Drive Line angle

[Cudakiller70]

I would say "zero".

Anyone else?

This really isn't that hard to understand.

Yes zero maybe plus one.
If I understand Dr Diff right he is saying that at static a pinion measures 2 degrees less, than trans.
So if your trans angles down 3 degrees, your pinion angle should be up 1 degree static/no load
Then when under load your pinion will rise up 2 degrees then be at up 3 degrees which will make your pinion and trans centerline planes parallel.

[soundcontrol]

Yes zero maybe plus one.
If I understand Dr Diff right he is saying that at static a pinion measures 2 degrees less, than trans.
So if your trans angles down 3 degrees, your pinion angle should be up 1 degree static/no load
Then when under load your pinion will rise up 2 degrees then be at up 3 degrees which will make your pinion and trans centerline planes parallel.

Thats how I understood it also. Now, when measuring this, is the tranny 3 degrees down from actual level, or from the level of the car? If the car is jacked up in the back, the actual level of the tranny will be less. (when I say actual level I mean level measured with gravity)

[Racer57]

But "while not under power" was your question.

"Under power" puts you back to the "parallel" picture.

My confusion is caused by not knowing whether the diagram is referring to the driveline being under a load or not.

[Racer57]

Thats how I understood it also. Now, when measuring this, is the tranny 3 degrees down from actual level, or from the level of the car? If the car is jacked up in the back, the actual level of the tranny will be less. (when I say actual level I mean level measured with gravity)

Are we over thinking this ?

This has been causing me even more confusion.  Like a lot of you when I was younger I would put air shocks on my cars and jack them way the hell up because tires were way too wide and wanting to look cool. Thinking back on it, I never had any vibration problems.   So now I'm worrying about 1-2 degrees  !?!?   

[Cudakiller70]

My confusion is caused by not knowing whether the diagram is referring to the driveline being under a load or not.

Found this quote from Dr Diff
Got it from here http://board.moparts.org/ubbthreads/ubbthreads.php/ubb/showflat/Number/6271185/site_id/1

Pinion angle is the relationship between the transmission centerline and the pinion centerline, not to the driveshaft and not to the ground.

Ideally, the pinion should become relatively parallel to the transmission as the pinion wraps up under power.
This is how U-joints are designed to run.

Make the pinion parallel to the transmission as a base line, then tip the pinion downward 2 degrees (for a street car). This is referred to as 2 degree negative pinion angle.

As a rule of thumb, I don't like to run more than a true 4 degree negative pinion angle.
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[soundcontrol]

Are we over thinking this ?

This has been causing me even more confusion.  Like a lot of you when I was younger I would put air shocks on my cars and jack them way the hell up because tires were way too wide and wanting to look cool. Thinking back on it, I never had any vibration problems.   So now I'm worrying about 1-2 degrees  !?!?

I dont think a few degrees matter, I understand the concept, but I'm confused on how to actually do the measuring.

[Cudakiller70]

Are we over thinking this ?
This has been causing me even more confusion. 

Maybe  but it wouldn't be CC.com if we didn't, or if this thread didn't go sideways like the rising price of candy bars.

[Cudakiller70]

I dont think a few degrees matter, I understand the concept, but I'm confused on how to actually do the measuring.

The way I see it, as long as the rear end is not hanging down on the springs, but the rear end leaf springs are supporting the cars weight, it doesn't matter whether the car is on the ground or rear of the car is off the ground. Dr Diff is right it's the angle of the pinion in relation to the trans. If you draw a rectangle and then draw 2 parallel lines, no matter which way you turn the rectangle the lines stay parallel.
That is basically what you are trying to do get the trans centerline parallel to the pinion centerline. 

[ShelbyDogg]

Wow, wow and wow. This thread is still growing pages?


Now photobucket is down and my thousands of pictures aren't showing up.


Like I said before, pretend your driveshaft isn't there.  No adding or subtracting or doing ANY math.
Jack up the back of the car till your trans tilt is at 3 degrees. Stop and put jack stands under the rear end. Measure the pinion angle adjust to get your 2 or 3 degrees.

Make sure that your frame is supported and rear end dropped when loosening your u-bolts to add shims.