the other rear wheel is on the ground, start engine and put into drive. Will the wheel that's off the ground spin? Or will the car go forward and fall off the jack stand?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

Power will be sent to the wheel with the least traction. The car will not move.

Steve

That's the case if the car has an open diff., it's still pretty dangerous and somebody could get hurt when the spider gears in the diff. explode and the diff. locks up and the car ends up moving forward.



If the car has limited slip or posi-traction, both wheels will turn and the car will move even if one wheel is off the ground.

This is a really dumb idea and someone could get killed if the car starts rolling. the wheel with the least traction should be the only one rolling unless it has positraction.

On the 300D, the wheel that is off the ground will spin.

But, don't do this. The differential is not made to turn at the speed required for one stopped wheel and one spinning wheel. It's there to compensate for the different speeds of the wheels in a turn........nothing more.

You'll quickly overheat the diff and possibly cause internal damage to it.

Not to mention the wheel that is turning will be turning at twice the indicated speed on the speedometer.

Why would anyone do this?

Interesting! How long do you think it would take if it only idling in gear, with one wheel off the ground spinning unloaded before the diff overheats and damage is done?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

The bevel pinions in the differential normally turn very slowly compared to the rest of the gears, so they probably have plain bronze journal bearings with very little clearance. If they're forced to turn a lot and faster than normal it'll wear those journal bearings. If it spins enough, the pinion shafts could expand and seize in the bearings...although this is a worst case scenario.

If you chock the wheel on the ground, you'll get away with spinning the free wheel for a while..probably longer than a while, but the bevel pinion bearings will wear and you'll have a weaker differential.

Either way, not a good idea, rotating machinery is not forgiving, no matter what part of your body it gets a hold of..if you're willing to take your life in your hands, jack up both rear wheels when doing this. Then at least the car won't really be hurt.

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1985 300TD-euro 352,000 mi
1974 240D (1?)52,000 mi - has a new home now

Long enough for someone to call a personal injury attorney.

i have done this before to try to isolate a shimmey.

i would get the wheel spinning with an indicated 30 mph or so to achieve 60 mph on the spinning wheel. there is some danger if the car fell off the jacks but the wheel would just spin a bit and stop imho. not like it would launch like a space shuttle.

i would just take it up to speed then slow down. i never damaged anything doing this but it is a little nerve wracking i admit.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.