Have a wierd one here hope you guys can help. Have a tremendous amount of vibration in the handle bars the vibration develops at exactly 40 mph. The vibration in my opinion is bad, if you let go of the bars at 40 mph you can literally see the bar shake approx. 1-2 " side to side. The bike is an 03 Road Glide with 9500 miles.
I've checked and adjusted the steering head, had the tire balance checked it was okay. The front tire is the original and appears to have some decent tread left with minimal cupping. I'm wondering if the belts inside the tire are breaking down and the magic number is 40 mph or maybe it's something else? Has anybody experienced a problem such as this?

 

Could be a bad tire or may be wheel balancing too.

 

What wheel (spoked?), is it true? (jack up & spin, put 1 gal paint can & weight pencil for indicator/pointer). Head bearings? Will check back for more in debth info if needed. I have a link on my site on how to align if it has to go that far. We can fix it if you try.

 

The wheel is the cast wheel. I have put the bike up on a lift and checked for trueness with some dial indicators. Wheel has 1/32" variance, I've rode bikes with spoked wheels that where off farther than that and didn't get the shakes.

 

go to my site under do-it-yourself as you may try this :http://motorcyclemetal.com/
I will get it up in a few min. for you

 

I've got a thread going on this too. My 03 NightTrain is starting to do the same thing but not quite as severe. Right at 40. Especially on decel. A very noticable wobble in the bars. New Metzler on front with about 2k miles now. Probably notice it 5 or 600 miles ago. Don't think it is the tire. Goes in the shop tommorrow. I'll let you know.

 

Determine if the vibration is engine related first by running the engine in neutral on the side stand. Rev it up slowly from idle to about 2800 rpm and look at the mirrors. If they have a violent vibration at any particular rpm range, the problem is most likely something in the motor, motor mounts, loose exhaust mounts......

 

Have you thought about rear steer?

 

What's that ?

 

when your rear fork is loose due to the bearings or other stuff in the swing arm.

If you already went to my Do-It-Yourself page LINK: http://motorcyclemetal.com/ & did all that was asked of you to check, we can illuminate the whole front end as it does cover that.

The only thing you got left on a motorcycle is the second wheel. You have checked the rear wheel for being out of balance previously as well as made sure the rear tire was also good. Short of the drive train or a sail hanging from the bike, there is nothing left to wobble.

I spent almost all day yesterday on the "swing arm upgrade" on my site (which you already have in a 2003) section (not under the Do-It-Yourself but in its own section), so this information is also available to you if you pick and choose which to use (in your own case). Let me know as I check this site a few times per day. To check "Rear Steer" block up the frame with the rear tire elevated. Secure the bike so it will not move, than with much force, deflect the rear swingarm sideways.