Steering Wheel Shimmy 55-75

What exactly do you call "shimmy"? To most techs a shimmy is a back and forth motion of the steering wheel or vehicle. If that is that case, I would suspect a bad R&P. They go bad often.

For whatever reason you almost certainly still have a tire/wheel problem. I have more than once had to tell tire store employees that I will NOT accept that egg-shaped tire they just mounted no matter how many weights they put on it and call it "balanced." I am not familiar with this particular tire so I don't know how big it is, but you should look at no more than 2-3 oz of weight per wheel. There can also be a problem if you have custom wheels that don't readily accept outside weights and they are trying to balance the tires from one side only. That simply does not work!

Through the steering wheel in particular or overall in the whole car?

OK, that rules out inner CV joints.

If the bearing is horribly loose that will normally cause a violent shake set of by going over a bump at low speed.

Don

----The shimmy is a back and forward motion in the steering wheel. I can feel it specifically in the steering wheel even after rotating tires. The bearing is worn, but not to the point where it is horribly loose.

Something is out of true. Either the wheels are bent, not mounted correctly, or the tires are bad. My guess is bad tires. I used Goodyears once on my Buick. Had to go through 9 tires to find 4 that were reasonably true laterally.

Having read through the other replies so far, no one has mentioned the alignment. Many of the other suggestions are good ideas and the wheels/tires should be checked for any runout besides balancing. BTW. I do agree that sometimes even new tires are out of round and balancing them will not cure the problem. However, a shimmy at highway speeds can also be caused by alignment problems, especially if he Caster is incorrect. Has the alignment been checked?

Sorry, must have forgot to mention that. I just had it aligned also. The tires seem to be wearing well, i've noticed no cupping or irregular tire wear. But I do only have 1000 miles on them.

Ok, then in that case I would propose that some of the service you have had performed to alleviate this problem was not done correctly. Basically, if the alignment is correct and the steering and suspension is without worn or damaged parts (all should have been checked during alignment). And the tires are new, properly balanced, and correctly inspected for run-out ( as they should have been during balancing), Then there is little else that would cause a shimmy in the steering wheel only at 55-75 mph. Wheel bearings might contribute to a shimmy, but any play or problems with the wheel bearings should have showed up during the alignment. I suppose there may be some other yet unknown cause for your symptom, but it seems to me that you have had all the normal services that should have discovered the source of the problem. Therefore, it seems like you would need to start over, assume nothing has been done, and begin diagnosis of this problem from the most logical and most likely causes of steering wheel shimmy at highway speeds. That would probably be:

1. Have the tires balanced and checked for runout on the car.
2. Have the steering and suspension inspected and aligned. I bet that if you can get those two things done properly, the problem will be found.

good luck,

Thanks I'll do that. One quick question though. Could the car have came out of alignment and started to shimmy? I mean it started after I had the car aligned... but it just all of a sudden started to shimmy one day.

Reply is bottom posted.

It is most certainly possible for any number of things to cause the alignment to change suddenly. Usually, a severe blow such as hitting a curb or large pot hole is the culprit, but there are items such as fasteners that might get loose, or shims that might fall out, which could cause a sudden change in alignment. Also, it is possible to have alignment problems without them producing a pull in the steering. For instance, if the caster setting is not the correct amount of degrees positive, then the resulting symptom is usually a shimmy at highway speeds, but that will not necessarily affect pulling or tire wear

Thanks for all your help, guess im gonna get the alignment checked... (should be free since I have a 6 month warranty on the alignment)

In theory extreme excessive positive caster can cause wheel shimmy. In practice this is not the problem with your car. The caster angle is NOT adjustable on your car and can only be out-of-spec due to collision damage. It would have to be equally out-of-spec due to collision damage on both sides or you would notice a pull if it was very far off.

When you get some round and properly balanced tires on your car -- assuming no bent wheels -- your problem will be solved. Again, does your car have custom wheels such that somebody is attempting to balance them using weights on the inside only? That makes the wheels stay pretty but does not work for crap!

Don

That's what I thought. Well if there had been a problem with the caster being out from an accident, wouldnt the alignment service technician have told me? And my tires can't be out of round because I thought it was in the front tires and I rotated them, and the problem stayed the exact same... so they can't be, correct? And I have weights on the outside of the rim, as well as the inside. My rims are the stock rims on a Grand Am, with the 5 spoke "chrometechs."

Pretty sure he didn't mean caster, don't see how it's cause a shimmy, as it has to do with how the suspension leads the tire, not a tire wearing or occilation producing angle...

Most likely suspect on a GM of that age with alloy wheels is a condition of slight front caliper drag combined with unevenly torqued lugnuts....those wheels must be torqued at 100 ft/lbs evenly, or they will distort the rotors and caused tremendous brake shimmy on pedal application...and if the calipers drag slightly as many on those cars do, the rotor, runout will cause a sympathetic shake in the caliper that you will sense as a front wheel shimmy on the highway...occurs at the same speed and frequency as a defective tire or balance problem, can be frustrating to find...

More than one poor tire or not balanced coorectly.

Don

Tradionally textbooks have stated that extreme positive caster can cause shimmy and this is what Kevin referenced. I have never seen it happen. Toe and camber do not cause shimmy except indirectly through tire wear.

There was no mention of brake shimmy. My understanding is the shimmy was present while coasting. Surely if there was such severe rotor distorion as to cause a shimmy simply from the light drag without the brakes applied you would take a dump in your jeans when you used the brakes!

Don

View this thread:

Reply inserted near the end:

Don, Let's get this straight. I never said caster was causing his shimmy problem. I said CASTER not being CORRECT may also be one thing that CAN cause shimmy. I still think he probably has a bad tire or tire balance problem, or maybe some loose steering component (but I did mention other possible causes because I am not there to inspect it myself). BTW , excesive POSITIVE caster will NOT cause a shimmy. Only excessive NEGATIVE caster can and will cause shimmy if it is bad enough. Get your facts straight before you confuse someone.

Kevin

Everything

Ok let's get the facts straight ,

Here are some quotes from a quick Google for "positive caster shimmy:"

quoted from:

"A note about high amounts of positive caster, it tends to inducewheel shimmy, just look at the occasional wobbling front shopping cartwheel! Your suspension must be in very good condition to resist wheelshimmy when high caster angles are used....." quoted from: "Too much caster causes hard steering and can also result in excessiveroad shock and shimmy." quoted from Motor Age magazine:"THE CORRECT ANSWER IS B, TECHNICIAN B. Excessive positive caster willincrease steering effort, cause the steering wheel to return toorapidly, cause wander at high speed and shimmy at low speed...."

Qutoed from Autozone online tech reference

"A vehicle with too much (positive) caster will be hard to steer andshimmy at low speeds."

caster setting is increased to positive, vehicle directionalcontrol is also increased. High positive caster may result in lowspeed shimmy.

There appears to be a prevalent belief that positive caster can cause wheel shimmy. There are dozens more references but you get the point. NOWHERE was there a mention of negative caster causing shimmy. This is why I assumed you were referring to excess postive caster as a POSSIBLE cause. Of course you didn't say that it was for sure the cause. In actual fact it very rarely is.

Don