Expy 4WD system info.

[HolidayJones]

What's the difference between the 2nd gen's A4WD and the 4high? Cause I got my Expy stuck in Citrus Tract when I drove it over a 3' embankment, and I thought that 4high locked, but all I got was two opposite wheels spinning: the ones I didn't need. Probably wouldn't have got me out, but what does the a4wd do if the 4high doesn't lock?

 

[bedrck46]

all I can say is I hope you didn't have a chevy pull you out would be hard to live that down.

hope you didn't have any damage and got out ok

 

[HolidayJones]

Haha, unfortunately....I have to hang my head in shame...lol and when it was teetering the left side of the front diff was leaking gear fluid, and while trying to self rescue, my front axles just kept popping grinding. Idk if there's something wrong with it period as my 4low didn't seem to engage at all . It kinda let me down.

 

[BIG GREEN FORD]

Limited slip??? If not do you have advance track? If you have neither then press you I brake down 5 clicks and your brakes slowly accelerate and it looks your tires and pulls evenly

 

[toms89]

4 Hi locks the transfer case meaning you have power going to both the front and rear differential. A4wd engages the transfer case only when it senses slip.

Now if both front and rear differentials are open the wheel with the least traction (per axle) gets the power. So unfortunately if you have both a front and rear wheel with poor traction you may be screwed.. lol.

That's where advance trac is supposed to take over and apply braking to the spinning wheels thus sending power to opposite side.

If you have no advance trac a limited slip rear would be very beneficial for off road.

As was mentioned applying brakes sometimes helps as it can limit the spin on the wheels. The only problem is applies braking to all the wheels or both rears if you use the parking brake.

Lockers of course would be best for off road use. Then you can lock the differentials and all wheels get equal power.

 

[HolidayJones]

Ok good, that's what I needed to know. And yes, I was definitely screwed.lol

 

[tonydiv]

Keep in mind though that you can't put a limited slip or a locker in the front diff. The only option there is to get a selectable locker like an arb or e-locker.

 

[DetroitDarin]

^^ 'cannot' put a LSD in the front? i know of guys with TruTracks in front (F150s, etc).

 

[ExpeditionAndy]

HolidayJones,

This might be helpful.

Info from the 2005 manual:

• 4L (4X4 LOW) provides mechanically locked four-wheel drive when
extra power at reduced speeds is required. The “4X4 LOW” light will
illuminate in the instrument cluster when this position is selected.
This position is not recommended for use on dry pavement. Use this
position for off-road low-speed operation or when extra power is
required, such as climbing steep grades, going through deep sand or
pulling a boat out of the water.

Note: If your vehicle is equipped with AdvanceTrac with RSC, the
AdvanceTrac with RSC system will automatically turn off the stability
enhancement feature when you shift the Control Trac A4WD system into
4L (4X4 LOW). The brake traction enhancement feature will still be
enabled.

The AdvanceTrac with RSC stability enhancement system can be turned
off manually by pressing the AdvanceTrac with RSC button (refer to
AdvanceTrac with Roll Stability Control (RSC) Stability
Enhancement System in this chapter) while operating in 2H, A4WD or
4H while driving in deep sand, very deep snow or more strenuous
off-road maneuvers. This will disable the engine management feature,
allowing the vehicle to maintain full power and enhanced momentum
through the obstacle.

AIR SUSPENSION SYSTEM (IF EQUIPPED)

If your vehicle is equipped with four-wheel drive and you shift into 4WD
LOW, the air suspension will not move to it’s lowest position; instead, the
ride height is raised above the normal ride height position (at speeds
below 35 mph [56 km/h]) to improve ground clearance.
If a load is added to, or removed from the vehicle, the load leveling
feature of the air suspension system will adjust the suspension to keep
the vehicle at a constant level.

When exiting the vehicle, the air suspension will automatically lower the
vehicle to its lowest height to provide easier exit. You may hear a buzz or
click from the air suspension system when the ignition is turned off. The
air suspension system will stay active for 40 minutes after the ignition is
turned off to accommodate any load changes. (The air compressor may
run when the vehicle is off; this is normal.)

 

[tonydiv]

In order for advance trac to work properly, it has to be able to send power and braking to individual wheels. Lockers won't allow the system to do that.

Now if it's a trail truck, then go to town.