Seriously bummed with this drivetrain setup right now :(

[Turbo4whl]

Yes, I used 3 degree shims to point the pinion directly at the output shaft.

This is most likely your vibration. @Craig Nedrow explained this very well! If you need a visual here is this:

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[Craig Nedrow]

Most excellent Wayne!! Visuals are so nice, and this shows what happens. Recap, phasing, (u-joints exactly in line,) and angle within 1 degree. Wish you were closer Square root AKA Mike, is would be so interesting to crawl under the truck and check runout, and then to pull the shaft and static check phasing. I could fix that, but kinda far away. The angle you can check in the truck, and fix yourself with shims.

 

[SquareRoot]

@Craig Nedrow

So just to be clear. I had zero vibration issue with the slip yoke/208 T-case/ and u-joint setup beforehand.
Then I swapped in the 205 fixed yoke and new driveshaft with Double Carden Joint and a new CV style yoke. Based on everything I read, it said (unless I misinterpreted something) that with a Double Carden the pinion angle should point directly at the output shaft. Based on my measurements, I rotated the diff 3* up with pinion shims. Regarding phasing, I understand the concept with single "u-joints" but it seems a moot point with a Double CV because the rear joint is always aligned with one of the two front joints in the CV? Am I making sense? lol

 

[SquareRoot]

So unless I got the angle wrong, I'm confused. One thing I noticed last night driving home is that the vibration starts at exactly 50 mph. And its the vibration I feel thru the clutch when I shift from 4th to OD. It's NOT rpm dependent, it's definitely speed dependent. First chance I get, I'm going pull the rear shaft, inspect everything and drive it in front wheel drive mode (I can do that now! lol) at highway speed.

 

[Craig Nedrow]

Driveline/Propshaft 101

Still think your angles are wrong.

I was under the impression that a CV should point directly at the output shaft?

No. rear and front angles MUST BE WITHIN ONE DEGREE, parallel with each other. For simplicity, if you had a shaft coming out from both tcase and rearend both 4' long, that angle would be as close to parallel as you can get. One would be higher, the other lower, but where they overlapped, that would be parallel. Looking at your excellent pictures, if you have an angle gage, when the shaft is out, make sure there are no burrs and attach the angle gage to the U-joints (the flat part where it bolts up,) and check your angle. BTW that really looks good, strong, and clean

 

[77 K20]

Following this- I went from a NP203 to a magnum/NP205 and have new drive shafts. I now have a vibration. So far been traveling too much for work to even drive the truck- but disappointed in the highway vibration.

Mine is a bit more confusing as I have full time 4x4 slugs in the front axle- so I'm turning both driveshafts all the time.

Just reading and learning for now as this is real useful information.

 

[Bextreme04]

Driveline/Propshaft 101

Still think your angles are wrong.

No. rear and front angles MUST BE WITHIN ONE DEGREE, parallel with each other. For simplicity, if you had a shaft coming out from both tcase and rearend both 4' long, that angle would be as close to parallel as you can get. One would be higher, the other lower, but where they overlapped, that would be parallel. Looking at your excellent pictures, if you have an angle gage, when the shaft is out, make sure there are no burrs and attach the angle gage to the U-joints (the flat part where it bolts up,) and check your angle. BTW that really looks good, strong, and clean

You are wrong. If you only have two U-joints, then you are absolutely correct on them needing to be the same parallel angle within <1degree. For a CV setup, the differential needs to be pointed directly at the transfer case. He could be getting the same vibration issue if the diff angle is off from straight though.

https://4xshaft.com/blogs/general-tech-info-articles/driveshaft-angles

 

[Bextreme04]

Call your driveline guy and ask him.

 

[77 K20]

Driveline angle link

I have Tom Wood's front and rear driveshafts (both new). He had this nice page where I had measured everything and then wrote it down. I then lost the paper and need to remeasure it.

Might be useful for you.

 

[SquareRoot]

Driveline angle link

I have Tom Wood's front and rear driveshafts (both new). He had this nice page where I had measured everything and then wrote it down. I then lost the paper and need to remeasure it.

Might be useful for you.

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Tom Woods has a great YouTube page and one of the videos specifically addresses the vibration issues, including the difference between a cardan (u-joint) and CV (double u-joint). He also describes the two causes of vibration (angular and dynamic) and the "symptoms" of each. Mine leans more towards dynamic based on his charts. I'm hoping its angular, since every piece in my puzzle is brand new (and balanced).

 

[RaisedK5]

Not sure if anyone mentioned this but in all reality you want the rear pinion pointed a couple degrees down from directly at the t case with a cv because youll get pinion climb under load. That way it'll be near zero under load.

 

[PrairieDrifter]

Following this- I went from a NP203 to a magnum/NP205 and have new drive shafts. I now have a vibration. So far been traveling too much for work to even drive the truck- but disappointed in the highway vibration.

Mine is a bit more confusing as I have full time 4x4 slugs in the front axle- so I'm turning both driveshafts all the time.

Just reading and learning for now as this is real useful information.

I would say it's your front axle being locked in. Mine starts to vibrate around 50 with the front hubs locked. But I have 35's and a 5 inch lift.

Completely smooth to 80 something but if the hubs are locked the vibration starts right around 45-55

 

[CalSgt]

You are wrong. If you only have two U-joints, then you are absolutely correct on them needing to be the same parallel angle within <1degree. For a CV setup, the differential needs to be pointed directly at the transfer case. He could be getting the same vibration issue if the diff angle is off from straight though.

https://4xshaft.com/blogs/general-tech-info-articles/driveshaft-angles

^^^^ This. To rough it in it should point directly at the TC output, to fine tune use an angle finder to compare the angle of the u-joint cap to the angle of the shaft. A socket used as a shim between the ujoint cap and angle finder helps.

Not sure if anyone mentioned this but in all reality you want the rear pinion pointed a couple degrees down from directly at the t case with a cv because youll get pinion climb under load. That way it'll be near zero under load.

I was thinking this too, may be getting a little axle wrap at higher speeds pulling up on the pinion snout. I know in the Jeep world (lots of double cardan rears shafts) with control arm type suspension they suggest setting pinion 1 degree (or so) off to compensate for rise under load.

 

[SquareRoot]

^^^^ This. To rough it in it should point directly at the TC output, to fine tune use an angle finder to compare the angle of the u-joint cap to the angle of the shaft. A socket used as a shim between the ujoint cap and angle finder helps.


I was thinking this too, may be getting a little axle wrap at higher speeds pulling up on the pinion snout. I know in the Jeep world (lots of double cardan rears shafts) with control arm type suspension they suggest setting pinion 1 degree (or so) off to compensate for rise under load.

Wonderful. Ya'll know what a PITA it was to put the shims in the leafpack? Now it's literally 150 degrees here and I gotta crawl under that B***h in the driveway . Man gotta do what a man gotta do. At least my new console makes me keep going.

 

[CalSgt]

Wonderful. Ya'll know what a PITA it was to put the shims in the leafpack? Now it's literally 150 degrees here and I gotta crawl under that B***h in the driveway . Man gotta do what a man gotta do. At least my new console makes me keep going.

Sorry for your luck Sir…