I was thinking of running a sm 420 with a divorced 205 out of a Ford and was wondering how long the shaft between the tranny and the t case has to be. Ive heard of making it to a length that centers it between the axles to make both drive shafts the same length, but what is the minumim length that it could realistrically be.

I would think that the minimum length possible would be zero, since you could quite possibly just put a u-joint between the two yokes.

Originally posted by joefear7
I was thinking of running a sm 420 with a divorced 205 out of a Ford and was wondering how long the shaft between the tranny and the t case has to be. Ive heard of making it to a length that centers it between the axles to make both drive shafts the same length, but what is the minumim length that it could realistrically be.

I've a M725 with 4 driveshafts. The shortest one is 9 inches. That's about the shortest slip jointed one I've seen. Ask Jesse at High Angle Driveshafts. He visits this board,gives away free shafts in monthly drawings and is a all around nice guy.

I'm not sure if I would do the single joint between trans and t-case. My '91 GMC K3500 is running a 4L80E auto trans with a divorced Ford NP205 and I used a 1350 CV joint "H" yoke for my complete driveshaft, with a short slide-in yoke in the trans, all in all, it's about 3-1/2" if I remember correctly, and there's just enough room to pull it out for service without dropping the t-case, I could shorten it another 1/2" and make the t-case mounts slide back for service, but I'm not that concerned about length, just needed to keep the t-case ahead of my gas tank.

I'm not sure if I would do the single joint between trans and t-case.

I'm bringing this post back from the dead because it raises but does not answer a question I was searching on.

I'm converting my 2wd F-250 to 4wd using a divorced NP205 behind the original E4OD. Since the E4OD has a slip-yoke output, I was pondering mounting that yoke to the front of the NP205 directly, and have that NP205 input directly in-line with the output.

The question, of course, is whether this would possibly side-load the E4OD output too much, since they'd be on different crossmembers and there's no practical way to ensure the output and input are directly in line at ALL times.

Whereas even a VERY short intermediate shaft would allow for that output/input misalignment with no problem whatsoever.

So has anyone SUCCESSFULLY run a single U-joint in place of an intermediate shaft between a slip-yoke and a divorced transfer-case input?

If everything (engine, trans, transfer) is mounted solid with no flex, you could get by with one U-joint and the slip yoke. In the real world, the engine and transmission is torquing back and forth and moves around quite a bit. A single U-joint and a slip yoke in the trans is not going to allow for the trans to rock up without binding the slip yoke. You will need two U-joints to allow the slip yoke to stay in alignment with the output shaft in the trans. Otherwise when the engine and trans rock up, the slip yoke will try to bend the output shaft at an angle.
As far as length, like posted above, the shortest I have seen is in my M715 and it is about 9". It has NO slip yoke in it at all though, and I do not care for that design. Both of my Dodges have slip yoke intermediate shafts about 13" long.

Thanks for the reply; that's what I was thinking. I found another post where a guy mounted the transmission and divorced-case in a rigid cage, but this is in a longbed Supercab where it would be impossible to keep the axis of the output and input shafts perfectly in-line. Even a CV-joint outer housing without the centering-ball would work as a short driveshaft (idea from that other thread) in this instance; just have to mate it to the two yokes.

The other thing with going yoke to yoke (a buddy of mine did it) is that it will work great...until you have a u-joint problem. He threw a cap which then caused a massive vibration in those two coupled components and busted the housing of his TH350 in grand fashion! I've been running divorced 205 for years now and have been running no slip jack shafts without problems...I' also running 1410's...but that's beside the point.

Spicer, I know a lot of you run the intermediate shafts with no slip yoke and have no problems, from the conversations we've had on The Zone, but that idea still freaks me out. That has got to cause some stress somewhere in the deal. To my way of thinking, when the drivetrain rocks, it pulls on the shaft. Also, the further the shaft goes from it's centerline, the shorter it gets. Maybe I'm being too anal about it, but that still bothers me. It's the sort of thing that would keep me up at night wondering when I was going to spit out a tailshaft bearing or something, lol.

Now if the transmission mount was a sort of saddle mount like the engine, only perfectly inline with the output shaft centerline so that the transmission sort of rotated in the axis of the tailshaft then it would be less of a problem. Now there is a totally useless and overly complicated idea to think about...

The slip is already there in the output of this E4OD. Upon thinking about it for a bit, for a single U-joint to work, I realized that the centerline of the output and input shaft would have to meet about the center of the U-joint to work. Even if they meet at an angle, they would still have to meet. If they were displaced at all from the center of the U-joint, it would put a side-load on the shafts, which at least the output on the E4OD would not handle for long.

With two joints and even a very short shaft, that displacement would be compensated for by the second joint and the angle of the shaft/coupler.

what about a double cardan joint? If you have a slip yoke then this i think would be the shortest way to connect the 2 without using a single joint.

Elwenil- I also use it as a type of safety as well. This might seem wickedly boarish but it's like it the upper bar in a 3 link set up. A couple years ago I got the truck hung up on the 205 REAL bad and bend the hell outta the Xmember mounts BUT the t-case stayed where all my linkage would still work and didn't change the length of my driveshafts like it would have if it would have gotten shoved back like it really should have that day. That's me though...I'll risk the occasional abuse of the 1410's in a shaft like that cause I know what a grease fitting is for.