Um, Yeah. I know how differentials work. You though, apparently, do not. If both tires have equal traction, both tires get equal power. If one tire has no traction, it gets ALL the power. You can prove this by putting one tire on ice, and one on pavement. Step on the gas, the vehicle does not move, it spins the tire on the ice. If it were indeed sending equal power to both wheels, then the wheel that actually has traction, would move the vehicle. The only way you get power to the wheel with traction in such a case, is if you have a limited slip diff of some description.

You can prove this on a rack as well, or simply by jacking both rear tires off the ground, and letting the vehicle idle in gear. Use a long bar under one of the tires, and apply some pressure to it. It will slow, and the opposite wheel will speed up, unless there is the aforementioned LSD in there.

 

In both of those situations with an open differential both wheels are getting the same amount of torque, it takes very little torque to spin a wheel that is on ice or up in the air, the other wheel is receiving the exact same about of torque which isn't enough to move the vehicle.

 

No. They aren't. The power goes to the wheel that is slipping. If you apply 50,000 lbs/ft of torque (yes, and exaggeration, but, just to illustrate the point) and you have one wheel with zero traction, and one wheel that actually has traction, the open differential will send all the power to the wheel WITHOUT traction. If things were as you say, and it was an equal split, then there would be no need for posi differentials.

The ONLY time an open diff will apply equal power to both wheels, is when both wheels have traction.

Read here if you don't believe me. There are numerous other sites that will state the same thing.

 

You are still getting the same amount of torque to both wheels even if one is spinning. The only time an open differential will spin both wheels is if traction is equal on both sides which is almost never in a real world situation. When one wheel on an open diff is spinning the opposite wheel is receiving the same torque as the spinning wheel, but it isn't enough torque to move that wheel. Limited slips and lockers are needed so the wheel with greater traction will get more torque than the wheel with less traction.

 

You need to brush up on your basic physics. You are wrong, and continue to be wrong. I have explained it to you several times, yet you still cling to your misconception, even when PROVEN wrong by outside sources. Please show me ONE source that agrees with you. You won't find one.

I never said an open diff will spin both wheels. (although, you are correct, that in the right circumstances, it will.) What I said was, the ONLY time power is distributed equally to both wheels, is when both tires have traction. (and the vehicles is traveling in a straight line.....)

 

Here is a few

https://www.matfoundrygroup.com/News..._How_They_Work
"The disadvantage of this type is that because the torque is split evenly between both wheels, the amount of power able to be transmitted through the wheels is limited by the wheel with the lowest amount of grip."

https://www.carthrottle.com/post/eng...table-for-you/
"Open differentials are the most basic form of a differential. The purpose is to allow for different speeds between the two wheels, while torque split is held constant at 50/50. A common misconception with open differentials is that when one wheel is lifted, 100 per cent of the torque is sent to it. This is not true, however the amount of torque sent to the wheel with traction is very low because the amount of torque required to spin a wheel is also low. Remember, both wheels always receive equal torque, but if one has no resistance (eg. if it’s in the air), the amount of torque sent to the drive axle as a result is very low."

https://oppositelock.kinja.com/your-...rks-1661277563
"Which leads me nicely into my first point regarding differentials: All differentials have a TBR of at least 1:1. The practical application of this is that open differentials, the cheapest and most common type, always split the force from the Trg half to one wheel and half to the other…50/50. Yes, always.
The amount of torque an open differential sends down each shaft is ALWAYS 50/50. This is due to the spider gears being pushed with equal force by the carrier because they are mechanically meshed. An open differential was designed to solve the speed differentiation issue, but its design isn’t capable of biasing torque across the differential and what that means is that what one wheel gets so does the other…always.

So what is going on when I’m stuck in snow and ice with one wheel spinning going nowhere? We need to look at the tractive force.

• 4000 lbs car
• 1000 lbs per wheel (assuming balanced car)
• µ snow = .3
• Tractive Force = 300 lbs (1000 x .3)

That tractive force is the max amount the tire on the snow can apply to the ground before losing traction. Because an open differential has a TBR of 1:1 it means that the amount of torque that can be applied at one end is the max of torque that can be applied at the other, thus 600 lbs of force (300 x 2) is all the car can put down even if the other side has much higher traction potential. Since this is an insufficient amount of force to overcome inertia what happens is that the wheel with less Tractive Force slips and the car goes nowhere.

In a perfect situation (equal available traction) there is no disadvantage to an open differential since it will send 100% available Trg to the tires and then the road if the road has sufficient resistance to meet its demand."

https://drivemag.com/red-calipers/on...-car-must-have
"On top of this, since open diffs split power exactly 50/50, one tire loses traction and this limits how much power is sent to the tire that is still gripping. It’s all very safe, but it essentially limits the fun you can have in certain vehicles."

 

You are misinterpreting what you read. It says exactly what I have been saying all along. I will grant that 100% of the power doesn't go to the wheel with no traction, *some* power is transmitted to the wheel with grip, simply because of friction within the system. It is NOT a 50/50 split.If it is insufficient to move the weight, the vehicle doesn't move.

It's physics, plain and simple. So, jack up your car/truck/whatever, (assuming it has an open differential) start it up, but it in gear, and let the engine idle. Both wheels turns. Now, grab a hold of one of the wheels, apply pressure to it, and you can stop it. Do you still think it is getting 50% of the torque the engine is putting out? In case you are wondering, the answer is no. It's not, if it was, you wouldn't be able to stop it.

 

Replies in red.
Also for an engine to produce torque their has to be resistance in the form of traction. An engine rated 400 ft lbs means it has the ability to produce that much torque if the resistance is there, an engine with no load can't produce torque. In a vehicle with both wheels off of the ground it takes very little torque to spin the wheels so you can easily hold one by hand and the other will spin, but they are both still getting the same amount of torque from the engine which is very little. If you tried to stop the other wheel the engines torque would increase because the load is increasing and you wouldn't be able to hold it, both wheels would still have the same torque because it is always a 50/50 torque split on an open differential. The second video and 2nd and 3rd links I posted explain this well.

 

Ok, I see where you are coming from here. There may indeed be a 50/50 torque split between the wheels, but, if it only take 2 lbs/ft to break traction on one wheel, that's all you are going to get on the other side as well. The rest of the energy is used spinning the tire with no traction.

 

Yes your starting to get it, it took me awhile grasp that whole concept as well, but once you figure it out it makes sense.