Too much driveshaft angle?

[DeclansDaddy]

If you've looked at my build thread you seen that I lifted my truck in the rear with a 2" Add-a-Leaf and a 2" angled blocked. Originally when I did it I put the block in so it pointed the pinion pretty much straight inline with the driveshaft. Well it had a pretty bad vibration and after looking more into it I found that I was wrong on how I put the blocks in. So after spinning them around the angle on the flange on the pinion and the angle on the flange on the back of he trans were identical and viola my vibration was gone. So in doing that it lowered the pinion ever so slightly to match it with the trans. Maybe 1/2"-3/4" lower than before. However ever since then if I accelerate hard from a stop I have a horrible banging sound which sounds like it's coming from under my seats. My first thought was it was the torque of the motor wanting to push the tailshaft of the trans up and the yoke was hitting my floor. So I crawled under there and see no signs of that. I checked the trans mount and all looks good. And actually there's some sort of shifter linkage that would hit the floor first and prevent the shaft from hitting it. Now with only 4 inches do you guys think maybe the joint at the yoke and driveshaft are binding under load and popping? If I take off normally it doesn't happen. Only if I try to get on it hard and I can only imagine if I tried wheeling like this I'd have a whole lot of problems with it.

 

[ajohnson]

Lift blocks induce axle wrap, so it sounds like the yokes binding could be the issue. I have an IFS front driveshaft (cheaper and easier to find than a SA front shaft) for my rear shaft, with the double cardan clearanced for more angle and the pinion pointed at the rear output. This solved my vibes.

 

[DeclansDaddy]

Well I plan on just getting 4" springs here soon. It had ran across my mind if since I have a slip joint on my rear shaft if then I could put a cardon joint at the trans. I could even get the shaft cut down if I needed to. I just swear I've seen more angle on shafts before.

 

[fourwd1]

If you go to 4 inch springs you'll need some degree shims to match what the angle on the blocks did.
If you go to a new drive shaft with a double cardan joint you'll still need shims, installed the opposite way, to tilt the pinion up towards the t-case.