Rear Suspension Overview Part 2 - Pinion Angle 

Dave Muller

Agreed. But, since these are full tube chassis race cars, they probably set the engine/trans angle so it was perfectly in line with the pinion.

Yup I'd agree; the pinion angle is only import with regard to getting it parallel to the gear box output shaft. Certainly worth checking for road cars where noise is important, not so sure about competition Cars?

Nope. The pinion angle is the most critical angle of any driveshaft system. Otherwise you'll tear the yoke clean out of the car at worst, or at the least produce vibrations and heavily accelerated wear. Generally you can't change the front angle - it is as designed or built into the car. You can however change the rear angle via the pinion. You NEED some amount of angle. The whole 'lineup method' is great on paper, but almost no car anywhere - street or race - is designed in that manner that a truck or heavy vehicle is with in-line parallel shafts. And to set a dead straight zero pinion shaft or build one completely inline, makes the tailshaft useless.

He said the exact parameters you want to stay within. The difference is the angle of pinion under power. A negative 1.5 pinion angle as shown here, will not stay negative 1.5. It will zero or go positive slightly under power as the diff twists itself upwards, which is why 'most' prefer a little negative - but not always. Lot of other factors including power, tyres, diff mounting and bushes or bearings etc as to how much it will twist under power and how much angle to add static.

Absolutely not. First, the pinion angle (let's say that it is 2 degrees negative) then the tranny angle needs to be equal, but opposite (2 degrees positive) Then, depending on what type of rear suspension you have, you take into consideration the amount of pinion rise you get when you stab the throttle. This next part is for serious racers only; They want all angles to be 0.0 while under the most power and flex, to go the fastest. With 4 link and ladder bar, you probably want between 0.5 and 1 degree negative angle on the pinion. This is so that when the motor tourques the driveshaft and the axle, and the pinion climbs the ring gear, it flexes to 0 degrees on all u-joints. On a leaf spring car wants around 4 or 5 degrees negative on the pinion, because of "spring wrap". You want all angles to be 0, at full throttle, max twist. This is for hard core racing for max speed. For the street, we want max u-joint life. So, if your tranny/driveshaft u-joint is 5 degrees negative, (like my car is), then you also want the pinion angle to be 5 degrees "positive" (equal but opposite).... At ride height. My tranny angle is 5 degrees negative (can't adjust it any further, my car is lowered with big tires in the back), so I must get 5 degrees positive out of the pinion. I can only get it to 4.2 degrees positive, but that's close enough. I have ladder bars so when it flexes, it might be closer to 5 degrees positive (a good thing). 5 degrees negative or positive on any u-joint is excessive (I can't help it). That almost the max limit for them. For the street, ride height u-joint angles should be between 1 and 3 degrees (equal but opposite) for best wear characteristics, and the angles should never be 0 degrees on the street (wears out quickly), while highway driving. Many considerations must be addressed when picking "pinion angle". Hope that helps.

@@jakefriesenjake Thanks! I appreciate the info. So to summarize, would that be 10* apart parallel?

@@tabcobra no, I don't think so. My car is 5 up front, and around 5 on the pinion. If my engine and tranny centerline was straight or parallel with the ground, then the driveshaft is pointing up, from the ground 5 degrees. Then, the pinion is then pointed back straight, like the engine is. The engine and pinion centerline are on the same plane. My actual engine is pointed down by 2 degrees, driveshaft is pointed up 3 degrees (5 degrees total) and then the pinion is pointed up (u-joint side is higher) by 1.2 degrees, (total of 4.2 degrees). Makes a z type of shape

Usually around 2 degrees and 10" crank centerline off the racing surface.

Up or dwn? Neg or pos?

You goddamn if you don't have one of them protractors you probably aren't building the car. That's literally the first thing you buy man harbor freight has manual & digital one's

Who are you ?