Driveshaft vibration still?

[prolinews]

Well since the last time I posted I got everything shimmed right. Same angle on pinion and tailshaft, I also put in some new u joints . For the most it's a lot better but still has a little vibration at all speeds under a load. I am thinking that a new driveshaft with a cv joint might be the cure? Would the one in the picture be the one I need? 88 k5 208 and 10 bolt 4" lift.

 

[rebelgregory]

There's not one shown for a 4" lift. You'll need one very similar to the first one with 1310 u-joints, but I would call them and take my own measurements. It's usually from the t-case output housing to the centerline of the pinion yoke.

 

[prolinews]

Another thing that I need to consider is eventually going to put a 14 bolt in. Is there much difference in the pinion length? The measurement they want is from the tailshaft to the pinion flange. I am going to try one last ditch effort at shims and rotate the pinion down 2 degrees from the tailshaft. I am thinking that since the springs are soft under acceleration the axle is wrapping up and causing the issue. It only vibrates under throttle at any speed , at a coast no vibration or light throttle flat grade very little vibration . It's so close to being right from where it was . I sure hope the shim and new driveshaft cure.

 

[rebelgregory]

For the new driveshaft - you do realize that you'll have to re-align your pinion angle, right? For a CV shaft, the pinion needs to be pretty much inline with the driveshaft. Mine is pinion down by 1 deg. Runs great.

As to the 14 bolt - I'm running a 14b with the same CV I used for my 10b with an adapter u-joint. The 14b is about an inch or so longer in the pinion dimension. This may or may not be a problem, depending on what your setup looks like. On mine, I was too worried about the shaft bottoming out in the t-case. I used WFO spring perches and u-bolt plates to mount the axle 1" back. All is well now.

 

[prolinews]

This whole situation has been a pain in the rear lol. I have a set of tapered blocks I'm going to try to with the with the shims and get my pinion down a degree or 2. Will that work with the cv driveshaft? Or do I need to set the pinion angle at zero for the new shaft? I know y'all are tired of my noob questions but I sure appreciate your knowledge. I'm pretty sure once I get it right I need to toss my u bolts for some new ones since I have torqued them 2 times already and going to be a 3rd or maybe a 4th time before I'm 100% happy with it.

 

[rebelgregory]

with the weight of the truck on the suspension, the driveshaft and pinion need to be almost inline with a CV shaft. People set the pinion a degree or so downward so that under normal cruising torque, the axle will wrap up to directly inline. As far as what works, it's hard to predict accurately, get your parts installed, measure-adjust-repeat.