My Disco II eats front driveshafts. I have had them rebuilt but my lift is clearly the issue. Unfortunately, Toyo Open Country M/T tires are both expense and seem to last forever, so reducing the lift is not an option.

I called two well known places about multi double cardan driveshafts and got some ridiculous information--I am sure of that because when I called the first one back, I spoke to the well known owner and he said the multi double cardan is perfect for a 3+ inch lift and that the information I got form his own employee was wrong.

I think I have about 3.75 inches of lift after the weight of my bumper and winch.

Almost all of my driving is on road, on highway.

I am hoping that someone can report their actual experience with a multi double cardan driveshaft to me, because they are quite expensive. I already have a double cardan rear driveshaft (because it wasn't much more than a standard one when I deleted my rotoflex), but the multi double cardan just looks to me like it could be unstable at highway speeds.

ANY advice would be appreciated.

 

As much work as you do yourself, I'm surprised you've not just begun rebuilding them yourself. u-joints are less than $7 each on Rock Auto for the stock size. I keep a couple of those around. I'd stock up with a few and just rebuild once in a while. Mine's not necessary yet, but I may do a write up some time soon anyway. By soon I mean some time in the next... I'd say 4 months at the most.

Sadly I have no actual experience with a multiple double cardon, so I can't help you with info there.

 

I will look for your write up! The rebuilds, here anyway, cost 100 dollars and I have to remove the shaft and supply the u joints myself.

I was under yesterday and noticed that the rubber grease cap on mine looked funny and that's why it is back on my mind. I don't have a solid spare at the moment.

On my first call the salesman told me that a multiple double cardan would make the problem worse. When I asked him what the driveshafts were for, then, he said they were for offset angles (where the pinion is not lined up, left right, with the transfer case). That's not what I'd read, so I called another place and got an different answer; the salesman told me the were only for slow trail driving. Again, that's not what I'd read and it caused me to question the Internet entirely. I called the first one back and the owner answered, and he told me that was all ridiculous and that the multi double cardan was for higher lifts and, if made properly, should never vibrate. He said it was for on or off road just like any other driveshaft. I tended to believe him because he has made a big name for himself with driveshafts. . And when the owner tells you something like that you don't want to call him back and say "are you sure about that?!"

I had other issues with the rover after that and decided to revisit it later. Now is later, it seems.

 

If you determine that the shafts are failing not from improper rebuilding I have another suggestion.

Are you still running stock castor arms? It's possible, the driveshaft fatigue you're experiencing is a direct result of improper geometry (operating angle of driveshaft in relation to diff / transfer case). It is said that optimum operating angle should fall into the 2-3* degree range and the further you stray from the optimal range the more stress is applied to the shaft's joints.

If you're still running stock arms I suggest upgrading to at least a 3* castor correcting arm. I believe RTE will will fab set of arms custom to your specific offset needs. With 3+" of lift of stock you may benefit from 6* offset. But don't take my advice measure to confirm your specific needs.

RTE should be able to determine your offset needs by answering some simple "lift over stock" questions.

If you're a math nerd like me, give this exercise a whirl.
https://www.drivelinesnw.com/part-tr...ngle-problems/

 

Coors that's very apt. I do still have stock castor/radius arms and have talked to RTE about changing the angle to fix twitchy steering. That is in my future but I haven't done it because I haven't settled on a particular level of lift and I am pissed at myself for sending my parts Rover to the Boneyard with castor arms on it that I could be using now to send to RTE. Right now my Disco has a slightly eager stance, as opposed to the dog squatting stance that I really hate. But the preferred stance is the floating on a 400 pound cloud of tires parallel to the planet stance.

Right now I have a theoretical 5 inches but the real lift is just under 4 due to bumper, winch, and spring settling (I still have MD springs). I haven't upgraded my springs because I'm afraid it will accelerate the driveshaft gluttony.

I've studied YouTube videos of huge lift Discos but I haven't been able to catch a glimpse of the front of the front driveshaft. And no one seems to have a multi double cardan setup or of they do, they don't know about the Internet.

But castor correction actually increases the driveshaft problem, as I understand it, because the arms are essentially lowered in the back to make the correction. That places the pinion face at less of an angle to the transfer case, resulting in a greater angle at front of the driveshaft, assuming a steady amount of lift.

Is that wrong? I figured that the multi double cardan setup would work regardless of the pinion angle (so, if the lift changes or I have castor correction, or not), at least within its operating range.

I sure wish we could just lower our transfer cases.

 

try BPU for a double cardon shaft there price was not much more on my P-38 over a standard shaft