L33T35T 4Runner

what does this mean? is it still a regular locker? or what? thanks for any info

joez

if i remember right, power is split 60/40, front/rear. with a kind of a limited slip sort of thing to bias power.

this allows it to be driven on pavement with no wear. when the center diff lock is engaged, it locks it to a 50/50 split front/rear, for better off-road traction. thats about all i can recall before i fall aslpe at the computer.

ravencr

On what vehicle? Most of the time these center differential lock systems are used on full-time 4wd trucks, where you can mechanically (usually with a switch) lock the center differential so you get a perfect 50/50 split between the front/rear axles. When this option is off, the ECU usually automatically distributes power to the wheels with the most traction electronically. Hope this helps!

Chris

L33T35T 4Runner

I was looking around at newer 4runners (i think it was a 2000 i saw it on) and saw the center locking diff. how would this help offroad?

why did toyota go from a rear locker to a center locker?

SkyRat

Once again,
I was wondering the same thing.

I have a 2000 4Runner Limited 4WD. Mine is NOT full time 4WD.
the Transfer Case Shifter says:
H2-H4
N
L4L (for locked)
H4L (for locked)

How is this different than the "lockers" I keep hearing about, but do not understand?
If I had a Low 4WD Locked, would I still need a "locker" to get better off road performance?
Let us all know.

L33T35T 4Runner

hey skyrat, where in so cali are you?

the way i see a center diff locker, is front and back would get 50/50, but wouldnt tires still slip, thus defeating the purpose of a locker?

L33T35T 4Runner

and how about traction control systems, how are they related?

SkyRat

I am in Granada Hills, in the Northern San Fernando Valley. Right next to Northridge.

I think the limited slip diff only works when in High 4. Some say you can ride in that all day on dry pavement if you want to. And when in High 4 Locked and Low 4 Locked there is no slippage and therefore cannot ride on dry pavement in those settings.

This is what I have heard, not what I know.

What do "lockers" like the air and electronic rear lockers really do anyway?

L33T35T 4Runner

that is one answer i know for sure. first you have to understand how a normal "open" differential works. the tire with the least traction will get the most power, so if you have one tire in teh air, that tire is going to get all the power, and you are gonna go nowhere. if you have a locker, it locks both tires 50/50. so no matter what, the two tires are going to spin exactly equal to eachother. so if you ahve one tire in the air, it wont matter and you will keep going.

the reason why i dont know why a center would help is if the front and back is locked at 50/50, then the front and rear diffs. are still going to slip.

so basicly i would like to know how a limited slip works a d helps on a 4runner (i didnt even know 4runners had limited slips). and how the center diff locker helps

joez

it works like a limited slip in the transfer case, allowing you to drive on pavement in 4wd(why would you want to do that anyway?).

but think of it this way, when you turn, dont your 4 tires move in 4 different arc's? yes, they each have their own path. in a 50/50 split, you are trying to make them go in 2 different paths. i cannot engage my 4wd withough wheelhop and binding on turns.

when the center diff is locked, and you have both front tires on the ground, but only 1 rear, the front will keep pulling. the rear tire will still get no traction, but the front will.

bassically it means to get wheelspin with 2 open diffs, you need one front and one rear to spin at the same speed. does it help, yes. is it needed, not in my mind. ill take my good ole' gear drive t-case anyday.

and really, runners dont have limited slips, at least not in the front or rear diffs.

o, and limited slips are usually clutch based, when one tire looses traction, the clutch tries to keep up. i hope you can understand this the way i wrote it.

L33T35T 4Runner

wait... one question about a regular 4wd system with no lockers.

say one tire is in the air, is 100% of the engine's power gonna go to that one tire? i sure hope not

HBoss

This topic has been covered many times here. Did a search for you, here's some useful info:

Locking Center Diff

Question about LSD & diff lock

diff lock/unlock '03

Select-mode 4WD question

When to lock center diff?

Hope it helps explain.

Woodbert

You guys should read this page from HBOSS:

HBOSS 4WD

Woodbert

DAMN. You beat me to it HBOSS!

Cebby

In your case (you are 2WD right?), you'll be spinny-spinny (stuck) An open diff on 2wd = 1 wheel drive The transfer case with 4WD doubles your chances of getting through. Dual lockers multiplies it by 4

EDIT: Damn I'm slow (but reliable - like my 4Runner)

L33T35T 4Runner

i understand this. but i was saying in a standard 4WD system. is the center diff open? is there even a center diff in a standard 4WD system? once again the question, with 4wd, if you have one tire in the air, say the left rear, is 100% of engine power going to go to that one tire? or will it get the rear's 50% (or 60%?) and the front is splits their 40%?

Sucellus

Ok, I've been reading up on this, so I'll try to detail what I understand about diffs.

DIFFERENTIALS:
Required info: A differential will have 1 power input and 2 power outputs.

Definition of terms:
Pi: power input
Po1: power output 1
Po2: power output 2
Pi=(Po1+Po2)/2

Open Differential: a differential which operates on the prinicpal that input power is freely averaged between 2 output axles. Thus in an open differential 1 output can be at 0%(IE not turning) and the other can be at 200%(Spinning really fast). This relationship is controlled by tire traction and brake-force distribution.
when pi=100%
Po1=0-200%
Po2=0-200%
Po1 is inversely proportional to Po2

Locked Diff: A differential where the input power is divided evenly
between the 2 outputs. Both turn at 100%. Static ratio controlled by the diff.
when Pi=100%
Po1=100%
Po2=100%
Po1 is directly proportional to Po2(Po1=Po2=Pi)

LSD: Limited slip differential. A differential which attempts to balance input power between the 2 outputs while not locking the two together. With an lsd, output power propotioning is controlled by the differential rather than by tire traction/brake-force distribution.
when Pi=100% in a 60/40 split,
Po1=80-120%
Po1=80-120%
Po1 is inversely proportional to Po2

Torsen Diff: Torque Sensing Diff. Type of limited slip using gears for power distribution. Generally reguarded as superior to other types of LSDs.

4 WHEEL DRIVE SYSTEMS:
Required info: in a 4wd 4runner you have 3 diffs. There is 1 for each axle, then 1 in the center(aka. transfer case).

Definition of terms:
Pc:Center diff Power input (always equals 100%)
Pc1:Center diff Power output 1(to rear)
Pc2:Center diff Power output 2(to front)
Pr: Rear diff power input(from center)
Pr1: Rear diff power output 1(to LR wheel)
Pr2: Rear diff power output 2(to RR wheel)
Pf: Front diff power input(from center)
Pf1: Front diff power output 1(to LF wheel)
Pf2: Front diff power output 2(to RF wheel)

Pc=(Pc1+Pc2)/2
Pr=(Pr1+Pr2)/2
Pf=(Pf1+Pf2)/2

Types of 4 Wheel drive:
AWD: All wheel drive--Suitable for dry roads. This is what happens when none of the diffs are locked. AWD was not offered in 4runners before '01. In '01-'02 4runners AWD mode is denoted by the symbols H4 and L4(High range/low range). In the absense of LSD's, if you loose traction on any one wheel that wheel will take all the power and spin 4x as fast as normal.
when Pc=100%
Pc1=0-200%=Pr
Pc2=0-200%=Pf
Pr1=0-400%
Pr2=0-400%
Pf1=0-400%
Pf2=0-400%

4WD: 4 wheel drive--Suitable for offroad only. This is what happens when both axle diffs are open and the center is locked. In 4runners prior to '01 4WD is denoted by the symbols H4 and L4. In the '01-'02 models this is denoted by the symbols H4L and L4L. It would take 2 raised wheels (1 front and 1 rear) to get stuck. In this scenario, the raised wheels would spin at 2x normal velocity.
when Pc=100%
Pc1=100%=Pr
Pc2=100%=Pf
Pr1=0-200%
Pr2=0-200%
Pf1=0-200%
Pf2=0-200%

4WD with rear locker: Same as 4wd but both center and rear are now locked. It would take 3 raised wheels to get stuck(2 rear and 1 front). Thus:
when Pc=100%
Pc1=100%=Pr
Pc2=100%=Pf
Pr1=100%
Pr2=100%
Pf1=0-200%
Pf2=0-200%

4WD with front and rear locker: Same as 4Wd but all diffs locked. It would take all 4 raised wheels to get stuck. Thus:
when Pc=100%
Pc1=100%=Pr
Pc2=100%=Pf
Pr1=100%
Pr2=100%
Pf1=100%
Pf2=100%

Futher info: To my knowledge toyota did not produce a LSD Transfer case for the 3rd gens or prior. Thus the options for the third gen transfer case are at best open/locked(for '01-'02); or just locked(prior to '01). The 4th Gens('03-) do get a torsen Center diff.

Locking diffs: 3rd gens prior to '01 were available with a rear locker. However, with the introduction of the '01-'02 lockable transfer case, the rear locker was discontinued.

Active-TRAC: This only works in AWD mode. This traction control system offered on '01-'02 4runners will slow down a raised wheel through the brake system. The inverse relationship between the wheels on the axle and across the center diff means that the non-turning wheels will begin to turn. This is kinda a patch for not having LSD's.

L33T35T 4Runner

ahh! so much information to read

thanks everybody

ravencr

This helps, because normally the ecu compensates for wheel spin electronically, which is fine under most conditions. But, when the terrain is slippery, muddy, or very technical, it's better to lock in the center differential, so there is a 50/50 split between the front/rear wheels 100% of the time.

Don't know, but the ideal off-roading setup for a full-time 4wd truck that has a center differential lock, would also be to have automatica ARB lockers front and rear. This would give you a 50/50 split fron front to rear, and all four tires would be pulling all the time. This is the ultimate traction you can have.

Chris

joez

well, toyota did it in the 80 series L/C's. but arb's are selectable, not automatic, like a detroit. toyota uses their own design of an electronic locker, and they were equiped front and rear, with a center lock in 4L. what i want to know is why this basic tecnology that works so well was dropped in favor of all of this techno-mumbo jumbo in the new runner. i mean, some people still wheel their runners.