Re: Front End Shimmy: Could it be my old tires?

Posted by carla on March 16, 1998 at 15:51:09

In Reply to: Front End Shimmy: Could it be my old tires?
posted by Anthony Gal on March 16, 1998 at 08:05:52

: On my '31 Slant Window sedan I still haven't been able to figure out the cause of my front end shimmy, which typically occurs at low speed (5-10 mph) and disappears completely at high speeds.It's worst when I first start the car, and gets better after I've driven it a while. And it occurs following
: braking or if I slow down without hitting the brakes.
: I once ran into a friend who suggested that the shimmy be due to old tires. This car was restored over 25 years ago; about 2000 miles have been driven since then. And the previous owner
: who had it for 20+ years (who only put 1000 miles), never had replaced the tires. The current set are Firestone nylon blackwall tires (4.75 x 19). There is excellent tread, but some fine longitudinal cracks on the sidewalls. The tubes
: hold air just fine.I currently keep them at 35lbs.
: Should I get a new set of replacement tires or search
: elsewhere for the shimmy?And if I need to get a new set
: of tires, can someone recommend a place to help install them
: in metro Atlanta?
: Thanks
: Anthony Gal
heres my 2 cents worth:old tires are gambling devices and to runold tires is to gamble with tragedy, its cheap at the price to fit new, best quality tires considering the consequences of a tire failure in today's road traffic.

about shimmy: flat spotted tires would be a good starting point.if your shimmy is side to side like someone wrenching the steering wheel back and forth violently, the greatest likelihood is that the tendency of the front tires and wheels to oscillate from road irregularities is being magnified greatly by lost motion or looseness somewhere between the steering wheel and the front hubs. i would inspect the front wheel bearings carefully, repack them and be certain they're properly adjusted, then i would inspect the entire steering system carefully. having someone move the steering wheel back and forth an inch or two while you watch the steering linkages move. if you can see one part move even slightly before its mating part starts to move with it, thats too much. likely suspects might be king pins, tie rod ends, etc., but all too often a shimmy will be tracked down to lost motion in the steering box itself. you can most easily inspect this by disconnecting the linkage rod from the steering drop arm, and whilst someone holds the steering wheel, attempt to move the steering arm back and forth. more than a few thousandths (the necessary clearance) would indicate a worn sector shaft bush, or other wear or mis-adjustment in the box.
something to think about: there are lots and lots of old cars out there which have been beautifully refinished but weren't given a complete mechanical refit, so a restored car may still need a lot of detail work before its fit and safe on the road
hope this helps

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