2013 Usidedown Forks/Shimmy - Yamaha FJR Forum : Yamaha FJR Owners Forums
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post #1 of 24 (permalink) Old 01-03-2016, 08:08 PM Thread Starter
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2013 Usidedown Forks/Shimmy

Hi,
Firstly although I have owned 2 FJR's (08 AS Auto Clutch for five years, then a 13 AS for two) and have lurked on various forums, I seldom post anything, so I apologise for my lack of postings

So to cut to the chase.....I had front wheel shimmies with both my FJR's and over the years whilst seeking various solutions both via these forums and thru dealership techies, never reached a solution to the problem, I tried all the suggestions...Five different makes of tyres and all replaced in pairs..many re-balances and every combination of tyre pressures...inspection repacking, re-torquing, changing head bearing types (to taper rollers) suspension setting checks etc etc..I think you get the picture that every base was covered including being over-checked by Yam Senior Tech....Nothing cured the problem, granted some tyre combo's were less pronounced than others, so I learned to accept the condition which lets face it isn't a big deal unless you like decelerating with no hands on the bars.

So when the new 2013my came out I traded my old steed in order to try the new bikes great features..y'know the cruise, the electric suspenders..the improved auto clutch etc.

Now whilst enjoying the new bike I'd completely forgotten about trying the hands off shimmy until the original tyres (B'stone 023's) were a good few thousand in so I was a little surprised to find that even with all the new fangled front end the shimmy was still there!

So...I thought.."Here we go again!!"
Didn't want to replace with the same tyres again so after checking head bearing torque decided to try a set of the then new Avon Storm 3D XM's especially after learning that the UK tyre development was carried out using Avon's own FJR test bike.
Ok so pair of boots fitted and dynamically balanced on a brand new bike tyre machine I fitted said wheels...only to find shimmy was the worst I have ever encountered!!
So the head scratching began...Tyres re-balanced...Head bearings checked for grease damage-all ok, so carefully reassembled to the letter of the factory manual.
I then had the Yam guy check over bike, he agreed on the shimmy but offered all the suggestions I had already tried!!

So I decided to remove the front end and recheck my work...which is when I stumbled on some rather excessive play in the fork legs! and it gets worse.....

Not only is the play at the axle 1mm on one side and 1.5mm on the other-front wheel and front mudguard removed, but can be felt at the point where the fork bushes live....except there are NO BUSHES in the fork assembly!! unbelievable I know but go and check the Official Yam Parts Manual..I did and there's no parts listed whatsoever
At last I thought I was on to something regarding the shimmy, so I printed the page from the parts manual and headed off to my dealer....who after a phone call to Yam Technical confirmed that the parts diagram is correct and that there are no replacement bushes available!!

So it seems that a serviceable part like the front forks cannot be overhauled except for seals and oil..to me this means that the fork legs must be changed in order to replace the bushes!!!

The other mind blowing snippet of info I was told was that the service limit on leg end play was 4mm!! which if you can visualise would feel like the legs were broken, as my fork legs felt pretty sick with only 1mm play in them.

As I couldn't believe the info I was hearing I asked the Techies to strip and check an unsold brand new FJR/AS, which they were happy to do as they could not believe what was being told to them via Yam Technical...

The dealer called me and asked me to call in at the shop as he wanted me to see what the techie had found.....Play of 2mm in one leg and 1.5mm in the other!!....This was a brand new bike!!

As I was investigating this problem of mine I discovered that the Super Tenere 1200 with the eletronic suspension adjustment with the same type KYB forks fitted has got REPLACEABLE fork bushes...WTF???

So if anyone out there has the upsidedown forks and happens to have the front wheel out take the front mudguard off, grip hold of the fork end and feel the area around where the fork bush inside the outer leg is to feel for any play you may be surprised to find like me that they clunk as you shake the fork end to and fro (the play can be felt sideways on to bike just the same as the play is in the bush clearance with the stanchion)
It will feel like the head bearings are loose, this is why you must remove the front mudguard as you can isolate the legs individually.

I could not believe that the seals would hold up with that amount of play but mine have not even wept a drop!

Sorry for the long post!

Regards, JT
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post #2 of 24 (permalink) Old 01-03-2016, 10:00 PM
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JT... I'll give you the short answer.... send that piece of junk over to me and I will ride it and get back to you in a few years

But seriously, this is amazing news. I have rebuilt several sets of FJR forks at tech days, so I understand mostly what you're saying. I was not an adopter of the E suspension and just recently purchased a 2014 A. I did see quite some time ago that there are no bushings in those forks, wondered about that. I thought we'd start hearing issues as these bikes were being ridden more..... it's still early. How many miles/kms on your bike, just curious......

I don't have any answers, it seems odd not to have bushings and I would have thought Yamaha had a good reason not to include them. That is a disturbing amount of play you describe. But, I am not a Yamaha engineer...... perhaps they do not realize the issue, but the more folks that bring forth the legitimate complaints the better.

I'll also mention the prior generations had a procedure for installing the front axle that included ensuring the right end of the axle was flush with the fork before you tightened the pinch bolts, i.e., no side to side play. Most of the time it wasn't an issue in my experience, but occasionally one would have to squeeze in the right fork leg maybe a mm or so. But it sounds like your play is in the opposite direction, fore and aft? Perhaps describe how you check it, just for clarity of the whole situation and being able to pass along to see if others have the same issue.

I think your comments are valuable, and I think you should post them on FJRForum.com as well... or with your permission, I could copy them over. Perhaps the collective can help Yamaha find a solution.
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post #3 of 24 (permalink) Old 01-04-2016, 09:54 AM Thread Starter
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Thanks for your reply,

I think that the procedure for installing the front wheel is the same as you describe, the play you can feel is in all directions IE front/back, sideways and can be heard and felt where the bushing is nearest the fork oil seal, and can be also felt where the top of the stanchion ends.

I understand that the forks are hanging in a fully extended state but you cannot check play in the compressed state without removing the springs..I never did this but I cross-checked my findings with my other bike fitted with bum basic upside down forks, a six year old Versys and with the front end hanging there no noticeable free play..only a minor fork deflection as you expect when a lot of pressure is used.

This issue first came to light with aprox 8thou miles showing as I wanted to change the tyres early as I had a big holiday planned and the tyres wouldn't make it.

The reply from Yam technical via the dealer (who by the way has a great track record with FJR's in particular and has sold more Auto Clutch models than the rest of the UK put together) has seriously knocked my faith in Yamaha's technology.
Why would the Super Tenere have replacement bushes available and the big road tourer not??

If you check the factory manual there's no section on replacing the bushes! which means to me that the whole slider must be replaced!!?

By all means share this post, at least it may give a snapshot of how many FJR's with upsidedown forks have big play in them.

I found Yam's statement of up to 4mm slack acceptable completely bewildering..in fact I was given the phone number of Yam Technical to ring and confirm what the dealer was saying, which is something they shouldn't do.

I mean would this amount of play be engineered into the latest R1M (the Electronic suspension model)?? It beggars belief!!

JT

Last edited by jonnyteabag; 01-04-2016 at 10:20 AM.
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post #4 of 24 (permalink) Old 01-04-2016, 10:13 AM Thread Starter
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By the way if you just raise the front wheel off the ground and grasp the fork ends as if checking for head bearing play you probably won't feel anything as the wheel assy is too much of a weight to feel for the slack in the fork legs. A friend of mine who has exactly the same model came by when I told him and when he checked for play by just raising the front wheel we both couldn't detect any..the same was found at the dealers when he checked my bike against a new one in the same way.

When I asked him to remove the front wheel and m/guard then recheck I could see he wasn't for believing me, so I said I'd PAY for the 'shop time he'd take to recheck if he found none.....Well upon my soul!! He discovered the slack alright!! and as I said the new bike had MORE slack than my bike with 8k under it.

So to feel this slack you must remove wheel and 'guard.

JT
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post #5 of 24 (permalink) Old 01-04-2016, 01:51 PM
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JT,
Thanks for the additional explanations..... I will post it up elsewhere to see if someone can verify a couple of things... now that I've heard a bit more, I have more suggestions and questions (for your dealer, or anyone who has one).

The first thing I think is, a fork fully extended should not have this kind of play, because it is possible for the forks to fully extend during riding, albeit this would be rare. What harm is there under that condition, I don't know, but I would want to be sure the forks would also re-compress without a hitch when the weight returned to the front end (no wheelies, then, OK?).

Second, physically when extended, there is less overall engagement of inner to outer, and it would be the worst condition for being able to move the bottom end of the fork. What should be done, is fork disassembled to remove the springs so the forks can be compressed/uncompressed on a bench, with free play measured at various fork lengths. I expect it less and less as the inner is inserted into the outer, as that would be natural physics. At this point, this should be measured on a set of GenII bushed forks for comparison (I'll attempt this at next tech day in April/May,but I kind of already know the answer).

The root question ultimately becomes, what is the diameter of the outer tube and the inner tube = ? relative to design clearance. We know that bushed forks have the lower bushing riding in film of oil, and there is a film of oil on the middle bushings (GenII), and yes, even the upper. The seals keep it all in there. With these USD forks, there is going to be a film of oil between the inner and outer anywhere above the seals. Of course, our traditional thinking is this clearance should be no larger than bushed forks......

You might want to 'convince' your dealer there is a design issue, and in the interests of satisfying his customer or his own curiosity, that he should go through my suggested measurements at various lengths, simply by removing the springs. Removing and rinsing out the oil is going to be another story (worse I would say). And of course, pass that along to Yamaha (who might want to participate?).

Keep us informed if you hear more, and I will see what the others have to say. Thanks again.
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post #6 of 24 (permalink) Old 01-04-2016, 04:24 PM
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While I agree that it is extremely strange that there are no bushes in the fork legs, and that there shouldn't be slack in the suspension legs, I cannot understand why people get so anal about the shimmy in the steering when you let go of the bars on a trailing throttle.

That is what bikes with telescopic front suspension do, all bikes to some extent. It's a natural result of this design, and cannot be totally cured, only reduced by careful maintenance of the relevant components. It's more a function of rake and trail of the suspension than anything else. Frame designers can either make the steering slow and stable, which is desirable in a touring bike, or quick and unstable, which is what racers want. All suspension designs are a compromise between those two requirements.

And, why people want to let go of the handlebars on a trailing throttle, is beyond me. I learnt not to do that a long, long, time ago. A shimmy can, and does, suddenly develop into a full tank slapper, and down you go. The old bikes from my father's era were very prone to this, but modern bikes not so much. You can safely let go of the bars as long as you have positive drive from the engine, but of course you need a throttle lock or cruise control to do this.

DON'T LET GO OF THE FRIGGING HANDLEBARS ON A TRAILING THROTTLE.
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post #7 of 24 (permalink) Old 01-05-2016, 08:45 AM
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While I agree that it is extremely strange that there are no bushes in the fork legs, and that there shouldn't be slack in the suspension legs, I cannot understand why people get so anal about the shimmy in the steering when you let go of the bars on a trailing throttle.

That is what bikes with telescopic front suspension do, all bikes to some extent. It's a natural result of this design, and cannot be totally cured, only reduced by careful maintenance of the relevant components. It's more a function of rake and trail of the suspension than anything else. Frame designers can either make the steering slow and stable, which is desirable in a touring bike, or quick and unstable, which is what racers want. All suspension designs are a compromise between those two requirements.

And, why people want to let go of the handlebars on a trailing throttle, is beyond me. I learnt not to do that a long, long, time ago. A shimmy can, and does, suddenly develop into a full tank slapper, and down you go. The old bikes from my father's era were very prone to this, but modern bikes not so much. You can safely let go of the bars as long as you have positive drive from the engine, but of course you need a throttle lock or cruise control to do this.

DON'T LET GO OF THE FRIGGING HANDLEBARS ON A TRAILING THROTTLE.
IMHO, and that of a couple well seasoned service techs, is that the shimmy causes other problems as well. We believe it's what caused my forks to develop multiple leaks in the first yrs of ownership. And it sort of makes sense- you hold the handlbars to "steady" the wheel but the wheel is still trying to wobble. Where's the slop manifest itself? In the fork tubes, specifically at the seals.

But back to the OP. I know you said you replaced the steering bearings with tapered rollers but did you to torque them to roughly twice the FSM values for OEM bearings? And did you in about 1,000 miles go back and re-torque them again? This is the exact procedure I followed and the only thing that finally relieved my '07 of the front end wobble.

Russ
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post #8 of 24 (permalink) Old 01-05-2016, 09:00 AM Thread Starter
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I largely agree that letting go of the 'bars is something I rarely if ever do, both FJR's I have owned have displayed this trait.
The first bike did this only when the tyres were past their best, however, the latest version with completely different suspension was far far worse. I have to say that both my FJ's have been ridden in the exactly the same condition IE always two up and fully laden.

The second one was so bad that even with one hand on the bar you could see and feel the bars shimmying under your hand...obviously this is rather disconcerting and needed to be investigated (if it had only been as mild as my first FJ I would have gladly ignored it as just an amusing trait of the bike)

The main reason for trying to investigate further was the fact that whilst riding along a smooth flat road with cruise control engaged, that is under steady constant power the bars would gently start to oscillate very rapidly gaining to a frightening tank slap!!
My wife on the back could also see this and indeed could feel the bike shaking when this occurred.

Now I realise that letting go of the bars is not the usual riding style but tank slapping whilst under cruise is showing to me that something is seriously amiss.

It was only when trying to investigate the issue that the slack in the forks came to light, and to my reasoning any amount of excess play in the front suspension must be conducive to having what I considered to be excessive bar shimmy. So I thought I had found my cause....but it seems that the play is engineered into the forks??


Just saying what I found using my dealers experience and Yam technical that's all.

JT
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post #9 of 24 (permalink) Old 01-05-2016, 09:24 AM Thread Starter
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The tapered head set I referred to in my original post were fitted to the first FJ, the second bike has had no such modifications as the head bearings have been inspected, checked for damage, re-greased,and re-torqued to factory setting three times!

I didn't want to change the head bearings on a new motorcycle as I felt the initial cause might have been a loose head bearing.

The shimmy is not a big issue for me it's the slack in the fork bushes and the lack of any replacement parts on what is a service "wearing" assembly!
If Yamaha hailed these forks as "sealed for life" it would be one thing but they're not!

As a former MOT inspector finding play in the front fork leg such as this would be a fail ticket being issued as it's not seen as being roadworthy.

The reason the play cannot be detected is the fact that the wheel and 'guard are hiding the play as they are very heavy, once you remove these (which is not allowed during an MOT inspection) the alarming slack can be felt!

This is just a heads up to others with the upside down forks fitted.

Just that when you discover this play don't go complaining to Yamaha as they will tell you that "they're all like that sir!"

JT
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post #10 of 24 (permalink) Old 01-05-2016, 11:04 AM
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The tapered head set I referred to in my original post were fitted to the first FJ, the second bike has had no such modifications as the head bearings have been inspected, checked for damage, re-greased,and re-torqued to factory setting three times!

I didn't want to change the head bearings on a new motorcycle as I felt the initial cause might have been a loose head bearing.

....

JT
I understand what you're saying but I'm thinking your bike is an anomaly and IMHO you're barking up the wrong tree. I'm not saying that definitively your forks aren't trash but I don't think all FJR inverted forks are trash. The FJR has had this wobble problem since its inception and I'm thinking that your bike is no exception, but that perhaps you've become jaded and can no longer see the forest for the trees.

Before I replaced my steering bearings from OEM to tapered, no amount of checking/cleaning/regreasing/retorquing removed the wobble. Nothing. Not replacing tires, not aligning, not balancing, not fork rebuilding, not front suspension work. Nothing. And what I found, finally, was:

- regardless of how close to OEM the replacement bearings' measurements were, the inner races simply would not fit without pounding them on, which I did not do. I spent the time with fine grit emery cloth on the steering shaft and inside the steering column to get the bearings to seat completely, like I felt they're supposed to. I've done industrial maintenance for quite a while now and I know how it's supposed to be;

- stiffen up the front suspension. From speed to no throttle, regardless of rider position, shifts a lot of weight forward. Too squishy a suspension in the front allows the front end to become unstable.

Summary? For me, the wobble problem was a combination of factors. I suspect it is for you too. This is a new bike- do not apply things from a different bike. Clear your mind, start at step 1 and go forward. Again-disregard all things tried previously on any other machine and work at solving your problem on this machine. Over the yrs I've learned that individual machines of the same model and even off the same assembly line have individual "personalities". Most people don't believe it but IMHO it's true. Sometimes you kiss azz, sometimes you kick azz; sometimes a good slap is needed and sometimes a gentle pat on the butt works- it's up to you to be patient enough to discover which your girl needs right now.
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