Severe vibration @ 90-110 KM/H on a 1993 G60-AMG

I would take it to a truck drive shaft specialist who is familar with drive shafts etc. They should be able to find the problem.

Hi Have your dealer check for a loose flange on the forward end of the transfer box output shaft and the flange on the front diff.. these are are held on with a large nut.. also check the wear in the bearing behind the the flange with a prybar.....was the other propshaft new or used??..is the vibration a shimmy felt at the steering wheel..if so it could be the steering damper which generates this problem at about the speeds indicated if it is failing...wheel bearings.. wheel balancing and drag link/trackrod ends I presume have already been eliminated.....

Hi,
I'm not personally familiar with your problem. However I read this really interesting post on the US forum a couple of days aga as it happens and thought it might help you. I'm not an expert but from what this guy writes I don't believe his problem & solution should be model dependant and so it may help you.

http://www.pointedthree.com/disc/forums/showthread.php?tid=14465&mid=150...

I've cut and paste the main article here - but there are other peoples follow up threads that may interest you. Interesting that his solution may be a good thing for any G owner with vibration problems to check first, as the solution is cheap and quick!
Good luck fixing your G.
FrogWagen

unbelievable... vibration problem solved...
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So... just because i like to tell stories...

For histories sake, i've been driving around with dual steering stabilizers for a while trying to figure out what the heck is causing my steering wheel vibration... not bump related... we're talking about general steering wheel vibration that started to be apparent around 60mph... i changed my suspension bushings which definitely made a difference. One of the two axle bushings per trailing arm were torn. However, having had the tires ballanced twice on a nice hunter road force machine and fresh steering stabilizer, and fresh front shocks, i could still not get the vibration to go away... hummmm...

So i'm driving down to LA... i've got 6 hours each way, getting quite nice mileage because i'm driving no faster than 60mph the vaste majority of time... anyway, i've got quite a bit of time on my hands to think about what the heck the problem could be... and i've got lots of time to play around and see if i can isolate the issue.... i've already noted that it wasn't consistently happening... sometimes it jiggled, sometimes it didn't... sometimes it felt like it would come on in turning, other times fading out.

So dring down to LA, i found that at 75mph i noticed that the vibration was coming and going with about a 20-30 second period... meaning it would cycle in and out a couple times per minute... so i think to my self... what on a car could possibly have "revolution" of 2 per minute? Nothing... well... almost nothing...

No individual thing is cycling that slow but it's is possible that the tires could be rotating at slightly different rates... you figure if the tires are rotating at about 630 rev's per mile... or 630 rpm given my speed... it's totally likely that the left and right tires could be rotating a couple RPM differently when driving straight down the road... so i'm getting back to thinking it's GOT to be something in relation to axles, drive shafts, etcetera... so how to i narrow it down? Diff locks. Diff locks would allow me to force different parts of the drive train to rotate together.

First i started with the center locker... this one would seem risky to lock on road becuase you can't turn left or right to unlock it... but since it was serviced recently i noticed it's been engaging and disengaging VERY quickly and easily in snow where i had decent traction so i figured it oughta be okay... sure enough, it engaged nice and quick and disengaged nice and quick, but it did nothing to change cycling in and out of vibration while locked.

I also wasn't that concerned about locking diffs on the highway in general becuase the turns were shallow and i've also understood that a difference between highway speeds and crawling speeds is that tires can constantly scrub to relieve stress better than at crawling speeds where you get the wind up and hopping of the tires... so anyway, after seeing that locking the center didn't change anything i went for the front... careful folks, you quickly find out which tires is the taller becuase the car will suddenly shift into a steady left or right turn... mine shifter into a left turn, so the right tire is slightly taller. Anyway, the amount of force i needed to apply to the steering wheel was not really any more than required to turn on dirt roads so i felt comfortable leaving it locked for a while. How to get it unlocked?

Becuase the tires are sligtly different diameter, the front locker is in essence now putting the car into a sweeping turn and you have to hold it in a straight line... doing so winds up the axle a little and so it wont unlock on it's own. If the car is constantly trying to make a sweeping left turn, and your holding it straight, you need find a way to make a sharper left turn than it's already trying to do on it's own before it'll unlock. If your truck is trying to make a right turn and you're holding it straight, you need to make a sharper right turn that it would do naturally to get it to unlock. So i need to steer the truck more leftward than it already was trying to do... so started from the left side of the lane, got it pointed toward the right side of the lane and when almost to the right side, i gave it a good quick turn for a quarter or half second to the left side and it would slip open... still staying in my lane. It probably looks a little questionable driving down the freeway, but i'm okay with that.

So what happened with the front diff locked?!?! Surprise susprise! At what ever stage of vibration the truck was in... it stayed that way for as long as the front diff was locked. I locked it when the vibration was worst, it stayed that way... i locked it when it was basically smooth (you could still feel some vibration in the seat, but not much) and it stayed that way. So now i KNOW the problem is in my front axle somewhere from the wheel bearings out based on the fact that it's related to the phase orientation of the wheels.

So i bring it into a shop i've taken my truck before that works on all kinds of cars, race cars, the works... to have them check my home alignement job, and strap it up on a rack so we can get it spinning at highway speeds to see where the problem might be... but first... just check the front wheel balance... they should be all good... last time i had them check (quite recently) one of the tires was still zeroed out... needing no adjustment... but check them anway.... SURPISE! First tire... 3.5oz out... that's almost a 1/4 lb!!! Second tire... 4.5oz out... that's more than a quarter pound!.... okay, check them all... all of them are around 1/4 pound out of balance. SHOOT ME NOW! So the original shops machine is pretty consistent, but totally off... and it's a hunter road force balancer the original shop was using... time to make a stop by there and tell them their equipment has a real need for calibration.

So i say forget the alignment check and forget strapping it up, let me drive it around and see how it feels... it had a half pound of total imbalance between left and right tires when they're out of phase... and when in phase it would only cause vertical vibration becuase the left and right swinging will cancel eachother... sure as $hit, it's smooth at 80mph now... TIRE BALANCE!

Moral of the story? It doesn't matter what the hell equipment they balance it on... if you can't get vibrations to go away, ask for their calibration paperwork and see when it was last calibrated, how often they calibrate it (once a month would be nice), and if it's routinely needed adjustment to keep it in spec? If you see a history of routine adjustment required to pass calibration, that's a likely indication of problems too. do NOT take for granted that a nice piece of equipment is giving you a nice balance. The shop that was giving me bad balances has previously done a good job, so the quipment has shifted over time.

Edited by ewalberg 5/8/2009 5:31 PM

Looking good, I suppose it has centre and rear diff locks only like the 500GE. The rear wiper is in a bit of an usual resting position!

Very rare G that you have. I knew that it existed, but I never actually knew one of these. Tuned by AMG on the basis of one of the 500 500GEs made between 1993 and 1994, it therefore lacks the front diff lock.

The officially named 500 GE 6.0 AMG (M117 E60) eas the first GWagen to surpass the 200 Km/h top speed mark, thanks to its 331 HP. It used the same engine developed as a prototype and installed in the GWagen that Klaus Seppi and Clay Regazzoni entered in the 1989 Paris-Dakar rallye.

I would love if you could e-mail me some hi-resolution pictures for my collection: mortinsonattelefonica.net

Enjoy it!