Center differential explanation (1 Viewer)

[undecided]

Ive looked around to get a good explanation of what the center diff is compared to a regular transfer case but haven’t really gotten a good answer. I know when the lock is engaged it splits the torque but isn’t that what a regular T-case does too? Does it split it more evenly?

and more in depth, how is it mechanically different from a T-case? Like if I take it apart what am I gonna see that separates it from just a regular ole t-case.

also noob question to piggy back on this, don’t roast me pls, when switching between 4WD levels it needs to be in neutral correct? Do I need to roll backwards after to engage it? I had a Ford exploder where I had to do that but with my POS Jeep I could engage 4WD with it in drive.

 

[Pascoscout]

Ive looked around to get a good explanation of what the center diff is compared to a regular transfer case but haven’t really gotten a good answer. I know when the lock is engaged it splits the torque but isn’t that what a regular T-case does too? Does it split it more evenly?

and more in depth, how is it mechanically different from a T-case? Like if I take it apart what am I gonna see that separates it from just a regular ole t-case.

also noob question to piggy back on this, don’t roast me pls, when switching between 4WD levels it needs to be in neutral correct? Do I need to roll backwards after to engage it? I had a Ford exploder where I had to do that but with my POS Jeep I could engage 4WD with it in drive.

For the noob question, yes you have to be in neutral to shift but no you don't have to roll back or anything to engage, just shift and go.

This is my understanding on the center diff; has a viscuous coupler in it. When in high range it allows the power to go to whichever of the 4 wheels loses traction. When you shift to low range the coupler locks and acts like a regular transfer case, splitting the power equally to the front and rear axels. If you have a Center Diff Lock button you can make it function that way in high range too.

 

[undecided]

For the noob question, yes you have to be in neutral to shift but no you don't have to roll back or anything to engage, just shift and go.

This is my understanding on the center diff; has a viscuous coupler in it. When in high range it allows the power to go to whichever of the 4 wheels loses traction. When you shift to low range the coupler locks and acts like a regular transfer case, splitting the power equally to the front and rear axels. If you have a Center Diff Lock button you can make it function that way in high range too.

ah awesome that was my assumption but i wasn’t sure and didn’t wanna make an ass out of myself lol. I figured it functioned more closely to a differential. I didn’t realize it would lock in low range without the CDL.

with a regular t-case it doesn’t split it equally tho? Just pushes it wherever it’s needed?

 

[graham5david]

When locked it splits power 50/50 between front and back. When unlocked its an open differential sending power to all wheels if all have traction and allowing them all to spin faster if needed in turns. Unlocked equals all wheel drive. Locked is your traditional 4x4

 

[Pascoscout]

As far as I know all t-cases (except the full time 4WD versions without a true low range) spit power 50/50 when engaged. Power is then split again at the differentials which, unless they have lockers, sends the power to the slipping wheel.

 

[undecided]

As far as I know all t-cases (except the full time 4WD versions without a true low range) spit power 50/50 when engaged. Power is then split again at the differentials which, unless they have lockers, sends the power to the slipping wheel.

wont the power only be split at the diffs if there’s a limited slip diff or a locker tho? I thought it only sent power to one wheel regardless if it was slipping in a traditional 4WD with unlocked axles.

 

[baldilocks]

The coupler does not lock. The differential itself does not lock. When the “lock” is engaged, an actuator translates a splined sleeve rearward to to engage another shaft. The fsm explains this very well.

 

[Pascoscout]

The coupler does not lock. The differential itself does not lock. When the “lock” is engaged, an actuator translates a splined sleeve rearward to to engage another shaft. The fsm explains this very well.

Ok so I over simplified the explanation....

 

[Pascoscout]

wont the power only be split at the diffs if there’s a limited slip diff or a locker tho? I thought it only sent power to one wheel regardless if it was slipping in a traditional 4WD with unlocked axles.

The differential always splits the power, just not always equally. If you are driving in a straight line on a level surface then in theory it's split 50/50. However, when you turn or one wheel lifts then the differential will send most/all the power to the wheel that is slipping. A limited slip helps to send a little less power to the slipping wheel and keep more on the wheel with traction. A locker splits the power equally when it's engaged.

 

[baldilocks]

Ok so I over simplified the explanation....

I think it’s simpler than you thought. I had to cut my explanation short because I can’t remember every detail from when I read it four years ago.

 

[flintknapper]

The differential always splits the power, just not always equally. If you are driving in a straight line on a level surface then in theory it's split 50/50. However, when you turn or one wheel lifts then the differential will send most/all the power to the wheel that is slipping. A limited slip helps to send a little less power to the slipping wheel and keep more on the wheel with traction. A locker splits the power equally when it's engaged.

There is a common misnomer about OPEN diffs that folks often repeat (quite innocently) when they confuse Torque Bias with the ability of a differential 'type' to "send" power.

This guy is a little goofy, but has his facts straight. Worth watching.

 

[jonheld]

This was posted years ago before Mud was Mud. Always a fun read.

Welcome to Land Cruiser Owners On Line

 

[BILT4ME]

Be aware that without the CDL engaged or in Low Range (locked CDL), you can lift ONE tire (or have one tire on slick mud or ice) and the truck will roll down hill or be stuck.

I have intentionally pulled the front of my truck onto a pile of snow in a parking lot to test this. As soon as one front tire was on the snow and I powered it a bit, it would spin and I went no where. If I stood on the throttle, it would inch forward because the viscous coupler would start to push it a little, but that WILL smoke a VC.

As soon as I shifted to Low Range to lock the CDL, I was able to move and push up into the snow and over the pile because now both front and rear axle would get power, not just one slipping wheel.

If you are on a steep driveway and jack up only one wheel, the truck WILL roll down the driveway unless chocked and/or the CDL is locked.

 

[undecided]

do I need to be in neutral to engage the CDL as well?

 

[BILT4ME]

do I need to be in neutral to engage the CDL as well?

If you have the separate switch, no.

 

[retrofive]

More info in the FAQ sticky as well:

80-series FAQ for General Info, Modification and Repairs

The Frequently Asked Questions (FAQ) for the 80/LX450 series tech section continues to be a work in progress. The goal is to have links in the below to other threads and tech articles. By having these linked, instead of pasting the text, the threads will remain live. The live threads can...

forum.ih8mud.com

 

[flintknapper]

Be aware that without the CDL engaged or in Low Range (locked CDL), you can lift ONE tire (or have one tire on slick mud or ice) and the truck will roll down hill or be stuck.

I have intentionally pulled the front of my truck onto a pile of snow in a parking lot to test this. As soon as one front tire was on the snow and I powered it a bit, it would spin and I went no where. If I stood on the throttle, it would inch forward because the viscous coupler would start to push it a little, but that WILL smoke a VC.

As soon as I shifted to Low Range to lock the CDL, I was able to move and push up into the snow and over the pile because now both front and rear axle would get power, not just one slipping wheel.

If you are on a steep driveway and jack up only one wheel, the truck WILL roll down the driveway unless chocked and/or the CDL is locked.

^^^^^

Discovered this myself (much to my surprise). Good warning.

 

[bhsdriller]

^ yep me too lol

 

[Rifleman]

If you are on a steep driveway and jack up only one wheel, the truck WILL roll down the driveway unless chocked

To me always chocking your wheels anytime you jack up a vehicle is a common sense safety item. I got into the habit of always chocking the wheels of any vehicle I'm working on after seeing a 5 ton truck MOVE after being jacked up.

 

[undecided]

One more noob question since I have you all gathered here, what do the PWR/2ND buttons do?