Double Cardan Drive Shafts?

The push behind keeping everything 1330 joints is (a) that's what Toyota designed in the first place (b) downgrading parts isn't wise for upgraded trucks and (c) the difference in cost should be marginal so why not? At this stage it's a matter of what combination of shit will work - I just ordered a bucketful of parts to find out.

My plan has always been 35s, 4.10s or 4.56s, and forced induction. Might as well get the driveshaft sorted now and not have to worry about it later.

 

I know everyone is different to a degree.

I installed the Allpro Expo packs on my DCSB about 2 years ago. It lifts the rear up 4.5" unloaded so ride around with 400# of sand bags to keep things civil. I do everything with my truck from wheeling to loading 1000# pallets of masonry to towing a travel trailer across country.

Since the truck was new, I always had a vibration from what felt like the rear end between 7-10mph only while accelerating. After the lift, I notice the vibration get much worse, but always smooth sailing all the way up to 80 and higher. I have added the OME carrier bearing drop spacers (1/4") and then got crazy and added about another 1/2" with washers and extended the bolts. The whole shaft from transfer case to differential is only off by ~.5° through it's entire length, measuring with a magnetic angle finder. The same vibration remains, unless I load the rear down to an equivalent of 3" of lift in the rear. Then its almost negligible.

After reading this thread, wouldn't a silver bullet be to just:
1. Add a double cardan after the carrier bearing
2. Add another right before the differential flange
3. Shorten the yoke proportionately so the DC joints don't cause the 2 shafts to bind at full compression

This is for stock gearing and 31.5" tires. All I've seen here is 1 DC joint and shortening of the shaft or single shaft with DC joint.

Any thoughts?

 

Reading what you're symptoms are, there's a few things that stand out to me (based only on what I've read and what I've experienced during my driveline adventures).

1. It might more of an axle wrap issue rather than only angles. There's some equipment (brackets, stiffeners, etc) that folks say will help alleviate/lessen the axle wrap.
2. When you load up with weight, you say the vibrations become negligible. Why not measure angles without weight, then remeasure with that ~300# in there and find out how to set those angles as your everyday angles (whether they're the "ideal" or not, they'll be the real world best angles apparently). I've heard certain angles on the axle/diff angle help minimize the axle wrap too.
3. A double cardan joint after the carrier bearing will be enough, no need to add another by the diff...and I'm not sure that won't cause more issues than it fixes.