Needed: Wide Trac Center Diff Housing

[J20 project]

Run the damn thing. A j20 in 76 had the same axle whether wtrack or dana20.. Just run it. I did this conversion about 6 times. It works, quit worrying about it.

[cu4whln]

Run the damn thing. A j20 in 76 had the same axle whether wtrack or dana20.. Just run it. I did this conversion about 6 times. It works, quit worrying about it.

OK ! lol. Regular driveshaft? J20 has a much longer driveshaft I believe...

[J20 project]

Did it w/ wags also. I currently have an offset J20 D60 in my chero. I did however roll the pinion up for my lift and i built a double cardan shaft for it. Mine has a centered np208.

[tgreese]

The driveshaft does not know the rear is offset, an angle is an angle, it doesn't see it as two angles. If the driveshaft is phased correctly ...

Fairly sure this is the issue. Regard the offset plane in reference to the u-joint cross. The speed of the driveshaft changes slightly with the orientation of the u-joint crosses. There is a single plane where the phase of the two u-joints can always be aligned. Typically the pinion and output point up and down in that plane, splitting the angle between each end. Add a second plane of offset, the u-joints are rotated slightly wrt each other, and they are no longer perfectly in phase. The combination of angles causes the ends to always be slightly out of phase. Vibration results.

I am not an expert in this area, and I expect there's both science and art in making such an application work. I previously mentioned high-angle u-joints - no personal experience with these, but it's a product that Tom Woods and others sell. There's even a competitor to Tom Woods called "High Angle Driveline" IIRC. Seems much of their business targets making these unusual applications work.

[J20 project]

Every u joint has an operating angularity where it begins to throw its' inertia into a square shape as opposed to the inertia being round. When this happens, it beats the ujoint up and can cause vibration. This is why it becomes very important to change things up when lifting a rig. Double cardan shafts and rolled pinions deal with this quite effectively(other stuff too).
That being said, I have had no issue with running offset rear ends on Q track converted Wags, Cheros, and J trucks.
As stated, the J trucks ran the same rearend regardless of tcase in the mid and to late 70s.
Off set ujoints only increase the clearance on the yoke they are installed on. They don't change the physics of what is happening to the centrifugal mass. Too much angle,,,,is too much angle.
If the OP is running a huge lift kit with this situation, it might be an issue.
At the very least, it is worth running and trying prior to making wholesale changes. Even if you have to tweak the length of a driveshaft a bit...still worth doing before spending money on a new axle, regearing, and oh yes, lets buy a locker and put it in while we are at it.

J20

[Ristow]

Run the damn thing. A j20 in 76 had the same axle whether wtrack or dana20.. Just run it. I did this conversion about 6 times. It works, quit worrying about it.

ding ding ding! J20 is right. there is a lot of OEM applications running multi angle drive shafts. a lotta big trucks do. especially between the two power axles.

[bufurd]

Yup....

[cu4whln]

OK.. ordered a driveshaft from Tom Woods.

Off center diff stays . . .

No more advice needed ! LOL

[J20 project]

Dang, too bad you didn't see that I build shafts too...
Spicer parts is spicer parts.
J20

[rang-a-stang]

Dang, too bad you didn't see that I build shafts too...
Spicer parts is spicer parts.
J20

Bud built my front shaft and it's super awesome!

[crazydog]

Sorry, I am late to the show. I am running the stock offset Dana 44 with a NV4500 and Dana 300. No problems to date running a stock style driveshaft.

I am running a fuel tank in the rear where the spare tire mounts, so no more coffin tank.