Driveline vibration

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69dodgedart360

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I have a driveline vibration only in high gear at freeway speeds (55 on up). I haven't recently changed anything on the car. I pulled the driveshaft and took it to a shop. The shop said it was twisted and they had to cut it, re weld it, and balance. They also put in new spice yoke and u joints. The guy said it was violently out of of balance at low speed which I didnt understand if I had only noticed it at freeway speeds. Either way, the vibration is still there. I pulled the driveshaft out and saw these marks, could it be the tailshaft bushing causing this? The car is a Duster with a 360/727/8 3/4. Pinion angle has not changed. The yoke is exposed 1.5 inches out of the tail shaft.

20190725_124202.jpg
 
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It sounds like you need a different drive line tech. This should help clarify things somewhat.
 
The guy in the video said that if the driveshaft isn't long enough that the yoke won't be riding in the entire bushing; not correct at all. The problem is that the further back you have the ujoint; the more apt it will vibrate from an imbalance or a worn bushing. An incorrectly installed ujoint can cause a vibration; they can be off center slightly and the clips still go in. The op pic shows a worn yoke, but I thought I read that it was a new yoke. And 1 1/2" sticking out is too much but the pic shows marks indicating to me that it wasn't sticking out too far. Rock both ujoints back and forth in both directions and feel for binding.
 
69dodgedart360 said:
I have a driveline vibration only in high gear at freeway speeds (55 on up). I haven't recently changed anything on the car. I pulled the driveshaft and took it to a shop. The shop said it was twisted and they had to cut it, re weld it, and balance. They also put in new spice yoke and u joints. The guy said it was violently out of of balance at low speed which I didnt understand if I had only noticed it at freeway speeds. Either way, the vibration is still there. I pulled the driveshaft out and saw these marks, could it be the tailshaft bushing causing this? The car is a Duster with a 360/727/8 3/4. Pinion angle has not changed. The yoke is exposed 1.5 inches out of the tail shaft.

View attachment 1715370430
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Somebody is full of ****.:D
If the yoke is out of the bushing then the yoke is about an inch from falling on the ground.
Looks to me by the yoke it was about the perfect depth.(Inch to inch and 1/2 out)
If there isn't a groove in that yoke you can polish it up with crocus cloth and run it.
I almost hesitate to mention this, but it looks like someone might have installed a new bushing at some point but didn't orient it correctly to have the oil hole in the bushing facing the right direction. (the dark area on the yoke looks like lack of lube to the bushing)

It is true that the more yoke shaft there is outside the tailshaft the more likely you could have a vibration from it (especially with a worn yoke or bushing.)

I have had vibrations before that before I took it to someone I pulled the yoke off and turned 180 and reinstall it.
A lot of people don't know that once a driveshaft is balanced the yoke ALWAYS go back on the shaft the same way. (Its good to mark the yoke and shaft to be sure of this when you change ujoints)
Just a suggestion.
 
I got some left field stuff as well. First off the only time I've had a drive shaft vibration is is when the pinion angle was wrong, but that's only my personal experience and not saying that's the only thing that could happen. But with that said, is there any chance maybe one of your rear tires could have lost one of its weights and it's not the Driveline?
 
j par said:
I got some left field stuff as well. First off the only time I've had a drive shaft vibration is is when the pinion angle was wrong, but that's only my personal experience and not saying that's the only thing that could happen. But with that said, is there any chance maybe one of your rear tires could have lost one of its weights and it's not the Driveline?
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Thanks Jason, I was going to suggest taking the tires off and see if it's still there but forgot when I wrote my post.
 
Thanks for all the info, I pulled off the tailshaft housing and the bearing is worn so I have ordered a new one. I also am going to take my driveshaft to a different shop and see if they recognize there still is an issue. Since the housing is off I have replaced the bushing too.
 
69dodgedart360 said:
Thanks for all the info, I pulled off the tailshaft housing and the bearing is worn so I have ordered a new one. I also am going to take my driveshaft to a different shop and see if they recognize there still is an issue. Since the housing is off I have replaced the bushing too.
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While you have it apart, measure the inside diameter of the newly installed bushing and the outside diameter of the yoke tube. A buddy of mine has traced a similar vibration problem to excessive clearance between the two components on his Mopar.
 
The upside for the 727 is the extension housing bushing there is only one for it. It's been the same since 1965. It is also the same bushing that Ford uses in the C6 since 1966.
 
transman said:
The upside for the 727 is the extension housing bushing there is only one for it. It's been the same since 1965. It is also the same bushing that Ford uses in the C6 since 1966.
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Exactly. This is what my buddy found when looking into this issue. He had brand new parts and the clearance was still too loose.

If there is excessive clearance between the two parts, the only option is to either have the yoke plated and ground to the correct outside diameter, or machine a custom bushing. He is a machinist, so he made his own bushing. I asked him to do the same for me, as my car has an increasingly resonant drive line vibration starting at 98 mph and on up. It's dead smooth below that.
 
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