Quote:
Originally Posted by Richard
Curious how the spider will change the reading? I do not believe it operates like a planetary gear set. I think you will find that the opposite wheel will tend to rotate in the other direction with an open diff and both wheels off the ground. That can lead to an "erroneous reading"
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It really don't matter which direction the tire rotates for our purpose here. With one wheel stationary then the spiders WILL act as a planetary. When the carrier is turning with both axles equal in traction, the carrier drives the cross shaft, the cross shaft drives the spiders, which drive the side gears which drive the axles. No gears are turning inside the carrier at this point so the axle speed to carrier speed ratio is 1-1. With say the left side gear stationary (left tire on the ground) as the carrier is turned the spiders are driven by the cross shaft around the stationary side gear. The ratio of side gear to spider is about 2-1, that is the side gear has twice as many teeth as the spider, so the spiders will drive the right or rotating side gear at a different speed from the carrier, which is where the erroneous reading will come in. Ever notice when you're on your tractor & you apply say a left brake that the tractor speeds up while making the turn? Same forces at work thru the diff on the tractor.
When yall get time jack up one side of a truck with a known ratio & try it.
If you jack up both sides & mark both sides & the pinion then rotate the drive shaft be sure to have some one on both sides of the axle to make sure the tires stay together, brakes dragging or other forces can make one tire fall behind the other as they are turned.
I know this is confusing, may as well pull the cover & count teeth, our old trucks always need something else fixed in there anyway!
