Chevrolet C60s - Front Wheel "shimmy"

[Hanno Spoelstra]

Originally Posted by cordenj

So what lessons from all of this that might be useful to others? Well my interpretation based on the practical lessons of my truck of last 3 months:
*snip*
6. New tyres made a MAJOR improvement.

7. Tyre pressures seems critical on my truck. New tyres printed with recommendation of 65 psi; practical user recommendation of 55 psi seems to work well. I had previously tried 35 and 43 psi on the other second hand ex-Bedford RL tyres

8. Wheel balancing: made no difference to onset of shimmy. So a waste of time in my view at speeds I am going at (30 -35mph)

Originally Posted by Richard Farrant

I believe the actual reason is tyre circumference not concentric with the wheel rim in a lot of cases, which will upset the balance, also these vehicles stand around a lot and it takes time for them to warm up and the casing to reshape itself. Bar tread type tyres can develop strange wear patterns on the front wheels, none of this helps.

Just adding my 2 cents, worth... The big, heavy tyres used on CMPs certainly play a role in making any play in the steering and suspension apparent.

I had flat spots on my tyres from standing still. It was so bad it would not go away by driving a long distance to heat them up.

So I had the tyres trued up to make them perfectly round again. After this: no more shimmy.

HTH,
Hanno