Harley wobble-tragedy

[bob deluke]

Once again guy thanks for your opinions, great info on this issue. I talked to Phil’s wife and his daughters at the funeral yesterday. She was holding it together pretty well. She’s going to retain a lawyer to investigate the accident. Phil’s oldest daughter is working with his wife to retain a lawyer ASAP. She told me she looked at the bike at the impound garage, and said the bike didn’t look that damaged. I suggested they get an investigator familiar with motorcycle accidents to look at the bike and she agreed. Time will tell I guess.

[flatbutt]

Originally Posted by Baz

I just got back from visiting my mechanic and a customer of his came by to check on his '59 Chevy delivery wagon rat rod.

This guy owns a Harley repair business.

I asked him about the wobble and he said most of the time it's due to worn bearings in the front suspension.

Sorry about your friend, Bob. A real reality check.....

This was a new bike so unless the factory built it with faulty bearings I don't see how that applies. Further, although I'm not a mechanic what part of the suspension uses bearings? Wheel bearings and a steering head bearing for sure but what else? A faulty valve in the front fork?

[javadog]

Originally Posted by flatbutt

This was a new bike so unless the factory built it with faulty bearings I don't see how that applies. Further, although I'm not a mechanic what part of the suspension uses bearings? Wheel bearings and a steering head bearing for sure but what else? A faulty valve in the front fork?

Steering head bearings would be the first place I'd look. Headshake is often cause by steering head bearings without the proper amount of preload. Who knows if this is checked on a Harley assembly line? I know I check it every time I get the front end of a bike in the air. All you need is a simple strain gauge (even a fishing scale would work) and an idea of what force the designer thought was optimum for the amount of force required to rotate the front forks.

The other thing I'd check on the front end is tire pressure. Too much pressure reduces the damping effect of the tire on these sorts of problems. Bikes can be very sensitive to tires. I remember visiting with Paul Dean in his office at Cycle World about 10 years ago, and we talked about the US introduction of the Suzuki GSX-R750 at the Laguna Seca racetrack. Suzuki had prepped a bunch of the bikes for the US journalists to ride around the track and they had two different tire brands on the 750s. Paul said one brand made the bikes handle very well, the other brand made them feel like they wanted to spit the riders off in every corner. Same bikes setups, same tire pressures, same tire sizes, just differences in the tire constructions.

As for what other bearings there are, the most obvious ones would be the swingarm bearings. They are more of a problem with weave than wobble, but we don't yet know if the bike was wobbling or weaving. The former has a higher frequency but the witnesses may not know to make that distinction. Either problem looks bad to the untrained eye, they just know that something is wrong.

I have seen riders spit off of racebikes at the track from headshake. It's a horrible thing to witness firsthand.

[flipper35]

A friend of mine lost his dad to high speed wobble. He was on a Honda Shadow. It can happen on any bike, street, dual sport or dirt.