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2 Piece Driveshaft Phasing

LNielson

LNielson

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How should this be setup in my truck?

I'm chasing down a driveshaft vibration and an wondering if the way my 2 piece shaft is phased could be contributing. I am going to be correcting for pinion a pinion angle too but just wonder what others know about the correct way to set up the phasing of this shaft.

The local shop that built my drivelines told me to run it with the first shaft slip yoke 90 degrees out of phase with the fixed yoke end.

I found some data in a Spicer install tech document that agrees with this. It says if the angle between the output yoke and shaft are within 1 degree of each other to set it up this way, 90 degrees out of phase.

Almost everything else I have found or others that I have talked to say to run it with the yokes on the shaft in line with one another.
 
I had them the latter. The 1* phasing thing is to make the bearings roll in the caps
 
My 2-piece crew cab drive shaft is having some vibration issues as well. I am no driveshaft expert, but I think I remember that the 2-piece drive shaft male slip yoke is keyed, in order for the rear female slip yoke drive shaft to go on in only one way. But, there is a blue plastic piece on the male side of the slip yoke that can be removed so that the female side of the slip yoke can go on any way you want it.

I had to drop my carrier bearing down about 3-1/2", in order to get a 0-degree angle on the all of the u-joints, but the one coming out of the transmission. The one coming out of the transmission is at 3-degrees of operating angle. Mine has a vibration at only 40-MPH, but nothing below or above. The problem with dropping the carrier bearing down to compensate for angles is ground clearance. When it hangs down to low, it could get ripped right off if high centered over an obstacle.

It will be interesting to see if different phasing helps or cures your driveshaft problems. I will try the same re-phasing of my driveshaft if it works out for you.
 
I don't fully understand phasing but I would think you should put the shafts together in the same orientation it was balanced in. The 2 times I've had the rear shaft worked on, the driveshaft shop was adamant I bring in the entire assembly so it could be balanced as a unit. I would think rotating one half of the shaft would mess with the balancing.
 
mrk5 said:
I don't fully understand phasing but I would think you should put the shafts together in the same orientation it was balanced in. The 2 times I've had the rear shaft worked on, the driveshaft shop was adamant I bring in the entire assembly so it could be balanced as a unit. I would think rotating one half of the shaft would mess with the balancing.
Click to expand...

You can bank on what @mrk5 says. He has been through the meat grinder on this issue. ;)
 
the rear shaft can definitely play with your setup. I had a xfer case drop kit (I didn't put it on) and it pitched my motor and my dizzy was up against my firewall.
Then the guy installed the bearing drop as well to get a better angle on my rear shaft. I had what was supposed to be 12" suspension lift with my 40" hawgs..
last weekend I removed the xfer case drop kit and left my bearing down low and took it out. Seemed better than it used to be. If I took off from a light HARD.. I could get the entire rear end to bounce the tires off the ground!!!!!!

now my setup goes from np205 angled down to bearing then slightly less angle to rear axle.
20171028_075430.jpg
 

@obijuank5 put this up for me to view on my build thread, doesn't explain why the spicer install document says to put your yoke 90 degrees out of phase for shallow angles, but makes it pretty obvious why phasing is important for smooth operation.

IMG_5190.PNG

I think the shafts are balanced as separate units, front and back, but I don't know that for fact.

I'll update this with my results as I adjust my driveline angles.
 
1-ton said:
When you say 1-degree of phase, do you mean 1-degree of operating angle?
Click to expand...

Yes, that is what he is talking about, in reference to the spicer document I put the picture of a post or two up the thread.
 
Two piece shafts are balanced as a unit I do know that.

My driveshaft guy Craig is a great resource. Driveshaft specialist .com out of san antonio tx. He wheels too.
Maybe give him a call and see if he can help you or sell you the right stuff?
 
I recall reading in one of my service manuals some service bulletins regarding vibration with 2 piece drive shafts on 70's GM trucks ,mostly noticed when the transmission shifted into second gear (I assume automatics )--their "fix" was to add a 1/2" spacer under the carrier bearing...this was for stock unmodified trucks,not lifted ones..

There was also some 2 piece shafts that were not keyed,so the yokes could be assembled out of phase,also I recall it saying some shafts like those had to be assembled something like 4 splines "off" from 90 degrees to get the shafts to cancel out their vibrations properly..
 
LNielson said:
http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml

This is a great article on driveline setups. There is a good section on 2 piece shafts in here too.
Click to expand...

According to that article I am going to have to redo some angles on my 2-piece drive shaft. The article states that a 2-piece drive shaft needs to have two u-joints at same opposing operating angles, and one a 0-degrees of operating angle. Mine has the opposite... two u-joints at 0-degrees operating angle, and one at 3-degrees of operating angle.
 
1-ton said:
According to that article I am going to have to redo some angles on my 2-piece drive shaft. The article states that a 2-piece drive shaft needs to have two u-joints at same opposing operating angles, and one a 0-degrees of operating angle. Mine has the opposite... two u-joints at 0-degrees operating angle, and one at 3-degrees of operating angle.
Click to expand...

Mine is like that now two, t case - shaft 1 measures 0 degrees, shaft 2 - pinion measures 0 degrees, 4 degrees between shaft 1 to shaft 2, not ideal.

The terminology refers to that as broken back, but I feel uncomfortable using that and two shafts in the same sentence...

I'll update this as I make changes today.
 
OK, so I pulled the splines apart and aligned the joints on the front shaft (they were out 90 degrees) Shimmed the carrier bearing down .8". Tcase angle 4 degrees, shaft one 5 degrees, shaft two 6 degrees, pinion 7 degrees. (this is setup 3 from that article I linked, all joint angles equal) There is still vibration coming from the driveline can feel it between 30-50 mph and a faint pulsing vibration starting around 60 on up past 70. Vibrations are lower magnitude than where it was.

Going to readjust and try again.
 
The only other reasons for driveshaft vibration are (aside from balancing) is u-joints not being concentric. Sometimes cheaper brand u-joints are not manufactured so great, and they are not perfectly square. I have heard the best brand for a daily driver is Dana/Spicer Life Time Series u-joints.
 
LNielson said:
http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml

This is a great article on driveline setups. There is a good section on 2 piece shafts in here too.
Click to expand...
Cool article. My setup doesn't fit the examples though because I have a 2-piece with a CV joint. :doah: I just setup the rear section like you would on a 1-piece shaft and left the intermediate section to fall where it ended up. I don't notice any vibrations but a 2-piece shaft with a CV is expensive.
 
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