[grumppyoldman]

Others mentioned brake drums out of balance, I even went that far trying to get mine balanced the best I could. Took off tires with rim, removed the hubs, washed out grease, installed hubs and let them rotate to heavy spot on bottom, took side grinder and removed metal at heavy side until it set where ever I stopped it. This may seem like overdone, but the shimmy I had was driving me up the wall. The biggest factor causing it was the toe-in was not set right. Al