Bad vibration when given partial throttle
Thread Starter
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Mountain Pass
Joined: Jul 2009
Posts: 166
Likes: 4
From: Tacoma
ok. rear u joint is toast, i can move the driveshaft up and down freely with almost 1/2" of play.
Now on the tranny end of the driveshaft, when I grasp the slip joint with one hand, and the driveshaft with the other (like holding motorcycle handle bars) and twist, there is a tiny tiny amount of plaqy, maybe 1mm or 2
Now on the tranny end of the driveshaft, when I grasp the slip joint with one hand, and the driveshaft with the other (like holding motorcycle handle bars) and twist, there is a tiny tiny amount of plaqy, maybe 1mm or 2
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
The U-joint is probably the problem.
But the way to test the slip joint is to push side-to-side in the center of it - not twist. Any vibration from it comes from the wear allowing the rear shaft to take a slight angle from the front shaft. That means the spot at the slip-joint is off-set with respect to the centerline of the shaft. So, it will be out of balance and vibrate. But, since all of that depends on how far it is off-set, and that can change as the shaft extends/compresses, the vibration changes with conditions.
But the way to test the slip joint is to push side-to-side in the center of it - not twist. Any vibration from it comes from the wear allowing the rear shaft to take a slight angle from the front shaft. That means the spot at the slip-joint is off-set with respect to the centerline of the shaft. So, it will be out of balance and vibrate. But, since all of that depends on how far it is off-set, and that can change as the shaft extends/compresses, the vibration changes with conditions.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
If the splines come apart easily then I'd do so, clean it, lube it, and put it back together. But, in my experience they don't come apart easily and, if so, I'd leave it together and just lube it.
As for the transfer case flange torque that depends on which t-case you have. The two I have spec's on are the typical NP208, which is torqued to 90 to 130 ft-lbs, or the BW1345, which is 100 - 130. So you can't go wrong with 100 to 130. However, unless you know there's a problem I'd leave it alone.
On the diff I don't know as I don't know whether you have a 9" or an 8.8". The 9" doesn't have a removable rear cover and if you have that one do not try to torque that nut. On some of them there's a crush sleeve inside that has been mashed to give exactly the proper pre-load on the bearings. It should not be changed, so leave it alone. If it is an 8.8" then I can't help since I don't have the spec's for it in my shop manual. But, if you don't know there's a problem I'd leave it alone.
As for the transfer case flange torque that depends on which t-case you have. The two I have spec's on are the typical NP208, which is torqued to 90 to 130 ft-lbs, or the BW1345, which is 100 - 130. So you can't go wrong with 100 to 130. However, unless you know there's a problem I'd leave it alone.
On the diff I don't know as I don't know whether you have a 9" or an 8.8". The 9" doesn't have a removable rear cover and if you have that one do not try to torque that nut. On some of them there's a crush sleeve inside that has been mashed to give exactly the proper pre-load on the bearings. It should not be changed, so leave it alone. If it is an 8.8" then I can't help since I don't have the spec's for it in my shop manual. But, if you don't know there's a problem I'd leave it alone.
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Thread Starter
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Mountain Pass
Joined: Jul 2009
Posts: 166
Likes: 4
From: Tacoma
Ive read the numerous posts about the pinion nut getting worked loose over time. Most said they torqued to 160ft lbs, but those were later year trucks than mine so I wanted to verify.
Now that my joints are out, Im comparing them with the new. The diameters are correct, but the new u joints have grooves in the caps that the old ones didnt. Every U joint I've looked up has the same groove. Do I have the wrong U joints? My truck - 1986 F250 4x4 standard cab long bed automatic trans 10.25 rear - the part numbers Im coming up with for the rear of the drive shaft are 434 greasable, 265 greasable, 264 non greasable (moog and precision). then ac delco has 45U0144
What u joints did you use?
Now that my joints are out, Im comparing them with the new. The diameters are correct, but the new u joints have grooves in the caps that the old ones didnt. Every U joint I've looked up has the same groove. Do I have the wrong U joints? My truck - 1986 F250 4x4 standard cab long bed automatic trans 10.25 rear - the part numbers Im coming up with for the rear of the drive shaft are 434 greasable, 265 greasable, 264 non greasable (moog and precision). then ac delco has 45U0144
What u joints did you use?
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 38
From: EXTREME southwest CT
The grooves are for U-joints that retain from the inside.
Didn't your joints come with full circle clips too?
My pinion came loose, that's why I had to buy crush collars.
On trailing throttle the gear will get sucked into the carrier and cause all sort of noise and devastation.
Not sure what I torqued it to.
Didn't your joints come with full circle clips too?
My pinion came loose, that's why I had to buy crush collars.
On trailing throttle the gear will get sucked into the carrier and cause all sort of noise and devastation.
Not sure what I torqued it to.
FTE Legend
Joined: Jul 2010
Posts: 32,875
Likes: 48
From: Northeast, OK
I don't know what #'s to ask for at the parts store, although you should be able to look it up on-line. However, I do have the master parts catalog for these trucks and can get you a Ford part #.
The second page, below, shows your driveshaft # and that it takes #42 u-joints both front and rear. The first page shows the part # for those u-joints.
Hope that helps.
The second page, below, shows your driveshaft # and that it takes #42 u-joints both front and rear. The first page shows the part # for those u-joints.
Hope that helps.
Moderator
Joined: Jan 2001
Posts: 56,977
Likes: 2,733
From: Virginia
If you have done any searching on the large nut that comes loose all the time, you have probably run across where I just torque as tight as I can get it and let it go. Seems to work ok for me. A little locktite would not hurt either on the threads of the nut.
As far as the torque on the u-joint caps, I don't have any fancy wrenches I can measure the torque with, but I will tell you do not over tighten them. You can over do it and squeeze the u-joint cap out of shape and it will lock the needle bearings up. If you have the type with the bolts you do not have to worry as much about this, they will bottom out before they get too tight.
You look at this thing and imagine what would happen if it worked loose, but all I do is tighten it up as tight as I can get it with a regular combination wrench. Going round and round tightening them evenly is important also.
As far as the torque on the u-joint caps, I don't have any fancy wrenches I can measure the torque with, but I will tell you do not over tighten them. You can over do it and squeeze the u-joint cap out of shape and it will lock the needle bearings up. If you have the type with the bolts you do not have to worry as much about this, they will bottom out before they get too tight.
You look at this thing and imagine what would happen if it worked loose, but all I do is tighten it up as tight as I can get it with a regular combination wrench. Going round and round tightening them evenly is important also.