Driveshaft Flexible Coupling - PeachParts Mercedes-Benz Forum

Alan Robertson · #1 07-21-2002, 06:49 PM

I am changing the front flexible coupling on the driveshaft of my 1992 300E auto. I have removed the 6 coupling nuts and bolts, the heat shield over the driveshaft, loosened the compression nut on the driveshaft splined joint and disconnected the centre bearing support. The front end of the driveshaft will not slide back to give clearance for the removal of the flexible joint. Am I doing something wrong or does it just need more force?

WRM · #2 07-21-2002, 11:18 PM

there is a big ( i believe) 32 mm nut between the 2 pieces of drive shaft that needs to be loosened. if you don't have a 32 mm put a pry bar between the driveshaft front flange & flex disc & pry apart. it is easier to pry back with the center support mounted tight.

Alan Robertson · #3 07-22-2002, 06:48 AM

I had loosened the 32mm nut. However I took up your suggestion and refitted the bearing support. With a bit more "persuasion" the shaft slid back OK. Thanks for the help.

Alan Robertson · #4 08-04-2002, 05:23 AM

Now that I am happily back on the road I have time to be curious about the splined part of the driveshaft.
Is there a small movement on the splines corresponding with movement of the rear suspension?
Is the spined part only there to take account of manufacturing tolerances in the body and driveshaft components and for ease of fitting and re-placing components of the driveshaft?
Should the 32mm nut be tightened to a precise torque?

#5 08-04-2002, 09:42 AM

No, the big nut just needs to be tight.

The spline is there so you can collapse the driveshaft for servicing. There is no movement of the differential in an independent rear suspensioned car.

I put a flex coupling in my 300E several months ago and was pretty irritated about having to lower the exhaust, I think you have to lower the exhaust when doing anything on these cars. I'm surprised they didn't put it together so that you had to lower the exhaust to replace the spark plugs.

I'm sure you're as happy as I am to have the job behind me.

Have a great day,

pmizell · #6 08-04-2002, 10:03 AM

How much play, if any at all, should there be in the front driveshaft? When I grab the driveshaft near the front flex disc I can turn it 10-15 degrees either way.

Is this indicative of a worn out flex disc?

TIA

Alan Robertson · #7 08-04-2002, 11:31 AM

There should be no play between the output shaft from the gearbox and the drive shaft i.e. over the flexible coupling. I could not detect any play on the coupling even although it was faulty. It showed up as a vibration at high speed and a slight "clonk" sometimes when engaging gear.
I agree with Larry the worst part of the job was having to lower the exhaust. Rather than part the exhaust I lowered the whole system from the manifold back. Oh and I am also lowering my head,obviously I still think in terms of solid rear axle suspension.

MikeTangas · #8 08-05-2002, 12:51 AM

On the 560 I found it was easy to just lower the system from the back - muffler and center resonators. That gave just enough room to slide the tunnel cover off toward the rear, which opens the access to all driveline components.

Cap'n Carageous · #9 08-05-2002, 01:08 AM

When I replaced mine, all I did was put my floor jack under the trans pan (with a small piece of plywood between), remove the rear trans support, which includes the exhaust bracket, remove the flex plate bolts, pry back the driveshaft and reinstall in revese order. I didn't remove any shields or "drop" the exhaust. This is one of the few success stories I've had with this car. Oh yeah, the German printing on the new flexplate means to install toward the rear of the car.

patrik_the_swede · #10 08-06-2002, 07:07 AM

I also have a big "clonk" sound when changing gear from R to/from D (automatic) and the car moves slight even with my fot on the brake pedal. Would this indicate a bad flexible coupling?

Then I have this annoying loud sound coming from the rear at ~85km/h and ~145km/h. I can hear the same sound but much much lower all the time but at the given speeds it is really loud. Would this also indicate a bad (or two bad) couplings?

Alan Robertson · #11 08-06-2002, 11:56 AM

The faulty coupling did not make any running noise in my case. More likely to produce a noise would be a faulty centre bearing or the differential. Is the idling speed too high when you are engaging D or R?

patrik_the_swede · #12 08-08-2002, 03:09 AM

The idling is ~750rpm in (N) and moving the stick to (D) or (R) it goes down to ~650rpm. The car jumping/moving is less notice from (N) to (R). Though, I can see a small oil leak from the differential maybe I only need to fill up the oil (and fix the oil leak)?

Or I maybe need to install the vibration damper (#124 350 06 72) 'to the rear axle center piece mount of rear axle carrier' suggested in MB Ref 41/018, date 950401? (The car has only travelled 122.000 km). P.S I have subscribed on http://www.alldatadiy.com/ for 24.95USD/year for my car.