W123 Driveshaft Center Support
 

Yes, I spent some time looking but didn't find this .

1982 W123c 240D with automatic .

I heard the thump and went underneath the car, the rubber bushing is toast .

So, is there a good D.I.Y. on this ? .

Do I need to have it pressed on my a driveling shop ? .

Any other comments/ warnings/ tips ? .

TIA,

Nate,

Most important to match mark the halves BEFORE doing anything so it is balanced upon reassembly. Machine shop press isn't needed. Watch for shims between the old one and the tunnel, put them back if there are any.

Order a new boot that covers the splines and replace it while the shaft is separated.

Inspect the flex discs, order and replace if needed.

There is a centering bushing on the forward end at the transmission that could be replaced too depending upon condition.

There is DIYs here: DIY Links by Parts Category - PeachParts Mercedes-Benz Forum

I am less familiar with them but there are also wikis.

Other issues.

Finding a decent drive shaft support. I did mine so long ago I don't know what folks are doing for one now.

When you are removing the support bearing from the shaft there is 2 kinds of retainers. I don't know which one you have.

Inspect the flex discs really close as it can be hard to see the small crackles on them.

You might find that the U-joint sticks in a certain position. The nick name is notchy. There is no factory spec or instructions for replacing the U-joint bearings.

On each end of the drive shaft is a centering bushing. The URO copies are fairly cheap. I don't know how you determine if one is worn out of not but if the rubber seal is toast that will give you an idea. Also, they need to be greased before they are installed.

There is a big nut called the coupling nut. I can't remember if it is 46mm or 48mm and the counter hold is I believe 42mm. You will decide what you want to do on that.

There is no instruction in the W123 manual on this. When you are nearly finished, and it is time to tighten the coupling nut the car needs to be level on something with the weight on the wheels. You put the car in neutral engine off and you push the car back and forth and block the wheels and put the emergency brake on and get under and tighten the coupling nut. That is supposed to center the drive shaft inside of the coupling nut.

There is a torque for the coupling nut, but I have not read of anyone doing that. You would need to have a pit or lift to be able to do that. If you are fat like me, I had a thought time squeezing under the car to get the wrench on the couple nut and the counter hold to tighten it. But I did.

Something about the U-joint. Post #31 has a picture of my notchy Y-joint.: http://www.peachparts.com/shopforum/diesel-discussion/293976-drive-shaft-u-joint-staked-crimped-place-now-what-do.html

Helping Hands Drive Shft Service
 

THANX FELLAS ! .

I was hoping there'd be some discussion on the various brands, I don't want to re do this job .

I'd forgotten about the U-Joint in there and I've never even looked at it, with close to 1/2 million miles I think I'll just yank it out and let Cannon Drive Shafts. 10921 Chandler Blvd North HollyWood, Ca. have at it, the staked U-Joint is why I don't want to mess with it, they always use greaseable replacement U-Joints .

I'll have to go by and ask if they want me to supply the boot and center support .

It's pi$$ing down rain here in The Land Of Fruits, Nuts & Flakes so of course I'm diving the damn thing, I've been trying to adjust the slush box tranny but can't seem to find my banjo fitting, I made up a nice tool with long hose on it so I could drive and watch the gauge as I test drove and fine tuned the I.P.'s V.C.V. on my Coupe, I hate it when I put things "away" then forget where :rolleyes: .

I'm thinking of putting the whole car up on a set of those ramps then schrooching underneath, I'm "Horizontally Enhanced" too :rolleyes: so the ground clearance is an issue .

The torque spec. on that big nut is pretty low .

Worked for Mercedes of North America for a number yrs. Best way to remove rear drive
shaft. Do not loosen large nut, when all bolts are out, just tap rearward on bolt hole ears,
to reinstall grease splines line up well tap back in, works 98% of the time.
Time saver, if going to replace center support, drive line is out of splines just jerk hard on
drive line several times ,if rubber is torn, rubber will tear rest of the way, leaving support
loose from drive line, now drive line easy to remove, than reach and remove support.

Be sure to post back if they will do the job. Years past feedback was that the driveshaft rebuilding places don't have what it takes to put the 3-hole yoke onto the machines to balance the shafts.

The support rubber and the bearings if you buy them separately. In the past it was possible to get German support bearing rubber and the bearing can be ordered separately and if you go on eBay you can pic a bearing made in whatever country you want. Just be sure ask the seller what country it is made in as some sellers us some stock photo from the internet.

There are ones with the bearing and the rubber all as one assembly, but they are invariably Chinese.

The is an overall problem of the good quality parts disappearing and in fact sometimes being no longer made.

This is the output shaft yoke, but the drive shaft also has a 3-pronged yoke on each end. In the past it was said the balancers don't have the adapters for the I guess any more.

When I replaced the U-joints on mine I did not attempt to find a place to balance the shaft.

The wrench sizes for the clamping nut are 46 and 42. I used a 46mm and a
1 5/8". It's what was readily available. Torque is 30-40nm. Chapter 41 of the FSM gives the what and how but never the why. hercules is the professional mechanic. I am just a plumber. It seems to me the big nut clamps down on the splines gently so any engine or rear end movement has somewhere to be taken up. Loosening the big nut allows the drive line to compress easily so the centering sleeves will come off the 3 eared flange at the diff. The whole drive line then slides out to the rear. Of course you have undone the flex discs and removed the bolts holding the center bearing. On my '81 240D and '85 300D parts all looked the same. The center bearing pulled off easily and I tapped a new one on. I thought it was pretty straight ahead and easy.
But then I land somewhere between pigheaded and glutton for punishment.
I was dropping the rear suspension, so I put 3/4" all thread into the jacking holes with nuts and washers so nothing could slide. I jacked up the rear and put jackstands under the all thread. I then jacked up the front until I could slide the ramps under the tires. It felt very secure. West Coast, rust free cars.

I am not exactly sure what you are speaking of. I was describing methods that others on the forum have used and I also used.

If you read what others have done, I don't believe you will find someone torquing the coupling nut.

Also, if the coupling nut is not tight enough there are those who found the splines on the front part of the drive shaft badly worn. Remember that the part with the coupling nut is springy hence sotfer than the shaft that goes into it.

The thing with the ramp issue is you cannot role the car back and forth to center it before you tighten it.

The reason for the small torque force is that you are tightening something that is tapered. Normally when you torque a bolt or a nut and stud you are stretching it. In this case tightening is compressing not stretching.

Also lube the splines on that go inside.

Tip: if u joint is stiff or notchy set drive line at u joint bearing cap on anvil, vice pad or
other hard flat surface ,with larger hammer rap other side of bearing cap holder
4-5 times, flip and repeat, feel u joint, do until joint feels smooth ,has worked well
each time.

THANK YOU ALL !
 

Okay ;

It turns out the driveline place I've used forever is "Permanently Closed" :( .

It also began pouring rain and kept it up all day and last night so I'll wait until things are dry again .

Anyone know a reliable driveline shop in the L.A. Basin ? .

I don't mind traveling, I have a truck .

TIA,

Who would know that infomation on who might rebuild the drive shafts would be that place where people get the rebuilt transmissions in Sun Valey. They also sell used parts as it is where I got my used rear control arms.

Helping Hands
 

Thank you ! .

I'm back up to my eyebrows in my vintage VW but I do want to get this done, it's getting hot again so I need to buy (ack) or borrow an AC vacuum pump before I open the system to repair the leak .

I decided to look a bit more. Sumit racing has single Dorman rebuilt in stock. However, the attached pic is an is an O'reilly auto parts ad. Not sure but I think O'reilly auto parts is part of CarQuest and or advanced auto parts.

Out of stock at O'reillys.

Now I am curious to see what NAPA has. NAPA price $689.99 they want more info and say nothing about availability.


Note that $479 seems like a lot but you get the transmission mount, the new U-joint installed, shaft balanced, and I assume 2 new centering bushings on the drive shaft.