Originally Posted by yogarda

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

Originally Posted by Diesel911

I put this thread in My Notes.

I replaced My U-joint and that may not have been needed if I had known about the Needles Rusting.

However, there is a detail missing. What was done freeded up the U-joint but how was the Rusted U-joint re-lubricated?
The last comment on what got inside of the U-joint was PB Blaster. That does not sound like a good U-joint Lube.

Originally Posted by winmutt

It could be that the rarely used portions of the needle bearings had just gotten dry and by doing what was done, breaking them and moving the joint got the grease flowing there again?

Originally Posted by Diesel911

I don't think soaking Gease in PB Blaster restores the Grease.

I think what was achieved was a great diagnosis and a temp. fix. But, time will tell on that.

Way back in the early 1960s I remember someone saying Bikers used to put the Drive Chain in a Can of Grease and bring it to a Boil and that was supposed to Lube the Chain.
Perhaps the U-joint could be re-greased by imersing whole assembly in heated liquefied
Grease.

Originally Posted by winmutt

Bike chains were a bit different back then, they are now sealed. I think all that was really needed was forcing grease back into the rusted bearings, providing a wee bit of lube and then some movement to break it all up. No need to regrease it as much as just move it around?

Originally Posted by yogarda

Hi All,

This is regarding my 1983 300D. Sorry for the long explanation below but this problem is detailed and has some subtle distinctions. I've read many posts about this and none has yet solved my problem.

Early last July my car suddenly developed a vibration in the driveshaft that is related to engine torque and specific speeds. Everything about the car had driven smooth and fine until I turned up an unusual road where there was both a sharp right turn and a steep incline at the same time. While climbing the (rather long) hill I reached 30mph and suddenly there was a violent shaking that eventually ripped the rubber mount that holds the propeller shaft bearing.

The character of this vibration is that it occurs only between 25-30mph, only under heavier torque or climbing any incline. I can let up on the pedal and accelerate slowly and prevent the vibration. I can accelerate moderately downhill and there is no vibration. It is definitely torque-related, and related to the angle of the car.
If I turn hard left, the vibration may not happen at all through 25-30 and beyond. If I turn hard right, it will be worse. This is reminiscent of the day this first occurred.

Over the past year I have ripped through TWO center bearing mounts. I have read many posts regarding similar vibrations and changed nearly everything that wears in my driveline. I'll start from the front of the car and note whether each part replaced seemed to be needed or not:

Engine mounts - needed
Transmission mount - maybe needed
Front flex disc - needed
Front propeller shaft centering bushing - not needed
Propeller shaft bearing - not needed
Propeller shaft bearing mount - ripped twice, I'm on my third
Rear flex disc - not needed
Rear propeller shaft centering bushing - needed
Differential mount - not needed
Both rear axles - 1 had a torn outer boot
Rear tires - eventually needed but not when the problem developed
Rear alloy wheels - I have a spare set for snow tires and the problem did not change with either set of wheels

The propeller shaft U-joint feels a little less smooth when bent to extreme angles but seems smooth at the minor angles needed when driving. I believe I've replaced every other relevant part. And yes, when the propeller shaft has been separated it was marked and reassembled in the correct alignment.

The problem developed so suddenly and has stayed so consistent that it isn't like a rubber part started to wear and is slowly deteriorating. Also I'd think if the shaft itself was out of balance it would shake regardless of the amount of torque being applied. The fact that shifting the car's position (via hard left or right turns) changes how it drives when straight... it's just plain confusing.

Does anyone have any other ideas for me? My plan of last resort is to put it in the dealer and ask them to run it on the lift to see if they can see anything.

Thanks as always for your time and your Borg collective brain!

Garrison

Originally Posted by yogarda

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