Is there any reason why this couldn't be done?
With the appropriate adapters, to get rid of the flex discs.
I am sure there is a reason why I can't find any information on this.

I am sure it is tough on the bearings, and seals.

The flex disc system is a really good reliable system - it makes for a really refined driving feel.

This system was used on the short wheel based vehicles. But for the longer wheel base vehicles - as in the factory extended "lang" versions - they used a double UJ system that looks a little more conventional. But again the propshafts are meant to stay in one position. There's none of this horse car sprung up and down with the back wheels nonsense...

__________________
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!

I do understand that the system is pretty reliable.
A brand new unit would hopefully last 150k to 200k.
I am faced with the necessity to buy a new driveshaft.
And it is unlikely that I will even get this much mileage out of the rest of the car. However I do not like the non serviceability of the units. And once the u joint begins to fail, it starts to take the rest of the driveline with it.
I would greatly prefer a serviceable unit especially considering who even knows if I will be able to find one for the car if it does last until the next drive shaft.

About 10 years ago I got a shaft from Driveline Service of Portland for my 115. It has a greaseable U, don't know if that suffices for you.

__________________
63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

I don't quite understand what you mean by serviceable.

The flex discs are (as far as I know) easy to find and replace. The centre drive shaft bearing and the carrier is also quite easy to find and change.

Even the original unit with the single UJ can be replaced - take it to a machine shop.

On the whole, however, my experiences of the W123 and W201 chassis (which has the same design requirements as your W115) have shown that you can get a perfectly nice drive line from a propshaft with a notchy UJ. I know it isn't ideal but the problems materialise when the propshaft isn't straight =>

There needs to be a straight line (think of the cross hairs of a gun along the length of the vehicle) from the front pulley on the crank - to the output shaft on the transmission / gearbox - to the centre propshaft bearing - to the input shaft on the differential. So long as you've got everything lined up the notchy-ness of the UJ doesn't matter.

To do this you need good motor mounts + a good transmission mount + good subframe mounts (at the front of subframe) + good "third" subframe mount / differential mount.

If you get these bits right and everything lined up the system works.

If one bit (or more) isn't straight then you get movement in your notchy UJ as well as the inherent vibration problems in a single universal joint.

Sure in some respects a double UJ system might seem like a good solution - but most of these double UJ designs need to have a large angle in the drive line (a difference in heights) so that the joint remains healthy and notch free.

In a Mercedes drive line (like the ones we are discussing) you could end up with two notchy UJs which might actually be worse than the system you have - you'd have to check with "lang" owners to see if that is true though!

__________________
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!

I believe I read a post from you before, I have attempted to contact them, to no avail. It was greasable, but was it staked in?
I sent an email, I will try to call.
I want a replacable u-joint.





What I mean by servicable, is that not every single component is replacable. The u-joint is staked, and no driveshaft repair shop in my area will touch it, because it is
1. Staked in
2. 3 prong flange
They do not have the provisions to balance a shaft with the 3 prong.

I agree, all of the parts are easy to source. But...at what cost?
I am not crying about the cost, but it is certainly a lot more than the cost of 2 u-joints, and requires ALOT more effort.
And there is still the case of the staked in u-joint. I believe you might be the one that replaced his own u-joint.
I was initially all for doing this, but given that I am not even supposes to be working on cars in my apartment (even though I have a garage) I decided, that it was not ideal.

Your statement about double UJ systems needing a great angle between the differential and the transmission, in all practical senses makes a lot of sense.

There is still the fact of 2 replacable uj's would only be a fraction of the cost, and time/effort of the current system.

Overall I am really just trying to explore all options, I will likely go ahead and buy a driveshaft from
Driveshaft Specialist Inc
I would really just be happy if I could buy a driveshaft with a cir-cliped uj.

I am sorry guys, I know this has been discussed a thousand time's but I have never seen any mention of an aftermarket shaft.

I plan to replace all of the mounts in the car. The only mount that appears to be bad though, is the transmission mount.
If front subframe mounts are good, I will probably leave them alone.
I am going to fill the engine mounts with Seka flex before I install them. And if the front subframe mounts are bad, I will likely fill those spaces with Seka flex also.
Seka flex is only a 27a durometer, and from my understanding that is about the right durometer.

I remain unconvinced.

However seeing as you're planning to go down this route I reckon you need to talk to people who make custom propshafts - perhaps people in the 4X4 world?

Alternatively

Two people (I can think of at the moment) on this forum who seem to have done such things are charliebob (1956 Dodge Truck Build with OM617) and perhaps mach4?

__________________
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!

Thank you for the advice. I will update here with developments

I think there are safety reasons to having a multi piece driveshaft compared to one long driveshaft. If there is a failure or an accident the shaft coming up through the floor is not as long.

__________________
Tony H
W111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux Pickup Truck-Dad bought new
'73 Toyota Celica GT

That makes good sense. I think I will be in the habit of examining the driveshaft every time I am under the car though, and also if I had servicable uj's I would also perform preventative maintenance on the unit.

I had my driveshaft rebuilt by Driveline Service of Portland a while back and they installed greaseable U-joints. I looked at their site today and now they install permanent U-joints. They used to cater to the Vintage Mercedes group but not so much now.

__________________
Tony H
W111 280SE 3.5 Coupe
Manual transmission

Past cars:
Porsche 914 2.0
'64 Jaguar XKE Roadster
'57 Oval Window VW
'71 Toyota Hilux Pickup Truck-Dad bought new
'73 Toyota Celica GT

I was finally able to get into contact with portland, you are correct, they no longer provide anything but a standard remanufactured driveshaft.

There is a shop in atlanta, that I heard about in a forum, I have to dig it back up, and that is the last hope, if not, I will have to get a standard drive shaft.

I dealt with the shop in Atlanta a couple of times when I lived in Cincinnati. They replaced a staked UJ for me, but I didnīt like their sloppy way of placing the drive shaft balance weights so I had to send it back to them. It never seemed quite right, so after I moved to CA I took it to a shop in Sacramento that installed a UJ using a cir-clip. I would guess this is what you mean by "serviceable" meaning "changeable".

If you are interested in a UJ with a grease nipple, you can probably find it in either staked type or cir-clip. In the end, itīs the stress more than inadecuate lubrication that causes the UJ to wear.

__________________

Don't Chrome them; polish them

Yes by serviceable I mean changeable/replacable.
A grease fitting would be nice too, lubed for life is great. But I think i would prefer a greaseable one.
But I want a driveshaft with provisions for a replacable u-joint.

The Mercedes setup has the crankshaft/transmission mainshaft prefectly aligned with the differential pinion. With no misalignment, you will tend to get notchy wear on the two UJ's, as happens with the single UJ in the center.

Best way to set up a two UJ shaft is with about 4 degrees of misalignment, to distribute wear on the joints. Oddly, a misaligned shaft will run more smoothly, as long as the UJ's are offset 90 degrees.

The likely reason for the single joint in the center of a Mercedes setup isn't safety. The most likely reason it's there is to raise the fundamental harmonic of the shaft system, but it may also facilitate assembly in some way. In either case, you'd want to retain the two piece shaft reagardless of what you do with the ends.