My Early Days of Fighting the Snake Wobbles

By Grandaddy Joe Smith, All Rights Reserved

In the early days (1969) when I fell down at Irwindale Raceway in the lights due to a lock to lock wobble it was on the first Chassis I built. When the wobble started it was a slow kind of snake wobbling and then all of a sudden it was lock to lock. At the time I didn’t know the first thing about Rake and Trail and when I built the chassis I gave it a little more than stock rake. When I built the next chassis I bought a book on Motorcycle Frames and read about Rake and Trail, now that I knew what they mean I could understand the mistake I made on the first chassis.

The next chassis I built had 7 ½ inches of trail, the rake was 43 degrees. At the time it was considered a space age designed but it still had those little snake wobbles. I went to Laid law’s Harley Davidson and borrowed the devise they used to spin the front wheel doing a wheel balance. I put the bike on a block of wood under the motor with just enough height for the front tire to clear the ground, spun the wheel as fast as the machine would spin it and turned the handlebars left and right and let go and the forks would come back to center, I tried every way I could to make it go into a wobble but it always returned to center. I spun it up again and went to the rear and gave the slick a slight slap on the sidewall and the thing almost fell off the block in a lock to lock wobble. I tighten the steering dampener like always thinking that would take care of it, spun it up again, gave the slick another little slap on the sidewall and it was worse. I took hold of the slick at the very back and moved the tire side to side slowly it would get that snake wobble. I started loosing the dampener until it was completely loose and lost the snake wobble. From then on the dampener was always loose; I eventually took it out of the neck.

It was right after that I was at the Harley Factory asking for a new truck and the President at the time was AMF, he came from Chrysler and while he went about getting me a truck he had someone take me to a meeting in the Engineer Department to get me out of his office. There were some pretty big guys sitting around this table including Dick O’Brian (racing Dept.). There were a lot of things being discussed and it came around to the Police Bike and its wobble problems. They discussed it for quite awhile and finally O’Brian looked at me and asks what I thought about the problem. He took me by surprise, but I knew he was trying to put me on the spot because some of my money came out of the Racing Department (most was from Advertisement) and he didn’t like it. So being the entertainer I am I stood up and begin talking.. “You Gentlemen know that the reason the Police Bike has a problem is simply because of the weight on the rear because of the Radio Boxes. They’re made out of steel, why don’t you make them out of Fiber Glass like your Saddle Bags and take that Dampener off the front forks and maybe your wobble problems will be on the way to being solved. Guess what?

The time I spent working in a Sailplane Company I learned some things that could be applied to building a chassis. The biggest thing I ever learned about curing wobbles came from there. They have there “Bench Racing” and one night I stayed to see what they talked about. During the conversation one of them ask me what kind of problems I face in the Drag Race world. I mention speed wobbles. He laughed a little and said we have our wobble problems too but it’s in the tail. He explained that when the Sailplane developed a tail wobble they try to correct it but they couldn’t move the stick the right direction fast enough to stop it, they just make it worse. They came up with the ideal of letting go of the stick and the tail stopped its wobble. He said he understood I couldn’t let go of the handlebars but maybe if you put even pressure forward with both hands it might work. On my singles even with the dampener out it had the snake wobbles occasionally but would stop on its own. When the next snake wobble started; I push forward with even pressure with both hands and the snake stop sooner.

I felt that what started the wobbles was the slick would get hooked up at growth and did what I called “begin to walk on the side walls” which cause the rear section to make the chassis pivot on the bottom bearing of the fork stem and if the dampener was tight enough it would work its way to the forks instead of staying there on the bearing.
The year I went to Bonneville I put those small dampener’s on that went from the frame to the forks and every run I made I had to shut down because of wobbles that started every time I shift gears. I took them off and It solved my wobble problems.

Every good run I made with my Double Engine Top Fuel Harley would get that snake wobble every time I shifted into high gear and I stopped everyone with that “push forward with even pressure with both hands”.

I’M NOT SAYING THAT YOU SHOULD DEPEND ON THAT WORKING ON YOUR BIKE. I’M JUST SAYING THAT’S HOW I LEARNED SOME IMPORTANT THINGS ABOUT BUILDING A CHASSIS IN THE EARLY DAYS. BUT IF YOU GET THE OLD SNAKE, GIVE IT A TRY...