Driveshaft phasing: no one knows what it is.

[greasytshirt]

Including the people tasked to reinstall them.

The two pieces of yellow tape are on the u-joints, and are supposed to line up. They're almost 90 degrees off, so the piece of tape on the right of the pic is nearly impossible to see.

So, what's the big deal? U-joints let things run at angles, right? Yes, but they create forces that have to be cancelled out. With a phasing issue like this, multiple things will go wrong. In this case, the bolt holding the transmission yoke vibrated loose and it trashed the seal.

Some of you are suffering from this right now and are unaware of it. Check your shaft!

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[piper1]

Or putting the slip yoke back together one or two splines off (if it has no master spline).....should be "good enough". Once knew a guy who spent a lot of money on new tires when all along the vibtation was an out of phase driveline.

 

[greasytshirt]

Or putting the slip yoke back together one or two splines off (if it has no master spline).....should be "good enough". Once knew a guy who spent a lot of money on new tires when all along the vibtation was an out of phase driveline.

Exactly. That's the same thing that happened on this truck. It was towed and when the shaft went back in, it went in at random.

The ones with the master spline have the one spline filled with plastic, and if you try really hard you can force them together. Getting them back apart requires dirty language.

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[greasytshirt]

Here's a really good video that discusses driveline angularity and phasing. It's clear that when the driveshaft is not set up correctly, damaging forces are always present when the truck is moving.

 

[brokcanadian]

Timely advice, have to pull mine this weekend to investigate a bearing noise (are carrier bearings supposed to let the shaft bounce up and down?)

 

[greasytshirt]

Timely advice, have to pull mine this weekend to investigate a bearing noise (are carrier bearings supposed to let the shaft bounce up and down?)

The rubber part is supposed to be fairly flexible. There shouldn't be any movement in the bearing itself.

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[Kip life]

Greasshirt, if and when I am in Virginia I will bring my truc to you for a PM

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[RETIDEPXE]

Last time towed I marked the slip joint with a chalk line. Learned not a good idea as the grime smeared from handling it almost completely wiped it off. I would recommend a nice indentation with a hammer and a chisel for a more permanent mark.

Question I have is, how long do carrier bearings last? I'm at 1.44 million on an M2 Straight truck and thinking it's time to replace, but they are not over heating at all.

 

[greasytshirt]

Last time towed I marked the slip joint with a chalk line. Learned not a good idea as the grime smeared from handling it almost completely wiped it off. I would recommend a nice indentation with a hammer and a chisel for a more permanent mark.

Question I have is, how long do carrier bearings last? I'm at 1.44 million on an M2 Straight truck and thinking it's time to replace, but they are not over heating at all.

Generally they're replaced when the rubber part collapses, and that time frame is highly variable.