Continued driveline vibration

[OUTFXD]

So,  not long ago I squished the needle bearings in the rear Universal on my 1946 Plymouth Super Deluxe. 

 

It took some doing but I got a rebuild kit, pulled the driveline, and replaced the needles, balls, and caps.  when I dropped the driveline I noted that the rear universal didnt have a cap and only the rear had a spring.

 

I was told that I needed to beware of over greasing the universal and that I should only put in an ounce of grease.   having no idea how much grease made up and ounce, I coated each ball with a liberal amount of grease.

 

after retightening and retightening the bolts holding the driveline in.  she drives SMOOTH,  upto about 40.  Then a constant vibration builds to distracting levels.

 

I replaced the cap on the rear universal with one provided in the rebuild kit.  I replaced the rear spring with one from the kit but did NOT put one in the front universal.

 

I decided before jumping back into it, id consult with the experts.

 

Anyone see something I did wrong? Suggestions? Advice?   All welcome!

[Doug&Deb]

Did you install the driveshaft in the same orientation as before? Before I remove mine I put witness marks front and rear so I put it on the same way.

[Sam Buchanan]

2 hours ago, Doug&Deb said:

Did you install the driveshaft in the same orientation as before? Before I remove mine I put witness marks front and rear so I put it on the same way.

 

I need some education, I'm probably overlooking something obvious. I have seen numerous admonitions to install the driveshaft in the same alignment as it was removed but I can't figure out why this is necessary. The shaft is balanced as a discrete unit on a test bench, not with the entire driveline intact. When we install a new driveshaft there are no witness marks to line up. I understand there are definite ways to orient the universal joints when building a new shaft to insure proper phasing but why bother with this when putting the old shaft back in the car? I've had the driveshaft out of my car several times (trans removal, servicing u-joints) and have never bothered with witness marks. What am I overlooking?

Edited September 16 by Sam Buchanan

[Young Ed]

If everything is new I would agree the alignment doesn't matter. I'm thinking once these parts are used putting them back in the same place puts them into the same pattern of use/wear

[Sniper]

There's a word for that we're knowledge is passed down from generation to generation and nobody knows where it came from or nobody knows why it happened to begin with. But I'll be darned if I can remember what that word is. In any event I suppose there might have been a manufacturer who balanced the drive shaft installed and that mattered and somehow it got applied to all drive shafts in all cars. I have pulled many a drive shaft and replaced them without regards to orientation and had zero problems. But hey you know what it's four bolts unbolt it, flipping around 180 bolted back in see if it makes a difference

Edited September 16 by Sniper

[soth122003]

Just tossing this out there, but how sure are you that it's the drive line? From what you said, you rebuilt the D/S and now you have a vibe at 40 mph. While I agree that it's the most likely culprit, a little bit of trouble shooting can save a lot of head ache later. When you get to 40 mph and the vibe is kicking hard, push the clutch in and let off the gas and see what happens.  If it goes away, it's probably in the clutch or tranny. If it continues, check the D/S. Did you put all the washers back in place? Did use mix new hardware with old?  You said you used a liberal coating of grease on the bearings and needles. Was it applied evenly to all areas? 1/8 oz of grease more at one point at high rpms can induce a fair vibe. I've trouble shot lots of problems where I was sure it was one thing and was something else entirely. 

 

On the subject of why put the D/S in the same way it came out, Young Ed is onto the most probable reason. Time and wear, road debris and nicks, crud built up on the shaft all contribute to the way the D/S likes to set. 

 

Joe Lee

[Sniper]

Oh hey I remembered the term it's called tribal knowledge.

[Los_Control]

I call it gossip.

 

Many things get passed on down through the decades ..... One of them is to use thicker oil in a high mileage engine.

 

When our cars were built, thicker oil actually had a purpose and worked.

When talking about a 1997 Dodge truck with a 360 .... We need the correct oil for the engine so it gets properly lubricated.

Tighter tolerances require thinner oil ....

 

I see no purpose to ever run a thicker oil in a modern car .... maybe I'm wrong.

 

 

 

Here is a 1997 Dodge 360 farm truck that never had a oil change in it's lifetime ..... Run thicker oil in it, it will be fine.

 

Lots of old stories out there that had some 1/2 truths to them .... no longer accurate today.

[Loren]

I just thought of something. ( I do think every once in a while lol )

On the old Saabs I still work on, they have a "T" shaft end which fits into a slot in the "inner driver" as we call it.

After years of service they get a wear "divit" in the inner driver which makes itself known as a kind of "Clutch Chatter" as the front of the car raises upon taking off from a stop.

The fix is real simple, you pop the inner drivers out and exchange them right to left. ( or left to right if you will lol)

So my question is, if you take the drive shaft out will you find a wear spot in the trunnions?

If so can you swap the drive shaft end for end or should the trunnions be replaced?

It's only a guess so please don't hate me. lol

[Sniper]

You know Loren makes a very good point.

[kencombs]

It's been years since I had a ball and trunnion apart but the symptoms sure sound like the assembly is not centered.   Assuming the pin wasn't moved due to wear the only way that could happen is if the end buttons, springs and thrust washers aren't exactly the  same side to side.   Are all of those new and the same or a mix of used and new?

reference pic: linked from somewhere on this site

[desoto1939]

I have sen on ebay where they made a sleeve that inserted on the u joint housing where the end buttons slide into the housing this was to take up any wear that had occured over the years.

 

I would not shorten the pin or anything else. I would first check that the pin is completely center between the end ball of the driveshaft.

 

I think I might have the metal housing for the 46 Dodge. If I remember correctly the housing on the 46 Dodge is different then the other cars.  Let me look in my NS parts.

 

Rich Hartung

Desoto1939@aol.com

[kencombs]

I just reread your first post, and see no mention of the buttons or springs.  Where they present, where they in your kit?   Those are the only items that center the pin in the housing, assuming the pin is properly located.