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Old 07-26-2016, 05:37 PM
 
Location: San Diego A.K.A "D.A.Y.G.O City"
1,996 posts, read 4,767,759 times
Reputation: 2742

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I have had this problems for awhile now but I never bothered to address it until recently.

I am fairly mechanically inclined, but this one's a stumper.

The car is a 94 Cadillac Fleetwood with a 187,000 miles on it, with tires that are a little over a year old.

I just rotated and balanced the tires last week and it seemed to help the slight shimmy, but it's back again and I can't figure out what is wrong. I had an alignment done 6 months ago, and it didn't solve the problem.

Even with older tires, the car did the same thing, but now it has seem to only gotten worse recently.

Here are my symptoms.

There's a subtle shimmy at speeds of 50-70 mph, if I have a water bottle in the cup holder it will slightly shake back n forth or side to side. I don't have any vibrations or "shake" at the steering wheel, nor does the car pull to the left or right.

My first thoughts are the U-joints and driveshaft, but how could one surely know that's what the problem is?

When I accelerate and or let off the gas pedal, there's no changes in the shimmy even at cruise.

I almost think it could be a bad ball joint, but I don't know how much play a bad ball joint can cause a something like this.

The car sits evenly with new front and rear shocks, including new rear springs. Upper control arm bushings were replaced a few years ago, never touched the lower ones however.

The tie-rods are original and never been replaced though.

Wheel bearings are new.

Basically, even after doing some suspension work, brake work, having new tires installed, I have been dealing with this problem for a long time.

Another thing I would like to mention is that I notice now that the car isn't suppressing little bumps and road imperfections as well like it used too. Those small imperfections are now vibrating into the cabin.

The shimmy happens on most road surfaces, perfectly smooth ones it isn't so bad, but it's still there.

I appreciate any feedback!!
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Old 07-26-2016, 05:57 PM
 
1,831 posts, read 3,196,756 times
Reputation: 2661
I would jack each corner up one at a time and get down on the ground and spin each tire freewheel and watch the gap between the pavement and the tire surface as it spins. Leave about an inch gap. Look for a bulge or out of round, or a wobble. I have found tread separations and slightly bent rims this way. Spin fast and slow and watch it very closely for any flaw in the revolution of the wheel/tire. If it is a shimmy, I tend to look at the rear tires first.
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Old 07-26-2016, 07:44 PM
 
505 posts, read 846,924 times
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Get the front end up in the air and look for loose parts. Pay specific attention to the lower ball joints and control arm bushings. You said you had the tires balanced; a good tire tech should've picked up any bent rims at that time.

Rule out the transmission by shifting into neutral and see what happens.
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Old 07-27-2016, 01:59 AM
 
Location: San Diego A.K.A "D.A.Y.G.O City"
1,996 posts, read 4,767,759 times
Reputation: 2742
Thanks guys, I'll check the wheels and tires tomorrow, including the transmission.

Could a bad-tie rod or loose tie-rod cause a shimmy?

I remember that I did have a nail in one of the tires that got patched up, would that cause any issues?

Also my tires are some off brand chinese WW's, I am not sure if that might have anything to do with it.
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Old 07-27-2016, 02:46 AM
 
Location: SW Corner of CT
2,706 posts, read 3,374,764 times
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Definitely put it on a lift and check those front end parts for wear
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Old 07-27-2016, 04:37 AM
 
Location: Floribama
18,949 posts, read 43,571,506 times
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Quote:
Originally Posted by sdlife619 View Post

Also my tires are some off brand chinese WW's, I am not sure if that might have anything to do with it.
It certainly could. Have you checked the pressure in each tire to make sure they're at the recommended psi (according to the door sticker)? Many times tire shops will overinflate them to the max psi written on the tire.
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Old 07-27-2016, 08:27 AM
 
2,684 posts, read 2,397,471 times
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Quote:
Originally Posted by southernnaturelover View Post
It certainly could. Have you checked the pressure in each tire to make sure they're at the recommended psi (according to the door sticker)? Many times tire shops will overinflate them to the max psi written on the tire.
Sorry, but I disagree with this comment. If the shimmy is unaffected by having the tires changed, balanced, rotated, and an alignment done, then I'm going to go out on a limb and say that it isn't the tires. And it certainly isn't the tire pressure.

To me this points to a bent rim (which could be corrected by high speed balancing only), or potentially even a bent/off center axle component. Wheel bearings are also a possibility but unlikely since they tend to have other symptoms too like loud oscillating noises. I'm not terribly familiar with this year and model, but Cadillacs back then had rims with lots of embellishments, so a rim issue is what I'm leaning towards.

I really like Rivertowntalk's suggestion, as this technique will identify out-of-round tires, off-center axle components, and bent rims. It won't identify an issue with a rim embellishment but high speed balancing could deal with that one.
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Old 07-27-2016, 08:38 AM
 
Location: Outskirts of Gray Court, and love it!
5,671 posts, read 5,868,959 times
Reputation: 5802
My 2013 Chevy truck does that on newly paved/smooth roads,(Which in my oart of SC is hard to find!) and I know nothing is wore out or the tires are bad or anything like that. Im thinking its your choice of tire.
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Old 07-27-2016, 08:48 PM
 
Location: Out there somewhere...a traveling man.
44,620 posts, read 61,578,192 times
Reputation: 125775
60-75 mph shimmy is generally a out of balance tire.
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Old 07-28-2016, 12:19 PM
 
Location: San Diego A.K.A "D.A.Y.G.O City"
1,996 posts, read 4,767,759 times
Reputation: 2742
I checked out the tires and wheels yesterday, and they all seem to be fine. But when I jacked up the front end, and grabbed the front wheels at the 12 and 6 O'clock position, both wheels had slight play in them. Enough to warrant a wheel bearing adjustment.

It's crazy because I could literally turn the wheel nut loose by hand!

I retorqued the wheel bearings to spec as they were way off, and took it for a drive. The car drives and feels much tighter, and there is less of a shimmy now.

CA streets and freeways are in terrible condition, especially in the major metro areas, so after so many encounters with potholes, uneven pavement, bad and cracking asphalt and everything else you can imagine, it causes a major beating on vehicles suspensions/steering components. My car is no different, but what I can say, is that considering the Caddys age, parts have held up pretty well.

The shimmy is still there, but it's not as bad as before. My tie-rod ends have excessive play in them, so I need to get those replaced which I believe can also be causing the wheels to shimmy at high speeds.

The passenger side upper ball joint also has play in it, and could also be contributing to the problem.

Everything else looks good.

I will eventually replace those parts when I can, and report back in the future for an update.
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