140 Series vibration - maybe driveshaft?? - PeachParts Mercedes-Benz Forum

oldsouth · #1 05-28-2003, 11:55 PM

I installed new tires and went to the dealer to have them balanced and an alignment. I also had the engine mounts changed out. The tech called me and said that there was a vibration at around 60 mph. He said after balancing the tires he re-balanced them again to make sure it was not the tires. He said that the driveshaft, where it goes into the transmission was slightly worn and recomended replacing the transmission mount to bring the driveshaft back up a little. (The engine mounts raised the engine about 1-1.5" and changed the driveshaft angle). This healped a little but the vibration is still there. His next recomendation is to change out the driveshaft (very expensive). My question is -- would new flex disk help the situation any? Has anyone else had this problem? Sure feels like an out of balance tire to me.

mithra · #2 05-29-2003, 07:19 AM

a couple of suggestions that you may want to try before driveline work... if you still think it is tire related, try rotating the tire /wheel assemblies from front to back, and also make sure that the lug nuts are hand torqued to spec.(I've owned other vehicles where the torque value is critical to proper rotating balance) I'm not sure what balance machine your tech has, but other threads here indicate that there is a balancer out now that is extremely accurate, you may want to find where one is and give it a try. The dealership that i frequent has a machine that will apparently identify such things as a thrown interior belt. (maybe he is bs'ing me, not sure)
good luck, let us know how you make out.

#3 05-29-2003, 07:26 AM

The "other balancer" referred to by mithra is the Hunter GSP9700. To find a shop near you that has one, go to: www.gsp9700.com.

Before you resort to that though, make sure the tires are DYNAMICALLY balanced with weights inboard AND outboard. It is very common for shops not to use weights on the outer lip of alloy wheels because owners complain about scratching their wheels. These cars have nimble suspensions and wheels that are not dynamically balanced will vibrate, period.

Also, if the flex disk was bad enough to vibrate, you would be able to tell by a quick glance. It would be in pretty bad shape. If it looks good and wiggling it shows no slack, then it is not your problem.

Good luck,

mithra · #4 05-29-2003, 07:41 AM

that is the balancer that the local dealership has; I couldn't remember the model, but I remembered that it had a load wheel and that it was a gsp. amazing device.

sclassforever · #5 05-29-2003, 08:54 AM

You may also see if the tech recalls how much weight was used to balance your new tires. If they needed upwards of 5 oz. per side (inner and outer), you could have him break down the tire on the rim, turn them 180 degrees, reseal and rebalance them. Big 16 inch tires are a lot harder to balance than 13 inch.

royaiii · #6 05-29-2003, 11:30 AM

I had my driveshaft replaced on my 300E because it would make knocking noises under acceleration. I highly doubt that a driveshaft could cause such a vibration. I dont even want to think how much a driveshaft costs for a W140.

peter210 · #7 06-01-2003, 06:23 PM

I have '98 S500 and I have been experiencing the same problem. For a very long time I didn't pay much attention to it, but recently it really started to P me off. My tires were balanced 100s of times with MB weights on Snap-on machine and nothing. Never mind mentioning suspension problems. I take care of this car better than myself and there is nothing to look for. Driveshaft? Possible but very unlikely. I had a problem with the driveshaft on my '97 E320 (crap) but only due to dummy mechanic who took it off split it w/o marking and then never put it back the right way. Back then I felt vibration at low speeds already, therefore I don't see any reason for untouched driveshaft to just "go bad" for no reason. They last forever. On the other hand I have the same car with the same problem. Interesting isn't it? I'm pondering... When my tires were balanced I've noticed that the outside of the tires where the thread is does not spin evenly but "jumps" up and down as the tires were not ideally round. Defective Michelins? What do we do guys?

xp190 · #8 06-01-2003, 06:44 PM

Check the driveshaft and make sure the balancing weights did not fall off. As tiny as they are I bet they do make a difference.

and if you do need to replace it, find a used one first at www.car-part.com great resource for used cheap parts, especially for parts that last forever.

xp

peter210 · #9 06-01-2003, 06:51 PM

No sign of missing weights. I've checked. My car is more than pampered. Regarding your www.car-part.com it sure is a very good source for used parts but I'd never buy a driveshaft or similar parts in such case. In such case... I emphasize. How would you know if the one you get does not have missing weights? Betterr to have your balanced.

mr. Goodwrench · #10 06-01-2003, 07:07 PM

Driveshaft linerity is an issue with the 140 chassis. There are driveshaft alignment diagrams and measurements in the "Popular Mechanics" CD-R. The info is supplied by Alldata. I got mine at PEP BOYS for about $29.99. It is internet interactive. You have to be on line to access the information. You can also download the info at www.alldata.com. for the same price. I prefer the CD-R from the auto parts store. Don't replace your driveshaft.

xp190 · #11 06-01-2003, 07:15 PM

I got a brand new differential for my 190 using car-part, it had 17000km on it cause the donor car got rear ended. Since I put that differential in, the car floats on the roads, it used to vibrate in all sorts of ways, no more. In worst case scenarion, I'd go look, you might get lucky and find a donor that was even more pampered then yours, a lot of people, including me love these cars so much they forget to eat and breathe

xp

peter210 · #12 06-01-2003, 07:17 PM

I agree with you MR. Goodwrench or rather GM? No offence...
But we haven't yes determined the problem causing the vibration. There are cars that I know from CLS limousine co. (you must know them since you are from NY area) they are abused, driven hard and with high milage and do not have this problem. My next step is to replace Michelines for a brand new set under manufacturer's warranty and see what happens. I'll spend no money and wind up getting a set of new tires...

peter210 · #13 06-01-2003, 07:25 PM

XP190, true but it is different when you have an evident problem like you had with your differential. It is noisy, it vibrates and all kinds of things it just needs to be replaced. The subject we are discussing here is not a matter of replacing a d/shaft but rather determining the problem first and then taking appropriate steps.

oldsouth · #14 06-01-2003, 11:51 PM

Well, yesterday I put the car on a lift and looked under it real close. I can grab the driveshaft with both hands and twist it back and forth and there is a little play but I think all of it is inside the transmission. I can push up and down and there is a very slight play felt but I think it would not cause any vibration but not sure. The flex disk look and feel tight. There is a long aluminum pan between the exhaust pipe and the driveshaft and I did not remove it to look above, but everything feels tight. The size of the shaft looks to be bigger in the back than in the front so there is some kind of transition or coupling above the pan somewhere.

I stated that the dealer replaced the engine mounts and the transmission mount. I looked at the transmission mount and it looks like there is slack between the rubber part in the middle and the rubber that surrounds it. Is this normal or should the rear transmission mount be tight between the two rubber pieces?

I still think it is a tire problem. If a tire is out of round or bad, would it show up on a balancing machine?

keitharm · #15 06-02-2003, 07:56 AM

Guys, I can't offer any advice, but I sure hope someone figures it out. I have a 93 140 with the same problem. Mine is most evident at freeway speeds.