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Driveline phasing or timing


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I had to reinstall a drive line in a dump truck today and I always have to remind myself by looking at a drawing to be sure I have the drive line in phase or timed correctly - Here is a link to a article on the net about it...................same deal applies with pto shafts on trucks or farm equipment

http://jniolon.clubfte.com/drivelinephasing/drivelinephasing.html

Someone on a thread was writing about phasing a drive shaft so I thought I would throw this out there

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Here is what i have did for years and have tryed to get the younger guys to do but seems to be too much trouble. Before you pull a drive line down use a spray paint can and spray a red streak down the two joint that your pulling if a two peice or pulling the slip from a single peice drive line. Then its no problem to put it back same way it came down. If he didnt have a virbration when he came in he should not have one when he leaves.

glenn akers

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My trouble is I once in a while will get a truck that was towed in and the failed at brain surgery tow truck driver will take the whole stinkin drive shaft out - yokes on both ends. One time I got one that he even removed a carrier bearing and dropped the whole damn thing from the transmission back. I always have to kind of take a deep breath and collect my thoughts to get the "Zen and the art of driveshaft phasing" (ZADP) going again when I see such a thing.

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Our tow drivers dont drop enough drive lines. You dont pull one axle on a mack rears and tow it like you would a rockwell or eaton rears.And then when they pull a drive line they will always pull the slip apart. That would be ok if the new drive shafts had a timing mark on them like the older spicer. Now you have a 50/50 change of having to pay down the road to pull the slip and turn it a half round because some of them will virbrate.

glenn akers

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  • 7 years later...
  • 1 month later...

For a few years now new trucks can come from the factory with yokes that are not lined up (out of phase).   This is normal and engineered with regard to which suspension is on the truck to cancel our vibrations.  It’s mostly on the shaft between drives.  It is even more important now to mark the shafts when servicing. 

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Torsional vibrations are SERIOUS vibrations

Why? Because when you vary the speed of a drive shaft, you not only vary the torque on all of its components, but you vary the torque on all of the components that are connected to the drive shaft Torque is LOAD.

When you vary the load, at twice per revolution, you start to bend components.

You know what happens then……the same thing that happens when you bend a can lid back and forth. IT BREAKS.

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40 minutes ago, David Heberling said:

you don't know what your talking about BGarofalo  .when drive shaft is out of phase it makes it jerk two time every turn.  my new truck the drive tires only lasted 36000 miles because of this. and has tor up my hole drive line.  volvo and mack needs to recall this junk.

 

Torsional vibrations occur twice every time the driveshaft rotates. These result from excessive angles in the u-joints. They also can be caused by driveshafts that have been reassembled out of phase. A phased driveshaft generally is one in which the yokes are in line. However, it is not uncommon for chassis manufacturers to order driveshafts with special phasing.

"Torsional vibrations are one of the biggest installation problems you will encounter," Koedam said.

Koedam suggested that shops mark driveline components before disassembling them. Mark them in a way that makes it clear that the driveline is being reassembled the same way the manufacturer built it.

One good way to identify specially phased drivelines is to look at the weld seam on the tubing. If the weld seam is straight but the yoke is turned, the driveline probably has been built out of phase.

https://www.trailer-bodybuilders.com/distributors-upfitters/article/21739166/what-every-shop-must-know-about-drivelines

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As far as I know phasing of drive shafts is only needed when more than one drive shaft is used

Each shaft generally is not lined up, the yokes on each shaft must be lined up but the yokes shouldnt be lined up between shafts

As in the yokes should be not in a straight line down a drive shaft

Usually starting from the gear box end each is set one spline tooth  lagging the shaft in front

However this not always  needed . Unsure why and or whats differrent but I  think it may have to do if the shafts are balanced as a whole or separately 

I doubt there is many places that can balance a combination shaft 25 feet long 

I also think the phasing may have to do with one shaft interfering or affecting the other I do not know this and only am guessing 

 

Paul 

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