What is exceptable pinion angle? I have 5-1/2” lift with all for fun long arms and 2 degree caster bushings.
I have noticed that I don’t have enough caster for good return to center on the steering. I have not yet got any readings from an alignment shop but I will and I’m going to turn the inner c’s to fix caster.
I want to correct pinion angle at the same time if it’s necessary. Could those of you that know, let me know the optimal upper and lower limits? Thanks, Pat.
Gonna need more detail on your question. And you are going to get a bunch of different answers. And you will know that most of them are garbage.
I am sure that I have posted the solution several times, and It goes something like this: I will say "you should wipe your butt with your right hand from back to front..." and then someone will chime in and say..."but I have been wiping my butt with my left hand for years. Then someone else will say, "no, that's not right you should go front to back."
35 years of experience has taught me that there is no single correct answer. There is no single best answer. There are a bunch of compromises that have to be made, and you need to determine what compromise is the most acceptable to you.
Let's take a look at the standard Hooke's universal joint. It has a cross yoke, and two ears. Some will call it a Cardan joint. Credit should go to the original inventor, but since the marine compass gimbal mount was invented a thousand years ago...we'll start with Hooke. There are THREE primary failure modes in a u-joint.
1. Strength.
2. Vibration.
3. Wear.
1. strength. You need to look no farther than your front steering axle shaft u-joint to see that it operates from Zero degrees to about 33 degrees. You can also visualize a universal joint on your socket extension. It operates perfectly at zero degrees, and does not operate at all at 90 degrees. So as the angle increases, the amount of torque transferred decreases. Once you get above about 30 degrees, the joint loses well over half of it's strength.
2. Vibration. The vast majority of universal joint application engineering is based on angular velocity, rotational velocity, and torque. As a Hooke's joint rotates, the output shaft speed increases and decreases with every revolution. If these changes in velocity are not mitigated by a complimentary velocity change...you get vibration. The vibration is proportional to velocity, and angle.
3. Wear. Universal joints will wear out. The needles and crosses are not designed for significant rotation. Driveshaft u-joints start to wear prematurely at any angle greater than about 2 degrees. You can get needle Brinnelling at zero degrees, so there is a compromise there. Most application tables recommend a non-zero angle, and a maximum angle of 1 degree.
My Opinion:
1. This is the one that everybody thinks about, and is the least interesting in a front driveshaft. The Yokes start binding at about 15 degrees, which is far sooner than the joint stops transmitting torque. but everyone will tell you to run 1350's because they are "stronger". Nobody out there is breaking a 1310 driveshaft joint running between 0 and 10 degrees. So I'm going to say 10 degrees max here.
2. This is the big one. A driveshaft u-joint is looking for 1-2 degrees without cancellation. There is no cancellation on the front axle. But the vast majority of Bronco driver's are running at high speed with the hubs unlocked in 2WD. So THEY don't care. So they sacrifice vibration. I'm going to say 2 degrees here.
3. Wear. The correct answer here is 0 degrees. I KNOW that the design recommendation is 1-1.5, but that is Engineering stupidity. The model is inadequately constrained. Nobody designs a driveshaft at 0 degrees, because if you could actually run there...you wouldn't need a u-joint. So it's stupid. The driveshaft will move thru several degrees from normal motion and load. So the desired angle will be zero at nominal dynamic load height, and high RPM load. Meaning when sufficient torque is applied to propel the vehicle at 60MPH under normal conditions, the u joint angle should be zero. This means that a static height and zero load, the angle should probably be 1-2 degrees down.
@lars types faster than I do...
So I'm done now.
