w123 driveshaft service
 

i'm trying to remove the driveshaft of my 240D to replace the carrier bearing and flex discs. i'm stuck on the sleeve nut. i have the right wrenches, but they're way too big to use with any sort of efficiency with the lack of space underneath the car.
would it be possible to remove the driveshaft without disengaging the sleeve nut?

Yes it is possible but then the easiest way of doing it is to remove either the engine or the sub frame and the differential!

This is why the nuts are there to collapse the prop shaft by a very small amount so that you can get enough wiggle space at the flex discs. Even though there's a single universal joint which could in principle give you a bit of "sag" if you disconnected the centre bearing I doubt you'd get enough wiggle space at the flex discs especially if they are stuck - which they often tend to be...

...if I were you I'd persevere with the big spanners - you only need to loosen the nuts a bit. Put two wheels on a curb to get the car up in the air a bit more?

Well that nut is usually not real tight, but you can't get it off with your fingers either. I have had good luck taking it on and off with a pair of "water pump pliers". I know it is about impossible to get a 32 mm open end in there. Might not be 32 mm, but it is a big one.

would it be possible to remove the flex discs and carrier bearing bolts and slide the driveshaft out?

Well yes, I think it could be done that way. The nut holds the spline tight, but not "impossibly" tight. But I think it is a very difficult way to do it. I think you should spend a bit more time to get it out the easy way. Make sure you mark the two piece so that they go back together the same way. Most of them have a factory assembly mark, but it is easier to use your own mark I think.

One of the reasons the front section needs to be moved back is in the center of each Yoke on the ends where the Flex Disc are there is a Centering Bearing. In order to clear that centering bearing the Drive shaft needs to be moved about 1 and 1/2 inches backwards or forwards.

In the picture you the Arrows point to the Pin that has to be cleared and the Bushing is circled.
Check the center of the Bushing for wear and it needs to be greased inside.

When I needed to loosen that Nut I had no 46mm Wrench and I used a Pipe type Chain Wrench to loose it. As was mentioned it is not torqued very tight.

Read up on the other cautions like match marking the parts so that they go back excactly in the same place.

DIY Repair Links
DIY Links by Parts Category - PeachParts Mercedes ShopForum
PeachPartsWiki: Do It Yourself Articles - Mercedes Vehicles

The other pic is of one type of Chain Pipe Wrench. Measure around the Nut so you are sure you have enough chain to go around it and secure the Wrench.

I second water pump pliers, as that is what I ordinarily use. I have some that are about a foot and a half long that I found abandonned on a job site. Enormous adjustable wrenches work, too. Home Depot sells some large ones under the Husky name that is some kind of light forged steel that are easy to handle, and are under $20. The thing is so light that I frequently grab it instead of my ancient Proto adjustable wrench when I don't need to apply monstrous force to something.

Water Pump Pliers; a.k.a Channel Locks

Water Pump Pliers; a.k.a Channel Locks

I just bought a Husky Aluminum 14" Pipe Wrench at Home Depot 3 days ago for $15. I don't if there is room to use one of those.
Also while a lot of Pipe Wrenches are adjustable Wrenches If you ask a Mechanic to barrow an adjustable Wrench He is most likely to give you a Cresent type Wrench.

If you ask a Mechanic to barrow His Water Pump Pliers He is likely to ask you what that is.
I only found out Channel Locks were called Water Pump Pliers when I studied for a Mechanics Test and the Material I studied from was really old material like from the 1940s and 1950s.

The 46mm ATV Wrench or a 46mm Crow/s Foot are 2 tools that you can use to torque the Nut. However both of those Wrenches need to be used a a 90 degree angle to the Torque Wrench; other wise you have to calculat the Torque.

All good info posted above.

First I have the 2 sections paint marked with some cheap white Finger Nail Polish paint before removing anything.

Remove the 3 bolts that hold the Drive Line to the Flex Disc.

Loosen the large Nut in the center of the 2 sections. I also use a large pair of Water Pump/Channel Lock pliers to loosen the nut. remember, Righty Tighty. Lefty Loosey.
This is a 46mm Nut.

Pelican has the 46mm wrench. they show two.
Pelican Parts.com - Extra Thin Wrench, 46mm For R107, W108, W109, W111, 113, W114, W115, W116, W123, W126, W20 Chassis

Pelican Parts.com - Extra Thin Wrench, 46mm For R107, W108, W109, W111, W113, W114, W115, W116, W123, W126 Chassis

Loosen the 2 (I think 14mm) bolts that hold the center Carrier Bearing to the body.

Now with a big Pry Bar between the front DL Flange and the Disc, pry around different spots to break the bond of the rubber to the steel. once loose, pry back to clear the centering pin.
Then do the rear the same way.

Once both ends are clear, snug the large 46mm Nut a little to keep the 2 sections from coming apart.

Remove the 2 14mm bolts at the center Support bearing.

You can slide the whole DL out towards the rear and down and out.

Charlie

X2 on the big pry bar and if you have an impact driver thats a big help in unbolting the flex discs.

There is a troque spec for the Nut when you re-install it. How, do you do that with the above listed Wrenches?

Also on the 42mm one you only need to hold the shaft stationary while you tighten the Nut. Anything that you can get a good grip on the Shaft with will do that.

Or you can do as I did and not Torque it just tighten it.
If someone has made the decision not to worry about the torque on the Nut a 1-13/16 Combination Wrench (I bought this from a cheapie Tool Place for $15) works.

I ment to cut the Wrench down to size as it is extremely long but did not have the heart to.

Later I bought a short handled open end wrench on Ebay. They are sold as Service Wrenches just plug in 46mm or 1-13/16 Wrench into the search box and see what comes up.

The same Wrenches as Pelican sells also come up on eBay from time to time but the seller gets a good price for them.

I have the transmission in gear and the Parking Brake on, and just snug down on the 46mm Nut with my Channel Lock Pliers. It isn`t on all that tight.

I posted the 2 Links for the 46mm Wrenches incase someone is looking for these Wrenches as I remember seeing them.


Charlie

Got it! Front part of the driveshaft came out without a hitch. Now, this rear section is a whole another story. I haven't come across any rust, so I don't think that's the issue. I used a screwdriver to pry the front flex disc off, and have been doing the same with the rear. Is there any trick to getting the rear section off? Or just keep pulling?

The Metal Tubes in the Flex Disc get pressed into recesses and I guess rusted in. My rear one also took a lot of prying to beak them Loose.


Careful not to damage those centering Bearings.

I guess no one Torques that 46mm Shaft Nuts! Before tighten that Nut there is aproceedure where you roll that car back and forth to center the shaft on the splines before you tighten it.

I had trouble with that because My Wrench was long and I could not squeeze under the Car easily while it sat on the Ground.