[cordenj]

I'd welcome any thoughts on why this is happening and suggestions for curing it.

Tyres: 10 x 20 Bar grips (good secondhand)

Wheels: standard splitrims. I have had the two front wheels professionally balanced in an attempt to cure this. One wheel required significant number of lead weights to be pronounced suitably balanced. Had hoped that would cure it, but sadly not.

Tyre Pressure: 43psi in each side

Symptoms: At any speed above 20 mph the front wheels can suddenly start to violently "shimmy", usually triggered by a pot-hole (of which we have many in UK!). Slowing down causes the "shimmy" to slow and stop and the truck can then be driven on without coming to a complete halt. I say it is violent because the steering comes "alive" and when viewed from outside the cab appears to shake.

Checks I've carried out so far:
1. Checked tyre pressures to be 43psi

2. Checked wheel balance weight still on rims

3. Checked toe-in by stretching thin cord across face of fitted tyres and aligned to rears as I would for the Jeep. Very slightly "toed-in" - about 3/8 in . Manual say should be zero.

4. Camber: With wheels jacked off the ground, measured camber with spirit level. Found LHS wheel to lean out 1 1/4 in across the diameter of the tyre.
RHS wheel lean out just 1/4 in.

I probably should I check these again with the wheels on the ground, but is this a significant difference on these trucks?

5. Steering: With wheels jacked off the ground, about 2 inches movement in steering wheel rim before wheels start to move. Is this within reasonable limits for a CMP C60? My Jeep has similar play but does not shimmy.

6. Wheel bearings: with wheels jacked up, wheels rotate freely and there is no obvious play when the top of each wheel is pulled in and out.

7. Steering tie-rod: levered rod to see if any excessive play or movement. None visible.


Any thoughts or ideas based on experiences with these trucks are very welcome as the truck isn't driveable for any distance like this.

Many thanks