U Joint Connections. Which way Double joint to Front or Back?

[Ark Bigfoot]

I have a 72 Bronco. I replaced the 6 u joints on both front and back shaft. I am getting ready to re-install them. Which way do they go? I had thought the double joint went to the transfer case and the single joint to the axels. But I read where one said to put them in reverse so water and dirt would be more difficult to enter the spline shaft.

 

[DirtDonk]

While it can work in some situations with the double-cardan at the axle, on Broncos it was ALWAYS at the transfer case.
The slip-joint has a seal, so it's not that big a deal. The double-cardan section has a minimal seal too, but is far more critical to keep out of harm's way.

In a racing situation it would be argued too that putting the single joint down low also puts the "lighter" end of the shaft on the suspension side and the heavier side on the "sprung weight" side of things. It's true, but nothing we'd ever notice.

Oh, and the CV/double-cardan at the transfer case is the only way it'll work by the way.
The yokes are completely different and while the lower u-joint has a u-bolt clamp it to the open yoke, the upper double-cardan section is attached with four bolts to the special yoke.

Paul

 

[Broncobowsher]

As stated, they won't bolt up backwards. They only fit one way.

 

[Steve83]

Not only would the single joint bind as the axle travelled; there would be no cancellation of its variations in angular speed, so there would be substantial & probably-catastrophic vibrations.

Always install the major drivetrain components as-designed.