RonMar
Elite Member
Greg, yes I have done these tests more times than I can remember(been breaking diagnosing and fixing 4X4 for 30 years now). I do this test to the Jinma every time I crawl the chassis looking for loose hardware as it allows me to gauge how tight the front end drive and steering is.
Basic rule of simple/open differentials. with all 3 shafts free(both wheels and drive shaft), spin one, and either of the other 2 can spin depending on drag. Lock one and the other 2 can spin(but in opposite directions). Lock any 2 and the third is also locked.
With the front axle in the air(kinda hard to spin front wheels when they are not
), and the transfer in 2WD, when you spin one wheel, the torque you are applying ALWAYS takes the path of least resistance. This can be thru the other wheel, or thru the front driveshaft, or both if the drag thru those paths are equal. If you turn one wheel and the other wheel turns in the equal and opposite direction, the driveshaft is NOT spinning. If you block the opposite wheel and again spin the nearest wheel, THEN the driveshaft will spin. If you put the transfer in 4X, then the opposite wheel will ALWAYS turn equal and opposite because the driveshaft is locked. If you block that wheel, NOTHING will rotate. This is a good test to check backlash throughout the entire system. The gearbox being in gear or not has absolutely NO effect on this, just as the clutch use has NO effect on wether 4x will engage or not... Now if you are working on the rear axle, with both the rear wheels in the air, the gearbox being in gear or not makes a difference as in gear the "driveshaft" is coupled to the engaged clutch and the non-rotating engine. With both rear wheels on the ground and blocked(2 differential shafts locked) the rear "driveshaft" is already locked in place so gear selection is irrelevant.
I was bored this afternoon so I made a little Youtube vid below to illustrate this. You will note the gearbox has no effect whatsoever on the response.
Kinda glad i did this as I was doing some heavy brush busting a few months ago and may have damaged my driveshaft housing. The only time the front driveshaft was rotating was when in 2X and the opposite wheel was "coasting". It should have coasted much farther. When I later blocked it in place(shoulda did that in the video), the free wheel was very difficult to rotate indicating drag in the driveshaft or transfer case...
[ame]http://www.youtube.com/watch?v=4JkDslBUGIc&context=C34fe9f5ADOEgsToPDskIRgoAFVSGT_oSjzNvrLrfl[/ame]
If i am being a pain Greg, sorry. The old chief in me sneaks out every now and then and he is a real SOB when it comes to technical details
Basic rule of simple/open differentials. with all 3 shafts free(both wheels and drive shaft), spin one, and either of the other 2 can spin depending on drag. Lock one and the other 2 can spin(but in opposite directions). Lock any 2 and the third is also locked.
With the front axle in the air(kinda hard to spin front wheels when they are not
), and the transfer in 2WD, when you spin one wheel, the torque you are applying ALWAYS takes the path of least resistance. This can be thru the other wheel, or thru the front driveshaft, or both if the drag thru those paths are equal. If you turn one wheel and the other wheel turns in the equal and opposite direction, the driveshaft is NOT spinning. If you block the opposite wheel and again spin the nearest wheel, THEN the driveshaft will spin. If you put the transfer in 4X, then the opposite wheel will ALWAYS turn equal and opposite because the driveshaft is locked. If you block that wheel, NOTHING will rotate. This is a good test to check backlash throughout the entire system. The gearbox being in gear or not has absolutely NO effect on this, just as the clutch use has NO effect on wether 4x will engage or not... Now if you are working on the rear axle, with both the rear wheels in the air, the gearbox being in gear or not makes a difference as in gear the "driveshaft" is coupled to the engaged clutch and the non-rotating engine. With both rear wheels on the ground and blocked(2 differential shafts locked) the rear "driveshaft" is already locked in place so gear selection is irrelevant. I was bored this afternoon so I made a little Youtube vid below to illustrate this. You will note the gearbox has no effect whatsoever on the response.
Kinda glad i did this as I was doing some heavy brush busting a few months ago and may have damaged my driveshaft housing. The only time the front driveshaft was rotating was when in 2X and the opposite wheel was "coasting". It should have coasted much farther. When I later blocked it in place(shoulda did that in the video
), the free wheel was very difficult to rotate indicating drag in the driveshaft or transfer case...[ame]http://www.youtube.com/watch?v=4JkDslBUGIc&context=C34fe9f5ADOEgsToPDskIRgoAFVSGT_oSjzNvrLrfl[/ame]
If i am being a pain Greg, sorry. The old chief in me sneaks out every now and then and he is a real SOB when it comes to technical details
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