DRIVESHAFT VIBRATION

[r44raven]

This is a continuation of the thread I started "Is this a genuine M119 engine".

We've now completed the swop of the 4.2L found in my E500, to the 5.0 litre I've taken from an SL (what a transformation in performance!).

However, we've been left with what I can only assume is a driveshaft vibration. This can be initially (and only slightly) felt between 48 and 53 mph, and then it disappears until the 95 to 105 mph range, beyond which it again disappears.

(We have discounted wheel/tyre imbalance, having tried various sets of wheels/tyres - all meticulously balanced - with no improvement. Also, before we carried out the swop, there was no hint of vibration, so I assume we can safely assume that the fault does not lie with the flanges (all of which look good), or the centre flexible coupling).

To recap, the engine/gearbox/driveshaft front flange is from the SL. This front flange connects to the original front half of the driveshaft from the E500. We did have to remove the whole driveshaft when fitting the engine/gearbox, but have ensured that the markings front and rear of the centre bearing line up as per the manual.

However, as far as the front flange connection to the gearbox is concerned, in the MB manual I can only find reference to alignment arrows when it is (for want of a better description) a three-pronged connection.

My E500 (and the flange from the SL) has a four-pronged connection, and there are no arrows or other obvious markings on them which might suggest there is a correct way to line them up. However, could this area be the possible cause of the vibration? Despite having no obvious markings, is there a correct/incorrect way of lining up?

Any help, anyone?

Stephen

 

[jhodg5ck]

Do you have a driveline shop around Bath...been a while since I've been there and it wasn't on my list of things to keep an eye out for..;-)

Yes, there is a specfic way,everything is balanced as a unit. I'd go ahead and order up a new carrier bearing and carrier -->get a shop to go through it.

Alt, you can get some large hose clamps that fit around the drive shaft...move it around, see if you can't get the vibe to diminish or move around.

JOno

 

[mercepor]

You can find some very good threads here on driveshaft vibration, it is common prb of the e500e.
I would recommend to change the flex discs and the center bearing to new ones.
Indeed there is no arrow, but you should pay attention to the orientation/order of the bolts/washers/screws.

 

[gsxr]

I think you are correct that the issue is in the prop shaft. The two halves may not have been aligned exactly at the marks from the factory, and if it wasn't checked BEFORE separating the halves, you're starting from scratch with balancing. If the center support is old/original, replace that first with a new bearing. If the flex discs are old it probably would be a good idea to replace with new OE or OEM (SGF only). Someone posted on the forum to avoid the weird style SGF with holes in the flex disc, make sure they are solid. If all that doesn't cure it, you have 2 options:

1) Have the prop shaft balanced as a complete assembly WITH the flex discs bolted on. Take extreme care not to lose the orientation between halves, and don't unbolt/move the discs either.

2) If you still have issues after #1, there's always this factory procedure, which may be considered cruel and unusual torture in some countries:
http://www.w124-zone.com/downloads/MB CD/W124/w124CD2/Program/Chassis/41-080.pdf

 

[Rudy]

Hi,
recently I noticed vibrations going starting at 90-100 km/h (55-60 mph) from the rear.
Rear tires are new and therefore newly ballanced, flex disc done last rear.
Do I face (expensive) axle issues?
Thanks,
Rudy

 

[Raffaelli]

Why did you have to take the driveshaft apart in the first place?

 

[r44raven]

Why did you have to take the driveshaft apart in the first place?

I'm not quite sure to whom this question is addressed - Rudy or myself (r44raven)?

Following on from my problem with vibration from the rear (the driveshaft having been removed during the process of the engine exchange), this was finally rectified by having the whole driveshaft balanced as a complete assembly (as recommended by gsxr).

At the same time the centre bearing and universal coupling were replaced. The latter process was not simple, as the universal coupling was non-serviceable i.e. it was not fitted with circlips which would have allowed new bearings to be fitted. So a new u/c had to be welded on to the existing shaft. Interestingly, the new u/c has both circlips and a grease nipple! Ideal for easier maintenance.

Having said all this, there still remains a very slight and somewhat illusive vibration which is not always at the same speed. However, a previous owner has fitted a "sports" exhaust (I've no ideal what make - it appears to be bespoke!), and having read up about exhaust resonance and how it can set up vibrations, I am happy to accept that the vibration that remains is no long mechanical, but is caused by the exhaust. Maybe another owner has similar experiences.

(Forgot to mention that when we removed the driveshaft to fit the new engine, we did detect a small amount of "roughness" in the universal coupling, and as it was thought this might have contributed to the vibration, we had it replaced).

 

[samiam44]

I would guess they didn't get the new u/c centered properly.

FYI, there is very little movement in the u-joint. The subframe/trans movement relative is very very small. So the driveshafts tend to feel a little rough in a spot-but it might be nothing. If there is play, bad seals etc.. would worry. Slight roughness feeling- are both rear wheel bearings good?
It's had to desk top diagnosis.. really need to drive the car to understand it. I'm picky and mine is glassy smooth.



M

 

[r44raven]

I'm picky and mine is glassy smooth.



M

I'm really jealous if your 500 is glassy smooth. I'm picky too, and I'm still obsessed with the slight vibration I have - which having more or less excluded any mechanical cause - i.e. driveshaft, wheel balance etc. etc., I'm putting down to exhaust resonance.

Can you tell me what exhaust you have fitted? Is it stock, or has it been modified? I'm almost convinced to go back to a stock exhaust, so that I can hopefully totally eliminate the vibration - and so can then be totally sure of the cause. I would say however, if I did prove that the problem was exhaust based, I would probably refit the offending exhaust system! The sound under acceleration is fantastic!

 

[IanAtkins]

Raven, hi. I'm in the UK with an evasive, elusive and very frustrating vibration issues. Now after having balanced the wheels a dozen separate times, and refreshed the entire suspension setup at great cost, I'm left with a vibration that a. does improve/worsen depending on the wheel balancing, and b. now moves from place to place - i.e. when the vibration is at let's say 110km/h, if I keep the car at that speed on a perfectly straight road, in less than a mile the vibration will have disappeared, only to be found at a different speed. When discovered and held at the new speed, the vibration disappears again and will be found at another speed....

 

[gsxr]

Ian, can you post a complete list of what components have been checked / replaced, and details about any items replaced? Have you done anything with the propeller shaft (or axle half-shafts) yet?

 

[r44raven]

Raven, hi. I'm in the UK with an evasive, elusive and very frustrating vibration issues. Now after having balanced the wheels a dozen separate times, and refreshed the entire suspension setup at great cost, I'm left with a vibration that a. does improve/worsen depending on the wheel balancing, and b. now moves from place to place - i.e. when the vibration is at let's say 110km/h, if I keep the car at that speed on a perfectly straight road, in less than a mile the vibration will have disappeared, only to be found at a different speed. When discovered and held at the new speed, the vibration disappears again and will be found at another speed....

Hi!

I can emphasise exactly with your frustration! You obviously have read my experiences in this particular thread. My circumstances were very similar to those you have outlined. Because I had replaced the drivetrain with an engine and gearbox from an R129 (which included using the SL's front flex disc), we were uncertain if the vibration might have stemmed from this. So I had the whole propshaft (incl. the flex discs) balanced, which did help somewhat. However, I was still left with an obscure vibration, and even after numerous wheel balancing exercises, it was still there. It would not always be at the same speed - seemingly to come and go at will - and which would vary whether under acceleration or deceleration.

Eventually, having read of Road Force Balancing from devotees from "across the pond", I eventually tracked down a company in the UK which could offer this (Imperial Tyres in Swindon), and after they had done their magic on the car, the vibration was cured.

If you search "Road Force Balancing" on this site you can read more about it.

I strongly suggest, before you throw any more money at the car, you try it out!

Stephen

 

[Hakie]

This are the markings on the driveshafts witch has to be in line.

 

[IanAtkins]

Chaps, so sorry had a major problem with my computer and couldn't get access to my invoices from the mechanic. Thanks to gsxr, hakie and raven for the replies. Raven it seems like you've had the same symptoms as I have. Actually, you know the car - http://www.500eboard.com/forums/showthread.php?t=9363

I replaced the shocks all round, the engine mounts (one of which was completely shot), transmission mounts, wishbone bushes, anti roll-bar bush, track rods, idler bushings and steering damper. I've changed the wheels and tyres and found no out-of-round problem with my Evo II wheels which I thought was the problem after the first phase of work. Whatever I do, whichever wheels or tyres are on the car, a very good balance leaves me with a very slight high-frequency at exactly 100km/h, and a bad-average balance can have vibrations from 80-140 at various places, all coming through the steering wheel. The work on the car has definitely improved the ride to a great extent. If I'm accelerating even gently through 100km/h I won't even feel it.

I havent done anything with the driveshaft yet.

There's a brilliant company called Vibration Free near me in the UK and they do on-car balancing (which I've done twice with them - didn't help, just moved the vibration around some, spread it out and made the frequency lower) and next time I'm in England I'll be getting the car on the ramp there to see if there's anything coming from the drive shaft. Nobody knows what could be the cause. I don't even know what an axle half shaft is! It was their confusion about the source of the vibration which prompted the suggestion of changing the shocks, and to tell you the truth after all the work had been done, the car - this time with only a slight vibration at 90-95km/h - was an absolute and total joy to drive from the UK to Italy and back last Xmas on winter tyres with standard 16" wheels and the work that was done transformed what was a very good ride to a spectacular one. Apart from the slight vibration, the car rides completely like new. It's a revelation actually, but moving on...

I found the lad at Imperial at Swindon the time that I went there to do the RF balance a little too quickly, and it didn't get rid of the vibration. However, the very latest thing I did a month ago after refitting the 17" wheels was after I found an excellent shop in Knokke in Belgium on my last Europe trip and they really took their time and did a fantastic job, so I'm now back to a very minimal vibration at dead-on 100km/h - almost imperceptible, yet still wondering what the hell it is because - please please correct me if I'm wrong, a w124 shouldn't be so darned sensitive to wheel balancing, should it?

Quickly took it to a mechanic recommended by fancy classic Merc guys for a second opinion (I've been very happy with Terry Gates at Mercservicing), to see if there was something obvious about the driveshaft or flex discs and he tightened up one of the bolts at the back of the driveshaft - but he didn't have time to do a test drive nor to remove the exhaust to look at the clamp in the middle, so maybe...?

So, as I said, when back in the UK I'll go to Vibration Free and ask them to do their measurements on the car on the ramp and they can check the driveshaft to see if it's coming from there.

Steve, the boss at Vibration Free - http://vibrationfree.co.uk/about-us/ - Is convinced that vibration through the steering wheel is 99.99% a wheel-balancing issue, therefore all that needs to be done is "wheel balancing to the nth degree" as he's had a handful of e500e and they all have had vibration problems. I'm not so sure yet. I think that if he's seen several of our cars, they would only have come to him with vibration issues given his area of expertise, and as you guys will agree, this is not such a 'common' problem on these cars to have become a characteristic - and that most times the work that has been done on my car would have cured the issue. Also, Merc isn't going to hand-build a motorway specialist leaving loads of cars susceptible to vibrations at 80-140km/h is it?

So, let me know what you think,

Best,

Ian

 

[Allgonquin]

I have a persistant vibration also, and several attempts at high quality wheel/tire balancing have only helped slightly. I've thought that I should get my engine and trans mounts done before I start on the driveshaft and center bearing themselves, just have not gotten around to it.

 

[IanAtkins]

Yes, the reason I havent done that already is that the majority view holds that a vibration through the steering wheel only is at the front end....

 

[IanAtkins]

After I got the first work done, the mechanic had checked the condition of the suspension and steering systems, and the problem was still there, I immediately thought one of my 17" wheels was out of round.. sadly for me it was not the case and the head-scratching continued..

 

[TerryA]

Ian,

What brand of tires are you running? If the wheels are strait and no bad brake rotors you have to look hard at the tires.

I think you have replaced all of the suspension parts right? Tie rod ends, drag strut and steering damper ect; Through the steering wheel is definitely front end. What's left? Sway bar bushings, wheel bearings, brake rotors, wheels, spacers maybe? or tires.

If you have ruled out all of the above issues for a front end viabration then IMOP, a quality brand of tires like Michelin properly balanced would go a long ways in solving your problem.

I can see from other posts by U.K. members that getting a knowledgeable tech guy for 036 cars must be a real headache.
Pick one Tech you have confidence in and see this issue through with him. Using different Techs probably isn't helping much.

Good Luck

 

[IanAtkins]

Terry thanks. Wheel bearings they must have checked at the very beginning, brake pads and discs - all new. Wheels 17" evo II and 16" Alamak (oem)

Tyres
- Continental Sport Contact 5 for the 17" - unfortunately they are the XL version, heavier with reinforced sidewalls - unnecessary I think but not the root of the problem imo...
- Michelin Primacy 3 for the 16"
- Goodyear Ultragrip Performance Gen 1 (winter) 16"

Tyres all new, balances a million times....

 

[samiam44]

So,

since we are talking driveshaft- you feel it in the seat and the steering wheel is vibration free? When did this vibration start occurring... does it line up with recent tires/wheels/brakes? Wheels and hubs it's runout and not just balance. Ie it can wobble or not be concentric with the axle centerline.

Hard to diagnosis over the internet... you need someone to drive your car with you and make suggestions...


Michael

 

[IanAtkins]

Thanks - I know you're right which is why I need to find an 500/r129 guru in the UK.... It's in the steering wheel only, so off topic slightly. I've checked the wheels for runout, but not the hubs, however the on-car balance didn't get rid of the vibration...

 

[IanAtkins]

but then it might not be off topic..... as i'm going to get the driveshaft checked..

 

[samiam44]

Only in the steering - I would check the idler arm bushing and replace the steering dampener.

Pretty sure your problem is there- *IF* the front wheel bearings are adjusted to MB spec/FSM.

Bet it's one or all three of the items. I've seen chineese rotors and brake drums where they didn't balance them....

... I though you'd just drop by and have Ed China give it a look =0)

M

 

[gsxr]

If the vibration is coming through the steering wheel, if you let go of the wheel you should be able to visibly see the steering wheel shake. If so - the problem is most likely not related to the driveshaft. I would second the recommendation to double-check wheel bearing end play per FSM procedure (dial gauge), spec is 0.01 to 0.02mm, and unless your name is Klink or Jono, you cannot do this by feel. I doubt it's the cause of the issue, but it would be nice to rule it out. Brake rotors are indeed another possibility, but that can be more difficult to check without just buying new OE rotors/pads.

Driveshaft vibrations tend to be felt in the middle of the car, what MB calls "thrumming" in English. These tend to appear near freeway speeds and may never go away at higher speeds, just change frequency or intensity. The fun part is when you have new flex discs and new center support, and new engine/trans mounts, new subframe mounts, new subframe links, RoadForced wheels/tires, and still have the driveline thrumming. I've been chasing that on my one car for a couple of years and still haven't cured it.

 

[r44raven]

If the vibration is coming through the steering wheel, if you let go of the wheel you should be able to visibly see the steering wheel shake. If so - the problem is most likely not related to the driveshaft. I would second the recommendation to double-check wheel bearing end play per FSM procedure (dial gauge), spec is 0.01 to 0.02mm, and unless your name is Klink or Jono, you cannot do this by feel. I doubt it's the cause of the issue, but it would be nice to rule it out. Brake rotors are indeed another possibility, but that can be more difficult to check without just buying new OE rotors/pads.

Driveshaft vibrations tend to be felt in the middle of the car, what MB calls "thrumming" in English. These tend to appear near freeway speeds and may never go away at higher speeds, just change frequency or intensity. The fun part is when you have new flex discs and new center support, and new engine/trans mounts, new subframe mounts, new subframe links, RoadForced wheels/tires, and still have the driveline thrumming. I've been chasing that on my one car for a couple of years and still haven't cured it.

That's a really great post by gsxr. As I understand it, there are a number of E500E owners who have - and still are experiencing - vibration problems. Despite all attempts to get to the source, it seems in some instances, this is elusive.

Reference IanAtkins problems, sorry to hear that Road Force did not cure your problems - it certainly did for me. But I know what you mean about the guys at Swindon; they did seem to be very quick. However, I did get a good analysis printout from them of the status of each wheel - which showed one to be the problem - which they cured.

About getting an E500E guru to look at your car. I may have asked this before, but are you a member of the MB Club here in the UK? If so, you have access to Neville Wright, who is the UK's leading expert on W124s (and particularly E500Es). What he doesn't know about the marque isn't worth knowing! (He doesn't partake in forums, so you won't find him here).

 

[IanAtkins]

Thanks for that. gsxr I feel for you if you can't get to the heart of the matter it is blood-boiling, and know that I too have thrown thousands at the car to fix it, and haven't really gotten there. What I haven't checked is the wheel bearings, but I think that I can rule out hub out of round with the on-car balance.

Raven, I have been hoping each time I hear something that it will be the thing that fixes it. From the exploded engine mount, the possible out of round wheel, the alignment, the shocks, that final balance, those new tyres, the bushes - just waiting for that feeling to lift away like you must have felt after the RF balance...

Samiam - i've done the steering damper and the idler arm bushings - so wheel bearings maybe next - but I'm sure Terry would have checked that...

I'll try and track down Neville, and see if he truly is my Mr. Wright....

Best,

Ian.

 

[IanAtkins]

oh yeah and i've put new brake pads and rotors (discs in real English) on which got rid of a slight vibration on application of the brake pedal at the time, but I was still fuming about the shimmy....

 

[IanAtkins]

Greetings! It's a long story, but basically I realised that my vibration was also coming through the seat, and that it was pretty much everywhere, and not only at c.100kph... it was subtle, and it took me maybe 20,000 miles to realise, so I got Steve at Vibration Free to put it up on a ramp, disable the ASR and see if it was the driveshaft after all.... it wasn't. He said the driveshaft was true. But 2 minutes after the car had been running, he tells me its the rear diff, which is 'knackered', broken. There is a loud howling noise and vibration coming from the diff. I'm praying that finally we've found the source of this vibration.

Meanwhile, I need to find a second-hand 2.82 - and I'm nearer to Germany than the States so does anyone know where I could start looking?

thanks..

 

[r44raven]

You might try "the biggest MB scrap yard in Europe" - at Lokeren about 10 ks east of Ghent. Here's a link:

http://www.autopartsvandevelde.be/

Its only 2 hours from the Tunnel, so could be done in a day.

I don't think they do much trading via the internet, so you'll probably need to pay them a personal visit, which is a bonus in itself! Others on this site will be able to advise if they might have a 2.82 - it'll depend on whether this was fitted to any other MBs (?) because they don't hold a huge stock of E500E stuff.

Happy hunting!

 

[gsxr]

The 2.82 from the early 140.04x chassis (1992-1994 vintage) with optional ASR, will work with some part swapping (rear cover, maybe flanges).

If you aren't tied to the 2.82 ratio, the 2.65 diff from a 129.066 with optional ASR is 100% bolt-in after swapping the ASR sensors (the R129 sensors have shorter wires).

Of course the best option is to locate an E500E diff, but that may be difficult, especially since the shipping weight is near 100 lbs / 45kg.

 

[JC220]

Greetings! It's a long story, but basically I realised that my vibration was also coming through the seat, and that it was pretty much everywhere, and not only at c.100kph... it was subtle, and it took me maybe 20,000 miles to realise, so I got Steve at Vibration Free to put it up on a ramp, disable the ASR and see if it was the driveshaft after all.... it wasn't. He said the driveshaft was true. But 2 minutes after the car had been running, he tells me its the rear diff, which is 'knackered', broken. There is a loud howling noise and vibration coming from the diff. I'm praying that finally we've found the source of this vibration.

Meanwhile, I need to find a second-hand 2.82 - and I'm nearer to Germany than the States so does anyone know where I could start looking?

thanks..

I know of a 500E in France that's wrecked - I'll PM you details

 

[samiam44]

State side these are inexpensive units. Not sure what it would cost to ship, but a consideration. 2.82s out of a W140 will drop in with only switching the cover( I think) and you'd want to re-seal it anyway as they are a leak point.


Michael

 

[IanAtkins]

thanks guys JC220 I've already followed up the french car, waiting to hear back. samiam i'm going to start a new thread trying to find the easiest bolt-in ....

 

[IanAtkins]

OK guys, time for an update.

When I spoke to the mechs, one shook his head, and the other raised an eyebrow when I told them that the vibration expert had said that the only part of the car that was vibrating was the diff. I still went ahead and got a 2.65 off an r129 while waiting for steve h's 2.85 in November.

The diff was screaming, thumping and vibrating on the ramp don't forget.....

However the replacement did not get rid of the vibration.

Nev at Diamond Garage now has the car. He told me that the two parts of the driveshaft were 20 degrees out of alignment, and the center bearing was cracked and worn..

I'll know more tomorrow when I speak to him - but I'm hoping that this issue all starts from the misalignment of the driveshaft, the vibrations from there creating wear on the center bearing down to the diff....

 

[samiam44]

Thanks for the update!


Sorry to hear that wasn't the solution. Guess the diff being rubber mounted, it was excited by the vibration. 2 thumbs up for Dave's driveshaft input. You should be able to find a driveshaft specialist which can complete rebuild it. A new u-joint can be flash brazed in place, or even a c-clip groove machined. Then the whole thing rebalanced. Check the end centering bushings for damage too- It seems like they can get too much play or the seal goes out. I've replaced one for too much play and one on a different car for the seal. I think they were ~$30 ish aftermarket.

Take a picture of the old centering support next to the new one! I'm sure you need the dust boot on the spline too. Frustrating, but if you've now found the root cause- happiness is close!

Congrads on the engine swap.


Michael

 

[IanAtkins]

Thanks - but a strange one - Neville said that he couldn’t find the alignment markings on the driveshaft...

 

[r44raven]

If your car is with Neville, it's with the right person. If he can't sort it, no-one can!

(p.s. when I had all my driveshaft vibration problems, we couldn't find any alignment markings either!).

Good luck.

Stephen

 

[JC220]

Thanks - but a strange one - Neville said that he couldn’t find the alignment markings on the driveshaft...

You are looking for small indents each side to align – like the picture attached. Sometimes these are highlighted by a paint marker perhaps at the factory assembly line – but mostly they are just indents so easy to miss. I'm sure he knows this - but just incase it was overlooked that's all!



Specialist shops will also be able to check the balance of the whole assembly on a test rig and correct / re-balance if required. (That would be the next step if re-aligning the marks does not work)

 

[samiam44]

JC22- just noticing in your picture- the center support doesn't appear to be mounted straight- it's cocked like when the first bolt was tightened- it twisted the support.

 

[IanAtkins]

Thanks. Sent both photos now to Neville. Funny when I spoke to him this morning he said "believe me I scanned that thing...." and he knows the markings from other 124s... let's see if he finds them...

 

[IanAtkins]

Raven, was your driveshaft with Neville? If no markings does that mean it's not OEM?

 

[JC220]

JC22- just noticing in your picture- the center support doesn't appear to be mounted straight- it's cocked like when the first bolt was tightened- it twisted the support.

Thats not my car- maybe I should have mentioned I googled the picture!

 

[r44raven]

Raven, was your driveshaft with Neville? If no markings does that mean it's not OEM?

No, the shaft wasn't with Neville. However, I should have clarified that whilst we did have the alignment markings each side of the centre bearing, what we were missing was the alignment marks on the flanges at the front and rear of the shaft. There should be markings to align with corresponding markings on the flanges on the back of the gearbox and the diff unit.

I don't know if my driveshaft is OE or not, but there was a number of issues with it. First, the universal coupling was worn, and second, the spline at the centre joint was also worn. As a new unit was NLA, and the universal coupling was not repairable, I sent the whole shaft, including the front and rear flexi couplings to a company in (if I remember correctly) Coventry, and they repaired the spline, replaced the U/C with a serviceable unit, and then balanced the whole thing.

 

[gsxr]

No, the shaft wasn't with Neville. However, I should have clarified that whilst we did have the alignment markings each side of the centre bearing, what we were missing was the alignment marks on the flanges at the front and rear of the shaft. There should be markings to align with corresponding markings on the flanges on the back of the gearbox and the diff unit.

AFAIK, there are no factory markings at the flex disc flanges. The driveshaft + both flex discs is balanced as an assembly at the factory, and IIRC the FSM mentions marking these manually if they need to come apart for service. However when the flex discs are replaced, the markings would become somewhat irrelevant.

 

[whatever]

Damn, I'd love to see how that vibration ramp looked like.

BTW, had unbearable R129 shimmy, eventually, just new tires and it was 99% better.

 

[IanAtkins]

Brothers, an update:

Neville re-aligned the driveshaft and replaced the centre bearing. Both of us were very optimistic about this being the root cause of the vibration.

Sadly, the vibration is still there. This is more than upsetting now because Neville - possibly the most experienced and certainly the highest regarded 124 mech in the country with an abiding love and admiration for 500s - doesn't know where to look next.

We raised and lowered the rear diff with the shims - no difference. Neville is 100% sure it's not an out of balance driveshaft or mis-aligned drivetrain..

We had a transmission specialist look at the car on a ramp - nothing untoward at the transmission end..

The floor of the car is smooth to the touch when running at 100km/h when the vibration is occurring...

It's sure that it's something rotating somewhere that's not right. The vibration is pronounced at 100km/h, but the ride simply doesn't have that perfect integrity that any well-sorted merc has at any speed. There's simply something wrong with it somewhere.

The ride is ultra-sensitive to road surface change, wheel-balance and there's an exaggerated difference when the 17" wheels are on the car compared to the 16" wheels. 80% of the vibration is coming through the steering wheel..

I know it can't be at the front of the car because I basically replaced every single possible cause of the vibration because we first thought it was exclusively coming through the steering wheel, it's not the steering, not the suspension, not the steering box....

So next is to examine the rear brakes to check for runout on the rotors as there's a slight vibration on gentle braking from c. 120km/h down to 90...

Could it be out-of-balance half shafts??

 

[jhodg5ck]

if you feel the vibration mainly in the steering wheel it's not the driveshaft. You would feel that in your seat.

Def not half shafts.

How old are are engine is trans mounts?

 

[IanAtkins]

J hi. Trans mounts and engine mounts new last year. But there is definitely something in the seat as well.

 

[IanAtkins]

it's like it's something very subtle. Whatever is wrong, it's not out by much...

 

[jhodg5ck]

who made those mounts? If they aren't the Real/Right deal: OE Mercedes on trans, Boge w/ the paint marker letters on engine I bet they are letting go already.