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What's causing steering to shimmer?


tigersdad

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I have a 1931 Cadillac Town Sedan and replaced the older tires because the steering was shimmering to the point that I had to pull the car over to the side of the road. Long story short, got new tires and the steering still shimmers. The steering seems tight. Any suggestions?

Thanks!

Jay

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Guest elmo39

you could also check your steering knuckle pins (king pins) if they are to badly worn it will make no difference if you do a wheel alinement or balance your wheels it will still shimmy

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Guest stude8

Shimmy with cars that have front leaf spring suspension usually results from the change in spring arch due to sagging from age.

The common correction was and still can be addition of a wedge between the straight axle spring flange and the leaf that contacts it where spring set is attached. This will restore the king pin angle to where it is supposed to be.

These wedges came in 1/2 degrees increments and it only takes about 2-1/2 or 3 degrees to eliminate the shimmy. Find an old spring shop that might have an assortment on the shelf. Up until the 1990's some trucks used such wedges.

They come in the width of your spring (1-3/4" or 2" etc) are about 4 0r 5 inches long with a slot from one end to the center so they can be installed by loosening spring U bolt clamps slightly and then tapping them into place and retighten the Ubolts.

I have corrected two 1929-30 Studebaker President cars over the years I drove them. I might have a half unused box of them but it hasn't been seen for some years now. Stude8

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Stude8,

Thanks so much for the re-inforcement on what Owen had stated earlier. On the thread "Can you say shimmy", it appears that this problem is common and can be corrected by inserting the wedges. I'll check my Tire and Brake Shop here in town since they do work on the old cars and see if they have any. If not, you'll see an add in the WTB section of this forum. Thanks, again!

Jay

Novato, CA

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Guest stude8

Jay attached are photos of the shims you need, they come various angle increments, the one in photo is 3/4 degree.

If your shop has data books that list the correct angle for your Caddy and can measure what you have now they can prescribe the correct shim size to restore your caster angle and eliminate the shimmy. Stude8

post-31139-143138049254_thumb.jpg

post-31139-143138049256_thumb.jpg

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Guest stude8

Here are 2 pages out of 1934 Bendix alignment book about caster adjusting. I reduced them to fit this web site, if they don't blow up large enough for legibility send me a PM and I can email full res via regular ISP. Stude8

post-31139-143138049259_thumb.jpg

post-31139-143138049261_thumb.jpg

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Stude8,

This is worth a million words. Thanks! I printed our conversation earlier this afternoon and brought it to the tire and brake shop. The owner looked at it and said they could do it with no problems. He asked the width of the springs, 2", and will set out to find the correct shims. I am going to print this out and bring it down to them on Monday. This is invaluable! Again, everything is much appreciated!

Jay

Novato, CA

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  • 4 weeks later...

Gents,

A quick follow-up on the "shimmering" problem on the 1931 Cadillac. I had the Steering Modulator Springs replaced and the car ran fine up to about 25 miles an hour when once again, it began to shimmy, though it did stop when I slowed down. Shims were inserted to bring the caster back to the recommended angle. I don't know if I had mentioned that the steering is extremely hard.....like a Mack truck with no power steering. Could the steering box be part of the problem? Thanks again for the help and suggestions. Looks like we are finally nailing it down!

Jay

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How about the camber and are you sure you don't have too much toe in. Perhaps your toe in is not equal. One tire might have more than the other.

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