Tire power in 4x4 with locking diff

smmarine · Feb 19, 2014

Indy said: ↑

Quick primer on 4wd and differential function.

In 2wd with an open differential 100% of all availale engine torque is transfered to 1 axle. When both tires on that axle have equal traction the differential will split that power 50/50 to each tire. But when you get into a position that 1 tire has traction and 1 tire doesnt, that diff will actuall transfer 100% of the power to the wheel with NO traction. Thats where you see 1 tire spinning and 1 tire not moving.

If you have a locking diff, the differential will "lock" both sides together and split the power 50/50 between each side all the time. So even if 1 tire has traction and the other doesnt both will spin at the same speed regardless. The benefit being the wheel with traction can push the vehicle forward until the wheel without traction can catch.

When you engage 4wd the transfer case splits the engine power 50/50 between the front axle and rear axle.

In 4wd with 2 open diffs you end up with both ends runnng the same as above. If all 4 tires have traction you get 25% of all power at each tire and 4wd. If the back tires have traction and 1 front does, each back tire has 25%, the front with traction has 0 and the front without has 50%, essentially 3wd but only the back axle is doing any work.

And if you get in the spot that 1 front and 1 rear tire has traction, you see 1 tire on each end spinning, each receives 50% and 1 tire on each doing nothing and receiving 0. Essentially back to 2wd but no work being done.

The best solution is 4wd and having each diff locked. That forces the vehicle into true 4wd, all the time. Each tire will always receive 25% regardless of how much traction it has.

At some point though you will end up with all 4 spinning and even though they are all receiving power, no work is being done. At that point youll wither be really happy you have a winch and recovery gear, or someone finds your frozen body in a couple months
Click to expand...

This is why I'm putting a truetrac in my rear end. No more 1 tire fire haha

Paleus · Feb 19, 2014

TACOMABOSS said: ↑

One thing I don't understand about 4wd and open diffs. If you have open diffs front and rear, why does the drive train bind up on hard surfaces? (I don't speak from experience)
Click to expand...

There's a diff between the left and right tires on each axle, there is no diff between the axles, so if the tire up front getting power and the tire in the back getting power are not turning at the same speed, the driveline binds.

smmarine · Feb 19, 2014

TACOMABOSS said: ↑

One thing I don't understand about 4wd and open diffs. If you have open diffs front and rear, why does the drive train bind up on hard surfaces? (I don't speak from experience)
Click to expand...

Also on a hard surface, even with open diffs, each tire has 25% power. So when you try to turn and they all have equal power, it binds up

Indy · Feb 19, 2014

TACOMABOSS said: ↑

One thing I don't understand about 4wd and open diffs. If you have open diffs front and rear, why does the drive train bind up on hard surfaces? (I don't speak from experience)
Click to expand...

The differential in the axle is what allows two tires to spin at different speeds. There isnt any differential action at the tcase, so nothng to allow each driveline to run at different speeds.

Log in or Sign up

Welcome to Tacoma World!

Tire power in 4x4 with locking diff

#21
smmarine Well-Known Member

#22
Paleus Well-Known Member

#23
smmarine Well-Known Member

#24
Indy Master of all I survey.

Products Discussed in

Log in or Sign up

Useful Searches

Welcome to Tacoma World!

Tire power in 4x4 with locking diff

#21 smmarine Well-Known Member

#22 Paleus Well-Known Member

#23 smmarine Well-Known Member

#24 Indy Master of all I survey.

Products Discussed in Entire Site Forum: 1st Gen. Tacomas (1995-2004)

#21
smmarine Well-Known Member

#22
Paleus Well-Known Member

#23
smmarine Well-Known Member

#24
Indy Master of all I survey.

Products Discussed in