Hello guys. I've done some searching myself but wasn't able to find an actual how-to on how to do the flex discs on an '84 W123 300D.

Before I start the job, I of course first need all the parts and tools. Could someone help me out and let me know what I need to get?

First off, I need the Flex Discs. I will order those from this website. I believe I also need a big 47mm wrench, which can be had online for not too much money.

I saw that people advise to also change the 'carrier bearing'. What parts do I need for that? On this website I can find four parts for the drive shaft:

They are the driveshaft center support, the driveshaft bearing and the drive shaft bushing. Do I need to get all three?

Other then the drive shaft center support, are there any other parts I should get?

Tips, hints and advice are more then welcome. I've never done this job before.
Thanks to advice I got on this forum I've decided to do the job with the car on ramps, and to just jack up one rear wheel to be able to spin the drive shaft.

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

Ello' (practicing my British)

Should be fairly straightforward but of course nothing's easy. You're probably aware but be sure to carefully mark the drive-shaft orientation before you separate.

May not need the 47mm wrench if you have a decent collection of crescents and channel locks. The nut is not very tight. You may need to remove the exhaust, not sure I know on a 124 you kind of do although I did it w/ exhaust "in situ".

As for the bearing, I replaced the whole thing but that's up to you also depends on the condition of old one.

Be sure to note the bolt, nut and washer orientation on each flex disk.

Good luck!

I like the British! I'm not British myself, but a lovely ello' to you too, guv'ner!".

Thanks for the tip! Yeah, I'll mark everything, so the shaft will remain balanced.

I have a collection of pipe wrenches, one of which is quite huge. However one can never have too many tools, and a 47 mm wrench can be had for about 15 bucks online. If nothing else, it's nice to have it to whack a burglar over the head with, I reckon.

I don't know what the state of the bearing is, but I figure might as well replace it. Do I need a bearing puller and a press or something to change that out, or is it completely different from changing a wheel hub bearing?

Should I change the transmission mount as well?

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

You won't need anything special for the bearing, you'll see when you get it apart.

Sure, good time for it.

All right. So I guess I'll be ordering:

2 Flex disc kits (comes with bolts etc)
1 Driveshaft center support (Brand Febi)
1 Driveshaft center boot (Brand Mercedes Benz)
1 Driveshaft bearing (Brand FAG)
1 Driveshaft center bushin (Brand OEM)
1 Transmission Mount (brand Febi Bilstein)

And a 47mm wrench.

Is there anything else I need? I'm about to pull the trigger on these parts, and get this job over with before the end of the month.

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

I believe there are 2 drive shaft centering bushings. One at the transmission end and one at the differential end.

PaulM

__________________
84 500 SEL (307,xxx miles)

Where did you get a 47 millimeter wrench from? it's 46 millimeters! You also need another big wrench for the hex on the shaft. I don't remember the size (it's in the FSM). Do not over tighten - easy to do with a long wrench! 29 ft lbs iirc.

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

@pmckechnie
Sounds plausible...I'll do some more research. Thanks!

@Funola
Whoops, my bad. It's 46mm and the hex for the shaft is 41.

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

All righty, I bought all the flex disc stuff. Including shipping that adds up to 250 bucks. Estimated arrival is April 16th. Gives me two weeks to get it in. I told myself this car has to be drivable for some light commuting in May. I think I'm on track. After this it needs all fluids replaced (except engine oil, did that one already with the oil cooler lines), and then I guess I can get her insured and start driving a little...
I'm excited!

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

Why wait ? Do the other fluids now.

__________________
1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

@TnBob
Budget, mostly... Had some issues with my daily driver that I let the dealer solve. That wasn't cheap. And it was my wife's birthday a couple of days ago, and I might have gone a little overboard with the presents and spend a bit more then I should've. Oh well...

Anyway, enough about all that. Let's talk about the cool car again.

With the Benz I'll need to get power steering fluid + filter, brake fluid, tranny fluid + filter + gasket and diff. fluid, and while I haven't looked up prices yet, I'm expecting that to easily add up to another 200 bucks or so, so gotta wait till payday.

Though, I might wait with the diff. fluid altogether and just top it off, because I'll need to pull the left axle at some point (torn boot, probably has been like that for a while), and then I'll need to drain the diff again.
I had that planned around July, August or something. Should be fine until then.

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

Expect some serious trouble removing the old flex discs. They often rust into the recesses on the output flanges of the differential and the gearbox and on the propshaft of course.

Before you loosen the propshaft nuts (near to the centre bearing) consider marking both sides of the propshaft with white paint so you can reassemble it in the original position - by 1984 both sides of the propshaft should be marked with factory markings - and by 1984 the factory should have been paying attention to these markings (they didn't for quite a while!)...

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

@Stretch
Thanks for the advice! Greatly appreciated.

I read other folks that said the flex discs were super stuck. Mine will most likely be as well, as I'm pretty sure these ones are the originals. I am assuming though that I can just pry and start reefing on them as hard as I want? I have a 32" wrecker bar I can use for some leverage.

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)

Often the only option is to pry them off. Remember to kill the old flex disc and preserve the metal bits (like the yokes)

I have found a big flat blade screw driver is best for the job (much to my shame because I was taught to use the right tool for the right job)

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

@Stretch
Oh, I was taught that everything can be used as a hammer. I have a big flat blade screw driver laying around as well to do some prying with. I'm sure I'll get off somehow.

And hey, who knows: it might not even be that stuck. A man can hope...:-)

__________________
"The MB W123 is so bulletproof, you can drive them forever. Which is a good thing as it takes that long to get anywhere."
Betsie: 1984 W123 300D (hobby, 280k miles)
Myrla: 2001 Mazda Protege 2.0 ES 5spd (daily driver, 130k miles)
The Turd: 2007 Toyota Camry (wife's car, 118k miles)