Double cardan or CV joint?

[andyrad]

I was recently trying to improve my fuel economy by removing my front drive shaft. I immediately noticed that I have to run in diff lock but I have a couple questions

1. Removing the drive shaft made the truck very throttle responsive and also eliminated a small vibration that I had under load at a couple speeds. This vibration was also there driving into heavy head winds because the little tiny V8 has work so damn hard. My question is what is a better replacement for a front drive shaft, a double cardan style or a CV joint style like you can get from Safarigard. I do not YET have a lift but it will one day get done. Or should I just suck it up.

2. Next question is about the t case. I enjoyed driving it without the front shaft BUT there was a lot of clunking going on during shifts. It did not do this with the shaft in and the center diff unlocked but it does do it with the center diff locked. Is this indicative of an impending mainshaft failure or is it just a sloppy chain or something.

I really do not need full time four wheel drive and would love to be able to switch in and out of 4x4 like on a good old fashioned truck. Any suggestions?

[mdmccallum]

I don't know the answers to your questions here althought I think most people are in favor of the double cardan. But you got me thinking. Could you just put some manual locking hubs in the front to improve your gas mileage without removing the front drive shaft?

[andyrad]

I hope there is an easy way to go 2 wheelin because the truck rarely sees the trail anymore and felt so good in 2 wheel drive. I could almost hear the gas companies cryin the blues on this one.

[Buckon37s]

Contact Rovertracks about modifying your t-case to run in rear only and 4 locked. He can do it at what I remember was a reasonable price. Unfortunately, putting on selectable hubs will not net you anything. With the d-shaft, pinion and shafts all still spinning, there is almost no gain in performance and definently none in handling.

To your first question. A CV and a Double Cardan driveshaft is usually the same thing. I did just look at the SG site and that DS does look different. I don't know a thing about it though. This page is very informative if you are interested in a little more driveshaft tech:

http://www.pirate4x4.com/tech/billavista/PR-shaft/index2.html

With no lift, you should really not need one at all. If I were you, I would buy new u-joints for the one you have and take the entire assembly (ears too) to a shaft place and have them balance it. If that doesn't work you know it is not the shaft, and it should be no more than $100 max.

To question 2, these trucks just have a lot of slack in the drivetrain. It's almost inevitable. Although, it did decrease quite a bit with a spool in the rear and drivslugs up front, but don't do that!! Just something I noticed. Good luck!

[Neo]

Sorry to resuscitate this thread, but I too am very interested in this - the selectable hubs part. I understand the mechancis and reasoning why, with an "open" center differential it would not work, since all the power would then go to the front shaft where there is not resistance, and the fact there would not be anything really gained since, even in locked mode, all the components would still be turning, but is there a way that Rovertracks has found to literally disengage the front drive section from the rear, thereby allowing torque flow to ONLY the rear wheels, thus making a disconnection at the hubs (aka freewheel hubs) fruitful in the sense no more wear and tear on the d/s, diff, cv's at the hubs, etc? Will the CV's continue to flex enough to incur no damage if static when a turn is encountered? I really like the thought of reducing the mechanical losses and associated wear if at all possible. Thanks!