| gunner | -- 06-12-2018 @ 1:45 AM |
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My 1940 Ford 4 door has a bad shimmy around 55 MPH. I have new springs, ball joints, and king pins. The tires have been balanced. Some one did put on 15" tires with American Mag wheels. They barley clear the fenders. My tire shop said I could check for out of round and broken belts by setting a 6X6 block of wood close to the tire and spin it. I don't have more than a 1/16" gap and the same for the side wall. I have adjusted the TI/ toe in from zero to 1/4". It seems the best at 1/8" TI. It does have disk brake conversion on the front. I think I will try different air pressure. Would smaller tires help? Wheel bearings seem tight. I can get no wiggle any where when I have it on the hoist and pry and grab the wheels. Any ideas? gunner
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| carcrazy | -- 06-12-2018 @ 6:25 AM |
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Solid front axles can be tough to keep shimmy free. Do you know what the castor angle of the front suspension is? Sometimes you can increase the angle of positive castor to eliminate the shimmy. If the shimmy is confined to just one speed range I would suspect that the tires are out of balance. Aftermarket wheels sometimes cause problems because they either have too much runout or are not concentric. Do you have the correct amount of clearance on the kingpins?
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| ford38v8 | -- 06-12-2018 @ 9:36 AM |
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Gunner, As you have addressed the commonly known issues that cause a shimmy, I'd check the match of your wheel to the hub. Having mix and match parts, you may have defeated the hubcentic feature, which will put all the work on the lugs to center the wheel. (Lugcentric).No amount of wheel balancing will correct this issue. Alan
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| trjford8 | -- 06-13-2018 @ 7:22 AM |
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Take off the mag wheels and borrow some wheels that will fit and see if the shimmy goes away. Too much wheel off set to the outside can cause these type of issues. If your car has a disc brake conversion the wheels may already be moved outboard by 3/4". What type of front end do you have?The original front end ( solid axle) did not have ball joints and only had one spring(not springs). If your front end is not stock it may be hard to pinpoint the problem, especially if it was installed incorrectly.
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| trjford8 | -- 06-13-2018 @ 7:22 AM |
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Take off the mag wheels and borrow some wheels that will fit and see if the shimmy goes away. Too much wheel off set to the outside can cause these type of issues. If your car has a disc brake conversion the wheels may already be moved outboard by 3/4". What type of front end do you have?The original front end ( solid axle) did not have ball joints and only had one spring(not springs). If your front end is not stock it may be hard to pinpoint the problem, especially if it was installed incorrectly.
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| gunner | -- 06-15-2018 @ 2:36 AM |
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With all of your help I found it was the wheels. I did borrow universal mags for the front and no more shimmy! Yes it is the original straight front axil and all of the springs are new. I can see how to set toe in and out but with a solid axil can you adjust the camber and caster. I think I need a shop book. Any recommendations? gunner
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| TomO | -- 06-20-2018 @ 7:34 AM |
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Camber and caster are adjusted by bending the axle. Shops that service trucks may have the equipment. This service is rarely needed unless the vehicle was in an accident. Tom
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| shogun1940 | -- 06-20-2018 @ 8:44 AM |
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If you want to check camber put level from top to bottom on the wheel , you need a level with an adjustable degree a wheel, this will give you camber. Then turn the wheel in 20 degrees in and set the level to zero. Now turn the wheel out 20 degrees and this will give you caster. S.A.I. Is also important if you look at the angle of the kingpins and draw an imaginary line to the ground the center of you tire should intersect. This why wide after market wheels do not work sometimes. Last but not least is bumpsteer which is caused by the pitman arm having to much swing up and down as it moves back and forth to steer the car.
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