X-Man's Hints and Fixes For May 26, 2002:
By: Bobby Baldwin

Front End Shimmy

     Front end shimmy is noticeable in deceleration, corner wobble, or high speed wobble. Since it can become dangerous, it should be corrected immediately. There are four leading causes for front end shimmy:

1. Steering stem nut.
2. Front tire.
3. Front strut assembly.
4. Front wheel bearing.

     A loose steering stem nut is the most common cause of front end shimmy. To check and correct it follow these instructions:

1. Elevate and support the front to relieve pressure on the front wheel. Remove the acorn nut on the steering stem. Remove the handlebars. They will sit on the headlight, but be sure to cover the headlight to prevent scratches. 
2. Remove the upper triple tree studs and lift off the upper triple tree, the steering stem, and the top joint nut by slowly lowering the bike until the triple tree clears and then swing it out of the way.
3. The steering stem nut should be tightened until there is no end play in the rigid fork. This is like setting wheel bearings in a car. Make it tight, but not so tight as to bind it.
4. Set the jamb nut 25 lbs. of torque.
5. Reassemble the studs, upper triple tree, and handlebars. Here's a tip: when you put the handlebar clamps back on, replace the isolators (rubber bushings) if they are worn. Tighten the clamps so that the space in the front and rear are the same.

     Front tires that are worn, dimpled, out of balance, or not properly inflated can also cause the front end to shimmy. Check for each of these, and if there is any question, replace the tire. Based on recent input from owners, and personal experience, I am recommending the new Metzler ME-880's. Remember, if you switch tire brands, do the front and rear together!

     Front wheel bearing failure is not as common as rear wheel bearing failure, but it does happen. You can check your wheel bearing by grabbing the front tire and wiggling it. There should be no play; if there is, the bearing has to be replaced. Call me at 619-445-9993.

     I have seen a few cases where the front strut assembly has become loose. If you have corrected the above three problems and you still have a shimmy, then check the front strut assembly. To check it, simply grab the lower spring perch and try twisting it clockwise. The spring perch is the the widest section of the front strut assembly and is the area where the spring sits. It should not be able to move if it's correct. If it does rotate, you'll need to tighten it up with a good strap wrench.

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