The Stovebolt Site Forums The Shop Area Engine Shop Need help with front end shimmy

I have a 1983 Chevy 3/4 ton 4x4. It has 129,000 miles on it. On occasion, at low speed or when I hit a bump with the front tires, it developes a VERY bad shimmy in the front end that feels like I am going to loose control of the vehicle. I replaced both front shock absorbers and the front stablizer about a year ago when this had happened before and the problem resolved until about 2 weeks ago when it statred to happen again. I'm afraid to drive the truck anymore without getting this problem fixed. Please HELP! Thanis, Perry

Perry I'll give it a shot. jack up truck put front axle on jack stands. With wheels off ground and on jack stands, shake front wheels top and bottom and grab sides and shake wheels that way also, should be tight very little movement like 1/16 to 1/8 inch, if you get a lot of movement crawl under and shake tires under truck and look for loose steering or king pin ball joint parts. IE> tie rod, upper lower knuckle joints. shake everything. check leaf springs for broke leafs. also grab front drive shaft see if yoke or ujoint sloppy. check steering gear and drag link for slop. hope this helps and good luck.
jbennett
40 burb

My bet is a badly worn tie rod end with out-of-round and worn tires,
Scott

Thanks for the replys. The tires were installed new about 4,000 miles ago and are about 90%, so I doubt the tires themselves are the problem. Will check linkage and joints. Thank, Perry

I'm wondering what kind of tire man would change out the tires and not check out the suspension. It only takes a few minutes while its on the rack to walk around the truck and give everything the shake test and have a look at the shocks and brakes. That was required when I worked at Sears Auto Center in Reno.
I'd bet the tire tech could've spotted the problem back then.My guess is right tie rod.
Speed

Either bad ball joints or bad shocks (or both) could cause that condition.

Take a look at your idler arm.

This could also occur as a result of an improper caster setting in the front suspension. After rebuilding front ends on several old trucks I've had to adjust the caster settings. This is done by inserting wedge shaped shims between the axle pad and the spring. Redcoat

I would look close at the axle joints. Make sure they are not rusting up on you and binding. Jack up one side of the front axle. Turn the wheel out a bit and spin the tire.Make sure the axle is spining. The tire should spin free. If it turns hard or binds, the joint needs to be replaced. I came across this problem a few times while working at a garage.

You described the classic symptom of a loose idler arm. Check for up-down play and if any is present, replace the bushings. The symptoms can be exacerbated by caster angle problems, loose tie rod or drag link ends, but it almost always starts with the idler arm. When it happens, a quick application of the brakes usually stops it.

Redcoat is right on... I had the same problem with a '50 3600 that I had completely rebuilt the front end. I stopped by the alignment shop and he said, without even getting under the truck, "The caster is off..." The axle needs to be "raked back" a bit with caster shims between the axle pad and spring. Made all the difference in the world. Before it felt like someone had replace the front wheels with shopping cart wheels...

Andy