Two-Piece Driveshaft Angles & Geometry with BDS Shackle

[RMCB214]

Is it matched angles for each driveshaft section or within 1-2 degrees that works best? I am going to add the BDS shackle and want to figure out if my angle will be kosher prior. I've already had the shim and new driveshaft TSB performed which didn't do much.

I've been told that 1" of shackle lift will rotate the pinion up approximately one degree. The rear section of my driveshaft is one degree steeper than my pinion yoke so I'm really close there. I currently have 3/8" of spacers at the carrier/center support so I could remove those to get a little more angle if needed.

My stock angles (21 Tremor) with 3/8" center support drop are: 5.6 at rear pinion yoke, 6.6 at rear section of drive shaft, and 8.1 degrees at the front piece of the driveshaft forward of the carrier support.

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[Whiplash]

Is it matched angles for each driveshaft section or within 1-2 degrees that works best? I am going to add the BDS shackle and want to figure out if my angle will be kosher prior. I've already had the shim and new driveshaft TSB performed which didn't do much.

I've been told that 1" of shackle lift will rotate the pinion up approximately one degree. The rear section of my driveshaft is one degree steeper than my pinion yoke so I'm really close there. I currently have 3/8" of spacers at the carrier/center support so I could remove those to get a little more angle if needed.

My stock angles (21 Tremor) with 3/8" center support drop are: 5.6 at rear pinion yoke, 6.6 at rear section of drive shaft, and 8.1 degrees at the front piece of the driveshaft forward of the carrier support.

You having gone thru the TSB process of driveshaft angles to adress vibration, have a better grasp than most 5G owners....Back when I had the OEM 2 pc. I tried several different shim configurations, not completely successful, but I was able to move the vibration to a speed that I spent the least amount of drive time in... 65 to 70 mph...
Measurements of the the driveshaft angles are taken from flat face of transfer case output flange and flat face of the pinon input flange...angles of driveshaft angles make little difference becuase of U-joints change the driveshaft operation angle...You are trying to get the flanges as close to parallel a possible with the shaft angles balanced at a operation angles within 3.0° of each other ...that leaves room in the U-joint for grease to get in
and keep bearings lubed...Tranfer case out put angle is typically about 3.0° do not try to shim transmission to change this...it is what it is .. the angle changes are made with a combination of shims on the carrier bearing to cross member mount bolts, and wedge shaped spacers between rear axle and leaf springs, to change pinon input flange angle...when I switched to the Tom Woods 1pc. my transfer case flange was at about 3.0° down and pinion flange was at about 8.0° up....I added a 5.0° wedge between axle and leaf springs trying to get flange angles to parallel....after install of wedge, pinion flange angle was 0.4° lower than the face angle of t-case output angle, unintentionally leaving a little room for axle wrap while under operational load...

I hope all this long winded answer does not further confuse things...If your truck was a non Tremor the easy answer would have been replace with a Tom Woods 1pc and be done with it.....?....good luck....

EDIT: I'm on a 3.0" Coilover lift with rear raised about 1.0" by ICON WRX progressive Leaf springs...


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[RMCB214]

You having gone thru the TSB process of driveshaft angles to adress vibration, have a better grasp than most 5G owners....Back when I had the OEM 2 pc. I tried several different shim configurations, not completely successful, but I was able to move the vibration to a speed that I spent the least amount of drive time in... 65 to 70 mph...
Measurements of the the driveshaft angles are taken from flat face of transfer case output flange and flat face of the pinon input flange...angles of driveshaft angles make little difference becuase of U-joints change the driveshaft operation angle...You are trying to get the flanges as close to parallel a possible with the shaft angles balanced at a operation angles within 3.0° of each other ...that leaves room in the U-joint for grease to get in
and keep bearings lubed...Tranfer case out put angle is typically about 3.0° do not try to shim transmission to change this...it is what it is .. the angle changes are made with a combination of shims on the carrier bearing to cross member mount bolts, and wedge shaped spacers between rear axle and leaf springs, to change pinon input flange angle...when I switched to the Tom Woods 1pc. my transfer case flange was at about 3.0° down and pinion flange was at about 8.0° up....I added a 5.0° wedge between axle and leaf springs trying to get flange angles to parallel....after install of wedge, pinion flange angle was 0.4° lower than the face angle of t-case output angle, unintentionally leaving a little room for axle wrap while under operational load...

I hope all this long winded answer does not further confuse things...If your truck was a non Tremor the easy answer would have been replace with a Tom Woods 1pc and be done with it.....?....good luck....

EDIT: I'm on a 3.0° Coilover lift with rear raised about 1.0" by ICON WRX progressive Leaf springs...


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Thanks for your response and feedback. I only get a brief/mild shudder in the 5-10 mph range accelerating from a stop. Nothing noticeable elsewhere. Almost negligible when turning from a stop.

I tried to attach a photo showing my methods with the angle finder but they wouldn't upload for some reason. I zeroed the digital gauge on the garage floor right under the drive shaft as there is some slope built into the concrete slab.

I didn't get the t-case yoke angle but it looks like I'm around 2.5 degrees of difference between the diff yoke (flat bottom edge) and the drive shaft yoke/ears of the forward driveshaft piece. This is at the two-piece connecting junction right behind the center bearing.

The Rzeppa CV angle at the diff is what I'm concerned with after the shackles. Some have reported 1.25" of lift from them. I don't know the exact angle change but two degrees of pinion tilt would likely have my yoke at a steeper angle than the driveline, requiring center bearing adjustment again or reversing the leaf spring shims.

I wonder about the diameter and spline count difference between the Tremor rear CV and the Jeep JK. https://teraflex.com/jk-factory-replacement-cv-joint-kit-high-angle-rzeppa.html#

 

[Whiplash]

Thanks for your response and feedback. I only get a brief/mild shudder in the 5-10 mph range accelerating from a stop. Nothing noticeable elsewhere. Almost negligible when turning from a stop.

I tried to attach a photo showing my methods with the angle finder but they wouldn't upload for some reason. I zeroed the digital gauge on the garage floor right under the drive shaft as there is some slope built into the concrete slab.

I didn't get the t-case yoke angle but it looks like I'm around 2.5 degrees of difference between the diff yoke (flat bottom edge) and the drive shaft yoke/ears of the forward driveshaft piece. This is at the two-piece connecting junction right behind the center bearing.

The Rzeppa CV angle at the diff is what I'm concerned with after the shackles. Some have reported 1.25" of lift from them. I don't know the exact angle change but two degrees of pinion tilt would likely have my yoke at a steeper angle than the driveline, requiring center bearing adjustment again or reversing the leaf spring shims.

I wonder about the diameter and spline count difference between the Tremor rear CV and the Jeep JK. https://teraflex.com/jk-factory-replacement-cv-joint-kit-high-angle-rzeppa.html#

The low speed shudder can be , and most likely is, lack of grease in Slip Joint splines...there are several tutorial DYI threads on this site on "how to Lube your driveshaft "... alot easier than messing with driveshaft angles..?....

 

[RMCB214]

Driveshaft was replaced under TSB. No need for that yet...I believe that was a solution more for the slip bump/thud and not for the vibration/shudder. Keep my eye on it though.

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