All Mode 4wd questions (Im confused)

[denvern]

Sorry for the newbie question but I've read and searched but Im still a little confused with Nissan's All Mode 4wd system. When you're in 4Hi or 4Lo are all axles locked together like a "diff lock"? The gauge on the instrument cluster shows "locked" Does the Pathfinder come with a locking diff???

 

I read up on Jeep's Quadra Drive system....it seems pretty good. Is our's similiar?

Edited November 8, 2008 by denvern

[BowTied]

The auto mode system engages power to the front differential when wheel slip is detected (in AUTO setting). When in 4Hi or 4Lo settings, there is power full time throught the transfer case to the front axle just like when a manually shifted transfer case is put in 4Hi or 4Lo.

 

As I understand it, locking differentials are not linked into that system but rather determined by the presence of a limited slip differential (or locker etc.) installed at the ring & pinion gears for the axles.

 

I am not familiar witht he Jeep system.

[BowTied]

Ok, I did some quick reading on the jeep system. I was not clear in my previous post, I thought you were talking about the diff in the axles, duh, sorry.

 

The automode system has a electronically controlled hydraulic multi-plate clutch system centre differential. It is lockable (4Hi 4Lo). It works differnetly I believe than the jeep, but can similarily lock.

 

http://www.canadiandriver.com/testdrives/01pathfinder.htm:

Base Pathfinder XE 4X4 models come with a part-time, shift-on-the-fly four-wheel-drive system that includes a Low Range gear. For 2001, SE and LE models are available with Nissan's 'All-Mode 4WD' system, the same full-time 4WD system offered on the Infiniti 'doppelganger' QX4.

 

Via a console-mounted switch, drivers can choose 2WD (rear-wheel-drive), 4WD Auto (full-time four-wheel-drive), 4WD Lock (centre differential is locked for tough situations), and 4WD LO (a low gear for steep ascents and declines).

 

All-mode 4WD has an electronically-controlled centre clutch which varies power distribution to the front or rear wheels depending on which wheels have the most traction. In this full-time mode, the Pathfinder can be driven on dry or slippery roads without harming the drivetrain.

 

An interesting side-note is that U.S. model 2001 Pathfinders are not available with the All-Mode 4WD system, just the part-time 4WD system. In addition, U.S. XE models are not offered with a manual transmission. However, 4X2 models are offered in the U.S., but not in Canada.

Edited November 8, 2008 by BowTied

[Zibi]

Locking differentials require locking differentials, which Pathfinders do not come with stock. You may have a Limited Slip Differential which will act similar to a locker until enough torque is applied to one tire, but on an R50 it's not very much (breaking point is 250lbs or something).

 

A locked differential will always provide the same amount of power to both tires on an axle. You would know if you have a locker because they drive like @!*% on a normal road. When you turn your car, the tire on the outside of the turn has to travel a greater distance than the tire on the inside. If you have a locker, and therefor both tires can only travel at the same speed, your truck will do funky things when you turn on asphault and if you take it too fast you'll think parts of your truck just fell out. There are selectable lockers available for the pathfinder that use air pressure to activate and deactivate but they cost a bundle.

 

All your transfer case does is provide power to the front differential (and therefor the wheels). The All mode, which I believe has an auto setting (I'm not sure since I don't have all mode) simply will detect when your rear tires loose traction and then automatically provide power to the front. The 4-hi and 4-lo settings simply provide full time power to the front as BowTied mentioned.

 

So to answer your question, no, your differentials will not lock in your pathfinder. That little light on your dash is simply letting you know that you are in 4wd and that power is being provided to the front diff.

Edited November 8, 2008 by Zibi

[BowTied]

http://www.nissan.com.au/news_pdfs/pathfinder.pdf:

When set in the Auto setting, the All-Mode 4WD system automatically distributes torque between 100 per cent through the rear wheels to 50:50 front/rear when traction is difficult.

 

In the Auto setting, front torque distribution varies with:

Difference between front and rear propeller shaft speeds;

Throttle opening angle;

Rate of vehicle acceleration;

Braking force;

ABS operation; and

Road speed.

 

Torque distribution is via a hydraulically operated multi-plate clutch and in the Auto setting, the maximum split is 50:50 front/rear which is the same as the 4WD High manual setting. Hydraulic pressure to the clutch is varied according to requirements – the more pressure applied to the clutch, the more torque which is transmitted to the front wheels. Sensors monitoring factors such as front and rear propeller shaft speeds, engine speed, throttle sensor and ABS actuation deliver information to a transfer control unit.

 

Following receipt of that information, the transfer control unit varies the hydraulic pressure to the clutch via a series of solenoids and valves. Hydraulic pressure for the clutch is generated using two pumps. One is driven by the main shaft and produces oil pressure when the vehicle is being driven forward while the second is driven by an electric motor and is used when the vehicle is reversing or travelling at low speed. The two pumps guarantee constant pressure in the clutch system and are assisted by one-way valves and discharge valves to ensure pressure is maintained and the oil flow is correct, even when the main oil pump is in reverse.

 

Turning the 4WD dial on the dashboard to 4WD Low bypasses the clutch and locks the front and rear drive shafts, unlocks the sungear/input shaft and locks the planetary carrier which produces a reduction of 2.569:1 – this is actually lower than other Nissan 4WD models which have a reduction of 2.02:1.

Edited November 8, 2008 by BowTied

[denvern]

Thanks...i understand now.

The "locked" light on the dash confused me.

[01silvapathy]

I have a 01 LE with all mode, and it just seems like a pain, if your in doubt that you will get traction then you should be in 4wd anyways.

[BowTied]

I have a 01 LE with all mode, and it just seems like a pain, if your in doubt that you will get traction then you should be in 4wd anyways.

 

A great use for the Auto setting is on-road with variable weather conditions such as drifting snow, patchy ice etc. Not likley a lot of that in Texas Off-roading I would agree, 4Hi or 4Lo, not auto.