You said the movable range side to side of the driveshaft was 1/4 " if I’m not mistaken . It appears that moving the shaft from one extreme to another makes a lot of difference in the vibration . Wonder what would happen if you enlarged the slots in the desired direction another little bit ?
“Wonder what would happen if you enlarged the slots in the desired direction another little bit ?”
I worked with a mechanic once who said (and I hope he was joking), "A good cross-thread is better than a lock-washer!"
CSA
If Straightening the Angle of that shaft eliminated or reduced the vibrations that suggests that the U-joints near the bearing carrier are not moving smoothly… I wonder what the shaft felt like while it was out of the vehicle… all joints should have had that tight new feeling…but none should have felt “notchy”
I don’t much like this “solution” at all… In fact all it does is shine light on the actual problem a little more… Don’t you think?
That shaft wouldn’t go near my vehicle until it passed any and all balance tests out of the truck. The problem lies there somewhere… I hope you have good luck with this…because if this is the fix prepare to “Get the Shaft” sometime soon. Stay safe Amigo
Blackbird
Sloepoke, that exact same thought crossed my mind. But rain and people calling me to come out and fix their stuff has kept me from trying it. As soon as I get a dry couple of hours during the day I’m on it. I plan to try a drill bit in the slot and bear down on it sideways to see if it cuts. If it doesn’t I’ll get a stone with a spindle for the drill and see what that does. I have a rat tail file of right size that might work, too. Come to think of it, I could put that in the drill, also, and file like normal. I just have to make sure I have it rotating in the right direction. That should do the trick.
I also ordered an angle finder on eBay to check if the transmission yoke and pinion yoke are parallel. I read somewhere that it is very important.
@“Jack Dak87” I was just thinking that the 1/4 " that it already moves isn’t really all that much & seems to make a lot of difference so maybe just a little bit more might work . If it only will move about 1/4 " side to side , moving it all the way to one side is only moving it 1/8 th " off center the way it is now .
@“Honda Blackbird” “If Straightening the Angle of that shaft eliminated or reduced the vibrations that suggests that the U-joints near the bearing carrier are not moving smoothly”
The funny thing is that the adjustment of the carrier bearing that improved the vibration issue was not in the direction of straightening the two-piece driveshaft, but in the direction that bent it more. I determined this with the help of a 5 point Bosch laser level and a plumb bob. I thought that odd at the time, but here we are. Rain and work are conspiring to keep me from further diagnostic testing, but I will be on it as soon as I get a dry spell and some time.
Double Yipes! That doesn’t sound good at all Sir. This should not really be too hard to figure out however… This issue also should have been prevented when the shaft was out and in hand at the balancing machine… it should have never proceeded onto the vehicle. I mean what did they THINK would be the result. You know?
Well you definitely have me curious. If it were me I would take that shaft down and redo the joints…also…why cant you re-install the new joints and screw up the way the factory had it assembled? I think you mentioned a notch or key that prevented the half shafts from being married out of synch but that key cannot affect when you have the joint out and you are re assembling the yoke to the shaft… You can orient it any way you like… The problem may lie right there…OR a weight dropped off…
I’m not sure how bad this vibration is… But I can tell you that you do Not want a wonky shaft on your vehicle…all sorts of MAYHEM can ensue from this. If a weight dropped off…that could cause a lot of grief and or a big safety problem. Please be careful…you are in danger as long as this shaft is not totally “true”.
I just thought of something else… and a common issue when doing U-Joints. Not fully seating the bearing end caps. Perhaps one of those new joints caps is not fully seated correctly? Meaning one of the end caps of a joint is not all the way down and seated ? Do your U-joints have end clips? Are All the “outer” or “Inner” end cap clips installed and seated ? Definitely Check for that its easy to miss or dismiss. Make sure also that all the new joint end caps are the same… same depth or look identical.
Perhaps one of the new joints is just wonky…shorter legs on one side as a mfg defect… You can look for shaft deflection when the shaft is rotating. Many ways to rotate and observe shaft…pick the method best for you. I would pay close attention to any elliptical movements.
Anyway, I hope you figure it out… Let us know whats what…
Blackbird
So did you put in the new U-joints yet?
@“Honda Blackbird” @keith
keith, I haven’t been able to do anything since the last report because of rain and work demands. Tomorrow promises to be sunny and I have no work lined up.
Honda Blackbird, the shaft is at a slight angle even when the carrier bearing is pushed to the extreme drivers side allowable by the slot, about 1/4" out of line. I used very accurate tools to determine this, a five point Bosch laser level and a 12 oz. brass plumb bob from my carpenter kit. Pushing the carrier bearing to the other extreme puts the shaft almost 1/2" out of straight in the horizontal plane.
“that key cannot affect when you have the joint out and you are re assembling the yoke to the shaft… You can orient it any way you like”
I can only orient the slip yoke near the carrier one of two ways, the way it was originally, and 180º from where it was originally. As I marked it before disassembly, it went back the way it originally was. Same with the differential pinion yoke, only two ways to hook the shaft to it. The way it was and 180º from the way it was. In either case the phasing stays perfect. When I assembled the shaft with the new u-joints I pressed the circlips against the inside of the yokes, pressing down on the trunions at right angle to the one being pressed. I had to do this to get the joints to move freely. At no time did I stress the yokes. There was no play in the joints that I noticed at the time of assembly and none that I noticed after the shaft was back in the truck.
The guys at the shop said that the balance indicator on the machine would not stabilize, but continuously rotated slowly are the display. I read somewhere that Ford or GM glues cardboard inside some shaft tubes to dampen noise, and if it comes loose it can play havoc with the balance. Don’t know about Dodge, or the 87 Dakota. I’m thinking that maybe I used too much grease on the center slip-joint and it’s sloshing around inside the rubber dust boot. Or maybe when I topped off the grease on the u-joints I didn’t top off all the way. I’m also considering buying new straps for the rear u-joint although the existing ones appear tight.
I don’t see how offsetting the two-piece shaft a couple of degrees in the horizontal plane can cause a problem as long as the diff pinion yoke shaft is parallel to the transmission yoke shaft. The two pieces of the shaft are not straight in the vertical plane, because the transmission yoke shaft is higher the the diff pinion yoke shaft. I’m looking forward to a sunny day tomorrow and lot’s of time to poke around. I will post my progress.
There’s a special kind of synthetic grease I’ve heard about that can cure problems with the 2-piece drive shaft splined slip joints. Maybe somebody here used it and knows the details.
@GeorgeSanJose … this stuff?
Ford Motorcraft XG-8 PTFE Lubricant
I think so, but not sure. I’ve never used it myself, as I’ve never had a problem with the slip-splines. When I heard about this, I think it was in relation to a GM vehicle rather than a Ford. But maybe Ford has a similar product. It was definitely some kind of synthetic grease that is used on stubborn slip-splines in driveshafts.
Well you have “our attention” thats for sure. If it were me…I would simply redo the joints…what are we talking here? 2 or 3 U-Joints max? Those babies are cheap…and you may want to check on what the dealer wants for their U joints…sometimes parts from the dealer are NOT that bad a price… a few times I have been shocked by this. Whenever I run into potential quality control issues on things…I will call the dealer to see how much they want. Like I said Ive been pleasantly surprised more than a few times.
This may be due to defects in the U joints that you have…it could be that simple. You mentioned glued in pieces of dampening material…now if thats true…it could certainly affect how the shaft rotates. There isn’t much you can do about it however… Not unless you want to break out the cutting torch and try welding your shafts back together… JK Thats no way to go…
Anyway…Keep us posted
Blackbird
I think I found it. Jacked the rear end up and put the axle on jack stands. Aimed a Canon digital video camera up at the carrier bearing, the front, middle and rear ujoints, the middle of each drive shaft section, the left and right tires and ran the rpms in drive up to between 55 and 80. Vibration worse at 65. Tires look good. Everything looks unsuspicious except the carrier bearing. The large metal disc referred to as the “slinger” in this diagram: http://goo.gl/nLJdWe is obviously warped and dented. It was not that way when I took the front axle to the driveline shop to have them press off the old carrier bearing and press on the new one. Here is a link to YouTube of the carrier bearing in action: https://youtu.be/tBhyUandmyg - In addition to the misshapen slinger there is a godawful grinding noise at the end as the driveshaft slows down in neutral with the engine cut off.
Just for the record, I ran up the RPMs in neutral to make sure the vibration was not coming from the engine. It wasn’t.
Undoubtedly the slinger is bent up but I think the grinding noise is more than likely the source of the vibration . Have you isolated that noise to the carrier bearing ? If so I’d guess that the bearing was either defective from the beginning or was damaged during the installation process .
i
@Sloepoke “Have you isolated that noise to the carrier bearing ?”
Good question. I tried to duplicate that godawful grinding noise that starts at about 1:10 in the video, and catch it on video again, but couldn’t. Then I realized that in the video above I must have revved the engine, shifted to Neutral and cut the engine. But in the attempts to recreate the noise I must have cut the engine in Drive. This means that in the video above the inertia of the spinning tires was driving the driveshaft through the differential and in the attempts to recreate it, theinteria of the dead engine slowed it down. Then it got dark and I got hungry. Today is more rain but Christmas day promises to be sunny, at which time I’m at it again. Earlier in the day yesterday I fixed a wire to hold the driveshaft and pulled the bolts on the carrier. It spun freely and there was no stiffness or grinding noise. If it is in good shape, that leaves something in the differential, possibly the pinion yoke bearing (if I’m lucky), making the noise. When I videoed the rear ujoint spinning I braked right after cutting the engine, so no slow down like in this video, but I saw no vibration. There is however a sound reminiscent of a small prop plane straining to gain altitude. Not sure what that is, maybe the tire treads roiling the air?
In haven’t been this eager for Christmas since I was 10.
Looks like you are certainly on to the solution. If that bearing was Mis-handled during the install process…nothing will be right. I think you found the issue
Blackbird
@""Honda Blackbird"
Tomorrow when the sun comes back out I should be able to pinpoint where that grinding noise is coming from in the first vid. It may be from the differential.
One thing that I noticed when I had the back end jacked up, brake off and in neutral: when rotating the driveshaft by hand I would feel greater resistance about every one and one half turns. This may be the rear brakes dragging on one wheel or the other. I’m not sure what the ratio is between the driveshaft and the wheels, but I should be able to determine that with the rear end jacked up.