Transmission Angle/Rear Pinion Angle

[1952B3b23]

Hey Guys,

So im in the process of doing my first build and have gotten to the point of setting the motor/tranny between the rails and fabbing up the motor mounts (done) and make the tranny cross member (in progress). I just want to make sure that im setting my angles up right so i don't end up with a drive-line that vibrates like crazy. From the research that i have done i learned that U-joints like to operate somewhere between 1-3 degrees but no greater than 3. So heres my plan:

Set the angle at the output shaft of the tranny at 2.5 degrees down. Then when the time comes that I have the weight of the cab, sheet metal, bed, and other components on the chassis I can set the angle of the rear pinion at 2.5 degrees up. This will make the centerline of the rear pinion and centerline of the output shaft of transmission parallel to each other.

What'd you guys think?

Also this is a diesel motor so effects of the engine angle on the carburetor aren't an issue.

Thanks in advance,

-Chris

[Dirtyrat]

You can have about a max of 7 degrees on the U-joint operation.
You do not want your U-joints completely straight with no operation.
Safely plan for 2-5 degrees with both U-joints operating at the same angle.

[1952B3b23]

Thanks DR. So i should be fine with my 2.5 degrees. Since the engine/tranny is at a different elevation than the rear differential. Meaning that the engine/tranny is sitting higher than the rear diff. Setting the pinion angle at 2.5* up when the output shaft of the tranny is at 2.5* down makes there centerlines parallel, as required by the picture you posted. Makes sense?

-Chris

[Dirtyrat]

Originally Posted by 1952B3b23

Thanks DR. So i should be fine with my 2.5 degrees. Since the engine/tranny is at a different elevation than the rear differential. Meaning that the engine/tranny is sitting higher than the rear diff. Setting the pinion angle at 2.5* up when the output shaft of the tranny is at 2.5* down makes there centerlines parallel, as required by the picture you posted. Makes sense?

-Chris

That is about how I have mine as well the CL of the output shaft is parallel with the CL of the pinion.

[1952B3b23]

Originally Posted by Dirtyrat

That is about how I have mine as well the CL of the output shaft is parallel with the CL of the pinion.

All the stuff that i've read says that its required to have the two parallel for proper U-joint operation. I think it should work well then.

I just wanted to get other opinions before welding the tranny crossmember in.

Thanks for the replys,

-Chris

[1952B3b23]

So i called up "Tom Woods Custom Drive Shaft" for some clarification and they set me straight in about 2 mins. The way i described what im doing in Post #1 is what i told the guy on the phone and he agreed with this. He actually said that you could go up to a 7 degree angle and still be fine ( i didnt know that). He also said to make sure the slope of the drive shaft is around 7-8 degrees max for the best results.

-Chris

[Yankee Transplant]

I did not know this

[30sx]

when i,m confused about things like that i usually ask how the factory did it, have a 81 chevy short box with the one piece drive shaft, that has never been altered, did the measurements, the trans output was -3% down and the pinion was on the same plane as the drive shaft as in 0% has worked great for years, the side to side angle must be what makes the ujoints work,in the rear just my observations ,but the picture above is how most people do it so it must work

[Bamamav]

Side to side or up and down makes no difference as long as both angles are the same. You can even have both at the same time.