Pinion Angle:  Witchcraft, Sorcery and The Source of Your Vibration.....?

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Pinion Angle: Witchcraft, Sorcery and The Source of Your Vibration.....?

Today's voodoo/black magic topic is pinion angle.  In my experience, some guys just "get it". 

Pinion angle and how it's affected by the drive train and suspension angles with a quick layman's description on how to set it up and diagnose problems with engine, transmission and rear end angles.

The rest of us, have no idea the positive and negative affects pinion angle has on your drive line until it strikes and we have to blindly chase a vibration, rub or bind in the drive train.

For those that are tinkering with lightly modified street cars, you'll find that with OEM type suspension components, engine mounts and transmission mounts that your pinion angle isn't affected enough to create problems unless something is broken.  Even upgraded components that match OEM sizes and geometry maintain the manufacturer's original pinion angle.

Pinion angle and how it's affected by the drive train and suspension angles with a quick layman's description on how to set it up and diagnose problems with engine, transmission and rear end angles.

Though the opposite becomes very apparent once the car receives a drive train swap such as a transmission swap, engine swap or even just adjustable suspension.  

So, let's lay out a really simple "layman's term" definition for good pinion angle.

Good Pinion Angle - Equal and Opposite angles at the ends of your driveshaft at the universal joints.  Specific amount of angle depends on the type of suspension you have and how much rotation (wrap) your axle has under throttle induced load.

Pinion angle and how it's affected by the drive train and suspension angles with a quick layman's description on how to set it up and diagnose problems with engine, transmission and rear end angles.

Two things to note here:  One, at rest, the angles are equal and opposite to one another.  Two, the angles remain equal and opposite through out the movement of your drive train under load and suspension compression.

When setting up to measure and adjust pinion angle, you need to identify the center line of output shaft of your transmission, the center line of the driveshaft, and the center line of the pinion.  You can use a magnetic angle finder, protractor, or there's even apps for your phone to help find not only the center line, but the angle of these three parts.

Pinion angle and how it's affected by the drive train and suspension angles with a quick layman's description on how to set it up and diagnose problems with engine, transmission and rear end angles.

Though there is a few ways to set up pinion angle, we're going to briefly outline the most common street car application.  This involves putting the center line of the transmission output shaft and the pinion on parallel planes.

Aligning your drive train in this fashion creates a "Z" with your universal joint angles and driveshaft so that the natural movement of your suspension creates equal and opposite angles in both positions.

Pinion angle and how it's affected by the drive train and suspension angles with a quick layman's description on how to set it up and diagnose problems with engine, transmission and rear end angles.

So what symptoms would lead you to identifying bad pinion angle?

Drive train vibration at speed, wheel hop and universal joint fatigue/failure are all good indicators.

These things can come out of no where with suspension bushing failures, engine and transmission mount failures or even leaf spring fatigue and wrap.

Pinion angle and how it's affected by the drive train and suspension angles with a quick layman's description on how to set it up and diagnose problems with engine, transmission and rear end angles.

We could write pages and pages on the set up of your drive train angles, but our goal here is to give you a quick glimpse at a possible problem when building your car or diagnosing a problem that arose out of no where.

With all that being said, we hope this gave you a bit of insight and we'll catch you in the next one.

Go do work, son!

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