I strongly suggest that you take the driveshaft to a driveline balancing place, and have the shaft balanced, driveline straightened and u-joints replaced to eliminate the drive-shaft as a source of the problem. I further recommend that you find a shop that can balance the shaft WITH the u-joints and flanges in place when they balance.

Packman

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83 240D - 4 speed manual - Manilla Beige
189K miles, Tachometer mod, cool wooden shift knob from PeachParts, CocoMats, Original factory paint, manual windows, manual sunroof. Starting to add AudioWrap to this car too!

Not to contradict Packman at all - just wondering. Can they balance a two piece drive shaft as a unit or do the have to balance the front and rear separately? Seems like you would want to do the whole thing assembled but when I've watched them balance shafts they were a one piece and the balancers I saw didn't seem to be set up to run a two piece.

Dan

Not common of course but possible to lose a balance weight. Depending where I lived and there were pick and pulls. I might remove the two piece shaft from a wreck and install it if cheap. Including the used shafts flex rubbers. What I suspect that under load or torque for some reason the driveshaft is not running in a concentric fashion.

If the problem persisted with the new used parts installed then I might suspect the rear transmission bearing or pinion bearing letting the shaft go off centre under torque.

About an eighth inch of movement would enable your problem under load from experience. I had the wrong universal bearing in my driveshaft on my 39 buick resto rod and it would go off centre itself again.. Then seemed to self centre under lighter loading. Was not hard to locate because I suspected it the first time I felt it.

In some ways it would be my approach fashion in an economical way to eliminate certain things in a positive fashion. Without spending a lot of money. The indicator that the problem may be in that area for your car is some severe forces are destroying your centre bearing rubber mount in my opinion. That opinion could be wrong of course is also why I would want the cheap substitute parts for testing.

Yes the euro driveshaft savvy shops balance the whole driveshaft as a unit as did the factory. This is why it is necessary to mark the driveshaft if you take it apart at the splines so you can properly align it upon reassembly.

There is a specialty MB/BMW driveshaft shop in Arizona that does excellent work on these shafts. IIRC their name is Beier or something like that.

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

I have a spare 300SD shaft (same as yours?) that you can have but I don't imagine it makes economic sense to ship it. Holler if you want it - it seemed to be OK in the old bruiser it came out of.

Dan

If the problem changes when turning right or left your rear subframe bushings cold be shot and letting the whole thing shift a bit. Just a thought.

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'82 300D - Light Ivory, 2nd Owner (Back in the wind April 2013!)

'95 E300D - White, grey interior. (Suffering from stuck/broken glow plugs)

Deuteronomy 22:4-
"Thou shalt not see thy brother's ass or his ox fall down by the way, and hide thyself from them: thou shalt surely help him to lift them up again."

I agree - I wouldn't make the assumption that the prop shaft needs to be shipped off to the balancing folks just yet.

Work has been done on the rear suspension by the sounds of it - the rear sub frame mount has been replaced.

It is important to make sure that the crankshaft engine height + transmission output shaft height + prop shaft centre mount + differential input flange are all on one straight (hopefully horizontal) line. Whilst the W123 drive train has a universal joint (UJ) in the prop shaft it isn't meant to be something that is actually used as much as a "conventional" / old fashioned two UJ plus splined shaft set up with a live axle. {This has been mentioned earlier in the thread by Larry - but I think it is worth stressing this point}

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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 have helped a person solve out a booming sound and vibration problem in a W202 which he had bought for cheap, to his advantage he had access to a lift.

The manual tells you to start by first verifying the slip joint is in line, then it says to undo the front flexdisc and rotate the shaft to the tripod one leg and test again. Repeat till all three positions are done at front then repeat at rear.

First the shaft centre bushings were greased - they had grease that resembled glue. fresh grease and a few tests later the shaft suddenly went quiet when the diff tripod was moved 1 leg. I cannot explain it technically why it caused to be quiet - but it did.

during these tests I did notice those flex discs get hot and smell like tires after a highway drive in texas summer. I believe if you can find a truck repair shop they can shed more light on this, box trucks and flat beds utilise multi piece driveshafts.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

The "Z" man brings up a less discussed issue.

The Propeller Shaft is not only balanced ITSELF,
BUT also in It's relationship to the:
Flex Discs
AND
The Attachment Fixtures at either end
(Transmission and Differential).

MARKING Everything:
Driveshaft parts
Flex Discs
Attachment Fixtures

In their relationship to Each Other prior to dis-assembly IS NECESSARY.

____________________________________________________________________________________________________ ______

'Much easier to Re-Grease the Centering Bushings in either end of the Prop Shaft than replace them.

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'84 300SD sold
124.128

Hi All,

I tried shimming the center bearing mount with washers this weekend in a couple configurations, but to no avail. Unfortunately my third mount has ripped in the testing, so it's difficult to know how the problem is being affected by changes until I replace it again.

@fdanielson and Stretch: Yes I replaced the differential mount, but are there other subframe mounts somewhere to get at? I didn't mention in original post because I didn't think it mattered, but I also have 4 new shock absorbers in her - all replaced after the vibration started with no change after installing. I replaced them simply because the ride was getting too "floaty" and didn't expect them to affect the prop shaft.

@Zulfiqar and compress: I changed both flex discs so there was no way to know the original balance - BUT what you describe sounds promising as well. I'll mark where they are now when I take out the shaft to install my next center bearing mount. Then I can follow the procedure you describe. I'm particularly interested in getting some grease in the centering bushings as you had advised early on.

@Dan I sent you a PM.

Anyone know if an '82 240D prop shaft is the same length/etc as my '83 300D? I do of course have the little brother in the driveway who could lend his shaft for experiments.

Thank you for your responses!

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Garrison R.
'83 300D

I think you'll find that the wheelbases are different (at least mine were) so the shaft has to be longer on the 300D. Gotta go from here to there!

Dan

Alrighty then after many, many rainy days in which I could not work, we have the solution. I learned something very interesting from a local 300D lover that I met by chance in a Tractor Supply Co parking lot while buying a gallon of PB blaster to implement my grand idea. He gave me his card and told me to call him if I ever needed parts cuz he has a fleet of W123s.

I decided to soak my u-joint in PB blaster overnight to try to get the thing to free up and move - if that worked (which it did) then soak it in 80w gear oil for a couple nights so the places where dirty grease had been could be "revitalized" with some decent lubricant. All by capillary action. A shot in the dark. I figured if I could get the thing moving nicely, maybe it would drive okay for a month and then I could get a rebuilt ($365) with confidence.

So I did that. After the three nights, the joint in one direction felt like new, but the joint in the other direction still had a bind in the middle of its range of motion.

Now all this time I thought the binding was a pit worn in the joint - not in the caps but in the part the caps cover. However, I called over to the gentleman I met in the parking lot to see if he'd give me an opinion on the now-much-better movement coming from the joint. We were able to hook up and he taught me that the binding was not wear, but that the needle bearings in the caps were rusty in some spots.

Now here comes his brilliance: He had me hold the joint flat on his vice while he grabbed a deep socket that fit nicely into the where the caps are seated. Then he starts whacking it with a hammer. You could see the cap he was hitting sink down into the u-harness. Then he'd have me turn it over and whack it back towards the other side.
He did this about 5 times on each side, about 3 hits each. Tested the movement for smoothness after each flip. You could see wet rust oozing out of the cap seals. After the 5 times, this part of the joint also moved smoothly, almost like new.

Install the shaft, drive away... no more shaking, no more thumping, gun it as hard as you like.

So the answer to this mystery was a dirty u-joint. Never knew you could practically restore one with a hammer and a dream.
I imagine the joint itself may have more longevity if I had never soaked it in PB Blaster or gear oil. Maybe if the original grease were in there during the whacking it would take longer for the rust to ooze out but it would last longer.

Anyway, I'm gonna get as much time out of it as I can and I'll close up this thread when I know when it needs to be replaced with a rebuilt.

THANK YOU EVERYONE for your advice and support.
-Garrison

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Garrison R.
'83 300D

Anything is possible. If you lost a balance weight you should see the location it was in. Destruction of the centre bearing support means something is going on.

I do not kniow how tough a driveshaft is on these cars but the initiation of the problem was a high torque situation. I would drop refferance markers to make sure that the phase between the front and back yoke is still what it should be.

Really one for the books. A shredded rubber bushing, a bend bolt and damage to the universal flange on the transmission.

Id like to change the universal flange. Current car is 4 speed, but I have an AT with the flange.

Are these flanges universal between transmissions?

Can they be removed without tearing open the transmission?

Thanks

The Flanges ARE NOT universal...

They can be removed and replaced without opening the Tranny.
AT or manual.

'Un-clear if you've suffered a Flex Disc Failure. (Or is your "Rubber Bushing" the Flex Disc ?)

BUT, from your description Do Not Operate the Chassis until "Fixed".

Pictogram is of Flex Disc applicable for 1985 123.133

Attached Thumbnails

 

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'84 300SD sold
124.128