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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #1
New to a 1995 E320 Cab. Not sure I have a problem or it is just the nature of the car. I get what I think is excessive vibration in the steering wheel that feels more like a shutter when I go over bumps or rougher roads. Almost like a shimmy. There is a lot of body flex compared to a sedan. I installed a new steering damper but no change. Is this just the nature of the Cab? Struts seem OK and steering is tight. Tires are 4 years old with 10K and the car only has 55k. Sure is different than my sedan. I expected some difference but thought a Benz convertible would be pretty tight and not so much flex. Any thoughts?
 

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1996, A124, E320 Sportline Cabriolet x 2
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1,555 Posts
They are really very good, you sound like you have a problem.

I would suggest (lowest cost first) stabiliser bushes make a BIG difference (don't lube them on installation) and lower control arm bushes with GENUINE MB bushes INSTALLED IN EXACTLY THE CORRECT LOCATION. They are location specific for the exact reason you mention.


Suggest the lower control arm bushes are done by a Dealer ONLY AFTER READING THE HOW TO MANUAL FROM MB. Otherwise they will put them in the wrong place and you will be back to square one.

You will be amazed at how solid these Cabs are........
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #3
I know rubber parts are subject to age, but this car only has 55,000 miles on it. If the bushings are harden would that effect the feel of the car?
 

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1986 560sl,1995 e320,1999 Buick Le Sabre
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220 Posts
rubber

AND YOU SAY THIS CAR IS ONLY 16YEARS OLD,RUBBER GOES BAD,DOESN'T LAST FOREVER,DON'T GO BY MILEAGE,BY YEARS!!!!
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #5
What is the difficulty with the lower arm bushings? What manual are you referring to? I have done lower arm bushings on my Porsche. At first glance this project doesn't look too tough. Bushing kit at about $75 each side. Anti roll bar bushing nearly free at less than $3 each. I appreciate your input. Thanks.
 

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1996, A124, E320 Sportline Cabriolet x 2
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1,555 Posts
MB made the bushes different hardnesses, and vibration absorbant after complaints from customers about vibrations through the steering column. It is important to get the location of each bush and orientation relative to the control arm correct. Nothing hard, but critical if you want the full damping effect.


Hers is a little more info.....

http://www.mbworld.org/forums/e-class-w124/362060-never-ending-vibration-problem.html

Inspector.
 

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1996, A124, E320 Sportline Cabriolet x 2
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1,555 Posts
Front tyre pressure makes quite a bit of difference too. A worn suspension will struggle with a tyre @32 psi, tends to transmit a wobble like vibration. At 35 psi the effect is much reduced......
 

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95 E300, 91 300TE, 84 190D
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772 Posts
Cab front end

I've got the same issue with my Cab, but don't have an answer. Clearly poor compared to both my E300 and 300TE.

I replaced front struts because they were shot, and I thought that might help but did not. Replaced the steering damper. Tried different tire pressures. Ball joints, tie rods, drag link, idle arm all good as checked by MB mechanic. I even tried driving with and then without the lead vibration strut mount damper. No noticeable difference.

I/we did not look at the control arm bushings, so that's next for me sometime this summer.

Please post your progress as well. Thanks.
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #9
Welcome to the club. I have only changed the sway bar bushings. I thought I could tell some improvement. What I do notice is a big improvement with hot weather. This leads me to believe that the old rubber bushings in the LCA's are the problem. I plan to replace but am undecided as to which direction to go. The complete LCA at the dealer is $570 each. Bushing repair kit $170 each. I find Febi LCA OEM for about $180 each and bushings for about $55 each side. Big difference in price if they are the same manufacturer. I am leaning toward after market OEM LCA's and not just replace the bushings. I will post after I do this replacement.
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #10
Front tyre pressure makes quite a bit of difference too. A worn suspension will struggle with a tyre @32 psi, tends to transmit a wobble like vibration. At 35 psi the effect is much reduced......
Inspector, I will try the pressure change, but plan on replacing the LCA's. Thanks for for your continued input. I will post after the job is done.
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #11
Vibration Update

Will I now have done the following: New sway bar bushings, new steering damper, new lower control arms, new front brakes with rotors, rebalanced tires, and front alignment. The vibration seems a bit better but not what I would call rock solid. On certain roads there is a vibration that you feel in the steering wheel, in the seat and the floor. Much better with the top up. I have played with tire pressure but little or no difference. I hope to drive another Cab this week for comparison. The damper on the left tower looks OK to me. No cracks. The mechanic checked out all the steering linkage and says all OK. The left ball joint was not tight, but not badly worn. Not sure where to go with this next. Driving this car is not a joy but it is beautiful.
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #13
They were Febi. The bushings were in the correct orientation.
 

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1996, A124, E320 Sportline Cabriolet x 2
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1,555 Posts
Well I guess that leaves the struts and strut mounts, can't be anything else really, could it?

I have Continental Comfort Contacts on my car, not the all out low profile racers; that will make a difference I'm sure.

Have you got any pictures of the car.......
 

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1996, A124, E320 Sportline Cabriolet x 2
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You could try a strut brace from Weicher, but I really do not know how effective this would be. It means taking off the vibration damper from the LH strut mount. Others have said removing the damper made no difference, maybe theirs was worn out?? Fitting a strut brace might help.....??
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #16
I hate the thought of chasing the problem by continuing to exchanging parts. That maybe the answer. Hopefully I will get to drive another Cab this week for a comparison. Also maybe I am just to picky. I have never had a large convertible until now. I keep comparing the ride to my BMW, 930 Porsche and 4matic. Also your statement that these cars are "rock solid" makes me feel that mine is missing something. I will post the results of my comparison ride when it happens. Thanks you continuing to hang in there with your input.
 

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1996, A124, E320 Sportline Cabriolet x 2
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I was thinking just that when I was posting yesterday.

These cars were designed in the late seventies early eighties and were never designed from scratch to be a convertible. MB have not made a large convertible since 1997 with the last of the 124 Cabriolets, possibly for this reason. The car will not be as taught as a 930 with a roof, that is for sure.

Only other thought is to brace the rear bushes (of the LCA’s) across the car like the E500's had, together with a top strut brace; but that can be an expensive mod. Also it only braces transversely and I think the vibrations here are due to the longitudinal component of the source, ie the vibrations that flex the car along its length. That's why the top makes a difference, not so much to the twisting of the chassis but it helps to prevent the vibration that would tend to bend the car along its length. The top acts like decks on a ship in tension, it damps the bending.

There are vibration dampers in the boot and in the windscreen frame at the top. At 50,000 miles you'd certainly not think that these are past their best. I have never been in there to see, but it is conceivable that if they are bolted to the car maybe the fastenings have come loose, same goes for the cross braces under the car, there should be four, are they all there and are the bolts tight? Do you ever get a click or noise from the windscreen frame above the drivers head going over pot holes??

Do you notice any change in the characteristic of the vibration between a full tank and a very empty tank, with no tyre or tools? I notice a difference in the way it feels like it's absorbing the vibrations. But I am very sensitive to these things.

Also try a front seat passenger, is there any difference at all? Back seat passenger/s? Moving weight around can be a good way to mask/cancel out vibrations, not that you'd want to permanently carry extra weight - I know.

Do you notice any difference between having the rear windscreen in place as opposed to removing it with the top down?

At the end of the day the vibration is coming from the front wheels, everything we do now is to absorb what the struts & LCA bushes don't. My friends keep telling me to go visit Ohlin’s and get the suspension tuned to the car. I think MB had already done that, but there is an option to get one of their Engineers to experiment, or alternatively Koni do adjustable shocks for the front, that may very well be a good experiment, if everything else is in order.

I'd be interested to hear from others on possible causes/actions too, to be honest........
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #18
Inspector, thanks for the extended feedback. Waiting now to drive another Cab that is still in storage. Would like to have the comparison. Now that I have driven the car for a while after the new LCA's it seems to be somewhat improved. If I had to describe the feel it is like the steering damper is shot. But it is new. I will post the results after I drive the other Cab.
 

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1991 300E 4matic, Porsche 930, BMW 3 series, 1992 300E
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115 Posts
Discussion Starter #19
A new thought. My frame and alignment guy suggested trying two things. First lower the tire pressure to 25psi. I did that and made a big improvement. Not going to keep it there but it did make the vibration nearly go away. Second he questions why Mercedes and BMW specify such high caster angles. We are going to try reducing the angle next week to see how the vibration changes. He likens it to the front wheels on a shopping cart that can start to shimmy sometimes. Worth a try anyway. Any thoughts? I will post the results.
 

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1996, A124, E320 Sportline Cabriolet x 2
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1,555 Posts
32 psi on mine is worse than 35 psi. I think it's in the struts, not so sure about the alignment myself? But, it will be good to see what effect you may feel.....

What type of tyres have you got?
 
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