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1989 560SEL
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2,103 Posts
Discussion Starter #1 (Edited)
Haven't posted in a long time, but I need some advice... I've had my 560SEL for 10 years now and have been really good about maintenance. Since I've had the car, it's always had this vibration that sets in around 60mph and comes and goes at speeds above this. No mechanic has been able to pinpoint the problem, and I've been throwing money at possible fixes like wheels (new wheels, tires, balancing, alignment), various front end components (tie rod, shocks, etc), motor mount, center flex disc -- and nothing has helped. The car now has 210k miles on it, but it's been doing this since at least 126k, which is what the mileage was when I got it.

Below 60mph, the car rides fine. On the highway, though, it's another story. You can feel it in the steering wheel and the seats -- not bad enough to loosen fillings or anything, but enough to ruin the driving experience. The sunroof just broke, and for the first time I'm balking at throwing $1200 or so into repairing it given that it rides like crap on the highway. I'm seriously thinking of getting rid of the car and moving on to something newer. I do love the car overall, though (and it was my first car ever), and if this problem were finally fixed, I'd gladly keep it.

Any advice on a possible fix? One guy in the shop suggested a driveshaft balancing ($750) but another said that's unlikely to help. I refuse to just keep throwing my hard-earned cash at random guesses. What on earth could be doing this, and why can no one figure it out??? Any words of wisdom and advice?

(To clarify, by "advice" I don't mean, "sell the car" or "don't drive over 60mph" -- I'd like to hear what could possibly be causing the vibration that I haven't tried yet...)
 

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R.I.P. Never Forgotten
1983-2007 MB's
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8,023 Posts
Ah, the death wobble....

A well-known member had this happen, and it turned out to be low transmission fluid, causing the torque converter to spin off balance with decreased fluid.
 

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1989 560SEL
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2,103 Posts
Discussion Starter #3
Ah, the death wobble....

A well-known member had this happen, and it turned out to be low transmission fluid, causing the torque converter to spin off balance with decreased fluid.
LOL, death wobble. It's more like the Chinese Water Torture wobble...

The transmission was replaced 3 years ago with a rebuilt unit and is in great working order. The vibration hasn't changed pre- vs post-transmission replacement...

I should add I've been through a number of sets of different (good) brands of tires without any effect. And I've also had the wheel bearings replaced to no avail.
 

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from small to large
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885 Posts
Assuming you have done r/r tie-rod ends... one is mostly ignored but could be the cause - arm idler. You can buy a repair kit for less than $20 and replace it in 10 minutes.
 

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'82 Euro 500SEL, '85 Euro 500SEC AMG WB Cabriolet,'86 Euro 500SEC RUF
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9,487 Posts
I'll go a different route for a suggestion. Have you replaced your center carrier bearing and holder? even if the bearing is good, the rubber holder is more than likely toast after all those miles it is located under the back of the front seats in the drive line tunnel.
 

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1979 280SL, 1984 280SL
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5,654 Posts
+1 on the carrier bearing. The rubber mount or bearing could easily be the cause of this. A sticky brake caliper can also create a hiway vibration.
 

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Always Remembered RIP
1991 560SEC AMG
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10,146 Posts
Try this first?

The very exact thing happened to me about 10 years ago when I was in Orange County, CA.

Guess what it took to fix it completely?


I rebalanced the wheels!

Done. Never a probloem again!

I'd try that first if i were in your shoes..


I'd KEEP the car too, Janos.NOT the easiest one to herd around San Francisco (I did that for years!)bt till one of the best looking, safest, most long lived quality automobiles ever made.
 

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1989 560SEL
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2,103 Posts
Discussion Starter #10
I replaced the OEM wheels with identical-looking 15-holers from Tire Rack a number of years ago and it had no effect. I've had these wheels balanced countless times at places in Boston, New York, and SF without any change to the vibration. I'm pretty sure that's not where the problem lies.

Tie rods/ends have been done, yes. Ditto for the idler arm, though I can't recall if both sides were done. I'd assume so, but will check my records.

The carrier bearing suggestion is new and worth looking into. I don't think that's been done. Thanks.

Cascade, I hear ya and this is why I'm here talking to you guys. This car has been with me through a lot of ups and downs, but I really don't want to keep investing $$$ in it if the best I can expect in return is a car that's only good for around-town driving.
 

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W126, R107, W210 AMG, W221
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342 Posts
The carrier bearing and prop shaft rebalancing might actually help, I've done that on my CE some year ago and it worked as magic.

It's nice you want to keep your 126. To be honest, I would have tough time thinking about replacing it with something else, only another 126 (but unless you are able to figure this out, you might encounter the same problem again).
 

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It's got 210 k miles , needs a $1200 sunroof repair plus the vibration issue sounds like it will cost anywhere from $300-1000+ to fix

IMO time to sell.
 

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1990 560 SEL
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731 Posts
It's got 210 k miles , needs a $1200 sunroof repair plus the vibration issue sounds like it will cost anywhere from $300-1000+ to fix

IMO time to sell.
It's not always about the money. You can't put dollar signs on sentimental value. Perhaps he might consider selling it after all the suggestions here are exhausted, but to throw in the towel now would be a shame.
 

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W126, R107, W210 AMG, W221
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342 Posts
It's not always about the money. You can't put dollar signs on sentimental value. Perhaps he might consider selling it after all the suggestions here are exhausted, but to throw in the towel now would be a shame.
I agree. And also, well maintained 126 (124, 201) can run forever. Even buying low mileage car means replacing lots of rubber parts and potential additional costs.
 

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1979 280SL, 1984 280SL
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5,654 Posts
Thru '89 the 126 has a 2 piece drive shaft with front and rear flex discs, a center bearing and mount and a u-joint. Any of these components, including a previously misaligned shaft is probably the source of vibration. If you are not doing this yourself, have a knowledgeable shop use only quality (Not URO!) parts. You will be rewarded with a car that is incomparable at speed on the hiway.
 

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Greek God of the R129
SL500-500SEL-190E
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8,391 Posts
The drive/propeller shaft is factory balanced.
Both sections are MARKED.

One mark is on the front section where the large nut is located.
On the rear section are two marks, close to the universal joint.

The SINGLE line MUST BE BETWEEN the DOUBLE line marks.

The bad thing is that in order to see you must remove the heat shields.
Is it possible that when they replaced the discs, did not know about the markings?

You may want to see my thread.
Broken propeller/drive shaft. aam.
I have some pictures with the mark line painted yellow.

Regards,
aam.
 

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'02 E320 Wagon, '13 Chevrolet Volt
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Registered
1989 560SEL
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2,103 Posts
Discussion Starter #18
The drive/propeller shaft is factory balanced.
Both sections are MARKED.

One mark is on the front section where the large nut is located.
On the rear section are two marks, close to the universal joint.

The SINGLE line MUST BE BETWEEN the DOUBLE line marks.

The bad thing is that in order to see you must remove the heat shields.
Is it possible that when they replaced the discs, did not know about the markings?

You may want to see my thread.
Broken propeller/drive shaft. aam.
I have some pictures with the mark line painted yellow.

Regards,
aam.
Ok, sounds like there's consensus developing around the carrier bearing/drive shaft, and maybe the idler arm bushings.

The flex disc was replaced in response to the vibration, and did nothing to affect it -- so that vibration predates the flex disc replacement. But maybe the drive shaft was worked on before I bought the car.

I just got back from a highway ride and noticed that the intensity of the vibration changes as I turn the wheel slightly left or right to go around bends. Does that suggest a front end problem, or can it just be mild chassis flex affecting drive shaft components?
 

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1979 280SL, 1984 280SL
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5,654 Posts
IDK about the turning affecting the vibration- If you suspect the idler arm is worn, than of course it could affect vibration.

Just to be clear, you have mentioned changing "the flex disc." This should be plural; your car has two. One at the transmission, and one at the differential.

Although you mentioned changing this (only one?) not affecting vibration, when you do proceed to investigation your drive shafts, re-examine the discs for cracking/wear. There are substandard flex disc that are widely available, prone to premature failure. Only components such as Lemfoerder and OE MB should be used here.
 

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1989 560SEL
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2,103 Posts
Discussion Starter #20
Good point, Chiefrider. I don't think the disc near the diff was replaced. I'll add that to the list.


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