Handlebar Vibration...Resonance

[PolarisJay13]

I was wondering if anyone has had the same problem as I am having right now. I just bought my Rocket a few weeks ago, and am now starting to notice its quirks. At about 52mph while slowing down, if I let off of the handlbars, they will vibrate into what could be tank slappers if I did not grab the bars again. All it takes is for me to slightly touch the bars to keep them from doing it, though. It seems to me that I should be able to let off the bars at any speed and not worry about the bars slapping back and forth. In any case, is it just a front tire out of balance that is doing this? If so, let me know, and I will get her balanced. Otherwise, and tips would help. Thanks.

 

[Molinoman]

I've heard this on the Gold Wing forums a lot when decelerating around 35-40 mph. The common sense answer is keep your hands on the bars. With your hands off of the bars and you hit a hole in the road or an unexpected groove, tar stripe, etc...in the road...you're done. I know it's a great show off feature, but if it ever backfires...you won't be "showing off" for long. I am not trying to be critical here but doing it on a bicycle at a much slower rate of speed is one thing, but at a speed that we are able to attain with these engines it can be a disaster waiting to happen.

The other answer is if it is shaking that much, either your wheel(s) are out of balance or you could have a possible steering head bearing problem. Since your Rocket is relatively new it is probably in the wheel/rims if it is a problem at all.
Dennis

 

[PolarisJay13]

yeah.... it's not that I am showing off, but i noticed it when I was just cruising with one hand on the throttle. The bars just had a small shake to them, so just to see, I let off the other bar, and that is when the bad shake happened. I was just wondering if this was normal or not.

 

[RocketDaryl]

It's not normal. In fact, I was reading my owner's manual (new RT3) last night and it addresses "weeve & wobble" (I think that's the phrase they use). It can be caused by a couple of different things.

- Low tire pressure
- Improper weight distribution (luggage, etc...)
- Steering head bearing (I think was it, not around my manual at the moment) needs adjusting

FWIW - I had a Harley Heritage Softail Classic and I didn't need to keep track of my service intervals because I would get the dreaded "weeve & wobble" effect like clock work about every 4000-5000 miles. It was a simple steering head adjustment in my case.

 

[Sidecar Flip]

You need to get Triumph Shop Manual or have your dealer check the headstock bearing pre-load.

It's very important that the starting torque (pre-load) is set properly. There needs to be a certain amount of resistance in the steering head (headstock bearings). The easiest way to ascertain if, indeed, there is the proper pre-load is to lift the bike and get the front wheel off the ground (our famous Sears or Hardon Fright floor jack is the ticket). Put a small block off wood under the leading edge of the pad so the bike is slightly higher in the front than in the back. Get the bike off the ground and move the bars full lock right and left, then center the wheel. Apply a little pressure with your fingers to the RIGHT handlebar end, pushing on the bar to cause the front end to swing LEFT. If the the front end just flops to the left side after it is off center, without any apparent resistance, there isn't enough pre-load. Repeat on the other side was well to be sure.

You have to have the pre-load or starting torque in the headstock bearings. Without it, you will get what you are describing......headshake.

If you go by the shop manual for the R3 (I suspect the headstock bearing adjustment is universal for all models as my other bikes are basically, all the same too......
Slacken the locknut and adjuster nut....
Adjust the bearing free-play as follows:
a) Tighten the adjuster nut to 40 Nm
b) Slacken the adjuster nut fully
c) Re-tighten the adjuster nut to 6 Nm
d) Loosen the adjuster nut 90 degrees...(there will now be free-play)
e) Securely hold they adjuster nut in that position and tighten the locknut to 40 Nm.
Ensure that the adjuster nut does not move as the locknut is tightened.

Thats' right out of the Factory Manual, Section 14.16.

Setting the headstock bearings is just like pre-loading the bearings in any roller bearing application.

 

[RocketDaryl]

Wow, that's good info Flip! Thanks. I checked mine earlier and I have the same problem. I'll add it to the list. I have about 3 items for the dealer to check/fix when I take it in for the 500 mile service.

Daryl

 

[rusty]

Mine "flops" too.

I've noticed my front fork "flops" side to side as it's on the centerstand. In fact, there is a fine line of keeping it straight, if at all. The process Flip described "absolutely" introduces free play so that explains it.

But on second hand, there is no "free play" felt in the bearings (grab the front forks "low" and move forward & back to feel for free play), nor is there any wabble at any speed. I too have let go of the handle bars a time or two (not showing off mind you) and have felt confident in the ride continuing in a straight line.

I noticed in the list of "possible weeve & wobble" items to check for was not "tire balance", although someone did mention it.

See ya. And thanks for the spelled out version of checking the head stock Flip.

 

[PolarisJay13]

Nice. Thanks for the info. It sounds like that should be the ticket. That is the only thing about my bike that bothers me, and if that takes care of it, I will be one happy camper. I will let you know how it turns out.

 

[bigern2300]

My Trophy 1200 would do the same thing. I cured it by snugging up the neck bearings just a fuzz. Oh, and my '05 Rocket also does it also but not enough to annoy. Bigern

 

[Sidecar Flip]

More in depth....

We all know sometimes the factory forgets to do things. It may be a Monday morning and you bike is the first one down the line and someone has to run to the bathroom or coffee (tea) machine or whatever. ****te happens.

My new KLR came without any grease in the shock knuckles..it has a monoshock. I put on lowering links 'cause my feet wouldn't touch the ground and to put them on you must pull the axles out of the shock knuckles, well, the needle bearings were dry. Not now. Any bike is suseptible to human error.

When the shop manual says to torque the nut to 40Nm while holding the adjustment nut and allowing no movement, the factory knows that the pitch of the threads on the stem have a known amount of slop or freeplay. When the top nut is torqued to 40Nm, it removes that freeplay in the threads and a '0' freeplay condition results.

It's just like the wheel bearings on a big truck. You run the inner nut down to 50LbFt, spin the axle, back it off completely and then retorque to 10FtLb. Then you run the outer nut down and torque that to 150FtLb. The outer bears against the inner and takes the freeplay out. Same thing with the R3 but the bearings and nuts are smaller.

If, for some reason you had to take the stem apart like if your bearings were rough in movement (you can feel that with the front end elevated), they need to move freely side to side, I'd consider adding an alemite fitting to the headstock in a convenient place to inject a good quality grease ocassionally. Grease never hurts and the seals on the stem bearings aren't so tight as to not pass excess grease.