Driveshaft question....

Cummins Driver

Cummins Driver

THE Cummins Driver
Joined
May 16, 2007
Messages
2,405
Hey guys. I just got my truck back on the road yesterday with a Dana 80 from my 70 i had in it. All went well, but i have a question.

My slip yoke only has about 3/4 inch to slide into the t-case now with the truck on the suspension. Before, it was about 2 inches. I knew id need to shorten the shaft, but im driving it how it is for now until i can get to it. I wont be loading it heavy, or driving it crazy till i get it shortened, but im curious for those of you with 1 piece shafts, how much room is there for your slip yoke to slide into the t-case? I will probably shorten mine about 1 1/4 inches or so, but i was curious how far most people run theirs out of the t-case. Just dont want to bust my tailhousing on the t-case because the shaft was too long. Thanks!

Eric
 
If you have ladder bars on it I wouldn't be as concerned.

Do the a^2+b^2=c^2 that will give you a rough idea how far in it with the suspension compressed.
 
I dont have my traction bars back on yet, but they will be soon. Just have to weld mounts to the new axle plates.

How does that math you are talking about work? What numbers do you plug in?
 
Kinda surprising, Mine wouldn`t even go back in at all. About 1 inch or so to long. I`m changing out the 241dld for a dhd. wonder if that changes anything in length? Don`t matter, I`m gonna have a new shaft made anyway.
 
Yeah, i didnt know if it would work at all or not, but it does at least work. It basically has just enough room to let the shaft slide in enough to get the u-joint in.
 
"a" would be the height from pinion yoke straight up to a point that is straight back from the tcase yoke. "b" would be the length from the tcase yoke straight back to the point straight up from the pinion yoke (I taped a plumb line to the underbody of my wheeler and marked this point on the line). The interior angle from "a" to "b" must be 90 degrees. Solve for "c", the theoretical length of the driveshaft, with the suspension unloaded.

c=sqrt(b^2+a^2)

Then subtract the amount your rear suspension will sag when loaded/hooked from "a" and solve for "c" again. Find the difference in the two "c" numbers and that will be a ballpark figure for how far it traveled in the slip yoke.
 
Thanks for the information. Didnt realize you could do it like that.

On the other hand, it might be easier to crawl under the truck while i let someone push down on the bed with the loader tractor:hehe:
 
Cummins Driver said:
Thanks for the information. Didnt realize you could do it like that.

On the other hand, it might be easier to crawl under the truck while i let someone push down on the bed with the loader tractor:hehe:
Click to expand...

That sounds a lot easier. LOL
 
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