[PeterMMM]

On my 1996 S500 Coupe, I've had the dreaded vibration, I haven't found a comprehensive list of issues to check so I'm trying to compile one of the things I should check with a mechanic friend.

Anything I should add to this list or caveats?

Also, is 150Nm the torque spec for the wheel bolts?

Draft list:

1. Check all suspension bushings for damage (tie rods, upper/lower control arms, etc.,) - this is often from the lower control arm bushings but could be other components
2. Check front and rear flexdisks - the front flex likely has worn out more
3. Check the long “shaft mount” and “shaft bearing” - may be called the “center support bearing”
4. Do not use airtools for installing bolts unless using a torque limiter/meter ... install bolts in torque sequence using a torque wrench
5. Star crossed torquing is very critical because the stock rims have a very big center bore and lug bolt holes
6. Tires might have flat spots from sitting
7. Road force balance

 

[Joe-V12]

1. tire flat spots/out of round.
2. wheel balance.
3. steering damper.
4. steering idler arm.
5. steering box play.
6. worn tire rods/ball joints.

Items 3-6 really need to be all checked together.

Sign off on the above with correct torquing then worry about the rest.

Edit: I've had seven 140s. On every single one the ~50mph/80pkh vibration was the wheels/tires. The rest of the steering & suspension can dampen the 50mph vibration better if in good condition but if the tires are out of round &/or out of balance to begin with...

 

[anziani]

Definitely rotate and balance the tires first. America's Tire uses Road Force Balance at least here in the desert. And ask them to check for "out of round" wheels that might need straightening.
Anziani

 

[PeterMMM]

thank you!

I will add those to my list, it's good to know about items 3-6 and their potential relationship to the issue

 

[PeterMMM]

Anziani, on my car, per factory configuration I'm assuming, the rear rims and front rims aren't interchangable so when my mechanic went to rotate them recently, it couldn't be done. But I suppose the tires could be unmounted and swapped.
They've tried balancing multiple times with no impact on the vibration. The balance gets to 0.00 ... so, allegedly, not out of balance.

 

[TimeCapsule]

per factory configuration I'm assuming, the rear rims and front rims aren't interchangable so when my mechanic went to rotate them recently, it couldn't be done. But I suppose the tires could be unmounted and swapped.

Factory setup for US-market was 7.5x16" wheels with 51 mm offset. Tire size 235/60/16 on all four corners.
If you have different front and rear wheels, you have upgraded config. Likely AMGs in 18".
Staggered.
Front then should be 8 or 8.5" wide, rear either 9" or more likely 9.5" wide.
ET will be in the 44-47 mm range.
If this is what yo have, then, your mechanic is correct that they CANNOT be rotated.
Since the tire sizes are different too, tires cannot be moved from the wider to the narrower wheel and vice versa.

 

[will_c140]

My car still retains this characteristic after 3 years, everything above diagnosed and replaced, and 3 sets of wheels and tires. The symptom now appears irregularly, and if it happens (after the flat spotted tires have warmed up), it tends to happen after braking to a stop and starting off again. Something is moving when stopping, particularly after a not-necessarily hard but a less-than-slow stop. Who knows. It's a mystery. The only other thing that I believe needs to be done for vagueness is a steering box adjustment

 

[jal1224]

thank you!

I will add those to my list, it's good to know about items 3-6 and their potential relationship to the issue

The other thing that makes an amazing amount of difference is wheel bearing adjustment. Mercedes has very tight tolerances for this, and it can make a world of difference if they are even slightly loose. You really need a dial indicator and magnetic stand to measure it properly.

Jon

 

[will_c140]

The other thing that makes an amazing amount of difference is wheel bearing adjustment. Mercedes has very tight tolerances for this, and it can make a world of difference if they are even slightly loose. You really need a dial indicator and magnetic stand to measure it properly.

Jon

True. Search my vibration posts and I did both hubs which come with new bearings. That was the biggest improvement for mine, despite having done literally everything and then some on that list except steering box adjustment. How would this cause a 45-55 vibration that comes and goes with stopping?

 

[jal1224]

Any looseness anywhere can be excited vibrationally by any number of things. How they all combine on a given car and manifest themselves is unique. Something about the W140 makes it very sensitive to vibrations.

Jon

 

[will_c140]

How they all combine on a given car and manifest themselves is unique

I'm really hoping the key isn't replacing ALL these things brand new at once, at one time is not the answer over replacing all these culprits individually. If that ended up being the method, the 140 would definitely be the one car that would earn that award.

 

[Saccofan]

Some of the US spec coupes (if not all) did in fact have staggered factory wheel offsets. I believe the tire size was the same front to rear. As for the vibration, after eliminating the potential issues mentioned earlier, try new front upper control arms. This seems to do the trick if all else is in good order. Oftentimes they don't look too bad, causing them to be overlooked as a potential cause.

 

[jal1224]

Some of the US spec coupes (if not all) did in fact have staggered factory wheel offsets. I believe the tire size was the same front to rear. As for the vibration, after eliminating the potential issues mentioned earlier, try new front upper control arms. This seems to do the trick if all else is in good order. Oftentimes they don't look too bad, causing them to be overlooked as a potential cause.

I have 94 and 95 S600 US spec coupes, and both came with 7.5x16" wheels front and rear, just like the sedans. Some Euro coupes came with 8.5x18" wheels front and rear. I have a UK brochure indicating those were standard there. I'm not aware of any US coupes that came with staggered wheels from the factory.

Jon

 

[Saccofan]

I have 94 and 95 S600 US spec coupes, and both came with 7.5x16" wheels front and rear, just like the sedans. Some Euro coupes came with 8.5x18" wheels front and rear. I have a UK brochure indicating those were standard there. I'm not aware of any US coupes that came with staggered wheels from the factory.

Jon

Looks like they were only staggered from the factory here in the US from 1998 to 1999. This was the quickest link to proof that I could find: http://www.wheelcollision.com/store/MERCEDES-CL-CLASS-140-215-216CHASSIS.htm

 

[jal1224]

None of those are standard wheels. In fact the page says "upgrades".

Edit: I stand corrected. While my 95 S600 came with 7.5x16 all around, Mercedes EPC says model year 95 up came with 8.0x16 on the rear only. But then it says 96 and up came with 7.5x16 all around, so who knows. There were a couple of styles of 7.5x16 wheels used.

Whether any US coupes actually came with 8.0x16" wheels on the rear is another question. EPC is not infallible.

Jon

 

[JimF37]

1. tire flat spots/out of round.
2. wheel balance.

Edit: I've had seven 140s. On every single one the ~50mph/80pkh vibration was the wheels/tires. The rest of the steering & suspension can dampen the 50mph vibration better if in good condition but if the tires are out of round &/or out of balance to begin with...

Where were you when I needed some advice about my '94 S500 coupe's tires. When I made the change from 'stock' wheels/tires, 235/60-16 to 245/45-18 wheels/tires, there was a vibration that actually NEVER went away . . . for 12 years which was the life of the tires (Michelin Pilot Sport - early model tires). It was minimized but never removed . . . until I replaced the tires to Michelin Primacy MXM4 tires. NOT EVEN A WIGGLE at any speed!!

Who would have believed that this could happen. Tnx, Joe for your insight!

 

[Saccofan]

None of those are standard wheels. In fact the page says "upgrades".

Edit: I stand corrected. While my 95 S600 came with 7.5x16 all around, Mercedes EPC says model year 95 up came with 8.0x16 on the rear only. But then it says 96 and up came with 7.5x16 all around, so who knows. There were a couple of styles of 7.5x16 wheels used.

Whether any US coupes actually came with 8.0x16" wheels on the rear is another question. EPC is not infallible.

Jon

I did some digging in my reference library and found that, as you said, the coupes from 95 had wider rear wheels. That from the 1995 US model year Introduction manual (see photos). The 16x7.5 Thin Convex 6 Spk 1404011402 and 16x8 Thin Convex 6 Spoke 1404001302 wheels referenced in my previous post (see link) were standard equipment on the later 140.07s. There's no mention of them in the 1998 model year intro manual. I do recall seeing more than one come through the shop with the tires, wheels or both installed incorrectly. The slight visual difference front to rear seemed to confuse or completely escape the local tire shops.

 

[jal1224]

EPC says the 8x16 wheels came with different tires as well.

Why we didn't get the 8.5x18s like the UK did, I don't know. Doesn't make sense.

Jon

 

[will_c140]

Why we didn't get the 8.5x18s like the UK did, I don't know. Doesn't make sense

Even with it's 45-55 intermittent shimmy issues, the UK-market Eltanins do make the car night and day over the OEM (which mine came with non-staggered 16x7.5, for the record). Sorry for the quality, I must have smudged my lens glass.

 

[jal1224]

Even with it's 45-55 intermittent shimmy issues, the UK-market Eltanins do make the car night and day over the OEM (which mine came with non-staggered 16x7.5, for the record). Sorry for the quality, I must have smudged my lens glass.

View attachment 2611286

Roadforce balancing my Eltanins with Continental tires got rid of my shimmy issues. Before I did that, readjusting front wheel bearing freeplay made a big difference also. I still get shake for 5 miles after letting the car sit overnight, until they get themselves round again. I thought the tires might have some nylon plies, but they don't, so I'm not sure why they take such a "set".

Jon