Wheels Shimmy after 60 MPH

It would be easy to blame the 17" wheels (as they are easier to bend than the stock ones) but the combination of your two posts makes me think that the problem actually lies elsewhere. What you are describing as a "shimmy" - is it really more like a low thrumming or vibration? A shimmy would be a lazier oscillation of the steering wheel, what I'm thinking is you're actually getting kind of a low frequency vibration that builds and dies at a very low frequency - 1 Hz or less. That would be a beat frequency set up by two separate vibrations that are almost - but not exactly - at the same frequency. i.e. if you have one item vibrating at 1000 Hz and one at 999 Hz they will set up a beat at 1 Hz. I'm going to go out on a limb and suggest that you check your CV joints - is there a lot of play in them? That could account for *both* of the problems you describe, if you have at least two badly worn CV joints, one on each side.

Let me know if I nailed it or if I'm completely off base here :)

nate

Yup. He is describing a harmonic vibration, the point where two or more less noticeable vibes coincide with each other to produce a momentary shake that ebbs and flows...very hard to pinpoint....could be anything from drive axles to tires to intenal tranny parts, body resonations, etc...slightly bent wheel hub mating areas are good for that too...it would be a good idea if you know anyone with a similar vehicle to swap out wheels and tires for test drive...that might nail it and you could stop worrying about it...

Lets see if we can tie the problem to the wheels. Try swapping the rear wheels for the front ones and note if there is any change.

I tried this and the shimmy was still there. And when I did the balancing the first time, all 4 tires were balanced, so as to rule out the rear tire being out of balance.

When they did the balance jobs did you or the tech look specifically for rims that were bent?

I say this because my now deceased older Volvo 240 had some of the nicest aluminum wheels i've ever seen, and it used something like 60 or

65 series tires. And yet after 6 years of driving it shimmied and vibrated no matter how the wheels were balanced or rotated. A careful look revealed that time had taken it's toll and all 4 rims no longer ran true. Replacing them with steel wheels solved the problem.

Hmmm, I did not.

Rotating the tire positions and seeing if a noise or vibration changes in character is one old trick that won't hurt anything and might give some insight into these devilish problems.

I've this sort of problem caused by a bent alloy rim (caught by an alert tire tech) and on another occasion by an internal tread separation (caught by a diligent and persistent tire tech who thought it odd that he was using so many wheel weights, and that the computer was telling him to put them in a different place every time -- eventually he busted the tire off the rim and saw that it was smiling back at him from inside).

I've also certainly noticed that some road surfaces, speeds, and car+tire combinations are one thing too many. Be sure you're testing this effect on a genuinely smooth stretch, assuming there is one where you can hit a suitable speed safely (good mechanics often have local favorites that help them in various ways pay particular attention to specific problems).

Best of luck,

--Joe

my 99villager van has the same problem I've been through the tire and wheel,alignment gautlet,with no success(places telling me I have separated belts in my tires)So I took it into a ***** garage. they pointed out my very bad cv boots.(torn and grease coming out of them)they were replaced, had it aligned, rebalanced, same problem but maybe worse , now i notice the low frequency sound or humming( i guess)someone else has mentioned, originating, it sounds like, from the wheel bearing area or cv joint itself.could my cv joints be bad and causing this all along? or did the

******* guy not repack my wheel bearings? im looking for suggestions

your wheel bearings are probably sealed and pressed into the knuckles; they were either replaced or left alone, there is no "repack"

nate

My '97 Lumina had some really robust stock alloys, not the spindly spoked designs you see a lot of now, but really solid with a lot of meat in all areas and not very likely to be distorted by minor mishaps, but even so it has one that gives up a minor shake on the highway if it is on the front...it's been there through three sets of tires, has no damage on either face and runs as true as the eye can discern without a runout guage...but there is no doubt it is the culprit...I just ignore it when rotation brings it to the front, and enjoy it when it's on the rear where I don't feel it....

My 2000 Impala had some American Racing alloys that the tire shop could never get the shake out of, or get the self-adhesive strip weights to stay on the inside of, even after cleaning the protectant off and and scuffing the surface...finally I gave up with them and did two things, I broke the tires loose and re-clocked them so the factory markings lined with the valve stems (as I was taught, but some now claim is not neccessary) and two of them required NO weight and were self balanced, the others I cleaned the inside with denatured alcohol and re-applied the adhesive weights as indicated by my bubble balancer, splitting the weight into fourths and moving them outward apart from each other until a perfect static balance is achieved, then applying them, and then gave them a little runover with a torch to hopefully get the adhesive to set up a bit better....never had any more trouble. One of them they had 1 and 1/8th ounce all in one big wad in one spot, and then 1/2 ounce almost, but not quite directly across from that...i have no idea why that would look right to a dynamic balancer...that much weight in one spot has signifant centifugal mass at speed, and I believe that alone could have produced the shake I felt...my balance job required no more than 1/2 ounce at any point, which was then divided four ways, very low inertial mass....

Apart from listening to noise (there's none), how can I check my CV joints. I already visually checked them, and the boots are fine, no grease. They have a bit of play on them, but I've tried other cars and it seems the normal. Now, i know that varies from car to car, but, how much play can be allowed on the joints?

It is usually rotational play I look for to see if they are bad. This requires the wheels be blocked and the transmission be put into neutral to unload the drivetrain. You then can twist the axle to see if there is play in that direction either way.

Another give away is to take a tight turn slowly. Lots of time a bad CV will make clicking noises when you do this.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >

What factory marking are you referring to? I have been told to center the brand name on the valve stem, also the dot label and various other marking and have yet to see it affect the balance in any predictable manor.

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brand name on the valve

affect the balance in any

there should be a red dot somewhere on the sidewall of the tire, that should be lined up with the valve stem. obviously when mounting used tires you probably won't be able to find the red dot.

nate

Hello, I checked both by CV joints and I honestly don't think they are bad. The boots look very good and there were not loose or had any play where they shouldn't. Also, i took it to another place to try one more balance and the tech touched the tires and said that they felt out of shape. He said that no matter how much I balanced, the problem would not go away.

That's another possibility :/

do you have access to a known good set of wheels and tires from a similar car, i.e. you have a friend with the same car that would be willing to trade you wheels and tires for an afternoon?

nate

Easy to check. Rotate the tires... move the front ones to the back and the back ones to the front. If the problem moves, it's the tires.

--scott

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A viberation at 60-80 mph lmost always is atire or wheel blance problem.

Sometime a regular tire balancer will not get the job done. Some tires need to be balanced on the car at road speed and the cars weight on the wheel. A hunter GSP9700 tire balancer will balance the tires on the car at road speeds. And will almost even balance a square wheel. For a location near you that has one click on the link below.

Good Luck and let us know how it goes. MT

Actually, he said all my tires were bad. And I would believe it because I had them all balanced on the first try, and I did switch front to back, and the issue was there, probably worse.

I think I may have to change rims and tires. The reason being:

1. To see if the issue disapears.
2. I don't like those 17 inch rims. They are Crome. They came with the car
3. Tires for those Rims are really expensive

I will also try to see if I can find the balancer as recommened in the previous post.