Flywheel damper - does it exist?
 

I have some low speed kangaroo issues with my 300E manual. Feels like there's slop in the drive train, a subject on which I've posted before.

So, I've changed the front flex disk, engine and transmission mounts, rebuilt the diff, changed diff mounts and I'm satisfied that the rear flex disk and centre driveshaft bearing are OK. Afaik, that's everything in the drive train I can get at from the outside.

For the clutch and transmission, there is no bearing noise, clutch slipping, trouble with gear selection, etc, so I have pretty much ruled this out.

The problem has got better with each of the above repairs, but it still feels as if there's something that's not quite tight. At low speeds, with the clutch fully engaged. it feels as if there's a slightly loose connection between the engine and propshaft. The sensation is exactly like that of a worn flex disk, of worn rubber mounts. As I replace each worn component, the symptoms improve but the problem morphs slightly. Classic renovation on the fly behaviour.

My mechanic buddy thinks it could well be the flywheel damper, and I have to agree it feels to me that this is the likely culprit.

Trouble is, I can't find out if there actually is a flywheel damper to change. My manuals have very little transmission information, which is no surprise, and a search of this forum turns up no information.

Can anyone throw any light on this? I know I'm going to have to pull the transmission off to find out but I'd like to know what I'm looking for first. Is there a rubber damper on the flywheel I can change?

Some cars have "dual mass flywheels" - two segments separated by rubber similar to front torsional dampers than many engines have, however, AFAIK the Mercs of this era have solid flywheels.

The remaining moving part that you appear not to have changed is the clutch disk, which does have a mechanical spring/friction damper built into the hub, however, if this damper assembly failed there would probably be a lot of engagement chatter, or worse The clutch disk damper on my '81 Diesel Rabbit failed, and shortly after I realized there was a problem it became impossible to shift using the clutch, so I had to drive it to the dealer using a clutchless shift technique. If your clutch take up is smooth, the disk damper probably okay.

Mercs have relatively "rubbery" drivetrains in order to promote smoothness and damp out vibration, so they will never feel as "solid" as less expensive cars that don't have all the vibration damping features.

Maybe your best bet is to find someone with a manual transimission 124 or 201 and compare how it feels to your car. You've spent a lot of money, and you may be chasing a ghost.

Duke

[QUOTE=Duke2.6Mercs have relatively "rubbery" drivetrains in order to promote smoothness and damp out vibration, so they will never feel as "solid" as less expensive cars that don't have all the vibration damping features.

Maybe your best bet is to find someone with a manual transimission 124 or 201 and compare how it feels to your car. You've spent a lot of money, and you may be chasing a ghost.

Duke[/QUOTE]

I agree.......not a lot of people know this, but here's a little info on flywheels...

Most NEW flywheels have a taper face...that is about a 2 to 5 thou' taper from the edge to the middle of the face.....all shops that grind flywheels do not taper the face, but flat grind the face....This taper allows the friction disc to bite at the edge first..it quickly allows the friction plate to seat and the 'marcel' does the rest......without this,this can promote shudder in take up.

This is not always the case and in some cars this taper is important for smooth clutch engagement.........another reason clutches shudder, is oil leaking onto the friction faces.....JAFYI... :)


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some interesting thoughts, thanks.

I do have clutch chatter, but only when using it for the first time in the morning, otherwise not.

The symptoms, that of a jumping or lurching in the drivetrain, only occur with a steady or trailing throttle, never when under power. This is not accompanied by any sort of clutch slip, at least not recognisable as such, which is why I think its more of a damper issue than one of friction.

I plan first to check the clutch plate wear from the outside, then depending on the results, pull the transmission and check the release bearing and fork before I go any further.

Have investigated the two mass flywheel on WIS since first posting and I think, if I can understand the worksheet correctly, it didn't come into production until 1989, which rules out my car. Is that what production breakpoint means, when it is introduced? It doesn't seem to correlate with my engine and VIN numbers, which is a little confusing.

Would be very convenient if it was a flywheel damper, but looks like my 300E doesn't have one. Any other suggestions as to cause would be very welcome.

That behavior could be caused by an excessively lean mixture. Does your model have a lambda system?

Duke

There's an interesting thought. No, the car doesn't have a lambda system, no cat.

I did recently tweak the EHA as outlined in previous posts and it did improve the low speed nehaviour now I come to think of it.

Not having any electrical feedback to work with, I've adjusted the idle mixture in the past by squirting carb cleaner into the intake and adjusting based on that. I think I'll give that a go again.

I'm not very familiar with the non-lamda systems, but I do recall seeing some information in the service literature about adjusting non-lambda systems (which also means no catalyst) to a specified CO range, which is considerably higher than the lambda/catalyst systems CO range.

On the non-lambda systems the EHA probably only controls cold start enrichment. Once the engine is warmed up the mixture is controlled purely by air flow plate deflection just like the older K-Jetronic systems.

Bottom line is that there is a big difference in lambda and non-lambda systems and each should be adjusted IAW the applicable Mercedes service infromation.

Duke

A little while back I remember somebody on this site fixed their cold clutch shudder by changing the motor mounts.