Car shivers

Secrets, tips, tools, design considerations, materials, the "science" behind it all, and other topics related to building the cars and semi-trucks.
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pinedust
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Car shivers

Post by pinedust »

I just finished a 1.5 oz wedge car, added a 3.5 oz. wafer of weight over the rear axle area, when I weighed the front of the car, it showed 1.5 oz. of weight over the front wheels, used the pro body tool for good axles, and a matched set of "good" (not machined) wheels. The cars' rear end shivers down the track. Where do I start to resolve this problem? I have not aligned the car yet. This was the first test run. Any suggestions?
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TurtlePowered
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Re: Car shivers

Post by TurtlePowered »

Did you sand the wheels to get them smooth before the test? Did you sand and polish the axels smooth before the test?
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Stan Pope
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Re: Car shivers

Post by Stan Pope »

pinedust wrote:The cars' rear end shivers down the track. Where do I start to resolve this problem? I have not aligned the car yet. This was the first test run.
I can visualize several kinds of motion that might be described as "shivers":
1. Small rotational oscillations around the long axis
2. Small rising and falling on one side of the car
3. Small side-to-side oscillations.

Or is it something else?

Can you clarify for us, please?
Stan
"If it's not for the boys, it's for the birds!"
pinedust
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Re: Car shivers

Post by pinedust »

I removed all flashing and burrs and polished the axles.

Its hard to describe but the car makes rapid side to side movement. Seems like it whips back and forth.
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Stan Pope
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Re: Car shivers

Post by Stan Pope »

pinedust wrote:Its hard to describe but the car makes rapid side to side movement. Seems like it whips back and forth.
But these are small body motions, not wheels sliding on the track. Right?

If so, it is a speed limiter, and we need to get rid of it. I've seen this when the bore is not perpendicular to the plane of the wheel. How closely does the shimmy period match the wheel rotation period? About 1 full shimmy for every three inches of car travel? Faster? Slower?

If much faster, then look to the bore holes for crud. If about the same, look at the orientation of the bore holes and check interior for minor problems.


If you can't resolve it, build a new one and enter the old one in a hula contest. :)
Stan
"If it's not for the boys, it's for the birds!"
pinedust
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Re: Car shivers

Post by pinedust »

Well, I put a new set of wheels and axles on the car and it runs good! Now I'm going to tackle your wheel alignment process. Thanks for your reply!
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Stan Pope
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Re: Car shivers

Post by Stan Pope »

Okay!
Stan
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Jungle Jim
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Re: Car shivers

Post by Jungle Jim »

Upon seeing the topic I thought, "you should of seen my car when I was sitting in it today waiting for it to warm up :D
Jungle Jim
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