driveshaft wobble
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
driveshaft wobble
i removed the star shaped 12mm bolts from the yoke on the differential and slided the driveshaft out from the slip yoke. i did this so i can grease it, as well as inspect the ujoints because i am going on a trip to florida soon. i didnt index the thing or mark it, so i did not put it back on the same way i took it off, now i'm so screwed. any suggestions?
i spent all day trying different combinations. my uncle says the ujoints down the whole line (all 3) would all be parallel if you were looking at them, so it can only be a quarter turn out of phase. i mustof taken it for 20 test drives and tinkered with it every time and i cant get it. my truck was smooth as silk going 70mph before i messed with it, now it vibrates like crazy. any ideas? please help thanks.
i spent all day trying different combinations. my uncle says the ujoints down the whole line (all 3) would all be parallel if you were looking at them, so it can only be a quarter turn out of phase. i mustof taken it for 20 test drives and tinkered with it every time and i cant get it. my truck was smooth as silk going 70mph before i messed with it, now it vibrates like crazy. any ideas? please help thanks.
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
hmm okay i did some research and found that the ears of the yokes of all driveshafts must be parallel. meaning on the front of the driveshaft where the slipyoke is, if the ears are facing sideways, then the ears on the back part of the driveshaft must also be facing sideways. if there is a mismatch of this orientation it is out of phase because ujoints move in an eliptical pattern and one actually moves faster than the other. now the only other questions i have narrowed it down to are...
can it still be 180 degrees out of phase and need to be spun halfway around?
does the orientation of the yoke on the differential matter? i mean the drum with 8 holes in it, 4 of which are the ones in use with bolts in them holding the driveshaft onto the differential. i would have to imagine this is rotating mass, and since it has no weights on it, maybe when the driveshaft was balanced it was done with this connected to it? because that would leave 4 possible combinations for me to try out.
arent there any 4x4 guys out there or any drivetrain gurus that can chime in?
can it still be 180 degrees out of phase and need to be spun halfway around?
does the orientation of the yoke on the differential matter? i mean the drum with 8 holes in it, 4 of which are the ones in use with bolts in them holding the driveshaft onto the differential. i would have to imagine this is rotating mass, and since it has no weights on it, maybe when the driveshaft was balanced it was done with this connected to it? because that would leave 4 possible combinations for me to try out.
arent there any 4x4 guys out there or any drivetrain gurus that can chime in?
Laughing Gas
Joined: Aug 2003
Posts: 1,175
Likes: 9
From: So. Cal.
Technically, Ford will say that the slip yoke must be replaced in the exact same orientation as it was originally, due to balancing issues. But practically speaking, it usually isn't that important. Your uncle is right, and as your research has told you, the u-joints must me all lined up perfectly. If you're off by just one spline, then you will get vibration. Place your eyeball at one end of the driveshaft and look to the other end, and if it's off any, you should plainly see it.
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
okay well what i've found is that ujoints move in an eliptical pattern and one moves faster than the other, but only at certain times during the roation, ujoints are a crazy mathematical thing and after researching its amazing and very interesting. so they must be parallel down the whole line, and if they are not then terrible vibration occurs.
if you are ever going to work on the drivetrain invest in CHALK or CRAYON and mark it really good. i put it back on the wrong way the other day and drove it 100 miles at 70 mph, and i destroyed my carrier center support bearing. so now i already got the old one off, but its a pain shopping around for one, hardly anybody has them or has the right size or even knows what it is.
if you are ever going to work on the drivetrain invest in CHALK or CRAYON and mark it really good. i put it back on the wrong way the other day and drove it 100 miles at 70 mph, and i destroyed my carrier center support bearing. so now i already got the old one off, but its a pain shopping around for one, hardly anybody has them or has the right size or even knows what it is.
Thread Starter
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
wrong. it does need to be put back on only one way. horrible vibration occurs if its lined up properly but needs to be rotated halfway around or 180 degrees. i have also found out that the yellow calibration stickers on my front and rear driveshaft are parallel when aligned properly. i know all of this because i spent the whole evening with the rear on jackstands running it at different speeds and recording the oscillation of the driveshaft depending on different ways of mounting it. not trying to insult, just had to point that part out. i appreciate the help and the other advice was good.
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