At speeds of 60 to 70 mph both front tires develop a severe bounce that seems to alternate between the two tires after having hit a bump in the road. I’ve had the front end inspected by three different mechanics, balanced and rotated the tires, tightened the adjustment screw on the steering gear box. Nothing permanently fixes the problem. What could be the cause?
You may need an alignment which includes the rear axle.
Was this vehicle ever in a collision or been bounced off curbs? There may even be a bent rim to contribute to the shimmy.
Are there any loose wheel studs and/or stud nuts?
There may also be the start of a separation in a tire.
For your safety and those around you, I highly recommend you cease driving so fast as to induce this shimmy until the vehicle has been repaired.
I see you didn’t mention the year/make/model or mileage of the vehicle but weak shocks or struts can attribute to the bouncing too.
It would help if you could provide the year and make of car along with a rough guesstimate on the mileage.
If I go off the deep end and assume your vehicle is a Jeep, then you should probably replace the steering stabilizer.
If I go off the deep end and assume your vehicle is a Jeep, then you should probably replace the steering stabilizer.
Or a older original VW Bettle.
Ditto.
(And only on the Super Beetle; the standard Beetle did not have a steering stabilizer.)