Rear drive shaft selection & setup?

[sixb]

I am in the process of setting my rear pinion angle. This is on a 84 k5 with a 5.9 cummins, nv4500, np205. The drive train is very long seems to be as long as some of the doubler setups I've seen on here. My engine and t-case are sitting at 4.5 degrees which happens to be the same as my 91 cummins d250 fyi. I have mocked up my rear diff at 3.5 deg and took a measurment of 36" for drive shaft length with a 20.5 deg drive shaft angle, I took a piece of flat bar and set it on top of the 1410 @ the T/C and the 1350 at the axle to detrimine this angle, not perfect but close really I should come off the center of each joint but haven't come up with an easy way yet. Now I have researched this a bit and on the Tom Woods sight for a 2 joint drive shaft they need to be within 1 degree of each other and on here it's all over the place but the concencues is the same or to point it down a bit. BUT a 20 deg drive shaft angle according to Tom Woods is beyond the 15 deg max so it seems that I will need a cv shaft and to point it straight at it within 3 degrees.

Now I need to find a better way to detrimine my shaft angle before I proceed but if I detrimine that I indeed need a cv shaft how are you pointing it at the t-case accurately. Tom Woods explains the setup for the 2 angle shaft real good but no info on setting up a cv other than pointing it at it within 3 degrees.

Thanks.

 

[sixb]

Also I am running 56" rear springs and a diy shackle flip with 6" shackles pushed back an inch fyi.
Thanks.

 

[obijuan]

change your yoke to a flange and then measure the face of the flange to the pinion yoke center and a driveshaft builder will build you a cv shaft accordingly.
youre too short and tall to have a standard style shaft work well.

when you get it in, shim the rearend up or donw to just barely have a bend at the ujoint. you might get lucky and not have to move it at all with the 3.5 degrees you have now.

for what its worth, ive got the same rear suspension setup as you except for 7 inch shackles. i took the stock 14 bolt perches and used a 2.5 degree ship up. its in the perfect spot.

 

[sixb]

change your yoke to a flange and then measure the face of the flange to the pinion yoke center and a driveshaft builder will build you a cv shaft accordingly.
youre too short and tall to have a standard style shaft work well.

when you get it in, shim the rearend up or donw to just barely have a bend at the ujoint. you might get lucky and not have to move it at all with the 3.5 degrees you have now.

for what its worth, ive got the same rear suspension setup as you except for 7 inch shackles. i took the stock 14 bolt perches and used a 2.5 degree ship up. its in the perfect spot.

I don't have a flange for the np205 a 1410 was stock on the cummins t/c and will be changing the rear 14 bolt joint to a 1410 to match. So your suggestion is to measure the drive shaft length and order it install it then rotate the diff then weld it up.

I will pick up a 1410 next week for the rear for sure then point the rear axel roughly at the t-case, take my measurement order the new cv shaft then install the shaft set rear pinion then weld her up, I like it.
Thanks

 

[4X4HIGH]

I would buy the shaft from HAD (High Angle Driveline) and Jesse will walk you through the process of measuring everything correctly. You should mention that you're a member here and he might have some kind of CK5 discount to offer you. I do agree though that if you're into the doubler length with the drivetrain you're going to want a CV driveshaft. With a CV driveshaft you want to point the pinion about 2* down from being inline with the driveshaft (this accounts for axle wrap while driving and makes the pinion point at the shaft while driving. This is what you want).

 

[Desert Rat]

Ditto on High Angle Driveline. My front and rear are from HAD and I went with the 42 degree CV setup on the front and 1350 CV and 1410 on the rear.