First, though-

Posted by Bob Carabbio on January 09, 1998 at 19:53:51

In Reply to: Re: Front Wheel Shimmys & Shudders
posted by Tony Sillman on January 09, 1998 at 18:07:09

With the car up on Tony's jack stands check for loose stuff.
If you can shake the wheel and there's play between the brake drum and the backing plate, you should start by eliminating that play.What's REAL common is spindle damage in the area of the outer wheel bearing race.this prevents you from getting a good adjustment on the bearings. If you can see a groove in the spindle where the bearing runs, then the spindle should be replaced, although you could shim it temporarily. tightness here is critical
Check for warped drums.All drums are a little out, but serious warpage can cause wobble.
Check for looseness between the steering arms and the spindle.
wiggle the wheel from the 3 O'clock and 9 O'clock positions (like the steering direction) and check if there any relative motion between the spindle and the arm. ANY looseness is way too much.
With a large pipe wrench try to twist the front axle forward and back.check for relative motion between the axle, and the radius rod ends.ANY motion here is too much.
It's real common for this to be loose, and that plays havoc with the castor setting.It common for the taper (that the perch nut fits into) at the bottom of the radius rod end to be badly worn.loss of castor angle will make the steering really unstable. It should be 5 degrees, but if the radius rod is not bent, and the joint is tight it's most likely pretty close.
Don't worry about the king pins unless they're REAL bad
Wiggling the wheels from the 3 O'clock and 9 O'clock positions, look for relative motion between the steering arms and the tie-rod ends and the drag link ends. ANY motion here is too much.
The drop the car on the ground and have somebody wiggle the steering wheel back and forth about 1/4 turn while watching the radius rod ball socket under the flywheel housing.A little relative motion here isn't serious, but a lot should be corrected immediately.I think the rubber ball joint is a better way to go than the original spring loaded socket.
Then check the toe-in.
You should ALWAYS set toe-in with the wheels on the ground AND after you have rolled the car forward at least 3-4 feet.This establishes the real relationship of the components. Also make sure that wheels areset straight ahead.
Tony's line on the tires is a real good idea, and absolutely necessary if you can see wobble in the wheels when they are spun.Measure at 3 O'clock and 9 O'clock positions.The spec. is 1/16" but 1/16" to 1/8".Excessive toe-in won't cause shimmy, but will wear tires, and drive mushey.
Happy hunting
Bob Carabbio

Follow Ups:
Re: First, though- Giles Dillingham January 10, 1998 at 12:59:57(2)
Oh that- Bob Carabbio January 10, 1998 at 14:18:27(1)
Re: Oh that- Giles Dillingham January 10, 1998 at 19:24:49(0)

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