Where is causing this Vibration? Please help.
 

The car is a 1993 190E 2.6L. I feel vibration between 60 and 80 miles/hr on the steering wheel. I did the followings:

1) I went through 2 sets of 4 new tires.
2) Did alignment.
3) Balanced and rotated tires several times.
4) Checked worpage on rims. (Was fine)
5) Completely checked suspension and steering components. They were fine according to the person who did the alignment. He is a pro-suspension/alignment specialist with over 40 years experience in that fiels.

I accidently found out that: While driving through the mountains on a long trip, I noticed the vibration is greatly reduced while steering left at 70 miles. Any ideas how could this happen?

I suspect my drive shaft or center support bearing, but I don't want to replace it until I make sure it is not the problem.

I am really impressed with this board and how organized it is. Thank you all in advance.

Did you check you front wheel bearings?

I have replaced both front sides before I did the alignment. There is no side to side play.

It could be worn bushings, but I think I would opt for one more go at the wheel balance, on the Hunter 9700 computer balancer. I almost threw away a perfectly good set of tires to buy a new set, because I had balanced them several times, different places, still no good. Then I found one of only three places in town, with such a machine, and had them balance the front ones only. I did not get 3 miles down the road before I felt a totally new car. No more vibration in the steering wheel only the seat and rear. Had the rear done the next day, and has been perfect ever since.

By the way the difference in the front two wheels only were almost 3 ounces off, after just having them balanced a few days earlier. Thats how good this machine is, provided the operator knows what hes doing.

Keith

Road force balancing is the ideal way to eliminate the tires as a possibility. Out of balance brake rotors can be a cause, I've chased one on my own 380 SEC. Make sure that you have your steering box in the correct adjustment. This is not an easy thing to do on a 201 6cyl. but if its sloppy the spring setup thats used to compensate for wear sets up an ideal place for the steering to "bounce" left to right. Good Luck!

Brake rotors will cause vibration only while braking.

Has your tire balancing been done with weights on both the inboard AND outboard wheel lip? If not, and weights are only used on the inboard lip, which is not uncommon on alloy wheels, then you need to have them dynamically balanced with weights on both inboard AND outboard lips. You will not need the road force measuring balancer, but just a decent computer balancer with a competent operator(IQ above 70) who is willing to dynamically balance with weights on both planes.

If they have been balancing them with weights on both planes, then it is indeed time to find a Hunter GSP9700 balancer. This machine will not only balance the wheel/tire, but will also measure the tire for stiff spots.

If you need to locate a shop with a GSP9700, go to: www.gsp9700,com.

Best of luck,

The vibration sounds like its happening at speed and could include any recipriating mass. The brake rotors are a definate possibility. In the good old days we used to concern ourselves with out of balance hubcaps. Sad but true.
The road force balance eliminates things that a standard dynamic balance doesn't consider like sidewall flex, cord variation, out of round wheels etc. The quality consious dealers use them with great success.

Thanks for the info on the GSP9700 Larry. The list of auto dealers using it is impressive. A great looking piece of equipment. Sure beats the days of the old bubble balancer. :D

Yes, the 9700 is clearly the greatest tire related technology ever put in your local shop.

It is not, however, needed in 90% of wheel imbalance cases. A good computer balancer properly used with weights on both planes will in most cases get the job done. It is when you have a tire with excessive road force variation (a stiff spot) that the 9700 is necessary.

So, it is not necessary in every case to go running off to the 9700 shop. This only necessary after a proper two plane dynamic balance does not cure the problem.

Good luck,

How many shops have tried balancing the tires? As Larry says dynamic balance is very helpful. The GSP 9700 is best for problem cases, not always necessary. After several sets of tires and wheels I eventually changed the knuckle/hub flange and this seems to have cured any shimmies/vibrations that even on-the-car balancing did not solve - time will tell. Turning left or right or going uphill or downhill shifts the weight of the car making the problem more obvious. Alignment is for tire wear or handling problems, not vibration (except in the most extreme cases).