Front driveshaft dilemma
 

I've been a fairly avid reader of the forums for quite some time now, and I'm always reading the SAS buildups with the intent of doing a swap of my own. Well, I'm now starting to get everything together to start my swap, and I'm really indecisive about a front driveshaft. I got a donor 85 Pickup that I'm using for parts, including the axle. It also has a driveshaft that I'd like to use. However, I'd like to know whether it would be more financially beneficial for me to have the existing driveshaft lengthened or to build a driveshaft out of square tubing. Obviously, the square tubing method is cheaper, but this truck is also my DD and makes 120 mile trips between home and school once a month or so.

From your experience, what direction do you think I should head in? If I go the route of lengthening the existing driveshaft, what have you guys paid to have this done, and how much longer did you make it?

I know of a shop that makes square tube driveshafts for 40 bucks a pop.

Depends on wether or not what you have in the 85 will be the right length so it compresses and extends without any problems (flexing).

Well, if I go with the square tube driveshaft, I'm gonna make it myself. I kinda assumed that the driveshaft from the 85 would need to be lengthened, but I'm not sure how much longer it would have to be.

Unless you DD in 4wd I'm not gettin' ya there. Lots of folks do the square driveshaft in the front like that, and I've heard they can be extremely strong, when well made. Heard of a guy swaping in chev 1T runnin' gear, he did an extension sleave. It's only 1-2'' longer than IFS, don't quote me on that.

Haha. I guess the DD part is pretty irrelevant, but I try to be thorough, so I figured I'd throw that out there.

I don?t think you can just lengthen the stock 85 drive shaft and expect it to work. With the lift you?re going to experience more wheel travel thus moving the diff more and requiring more compression and extension of the drive shaft. http://www.trail-gear.com/driveshaft.html Since the diff is centered on the rear axle I don?t think most people run into issues with the stock rear drive shaft spline length.

Unless you DD in 4WD, the front DS just hangs out until the hubs are locked. I built a square shaft for my SAS and it works great, but I can't go over 20 in 4WD without a lot of vibrations. Probably my newbie fab abilities are to blame. There is a fair amount of slop between the square tubes that adds to the play and noise.

You will need a long travel front DS. Marlin sells a part you can use for this application. The long spline shaft runs $179 from them. If you shop around you may find that is not the best way to go... but that is the type of travel you will need for your new SAS setup.

Yeah, I know how the 4WD works. I'm not new to this stuff by a long shot, but like I said earlier, I just tried being specific. The only time my DD dilemma would come into factor would be if we got hammered with snow, and I had to drive to school or home from school, but it's something I'd like to take into consideration.

Also, has anyone ever tried getting a square tube driveshaft balanced? I might be wrong, but I can't imagine it would be too far from practical, since they just tack small weights on the outside of the shaft.