You must have some record for number of responses, and I confess I had to jump to the end - which was your update.

The two things in your message that stand out are: the vibration is between 60-70 mph and it feels very clunky when going over a bump or road divider.

The 60-70 comment pretty much mandates that it's rotation related. Very typical of a wheel/tire problem.....or alignment. Looks like you've chased all of those possibilities.

But the clunking over road dividers has nothing to do with rotational speed - more to do with bushings or connection points.

Has the car ever been wrecked, or hit up front (sorry if this has already been discussed)? Any service history at all (have you checked with a dealer to run a report)? At this point, you need some outside help.

Every town I've lived in has at least one shop, usually a frame/alignment type shop, that can work magic. Phone a few body shops and tell them what you're up against, and ask where folks take their tough frame/alignment jobs. I'll bet you get consensus after a few phone calls.

It's worth a try.

I wonder if something in the shocks - upper shock mount, or other mount part is not installed correctly. Recall Steve's info about dealer and non-dealer parts. As for me, I have at least one bad tire that can be attributed to my (second) vibration. Why the tire went bad, I am not sure (Yoko) but it is being replaced by tirerack. The harsh vibration that I used to have, went away with control arm replacement and has not come back, I think I've driven about 1500-2000 miles since.

Brian

767Flyer,

I was trying to identify the circumstances that seemed to make your problem disappear, then reappear, then offer a postulated explanation. MB shocks are a little more complex than some others out there, but it seems your bushing fix was more in line with the problem.

I think you should go back to the last shop, as they seemed to have found at least part of the ongoing problem. I am not familiar with the bushing that got replaced, but it sounds like it is not as straight forward as changing a tire and there could be something wrong again, or with another bushing/connection that was previously improperly adjusted or installed.

Good luck, Jim

__________________
Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)

I too did not relish the thought of reading 93 responses so I jumped straight to the end. My 300, well known here for being a *****, sat for eighteen months with no engine or trans, part of the time on jackstands. I used to love the way it rode but now that it's back on the road (sort of) it rides like crap. I can feel every crack in the road. It's almost as bad as my 1980 Datsun was with the old bias ply tires!! It doesn't even steer like it did. It's like another suspension sneaked under it while it was resting. I hope it's the tire compound (H rated Bridgestone Eagers) gone bad and not the car.

another thing if you have radial tires don not rotate them cris cross you can only rotate them from front to back on the same side or else the radial belt will become frayed within the rubber causing tire bounce and vibration also quick wear and eventually pop

you may also want to check out your transmission mount
if its soft or broke
or if the tranny bounces when pushed on that will also cause vibration sometimes not constent like it will come and go

Jeff

All major tire makers now recommend the "modified X" rotation. That of course is except tires that are rotation specific, Aquatread..etc..

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I knew I shoudn't have posted anything - I've tortured you guys enough. Everything you guys have mentioned has been checked and given a clean bill of health. The dealership bodyshop checked the car out for previous damage (I bought the car used) and it hasn't. I did this before I bought it too. I'm certain it is a shock related issue - it's transient.

__________________
Mark E.
Miami, FL
2 X 1997 C280

I had a slight but annoying persistent vibration at highway speeds with my 96 c280. New Michelins didn't help. I thought it might be my front shocks (KYB), as it would sometimes be worse than at other times. Well, a few weeks ago, I decided to purchase new tires, as my Michelins were history. I put a slightly wider set of Dunlops on. The car shook up and down at highway speed, so I took it back. -20 temperatures that day caused 3 wheels to throw their stick-on weights almost immediately after leaving the shop. They put on some coated knock-on weights until summer. The car is now the smoothest I have ever felt any car ever on the highway. At any speed right up to the governor. Now in the spring when I return to that same shop to have stick-ons put back on, I will have them do a dynamic, high-speed on-car balance (expensive and time-consuming, but worth it). I guess the positioning of the stick-on weights as dictated by the rim design was never optimized by a normal balance process.

Thanks Benzfan - maybe I'll give the weights you've mentioned a shot. It's been over a year now, still have my little "problem," but have run out of patience. Well, actually, I'm waiting for something to BREAK down there so I can resolve it once and for all. Then the next project will be the bizarre tranny behavior. I still get on here from time to time to see if anyone else feels my pain, and it would seem a few do. I am, however, devoted to my car.

__________________
Mark E.
Miami, FL
2 X 1997 C280