Shake/Vibration when Towing

[Caman96]

I’m far from a physics genius, but the only thing I see that affecting is the resonant frequency of the driveshaft. 2 u-joints, in the proper phase alignment and in the same rotational plane, will cancel out their inherent resonance. I’m probably wrong but it makes sense to me that the bigger driveshaft would just mask the misalignment by changing the frequency of the u joints.

Don’t stop there , what’s your thoughts on them saying the reduced sections are the cause of issue? I mean, my manual says I can tow 6K!
I should’ve included part of his point was the longer length of my driveshaft compounded with the 2 1/2” reduction was part of their assessment.
Yes, she said that too!

 

[Orpedcrow]

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This guy gives a really good explanation of pinion angles and such

 

[Orpedcrow]

Yea but that’s all factory stuff (as far as we know) the only difference being the springs you put on? Are they lift springs or just heavier duty?

 

[Orpedcrow]

what’s your thoughts on them saying the reduced sections are the cause of issue?

Bologna!

 

[Caman96]

Yea but that’s all factory stuff (as far as we know) the only difference being the springs you put on? Are they lift springs or just heavier duty?

Just a little more HD. You could’ve orthud truck with 4/5 springs like I’ve got.

 

[Caman96]

Bologna!

I want to believe just shimming it will resolve, I’m not talking their word as Gospel yet!

 

[Orpedcrow]

And you said it didn’t shake with the old springs? I still think there’s an angle issue

 

[Orpedcrow]

I want to believe just shimming it will resolve, I’m not talking their word as Gospel yet!

It’d be a cheap experiment and a heckuva lot cheaper than a new girthy shaft in the rear end…

 

[Caman96]

It’d be a cheap experiment and a heckuva lot cheaper than a new girthy shaft in the rear end…

OUCH!!!!

 

[Schurkey]

NITRO-GIRTH!

"Up" and "Down" refer to the angle of an item as installed on the vehicle, from front to rear. Higher in front is a downward slope, higher in the rear is an upward slope.

Measure your driveshaft angles WITH THE LOAD ATTACHED. I would expect the axle pinion to be a degree or three "down" compared to the transmisson/transfer case, because it'll rise under torque, and under torque the pinion angle should be the same or nearly the same as the transfer-case angle.

Here's a Spicer calculator for U-joint angles. Using your figures of 11, 7, and 5 degrees, all "down", your front U-joint is operating at a 4 degree angle, and the rear U-joint is operating at 2 degrees. Yeah, I bet it shakes. But again, the angles when loaded are going to be more important.

Spicer Driveline Operating Angle Calculator

Measure the angles of each component in your drivetrain, then use the Spicer Driveline Operating Angle Calculator to find the operating angle of each u-joint in your drivetrain.

spicerparts.com

and a video showing how to measure and calculate angles:

Measuring Driveline Operating Angles | Spicer Parts

Driveline set-up, diagnosis, and repair is an easy process, but it is often misunderstood. This video offers a quick tutorial that can makes measuring driveline angles a snap.

spicerparts.com