W124 Driveshaft Question
 

Hey everyone,

I'm in the middle of replacing some plastic gears on my 722.418 in my 300D 2.5... In order to gain access to the one plastic drive gear I've gotta take off the tailshaft housing. So I had to remove part of the exhaust. I originally planned on dropping the entire driveshaft, but when the rear flex disc gave us difficulty, I went inside to look up how the flex disc mounts to the shaft/diff..my buddy was trying to pull it off the car and he accidentally removed the front half of the drive shaft...

So my question... I know I've always read that you should mark the drive shaft before taking it apart so you know what orientation it should be in so that it is balanced.. Is this the same case with the 124? How do I go about re-assembling the driveshaft without such a mark?

Also, Should I replace the center carrier bearing/bushings? Take a look at the pics below:

Front Flex Disc:
http://i.imgur.com/gGdLil.jpg

Tail Shaft Housing, I'm told this is a 30mm 12-point nut. I do need to get a deep well socket ($10 I think) from the parts store here...
http://i.imgur.com/OCqG5l.jpg

Half of Driveshaft..
http://i.imgur.com/3cY01l.jpg
http://i.imgur.com/Jmpqcl.jpg

Questionable looking bushing thing:
http://i.imgur.com/8CUzMl.jpg

Oh crap!

Have you turned anything?

If not mark what you've got now so you are at least in the general area.

I think I remember Larry Bible saying he had some tips for this situation - I think he's now called Air and Road (you know the artist formally known as...)

Its been rotated. How many times and in what direction I've no idea in the least.

There is from the factory marking points red arrow on the picture

james find the marking points if that fails take the shaft to a shop that works on drive shafts ask them to find the balence point mark it and go on. it shoul be just a spin, they may have to do it several times to get it just like it should be. replace the rubber.

OK - all I can think of is to try and work out where it is statically balanced.


What I suggest is


1) Wait for other advice! (EDIT - like the advice given whilst I was typing this)


2) Remove the whole propshaft.

3) Make a temporary support for the centre bearing - screw it to a block of wood - support on bricks - whatever

4) Now if you think that was bad - here's the tricky bit. You now need to try and support the other ends of the propshaft. I'm thinking something like lathe centres - or other bearings...

My point is that you need to be able to spin the propshaft quite freely so that you can see if it favours a particular point or not.

Static balancing is achieved when you spin something and it stops spinning at random positions - if it always stops spinning at the same place then it is not statically balanced.

Q:-

Why is static balancing important?

A:-

You'll not achieve the more complicated to achieve dynamic balancing with out it. It is the first and important step to balancing the shaft.

For all the advice you hear, I'm surprised MB didn't make discernible marks after balancing.

[edit] Oops, just saw spit64's post. I've never noticed those marks.

Sixto
87 300D^2

I hope in this case they are marked. The one on my W123 isn't - may be by the time of the W124 they got their act together?

dont sweat it - the D shaft has factory markings that you need to align back as shown in the picture. Whilst you have it disassembled - get some high moly content grease - or the paste BMW motorcycles use on their rear wheel spline drive. Its a moly paste made by Dow. And is the same thing MB specced for lubricating the middle splines and bushings on the end of the D/shaft with. Both bushing ends take 6gms of this paste and the splines take a slather of it.

This special paste is also available at "level headed" honda motorcycle dealers or specialty motorcycle repair shops. Its light gray in colour and the only way it gets off your clothing is putting them in the trash.

Replace that little boot - its a 3 or 4 dollar part and is made from plastic now.