A slightly off topic diff question for you all to think about.
Turbo Mini Forums

Right, the scenario is this, you have a front engine, rear wheel drive car and you have the OPEN diff out of it on the floor.

Here is the question. If you spin one of the output shafts, do you spin the input shaft?
Yes?

Now put resistance onto the 'input' shaft as if that was driving a road wheel. Does the 'input' shaft still spin or do you simply spin the other 'output' shaft?
My mind says that you spin the other output shaft as there is no resistance againt this. Due to the fact that the pinion gears that mesh with the side (or output) gears can spin freely in their carriers without turning the crownwheel, and, in turn, he 'input' shaft. Make sense?

Now with both of the 'output' shafts spinning at the same rate, the 'input' shaft will spin with or without the resistance of the road wheel. Yes?

So in order to allow the 'input' shaft to drive with a resistance placed on it, you would need a greater resistance on the undriven 'output' shaft than that of the resistance to the 'input' shaft. I.E lock up the undriven 'output' shaft so as that the pinion gears have to rotate the crownwheel as the are spun by the driven 'output' shaft.

Does this make sense to anybody in the known universe? I ask because thinking about it all has made my head go cloudy and i could do with abit of clarification from a fresh mind.

Thanks, James.

No worries Sprox, did think it would happen with at least one part of it all TBH!

I'll try my best.

Baiscally what i mean is, say you have a resistance on the input shaft of the diff, where the prop would normally connect. Such as if you were to get someone to hold it and try to stop it from moving totally.

And then you yourself turn ONE of the output shafts, where the driveshaft would normally connect. And you have no added resistance to the other output shaft.

Are you now just spinning the output shaft that doesnt have the resistance? Or will the driven output shaft still turn the normal input and overcome that resistance?

Any better?

The oposite oputput shaft would then rotate in the oposite direction

If you spin one output shaft it will usually favor spinning the other output shaft as there is a gear ratio between the outputs and the inputs...

Goooood!

So now you lock up the freewheeling output shaft. The input shaft will spin?

yes,

Perfect.

So my theory is correct, if a little clouded. This is good to know.

with the input shaft turning, theoretically both output shafts will turn at an equal speed. Slow down or stop one of the output shafts and the other will increase in speed proportional to how much the other has slowed down by, the input shaft is still turning at the speed it was before.

also, if you flip the diff or the axle over, you will reverse the direction of the road wheels, so make sure you put the diff back in the right way up