Chasing Front-end Shimmy/Wobble

[Firehawk068]

Recently (the last 5 or 6 times I've ridden the FJ to work and back) I've started to experience a front-end shimmy, or "speed-wobble" at right around 45 mph.
It's not violent in any way, and most of the time just the weight of my hands on the bars will dampen it out. If I relax my grip on the bars, or take my hands off the bars it is visually noticeable.
If I speed up (above 50 mph) it goes away. If I slow down (below 40 mph) it goes away. It is only right around the 45mph range.

Since I now have around 3000 miles on this set of Shinko Raven 009's, I wondered if it was tire related? I've never had this FJ experience this with ANY tires I have ever used on it, so I started doing a little internet research..............Seems there are only a few folks who have had this sort of experience with these Shinko tires........I'm hoping I didn't get a bad one.
I tried adjusting the front tire pressure from 40 to 42 psi.............It made it slightly worse. Then I tried lowering it to 37 psi, and that made it worse yet!

So now I have to figure out if it's Steering Stem, or tire related...................I have a plan, and a backup plan (I have a Michelin PR2 front tire that is a few years old, with about 1/3rd tread left, that I can try in case it turns out to be the Shinko tire)

Since it has been forever since I last checked the adjuster and lock nuts on the steering stem, I figured I would start there...........
Both nuts on mine are keyed together with a tang-washer, so I cannot check the adjustment without removing the whole top triple-clamp.



So off it came!

After removing it, the tang-washer, and the lock nut I checked to see if the adjuster nut was loose....................It wasn't.
I only got about 1/4 turn on it before it was way too tight..................So off it came also.

Once I got the top bearing removed, I was baffled to find it was dry and crusty. Absolutely NO grease in it or on it!
Spinning it by hand, it felt gritty. 







Next came strapping the FJ to the floor, and removing the forks.



Lower bearing had little to no grease in it as well!



Upper race is pitted and groovy:



And lower race has deep grooves that I can feel with my fingers:



The top race came out easily with a punch and just a few taps with a BFH.
The lower race was stuck in place pretty good............Really stuck!
I ground a couple channels in the steering-head with my Dremel, so that I could get a better grab on the lip of the lower race with my punch.
I also "Pie-cut" the lower race to weaken its grip inside the steering-head. After that, all it took was a couple taps and it came right out.





Lastly, I used a bearing-splitter and my 12-ton press to easily get the lower bearing off the steering stem.



I just ordered the Bearing/Seal kit from Randy, so when that arrives this coming week I'll put it back together and test-ride....................

[Pat Conlon]

Very good Alan, curious...how did you get that bearing splitter around the steering stop nubs on the lower triple?

[andyoutandabout]

Bravo Al, another solid 'how to' mini project.
Initially I was going to shout tires, since new rubber has always cured handling vagueries over here.
Must rain in Colorado a bit more than Cal looking at those bearings.

[Firehawk068]

Very good Alan, curious...how did you get that bearing splitter around the steering stop nubs on the lower triple?

I went at it at an angle, so the steering-stop nub was in between the bearing splitter halves.

[Pat Conlon]

Ok, thanks!

[balky1]

I have the same problem with wobbling. I thought it were the fork bushings since I noticed a bit of free play on the fork, changed them, but no improvement. I am also suspecting the steering stem bearings (although it turns left-right nicely, without any problems).

[Firehawk068]

I have the same problem with wobbling. I thought it were the fork bushings since I noticed a bit of free play on the fork, changed them, but no improvement. I am also suspecting the steering stem bearings (although it turns left-right nicely, without any problems).

Mine always turned left/right easily, and I've never felt any notchiness in the steering. It never gave me any reason to suspect anything in the steering stem was amiss. (until recently with the steering shimmy)

[FJ1200W]

My shimmey went away with new tires.

Moved away from radials back to bias ply - and a careful balance.

[balky1]

My shimmey went away with new tires.

Moved away from radials back to bias ply - and a careful balance.

I also suspect the front tire to be the culprit. More than 10k kilometers on it.

[Firehawk068]

Earlier this past week, I received the Bearing/Seal kit from Randy.



Put the races in the freezer overnight, and then tapped them in place with my driver set.



Used my bearing packer to get them filled with grease, then installed the lower seal and bearing on the steering stem.





Installed the top bearing, seal, and guard in place. Torqued down the adjuster nut and steered the stem left and right a bunch of times, then backed off the adjuster to where the steering is free and easy(about a 1/4 turn) then installed the lock nut and keyed-washer.



Next, I loosely mounted the top yoke and the forks and then tightened everything down.





The next morning, I reattached the fender and re-checked everything over, adjusted the front tire pressure to 40psi...............Time for a test-ride.



I geared up, and went out on a few local roads where the speed limit is 45mph.......................I instantly realized that the shimmy was still there, just as bad as it was before. 
Although the steering-stem bearings were in desperate need of attention, they were not a factor in the shimmy at all............

Back home, and on to plan-B.

Got my tire changer out and bolted to the floor......Put my top-case on the FJ and loaded it up with sand-bags.
Removed the calipers and front wheel again..................Took the Shinko Raven off.
Barely any wear on it whatsoever!



Put my used Michelin Pilot-Road 2 back on, and added 1-ounce of "Counteract" balance-beads......



Geared up again, and this time went out on a much longer test-ride.
I rode it at a bunch of varying speeds up to about 65mph.......NO shimmy or wobble at any speed.
I even tried to induce a shimmy by removing my hands from the bars and slapping them left or right at various speeds. Each time, the steering self-centered and tracked straight and smooth.....

The end verdict is a bad front tire from Shinko.....................Now to contact them and see if they will do anything about warrantying it? 

[FJmonkey]

I have not ridden/owned a lot of bikes, but every front end problem was a bad/worn front tire. Even Cap'n Ron has a story on a bad front tire. One exception, a broken valve stem on the front. But I did not get far from home.

[FJ_Hooligan]

As with Monkey, every front end wobble I had was instantly fixed with a new front tire.

I don't remember the last time I had a wobble, but I have stopped using any front tire with a groove or tread in the center of the front tire that runs all the way around the circumference of the tire. 

It looks like the Shinko has such a groove whereas the PR doesn't.

I think my worst tires for wobble were Dunlop Roadsmart and Bridgestone BT020 both of which had a center tread.

[Firehawk068]

Yes,
The center-groove in the tire tread was brought up a number of times in the reviews of this tire...........It likes to follow road irregularities....
I noticed mine did this as well, but that wasn't much of an issue for me..

I suspected the tire from the start, but I secretly wanted it to be something else.........Something that was under my control....
I picked Ron's brain a little when I first noticed the shimmy, about his experience recently....His experience was a little worse than mine, but similar.

Anyway, at least this used tire should last me through the summer...........


Next up: "Chain and Sprockets" 

[Capn Ron]

My experience, like many other's has been it's always the front tire starting some sort of speed wobble.  If the headstock is is bad shape, the wobble can get severe.  It's a good time to get as thorough as Alan does with looking into all possible causes.   

[Firehawk068]

Figured I would post an update on getting the front tire "Warrantied".
It has taken me since August. I've been at it "on and off" ever since, initially with the Amazon seller that I originally purchased the tires from, and then with Shinko (Western Power Sports) directly.
Firstly, my experience with the Amazon seller "ATV-Outfitters" was Horrible!
Their communication would best be described as "nonexistent". After the initial description of what was wrong with the tire, and most every subsequent e-mail would take months to get a response back from them. Each time requiring me to send one or two reminder e-mails to get the ball rolling again.
After about 4 months of this, I took my claim to Shinko directly. Upon getting 2 different sales reps involved, and spending another month trying to get them to coordinate with ATV-Outfitters, it was finally agreed upon that they would ship me a new front tire (free of charge)
So about a month ago (5 months from initial claim contact) a new Raven front tire showed up at my doorstep!
I'm just glad that I wasn't in a hurry for it!