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300GD, 190E
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50 Posts
Discussion Starter · #1 ·
When driven faster than about 50mph, my G will sometimes (but not always) vibrate off and on. My master mechanic (who has considerable experience with Gs) says it's probably diffs needing rebuilding, or perhaps driveshafts needing replacement or repair.

I've driven with this for about a year, as my commute doesn't require me to drive much over 50mph...but I'd like to get a better idea of where to start to address the problem.

The tires I have on now are a bit larger than stock, and will be swapped for stock size when they need replacing...a year or two from now. Everything's well-greased, but maybe something (or some number of parts) need replacing/rebuilding.

Any ideas?
 

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1991 300GD, 1990 560SEC
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15 Posts
I had exactly the same problem with my 1985 230GE. In my case the front driveshaft u-joints needed replacement. Also, I had to have the driveshaft balanced afterwards.

Check out this page: http://www.vinthers.dk/troubles.htm
Loads of useful information.

Kaur
 

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TJs, FJ40s, JGCs, G500
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2,343 Posts
scary!

isn't it scary when a "master mechanic with considerable G experience" tells you your diff needs rebuilding when you tell him about front end vibrations?
The diff isn't even on my list of possible causes for vibrations.

Harald
 

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280 ges 1989
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321 Posts
Luckily, my front end vibration was cured (suppressed would be a better term) by the latest big 463 steering damper. It was caused I believe by having a stupid low offset, et10 and slightly bigger tyres.31x10.5x15. It was un-drivable between 45-60mph the steering wheel shook like crazy.

The wheel bearings and swivel pin bearings were ok. but I really need to check it with standard wheels if I can find some and remove the damper and see if it still vibrates.

If it’s a steering vibration check the wheel bearings and swivel pins. Check the damper- you really need to undo it and see just how soft/hard the resistance to movement is.

If it’s a drumming vibration (not predominantly via the steering wheel) I would be inclined to check out the drive shafts for play. They can be out of balance too if they have been taken off and not put back properly with the arrows aligned
 

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TJs, FJ40s, JGCs, G500
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looking back, it seems like vibrations is one of the most popular topics on this forum.
http://4x4abc.com/G-Class/vibrations.html

Harald
 

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300GD, 190E
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50 Posts
Discussion Starter · #8 ·
I wonder how many of these vibrations would be distinguishable if we recorded them and posted them...
 

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300GD, 190E
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50 Posts
Discussion Starter · #10 ·
I've balanced my wheels. The wheel bearings've been checked, too. I suspect it's a joint issue somewhere along the shafts...

That said, my suspicions could be wrong...
 

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'83 300GD LWB, 230E
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63 Posts
I once had a similar problem on my 460 - undriveable over 70kmh but fine at lower speeds. It was caused by uneven tyre wear. Went away when I replaced them.
 

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G320 & E500
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1,203 Posts
Describe the vibration more...
Is the vibration a fast or slow vibration (the speed of the driveshafts spinning, or speed of the tires spinning)?

Can you feel the vibration in the steering wheel?

Can you feel the vibration when you put your hand on the TC shifter?

What happens to the vibration while you are accelerating, constant speed, and take your foot of the accelerator.

Does the vibration always happen at the given speed, or does it develop like a harmonic?

Does the vibration change if you are driving on different types of surfaces?

Have someone else drive the truck. Sit in all four corners and see if the vibration and noise is localized... if you can?

I know that these may seem like alot of questions, but they go a long way on finding and resolving the problem. Let us know what you find. Reply back like filling in the blanks...
 

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1984 LWB 280 GE Auto
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112 Posts
Check also your exhaust mount bushings.My exhaust isnt standard and I belive that can also cause some of the drumming like vibration you can get at that spped.I also put alot down to age of the vechicle,mine is an 84.I would doubt that it is impossible to get a totally silent ride like off the showroom floor in A G with the age of the 460s.Maybe I am wrong on this?
Have replaced ;The fnt steering damper,accelarator linkage bushing,fnt bushings,fnt bearings[twice in a year]had the fnt drive shaft renovated,[that took 80% of the trouble and noise],checked tyre balance and pressure.Just go thru everthing on the link,it is a process of elimination.
 

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280 ge and 300gd
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201 Posts
Whilst the 280 and 300 of mine are ok and any vibrations are not worth following up I would consider the ones that make me a danger to others!.

If avehicle is undrivable within its design speed then some thing is way wrong and it is likely to cause a failure or crash.

A vibration is something spinning in an out of circular path
* Tyre wheel assembly due to failure or balence.
* Drive shaft due to drive shaft alignemnt of the
flanges causing lumpy motions see assembly table.
* Failure of a component mounting engine, t/f,
gearbox rear mount, overstiff exhaust brackets.
* Steering damper not operating, but this will only
damp out side to side oxccilations not vertical, in
the steered wheels if operational.
* Road damper settings not complient in some way.

I would look for a long steep hill where the speed can increase with coasting allow to build with engine in neutral and see if the vibrations start and at what point say 35mph, the lower the speed the bigger the out of balence mass. Do the same under power.
Both times compare with similar braking and acceleration.

Obvious movement in wear will increase the possibility of shakes but would look at all metal objects as an unbalenced mass that can upset the smooth running.

Remember that steering and suspension dampers are just that and that coil springs are friction free compared to a cart spring so achassis based defect will be felt much more than in say a L/R which the spring and damper act as one. (older models).

Blue print the set up values for shafts and tyres etc.

Get a bunch of heavy keys on a rope rotate them then let go and see how far they fly think of this as your roughness.

Regards Dave
 

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300GD, 190E
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50 Posts
Discussion Starter · #17 ·
Q: Is the vibration a fast or slow vibration (the speed of the driveshafts spinning, or speed of the tires spinning)?

A: When the vibration's there (usually at 60+ mph) it's like a pulse, coming and going with roughly one-second intervals.


Q: Can you feel the vibration in the steering wheel?

A: I have felt vibrations in the steering wheel, but can't say they're always there when the main vibrations are there. I'll double check.


Q: Can you feel the vibration when you put your hand on the TC shifter?

A: Oh yes!


Q: What happens to the vibration while you are accelerating, constant speed, and take your foot of the accelerator.

A: I'l have to double check...but I think I recall the vibration stopping when I'm in neutral.


Q: Does the vibration always happen at the given speed, or does it develop like a harmonic?

A: Sometimes it doesn't happen at all, but when it does happen, it's rythmic, going "hummm"-second of silence-"hummm"", etc...


Q: Does the vibration change if you are driving on different types of surfaces?

A: No, but then I'm only on one kind of surface at this speed, and that's tarmac.

More soon....and thanks!

Lucas
 

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G320 & E500
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1,203 Posts
The problem sounds like your driveshaft is slightly out of balance. The fact that it is surging, ...mmmMMMmmm...mmmMMMmmm..., your UV joints or bearings are probably wearing and loose too.

Slide under the truck and see if there is any movement in the front driveshaft. Push and pull on the shaft and see of there is any movement in the bearings at the axle and transfer case. Try to rotate the shaft and see if there is any rotational movement in the UV joints. Also look for any spots on the driveshaft where one of the weights could have flown off.

To fully test this theory, you can remove the driveshaft, and see if the vibrations still exist.

Chuck
 

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85 300GD 83 300TD
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978 Posts
Removing the front driveshaft will help determine if that is indeed the source of your issue.

-Danger - Warning - Will Robinson -

It is critical if you do this to engage the transfer case in 4 Wheel Drive or SA to test it. This keeps the transfer lubricated correctly and can be safely driven this way. If it is driven without being lubricated in this way the Very Expensive very Rare Transfer Case can be damaged. I have driven mine without the front shaft for thousands of miles without damage with the transfer engaged properly.

-Dai
 

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TJs, FJ40s, JGCs, G500
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And you can of course remove the rear drive shaft (shift transfer case to SA to drive) to see if that one is causing the vibes.

Before removing any of the drive shafts you should mark the mating flanges on each side with a punch or file to assure that the shaft will go back exactly the same way it came out. While the shafts are out, examine whether the arrows line up (someone may have had the shafts out before and not put them back the way they should). Aligne arrows if needed.
http://www.rubicon-trail.com/public/4161propshaft.pdf
While the shafts are out, check the flanges of diff and transfer case for concentricity with dial gauge. They should not be more than 0.07 mm out of round.

I should not really have to mention it - but I will: Never drive in SA or GA on pavement with both drive shafts in!
http://4x4abc.com/4WD101/axle-wind-up.html

Harald
 
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