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'03 STS, '99 SLS (sold), '02 Yukon, '02 Z28
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77 Posts
Discussion Starter #1
I have heard of a shimmy @ 60-70mph. What is it caused by and what can fix it. I recently slapped on some "20's and I can really feel it now. I am having the wheels and tires rebalanced to make sure that it's not them. I also heard that there is a specific proceedure and tourque specks to follow when mounting wheels and tires.
 

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2005 STS4 1SG: GM Acc Lights, Corsa, Platnium Grille, Volant
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15,987 Posts
another "worth while" post...
1. strut tower brace helps
2. road force balance
3. remove those 20 inch rims theyll destroy your VERY EXPENSIVE struts
 

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2002.5 F55 CORSA STS, 2014 Explorer XLT FWD
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69,112 Posts
:bigroll: The Seville Shimmy and Hunnter Road Force balancing have been the subject of hundreds of posts in this Forum. Use the Technical Archive and the search functions at the top of the page and be prepared to spend a couple of days playing "catch up" reader........As for the 20" wheels, you're now in for a long series of balancing and tire changes in order to get things right again. Always list your car info in your header......it makes diagnostics much easier.
 

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2001 Cadillac STS
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154 Posts
How many people had the shake/shimmy problem go away after installing a strut tower brace? I, like everyone else, am trying to get rid of it.
 

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2004 seville
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28 Posts
I had a 2002 deville with this shimmy vibration problem, I was certified and had struts, shocks, wheel bearings, tires, road force at 2 different shops, drive shafts, motor mounts upper bars and lower control arms. I got rid of it for fear of the viration. I got a 2004 seville, and have the same problem, road forced, tires changed, rear shocks, front bearings, computer ride vibration snesor system eval and I still Have a vibration. It is sad that the mechanic says this thing vibrates bad and Cadillac tells Him it is in an acceptable range. GM did something that makes these cars ride like a post accident yugo. I would avoid buying another, I drive 50k miles a year.
 

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White Diamond 2001 STS
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1,317 Posts
I had a 2002 deville with this shimmy vibration problem... I got a 2004 seville, and have the same problem...
Why did you buy the '04 knowing it had a vibration? If you knew it was a problem with the '02, I'd have really test-drove the '04.

Not all cars have this problem. My '01 is pretty smooth.
 

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1992 STS / 2005 MB G500 / 2003 STS / 2006 XLR-V
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11,694 Posts
Its another common issue, if a road force balance doesnt fix it, there are other issues in the suspension. 20 inch wheels do not help anything.
 

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97 Posts
I am experiencing similar problems with my 98 sls with 20's. But in my case i am positive its the rims because in the winter when i was running stock wheels and tires my car ran super smooth without any vibrations. So did you have vibrations prior to putting the rims on your car?
 

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'03 STS, '99 SLS (sold), '02 Yukon, '02 Z28
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77 Posts
Discussion Starter #13
I think I did have it prior to the rims. They just amplified the problem. Stock tires have a bit more side wall and are capible of asorbing a lot. To me it feels like when you have a "mis" @ low rpm's & under high load. It's just annoying. You can try to smoothing things out by retorqueing the wheels. When you do it make sure the wheel is off the ground. Torque at 60-80-100ft lbs. Stick a jack stand under the side of the tire to keep it from turning. It made mine just a bit smoother.
 

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2002 STS
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47 Posts
Is the shimmy destructive in any way? I am planning a 1800-2000 Mile Road trip and am wondering if I dont get it RFB before i go will it hurt the car?
 

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'03 STS, '99 SLS (sold), '02 Yukon, '02 Z28
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77 Posts
Discussion Starter #16
How does it feel? Like an annoyance or like the wheels are going to fall off? I am sure over time it will cause damage. Expecually with ''20's. The car was never engineered to to have them. If you have "20's, take them off for the trip. The Shimmy, lack of power, & lack of breaking caused me to take them off. I am only going to use them for car shows and other non frequent occations.
 

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The Northstar Tuner
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2,759 Posts
99% of the time a vibration between 60 to 70 mph is a wheel assembly vibration.
Tire vibrations occur at different speeds in different cars. I really don't want to go into all the causes of Vibrations. You need to figure in tire size, gear ratios, engine rpm's.
My point is Northstar Caddy's use two gear ratios and two rim sizes. This will make a tire rotation speed vibration come in at 60 to 70.
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You have too much Radial force or too much Radial run out.
Radial Force is the spring rate of the side wall of the tire.
Radial run out is the Run out of the assembly. This could be described as a egg shape assembly.
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If your rims do not center on the Hubs they can Vibrate.
If the hole in the center of the rim is too big your wheel assembly will not spin true. it will go up and down per revolution.
You can install Hub Centering Rings to correct this.
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The second picture is measuring Radial Run out
 
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