Thread: teach me a lesson

Tweet

just a simple question from a simple mind- is it important and why is it that the differential is angled in relation to the driveline? it seems to my simple way of thinking that stress on the u-joint can be eased by straightening out that angle. what am i overlooking?

Engines are built this way---when the carburetor mounting flange on top of the intake manifold is level, the rear of the engine tilts down about 3 degrees---this is to minimize the "hump" required in the floor to clear the driveshaft. The engine is mounted to the frame, so the engine never really moves in relationship to the frame. The rearend is mounted on springs, and as the springs compress and uncompress to match the road conditions, the rearend must move up and down in relationship to the frame. Since the engine (and the transmission output shaft)both tip down 3 degrees, it is a good plan to keep the input shaft on the rearend pinion on the same angle. WHEN THE CAR IS AT REST UNDER FULL NORMAL LOAD. That way, the driveshaft universals have the "midpoint" of their flex pattern. The angle can change to a plus or minus as the rearend moves up and down, but when the rearend stabilizes (as in the car is back on a level road) then the universal returns to its "midpoint" or neutral position.----also, keep in mind that there is a universal joint at both ends of the driveshaft.-------Does that in any way answer your question???

The least stressfull angle on a u joint is no angle. In other words the tranny u-joint and the rear end ujoint need to be on the same plane or angle with each other. In racing applications you normally point the pinion angle down about 2 degrees from the tranny angle so that when the rear end "wraps up" from torque the rear end u-joint and the tranny u-joint are @ the same angle/or on the same plane under full power. Lining them up (or point them at each other) .... sounds good in theory, but remember that angle is constantly changing because of bumps in the road, load weight, etc. Dunno' if that makes sence, or makes it more confuzzzzin' for ya'.

you guys are awesome! succinctly answering my question, and not calling me "dummy" btw, my 350 olds project into my 79 spirit is still on. looking and thinking and looking more, i think i can do it. space to work is at a premium here, so a couple honey do,s need to be finished first. anyone relate to that?

Strange as it seems, a u-joint that always runs perfectly in line won't last very long. A little deflection is necessary to move the rollers around and keep them from wearing grooves in the trunnions.

Originally Posted by R Pope

Strange as it seems, a u-joint that always runs perfectly in line won't last very long. A little deflection is necessary to move the rollers around and keep them from wearing grooves in the trunnions.

yes what is the way i see it to less pope and me are wrong nope

Originally Posted by R Pope

Strange as it seems, a u-joint that always runs perfectly in line won't last very long. A little deflection is necessary to move the rollers around and keep them from wearing grooves in the trunnions.

Cosmic point Mr. Pope and right on the money....

Might as well throw in another bit of u-joint trivia. The front driveshaft on a 4X4 that never gets put in 4wd will vibrate the u-joints out much quicker than one that gets used a lot." If ya don't use it, ya lose it!"

Working in maintainence for a large company for over 20 years with many driveshafts we always set them a various angles non were streight ever . Some section of a machine may have 20 or 30 shafts that move up & down all the time. Same rule applies.

This is a pretty clear discussion of the issue:

http://www.lehmantrikes.com/trikes-design.asp?ID=16