Chassis Wear

When we think about a motorcycle frame we normally are thinking of an item to which engine, swing arm and front steering parts are attached.  On the other hand we don’t often think of the frame itself as a component that wears out like the other moving parts that are attached to it.

Well, wear does occur to all motorcycle frames and some of them sustain more damage than others depending on design. The number of frame components that will wear out over time are:

  •  Upper steering race
  • Lower steering race
  • Foot brake pivot
  • Side stand bracket

Steering bearings have always been a problem for motorcycle engineers whether they be ball bearings, caged ball bearings or tapered roller bearings. The huge forces fed into the steering components are just too much for any bearing to manage over extended periods of time. As a result, they become “notchy” and should be replaced as needed in order to keep steering smooth and “safe.”

In the case of tapered roller bearings, I will offer you some hints that I picked up from a conversation with a Timpkin engineer during a long distance phone call 30 years ago. He said, “Tapered roller bearings are wheel bearings and were never intended for use in the steering head of a motorcycle.” He continued, “ If you do use them as motorcycle steering bearings, be certain to eliminate any “play” or they will self destruct within a relatively short period of time.”

Here at Top Gun we put a jack under the engine and lift the front end of the bike until the wheel is 1/3 inch above the table. After loosening the steering stem nut and four upper T-clamp fasteners, we adjust the steering until the wheel doesn’t “flop” from side to side. When it moves slowly from side to side, that’s it! The trick is to not overdo it or the bike will not steer well. “It’ll hunt!” We finish up by properly torqueing the fasteners and re-checking the steering. (Note: If you have a KLR don’t forget to Locktite the steering stem nut).

As for side stand and front brake pivots, they should always be bolted-on components that can be replaced when worn. Unfortunately, most are welded onto the frame.

My favorite bike, the Suzuki DR-650-SE has the worst foot brake and side stand set-up known to man. The side stand bracket is welded to the frame and the actuating springs are on the inside. WRONG! The foot brake pivot tube is welded in to the frame and the foot brake lever must be removed to facilitate lubrication. It’s a big pain and almost nobody does it!

The best I could do for the side stand was to lube the friction surfaces often with Hi-Tech silicon spray. In the case of the foot brake pivot, I came up with a better fix. Using a tap, a threaded plug, a drill, and a zerk fitting, I “zerked” the damned thing. (Note: At some point I plan to move the side stand springs to the outside).

If you don’t lube the Suzuki DR-650 side stand and foot brake pivot, you will eventually have to live with a “floppy” foot brake and scratches on your clutch cover. Additionally, on the left side of your bike, the side stand foot will at some point begin to put scratches on your swing arm.

Our KLR-650-A’s at Top Gun are a little better off. Although the steering bearings are “less beefy” and more difficult to replace, the foot brake pivot can be lubed and if needed be unbolted and replaced when worn out. The side stand bracket is welded to the frame, but the spring is on the outside allowing one to neutralize the pressure when moving it up and down. Pauline’s 125,000 mile 1993 KL-650-A side stand and bracket are like new because I move it up and down correctly and lube it and the foot brake pivot often.

It’s difficult to believe, but true: if you neglect to maintain the moving parts attached permanently to your motorcycle frame, you may some day be faced with some very complicated and expensive repairs.

Lube it or lose it!