Weird rear end question

Ok, Here me out. I think I must be missing something here. I needed to fix a leaking trans cooler line on the TH350 in my car. So I put it up on jackstands and I spin both rear wheels and they both spin. Well the car is in park. So I'm thinging the linkiage may be messed up. So as an "idiot check" I try and spin the driveshaft by hand and it does not spin. I put the car in neutral and it spins. WTF?? I fix the leaking line and take the car off the jackstands and Park works. I wont roll!!

So I quess the question is, why when the car is in park and both wheels are off the ground I can spin both rear wheels but when it is on the ground park works?? WEIRD! Todd

 

I am guessing that you have an "open" rearend, ie no posi or limited slip. If that is the case you can always spin one tire with the driveline locked in park. You just can't spin both tires at the same time.

Joe

 

See if you can push the car backwards ,I had a problem with my floor shifter cable ,It would engage sometimes and other times it wouldnt ,I replaced cable and everything is fine ,Would lock up in park if inclined and then one time in drive rolled backwards while in park .I hope this helps ....Only thing I can think of .

 

You will notice that the other wheel is spinning the opposite way.....

 

Yes it was. But what is messing with my pea brain is that while in up in the air in park I can spin either/both tires put when on the ground in park everything is fine (it wont roll) Todd

 

If you look I'm sure one wheel is going forward and the other backwards, the differential spider gears and axle gears allow this with the drive shaft stationary. It wont roll in park when on the ground because for one wheel to move forwadr the other must go backward.. Jim

 

your spider gears allow that to happen and like ratmotor said one is turning opposite

 

Todd. It's the function of the differential to allow one tire to turn at a different rate when the car is in a turn. With both wheels off the ground when one is turned, it reverses the rotation of the other wheel. Hard to explain but if you have another rear axle available, remove the backing plate and observe the spider gears, ring gear and pinion action.

http://www.google.com/search?source...erential+mechanical+device&btnG=Google+Search

 

I get it now. I'm just a meathead sometimes. At least nothing is wrong. Thanks to all. Todd