Max MPH with single DC driveshaft???

Doing research on a one-piece double cardan driveshaft for my '13 4x4 DCSB. I've called 5 or 6 custom driveline shops around the country. Two of them (repped by folks on TW) said a one-piece was a very bad idea because of "jump roping" when nearing critical speed. A local shop wanted to make the driveshaft 4" in diameter for added safety margin (4" won't fit without cutting the carrier bearing mount). Most places I talked to said the max speed with a 3.5" steel one-piece driveshaft that's 67.375" long is around 80mph.

My question is, for all of you that purchased one-piece driveshafts, did the shop give you a max MPH speed that you should never exceed due to safety issues?

 

If you are going to a one piece drive shaft, would you need the bearing mount? Maybe you wish to keep it for "backout" purposes?

http://www.4x4wire.com/toyota/tech/driveshaft/

 

Stay stock

 

bump...for max mph numbers...

 

Is your factory drive shaft broken?

What's the point in trying to use a one piece drive shaft?

 

It is not broken. After installing the Toytec BOSS lift I have the take-off shudder in 1st & 2nd gear. I'm in the process of trouble shooting the problem and looking at all options, one of which, is the one-piece driveline with a double cardan at the Tcase and a u-joint at the pinion. It is supposed to be a reliable fix for most/all vibrations. However, I am hesitant to subscribe to a mod that limits my top speed to ~80mph (because of the long length of the driveshaft) hence the reason for my post. I want to see if members that bought into the idea of a one-piece driveshaft were informed that there was a critical speed they may not exceed. Not one, of all the posts I have read, talks about critical speed and max mph which is surprising to me.

 

Because race truck.

 

What else have you tried to diagnose it as besides a driveshaft issue?

 

Yep.

I can never find the video I'm thinking of when I need it. There's a YouTube video that describes how to adjust the driveshaft angles to fix the vibration issue on lifted trucks.

 

This one! @bshifter watch this video before you screw up your truck.

 

Any update on this thread? Did you ever look into an aluminum shaft instead? I'm in a similar situation.

 

http://www.4xshaft.com/

They'll build them up to 75"; no info on speed rating!? These guys are great on the phone though and always very helpful.