The Stovebolt Site Forums The Shop Area Engine Shop Driveline question...

Ok first let me say my search has not narrowed down my question much... still said I had 40 pages..
Anyway, I am in the process of taking a 1 ton and cutting the frame down to a 1/2 ton size. At the same time I have taken an swapped out the axle, but knowing the height and the transmission(Manual Stock) and the axle are off(parallel). I am also off left to right of the main center by ~1 1/8" - 3/4" depending on how far I offset rear left to right. Now the center of the pumpkin is dead on with the center line of the truck and for that also the center of the transmission output.
I did read the dana documentation on compound angles and I can say I am more confused now than before. Is it ok to have it like this provided all the angles stay parallel to each other?

I am at a complete loss because I remember the last time I did this I just offset the axle and ran it with spacers on one side, but there it was only 1/2" off. Any help would be greatly appreciated.

Tech info: 52 Chevy - Stock engine/transmission - using an El Camino rear.

Offset left to right of the pinion is just fine, so long as the pinion centerline is parallel to the transmission centerline and they should be already unless your engine is installed somewhat sideways or your axle is askew.

Just like it is OK to have the pinion lower than the transmission, again so long as they have parallel centerlines.

The compound angle calculations come in when you figure if you're in the safe operating range for the universal joint. It's easy in one plane, can be measured with a simple angle meter, but throw in another axis and you need to do the calculations to find the total angle of the u-joint.

Skim through the driveline tech tip again http://www.stovebolt.com/techtips/driveline/setup/index.html and look at page 9 of the installation manual.
"When you have a compound angle, you have to calculate the "True Universal Joint Operating Angle" of each universal joint. It is
the True Universal Joint Operating Angle that must meet the three rules shown on page 5."

Grigg

If I understand you correctly you are willing to install your axle off centerline to ease the compounding of the driveline. Is that true? How was it set up in the one ton? If it was working Ok there then installing it the same way will work so long as you keep those parelell planes Grigg mentions. It would obviously be within the working limits of the joint. Placing your rear end off center will make for a strange driving vehicle.

How far are you shortening the driveshaft? As the U-joints get closer together, the angle will increase. It sounds like a swap to the right frame would be a simpler method of getting a short wheelbase, instead of re-engineering something that was never intended to work that way in the first place.
Jerry

The one ton consisted of a 2 piece drive shaft. Now I have simplified it by making it a 1 piece and the angles of the original were slightly off center to begin with and the 2 piece was extremely angled if anything.
If I understand the comments above correctly as long as the 2 pinions are on parallel planes from a horizontal perspective and a height perspective that the corresponding angles are within 1 degree of each other that they should in fact work without an issue. Now based on the fact that I am within 3/4" - 1" over a +50" distance I would assume the angle that I am questioning should be within the limits of the joint. As with the overall height difference between the Transmission and the Axle, the second half of the 2 piece worked at less of the distance that I am going to be making the one piece which created an extremely large angle.

As long as you have the axle in plane with the transmission, don't worry about the horizontal degree. Next time you are at a big truck dealership, look at the angle of the inter axle drive shaft. I'm not sure what you are reading, but it may be the minimum offset. U-joints have to have an offset. If not, the needles will stay in the same place and wear into the cross in no time.

From what you describe (parallel centerlines and offset in two planes, no extreme angles) I think you'll be just fine, in fact I'm sure it'll be just fine.

If the two planes thing confuses you consider changing your idea of horizontal for a moment. You can rotate your base line (in your mind) such that you look at your driveshaft and only see it offset in one direction. In simple terms that's what the math does when calculating the True Universal Joint Operating Angle, just simplifies it down to the one angle that matters which just happens to not be measured from a horizontal or vertical plane.

But none the less it'd be good for you to read the manuals and do the calculations and look at the charts just so you understand why it works and what the limits are.
Perhaps it's just me but if there is a way to figure and confirm what people tell me it's definitely worth doing, not that I don't trust people, it's that I like learning all I can about what interest me..

Grigg