Baja

Nice attitude.

fiveology

Dude, I wasn't trying to be negative, your theory is okay, just not really applicable as you describe it with the wrench. In a driveline the tranny or t-case output (the ratchet in your theory) is fixed, as is the rear pinion (your socket). Now as you said in a straight line (no universal) it is very easy to turn the socket with the wrench. This is because the wrench is in a relatively fixed position (can't move more than a few degrees in any direction relative to the socket) and easily transfers the torque you apply to the ratchet directly to the socket. Now add your universal to the mix, and now the rachet is no longer in a fixed position relative to the socket, as you apply torque to the ratchet not only is it trying to turn the socket but it is also trying to move the ratchet. Now in a driveline since the input and output are fixed (can't move relative to each other, excluding suspension movement, which generally doesn't change driveshaft angle that much in street use) the output (ratchet) is only trying to turn the input (socket), not also moving the output's location. Yes u-joints do create parasitic loss and increasing the angle will increase the parasitic loss to the point of bind. This is a very small percentage of your power output though, and I don't think you would even be able to measure the loss on a dyno, consistently enough to attribute it only to the u-joints. Take a bone stock truck, put it on a dyno, then take it off, lift it, do nothing to try to correct the u-joint angles, and make no other changes (same tires as before) and I think you will see little to no change in power output, and it certainly won't be repeatable enough to attribute only to u-joint angles. Sorry if my post sounded negative.

Ace

I would also add, that the "hard to do" part referred to by Baja WRT to the pinion angle is not anything like simply rotating the axle with shims or re-welding the perches to reduce the driveshaft angle relative to the diff pinion. The pinion angle is the pinion's angle relative to the tranny or transfer case output shaft. Any radical changes in that regard would call for shifting the entire drivetrain engine and all. That would of course, be very difficult to do, if not totally out of the question.

Baja

Good replies from both of you. I, and I may be wrong on this, have understood that street/drag racers will modify their rear ends to eliminate a few problems of real high horsepower and torque, and to add efficiency. One of them is power transfer. You may be right about the dyno test, it would be interesting to see one. I only mentioned the rear end, I know it is all but impossible to change the angle of the tranny or x-fer case, and have never heard of anybody doing that.

fiveology

Yes, drag racers are very careful with pinion angles, mainly because extremely hard launches on slicks can twist the axle so much that the u-joint can bind. The rear is absorbing so much power and the slicks refuse to spin, so the pinion actually tries to climb the ring gear, causing the pinion to twist the housing upward.

Baja

That is what I thought, axle wrap. Now, if we lift a truck 10", aren't we changing the pinion angles by changing the relationship of the tranny to the diff? If so, that angle change can be measured in degrees, and cars/trucks lose about 5hp to every degree of change. I always thought if you lift a truck, you change the pinion angles. How many degrees of change there is in a 10" lift, I don't know, there are many variables, but my guess is that it would be a lot (if my earlier thinking is correct). That is why I suggested power loss.

Ace

No. There is only one pinion angle. It is the angle of the pinion relative to the tranny output shaft, NOT the driveshaft. Lifting the truck increases the angularity of the U-joints, but the difference between the front and rear u-joint angles (i.e. "x" number of degrees down = pinion angle) stays the same.

Baja

Thanks. Again I learn something from DTR.

Ace

Pro shops and high tech joints use alot of expensive, fancy angle measuring tools to determine/set pinion angle. Fact is, within a degree or two probably won't make much difference in anything but the most demanding application (top fuel, whatever). Here's a tip for an easy way to check the pinion angle if you can get the vehicle on a lift: Take the drive shaft off and U-joints out. set the yokes on the trans and rear vertical and stick a broomstick in 'em. Use some duct tape or something to sleeve them up tight. Now step off to the side about 10 or fifteen feet and just look at it! If the sticks are parallel, you have zero degrees pinion angle.

yarddog

One thing that's important as far as vibes go is if the pinion flange and output flange are not parallel, you need a cv at the output side or it will vibe like crazy.

II = 2 u joints
\I = CV

Everyone has brought up great points. The best thing to do is go wheel it and when something breaks upgrade it. That up grade will move the weak point somewhere else so you upgrade that. If you keep upgrading, eventually you'll have a bullet proof truck.

Personally a full size Dodge is way to big for me, the turning radius would suck and I'd be dragging the rockers and sides of the body on everything. I like my Dodge as a tow rig to pull the little crawler