That being said, In the 42 yrs. you've owned this bike, how many times has it happened to you, or how many times have you heard of it happening to anybody? Brendan ^^^ is the only time I've ever heard of it. If it were a concern, the factory would have done something to make it more secure, cotter key, lock nut, or those bending lock washers, like on the brake rotor bolts. I do understand, a little extra safety could never hurt anybody.

[Brendan W]

My wheel incident was with a Fiat Punto. Got distracted with a phone call in the middle of putting a wheel back on and a mile into the test drive it nearly came off.
I've never seen a front fork cap come loose of it's own accord.

[Cipher]

Ummmm don't reuse your split washers and check the studs for stretching etc.

[zuluwiz]

If you're really worried about this happening again, try using safety wire on the nuts. It's a lot more work, but much easier to do and undo, once the holes are drilled.

[jharvey]

Yeah, my rational brain knows this is an exceptionally rare occurrence, but my paranoid brain, and the fact that the nut came completely off before I even knew it was loose, is having strong influence at the moment. I expect that for some months, if not years to come, I'll be looking at those nuts before every ride.

Tangentially, I WILL be interested if, post-repair, another symptom disappears. When the tires were first replaced, the bike felt a little 'squirrely' (normally a 'runs if on rails' feel). Not like I was building up my biceps fighting the handlebars, just about a 5-10% reduction in that rock-solid feel, which I put down to new, slippery rubber. Additionally, hands off, the bike had developed a slight tendency to drift to the left - again, not anything serious, careening me into oncoming traffic, but enough that after a few seconds, I'd be approaching the centerline and would have to correct. For that second symptom, ironically enough, we had a look at the REAR axle, thinking it might not have been precisely aligned on reinstallation, but it was fine. Never thought to look at the front wheel.

Of course, it could still be entirely unrelated - these new tires are a different tread pattern from the ones I've been using for about 30 years, and that may be the reason for the different feel, but as I say, it'll be interesting when I get it back.