Bump Steer Problem

[hitec1]

Hello, all,

I have a 1989 Honda Goldwing with 150K on it and I have begun to notice what I refer to as bump steer. I don't think this is a new or suddenly appearing problem. Instead, I believe that it has possibly just gotten worse over time. Now either its severity has increased or age or wisdom are telling me that this is not safe any longer. I notice it once some time ago at highway speeds on what I call a humpy interstate fly-over. As I leaned into the corner the road surface started a rhythmic bounce. As it did I notice that a wobble or bump steer effect was happening and I eased off the throttle and as soon as the bouncing stopped, so did the bump steer. While I'm sure this is suspension related, I don't think this was a speed wobble. Though I did feel like if left unchecked or at higher speeds, it may have resulted in a tank slapper.

More recently, at highway speeds again only on a straightaway section of a bridge with the same rhythmic bounce, I noticed again. I suspect that one of the front forks or rear air springs is weaker than it's opposite causing the bump steer. As soon as the road flattens our the bump steer stops and the bike rides fine.

Any help in determining the cause and how to identify the offending part would be greatly appreciated.

[Wing--Man]

Things to check...
One bad fork.
Swing arm bearings.
Wheel bearings.
Steering bearings.

[CrystalPistol]

As built by Honda, 1500s have two different rear suspension units …. one is a shock with spring, … and the other has an air chamber (no spring) … and so unequal pressure is applied to swing arm, … which was built to handle it.
There have been more than a few GL1500 swing arms suffer weakening due to internal corrosion. Such a swingarm could flex under changing loadings, resulting in a rear wheel moving around or leaning back & forth.

Something to check.

If it had happened only in sweeping turns, I would have suggested changing trail of front forks due to rear moving up & down as cause … but you said it happens on straights.

[dadztoy]

Front end wobble can be caused by any number of things but when I noticed it on my previous 1500 it was sue to insufficient steering head bearing torque... Simply re-torquing steering head bearings resolved the issue...