[Jeepster83]

this might help explain a little bit about how an open differential works. its a really old GM training video.

[YT]Em1zQToa_a8[/YT]

[TJamz]

Excellent writeup. Question: how safe is it to use part time 4X4 on the roads during winter? We get plenty of snow up here and useing 4x4 is a must. I use it mostly in residential areas where the snow is deepest and to start off from stop signs/red lights/etc. If the weather is bad enough I just keep it in four wheel drive all day/night. Can I do this or am I risking snapping parts and been left stranded in -35 plus (minus?) weather?

[EvilM0nkey]

If you're on the road with other cars you don't need to be in 4 wheel drive.

[Jerry Bransford]

Originally Posted by Jamzjeep

Excellent writeup. Question: how safe is it to use part time 4X4 on the roads during winter? We get plenty of snow up here and useing 4x4 is a must. I use it mostly in residential areas where the snow is deepest and to start off from stop signs/red lights/etc. If the weather is bad enough I just keep it in four wheel drive all day/night. Can I do this or am I risking snapping parts and been left stranded in -35 plus (minus?) weather?

No risk of snapping parts, it's not as big of a deal as some claim it is. If your roads are covered in snow or ice, it's fine to use your Wrangler's 4x4 system. Paved roads that are only wet from rain aren't suitable for 4x4 though, wet roads still have too much traction for the Wrangler's part-time 4x4 system. It's on high traction (like paved) surfaces when the Wrangler's part-time 4x4 system should not be used.

[RogueSpear2023]

I used my 4 wheel drive up here in MN in the snow for years never have had a problem in fact it is much more controllable in 4wd, the problem comes in is when you have 4wd many people think they can drive faster, but your stopping distances will still be the same so take it slow an easy just like everyone else. But feel free to drive in 4wd on ice, snow, or slush covered roads it won't cause any harm, plus it will help prevent the over steer that a normal rear wheel drive will have.

[TJamz]

Good stuff! That's what I figured, thanks for confirmation, gents!

[Squeekster1]

This thread definitely helped my understanding of an open differential. I understand it all but there is one related thing i didn't see an answer for. In reference to the transfer case, how is the torque split there? when in 4hi or 4 low, is the transfer case acting as a open differential? or locked?

Example: If i had my jeep with open diffs goin up a hill/climbing a rock or something and the front end gets one wheel in the air, but all other tires are firmly planted. How would the transfer case send the torque?

[Unlimited04]

Originally Posted by Squeekster1

This thread definitely helped my understanding of an open differential. I understand it all but there is one related thing i didn't see an answer for. In reference to the transfer case, how is the torque split there? when in 4hi or 4 low, is the transfer case acting as a open differential? or locked?

Example: If i had my jeep with open diffs goin up a hill/climbing a rock or something and the front end gets one wheel in the air, but all other tires are firmly planted. How would the transfer case send the torque?

when in 4-Lo or 4-Hi, your TJ's transfer case acts as a locked differential. Torque is split 50/50 front to rear in 4wd. there are some differentials that act as open differentials, or both as open and locked depending on mode, but these are in other models of Jeeps, not TJs.

[172heavy]

Originally Posted by Jeepster83

this might help explain a little bit about how an open differential works. its a really old GM training video.

[YT]Em1zQToa_a8[/YT]

this is a cool video!!

[Oregun]

Thanks Jerry, great write-up

I never knew why manufacturers cut gears differently front and rear until reading this, I always thought there would be some kind of advantage to it. Come to find out that it's just too hard to cut the different rings the same was kind of a shock.

[rs4race]

even with that being an old video, its actually really good. I wish there were movies like this for modern systems.

[Jeepster83]

Originally Posted by rs4race

even with that being an old video, its actually really good. I wish there were movies like this for modern systems.

there are. you just need to be in manufacturer-specific training courses. each manufacturer has them to train their techs.

[tjkj2002]

Originally Posted by Jerry Bransford

No, it's true that both sides do truly get 50%.

If one side is spinning, it has no resistance against it which is what the engine will see so the engine is producing very little torque... so now the other side is spinning but it is spinning with very little torque. Now if you are holding one side but the other is spinning, it is the one now presenting very little resistance to the engine, so the side you are holding gets very little torque. Now if you and a friend grab BOTH sides at the same time, then the engine is seeing a lot more resistance so both rear tires will suddenly see an increase in torque... which is why both of you, not just one, will be going for a ride.

Go to HowStuffWorks "Locking and Torsen" which is page 6 of a great explanation of how differentials really work. Starting at page one is a great way to really get it explained in an easy to follow explanation.

Here's an excerpt from page six of How Stuff Works: "The open differential always applies the same amount of torque to each wheel. There are two factors that determine how much torque can be applied to the wheels: equipment and traction. In dry conditions, when there is plenty of traction, the amount of torque applied to the wheels is limited by the engine and gearing; in a low traction situation, such as when driving on ice, the amount of torque is limited to the greatest amount that will not cause a wheel to slip under those conditions. "

There is plenty of information there that will more clearly explain what I have been saying and why each wheel truly gets 50% of the torque, not some variable number that adds up to 100%.

True for a rear diff where both axles are equal length(or near equal length) but not true for the front diff that one axle is longer then the other.The unequal length front axles will not give a true 50/50 torque split since the long side will always receive more torque due to that longer axle "twisting" more then the short side.

Torque follows the path of least resistance.

[Jerry Bransford]

That changes nothing explained about differentials above, the differential itself always (!) gives a 50:50 split.

[tjkj2002]

Originally Posted by Jerry Bransford

That changes nothing explained about differentials above, the differential itself always (!) gives a 50:50 split.

Not for the front unless you run a centered front diff.The difference is small but it is not a 50/50 split.