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First, Merry Christmas

Those old MP manuals had Lots of good info. In general thier advice on pinion angle was decent and works Fine in most cases.

U joints are forgiving and in alot of cases measuring pinion angle off the Drive shaft works fine.

And that Is what the MP manuals referred to as Pinion angle. But those old school guys were wrong But not that wrong that thier advice was bad.

Pinion angle off the drive shaft is just that, and that Only.

Lets take a example desired number, say 4* pinion down. We want 4* for a pinion angle with our setup.

And our car just happens to have a Perfect alingment between the Tranny and rear pinion.

Pinion-----------------------Tranny

0----------shaft-------------0 Like this!

This diagram shows 0 down pinion angle and we Dont want that, so we lower the rear pinion angle by 4* to the shaft as the MP manuel states. In this case it works out Perfect!! And you are indeed 4* pinion Down, not only on the Shaft, but from the Parallel angle off the "pinion and the tranny" too.


Now in the real world the tranny cl is hardly ever perfectly inline with the pinion cl. Throw in some SS springs to the mix your rear pinion and tranny are far from centerline.

So lets say that because of the above , the rear pinion cl is down say, 3.36" inches from the tranny centerline but yet they are still parellel with each other.

Whats our driveshaft doing, since the rear is down? At a 4'length its angling down at 4* towards the Pinion from the tranny.

Doing it the MP manuel way in this case, you wouldnt adjust the pinion down from the Shaft, because your already at 4* down.

Yep your 4* down from the shaft, but unlike in the first scenario you are not 4* down from the tranny and pinion parallel angle as you were in the First scenario.

In the first example 4* down from the shaft is 4* down from parallel.

In the second example 4* down from the shaft is 0* down from parallel.

We wanted 4* down for the setup. In the first example all the old dogs would of adjusted for it.

In the second example the old dogs would of said its dead on wrong

Im an old dog myself, But Ive been enlitend. I like Hellen Keller spent many years in the darkness.

But the lite is now shining Old dogs Follow the lite

With due respect to all, Merry Christmas, mike



Merry Christmas Mike and everyone else. but you know we can't convince some of these guys know matter how well it is explained