speedster, 33x3 wheels, front end within specs as with wear. Can be turning corner, go over a bump/dip, or just because. The guy who I'm writing for says the camber/toe in/caster has all been set though I wonder. He can be driving and the wheels begin to shake bad. To correct the issue, he makes a quick turn of the steering wheel one way and jerks it back to center and that stops the shacking.
If everything is tight, I would suspect the wishbone socket and ball is worn. Give it more caster by putting a curved shim above the wishbone ball, thus tilting the axle back more. Has the front end been lowered somehow?
Probably needs the spindle bolts and bushings replaced.
The bushings in the lower steering support bracket are often overlooked. Also, be sure that one of the spring hangers is not frozen up. Be sure that the pitman arm is tight on the steering column shaft.
Check the wishbone as stated, check the pitman arm, drag link ball, then if that does not resolve it - start looking at the wheel bearings and the wheels themselves. If they are wobbly or egg shaped or unbalanced it could be the root cause.
thank you all. will copy this and pass it along.
If it turns out to be the wheel balance - I have just recovered my Dynabead instructions page from the shattered remains of Gen III's website. I've posted it on http://www.tfoye.com for those interested.
On a side note my grandfather's Model A had a shimmy like yours, happened in braking and turning left and the wobble would persist until coming to a complete stop and starting over. Eventually the car became undriveable. He replaced everything in the front end twice and I'm not sure what the final result was, he died a year ago yesterday so asking him if/how he fixed it is not an option. I don't think he replaced the steering column so - maybe you will want to start there?
The last time I had one shimmy, the spindle arm was loose on one side. I tightened up the nut and put in a cotter pin and it has not shimmyed since. Anything loose including spring shackles, radius ball and socket, tie rods, steering column bushing, ball joints on ends of pitman arm etc. Wheel bearings and wheels not true, wheels out of balance. You just have to keep checking things out until you find it. I like to do one thing and try it out, then another thing and try it until I find out which one is causing the problem.
Norm, what happened when you had TWO shimmies ?
Just keep checking things until you have NONE!
Put the front end up on jack stands and start manipulating all the components. I have a suspicion it is more than one defective/worn part. You should be able to check the tires for dynamic or static imbalance by looking for scalloping in the tread pattern. I agree with John, sounds like a bushing/kingpin issue. But I do know a guy who has a '25 coupe that does roughly the same thing as described and rattles your fillings loose. His problem is the toe in/out is not correctly set.
Mine did that when I first got it. It was the spindle bushings/bolts. A couple of years later, a wobble came back. This time it was the tie rod end bushings. Mine only did it at slow speed, like turning into a driveway.
If you look real close, you'll find something that is not as tight as it should be.
My Tudor had a shimmy that was most noticeable going over speed humps.
It turned out it had two right spring perches rather than a left and a right. I'm not sure how many years it was driven like that but I would guess since the sixties.
Or, Mundinho, since it was originally built.I've seen way too many front-ends in the proverbial junkpiles like this for that not to have occasionally happened.
One of Ts did that once and new spindle bushings cured it. Your milage may vary.
Check the holes in the axle itself. They are usually worn. Be sure you have threads in the bottom hole. Stevens Front axle tool is the way to fix them. Dan