45 mph Shimmy - PeachParts Mercedes-Benz Forum

McRoth · #1 06-12-2002, 09:37 PM

Hello again all,

I've been noticing for the past week or so that right around 45mph, +/- 2 or 3mph, I get a shimmy or vibration. My car is an 82 240D, 4 spd manual. The vibration is wether I'm accelerating, decelerating or crusing. I don't notice it at any other speed. I have no clue what could be causing that. Anyone have any ideas?

Thanks!

#2 06-12-2002, 10:36 PM

When you get you tires checked, go to a place with a Hunter DSP 9700.

This thread explains it more: Shimmy

Good luck!

#3 06-13-2002, 10:01 AM

Although I believe in the GSP9700 and believe that it is THE greatest tire technology ever put into the shop, I also believe that MOST tires can be corrected with a decent computer balancer in good order and a technician that takes the time to do a correct DYNAMIC balance. This means weights on both inboard AND outboard planes of the wheel.

Most times when shimmy is due to wheel balance, and it often is, it is because the jerk at the tire store insists on doing a static balance with weights ONLY on the inboard plane of the wheel. This will solve the tire from jumping up and down, but will aggravate the dynamic balance which makes the wheel wobble. With sensitive suspensions such as the MB suspension of the last 30 or 40 years, this vibration is felt.

If you run into the rare case where proper dynamic balance does NOT cure the vibration, then it is probably an out of round wheel or a tire with excessive road force variation (stiff spot.) In this case it's time to seek out the GSP9700.

The warning now, goes back to ensuring that the GSP9700 operator knows what he's doing. Even this fabulous instrument requires an operator with a good attitude AND an adequate amount of grey matter between the ears.

I would expect that the situation you describe, I could correct 19 times out of 20 with my fifteen year old Coats 1001 computer balancer. After all I do have an IQ over 70 AND I care about getting a correct DYNAMIC balance.

Good luck,

#4 06-13-2002, 11:58 AM

Larry, you amaze me with your information on the tire issues... I just got my tires re balanced, and I must say, the car has not rode better! No more shimmy from 65-75!

McRoth · #5 06-14-2002, 10:20 AM

Thanks Everyone for the suggestions! I'm going to try to get it back to the shop today. I just got new tires a couple of months ago, so they should rebalance them for me. Maybe a weight fell off or something, I'll have to check. I know they did do a dynamic balance, weights on both sides. I'm not sure what kind of machine it was though.

Thanks Again!!

#6 06-15-2002, 08:24 AM

McRoth,

Been there too. There are about a dozen or more different weight types these days. I have had an excellent balance job done, but with the wrong weights that started coming off right away.

If your car has alloy wheels you need a one piece weight type "EN" The better choice, however, is the MB two piece weight, but many tire stores don't have these plus they require a special tool. I get by without that special tool, but I'm not sure if anyone at a tire store cares enough to want to try.

If they are steel wheels and hub caps, it is a standard steel wheel weight.

Good luck,

#7 06-22-2002, 01:31 AM

just another thought might want to jack up the passengers side and wiggle the wheel might be more than just needing a rebalance.
had a problem similar recently and come to fine out i had to replace my idler arm bushings. easy job go figure.
but if the wheel moves relatively freely side to side it might just be that. good luck

McRoth · #8 06-28-2002, 08:00 AM

Thanks everyone for the suggestions! I got the tires rebalanced & there is still some shimmy around 45mph. They had thrown at least 3 wheel weights! Anyhow, I finally jacked it up & checked for side to side movement & the driver's side is good, but the passenger side has a little, maybe 1/8th of an inch or so. I already need the lower ball joints replaced, so when I have them do that I'll have them check out the idler arm too.

Thanks Again!