2004 Ford Escape Drive Train

|I recently tested an Escape Limited with a 3 liter V-6 engine. It had a |2-position selector switch on the dash labeled as auto/4WD. The salesman was |uncertain what exactly the 'auto' mode did. Is the auto mode AWD? If so, |then why isn't the switch labeled AWD/4WD?

"auto", I believe, goes to 4WD when the computer monitoring wheel rotations indicates one wheel is spinning faster than the others.

4WD locks it into 4WD regardless of road conditions.

Lg

Ask the salesman to find out. That is what he gets his commission for.

I believe the answer given is correct (auto switches it to 4wd on need, 4wd is locked in with the 4wd position).

Jeff

There's a difference between Auto 4x4 and AWD.

In the Auto 4x4, there's usually a clutch between the front & rear prop shafts, which is electronically controlled; this clutch will direct power to the front prop shaft as needed, usually by monitoring the rear wheels for slippage. In AWD, there's usually a viscous clutch between the two prop shafts, which doesn't monitor anything; it just limits the slippage by it's viscosity.

I don't think there's a way to lock the prop shafts in an AWD system. In an Auto 4x4 system, when 4X4 is chosen, the prop shafts are locked together.

The Escapes has the Automatic Type 4 wheel drive. There is an electrically operated clutch to the rear drive shaft. In the "Auto" mode, when slip is detected, the clutch is cycled on and off at an increasing "on" rate until the slip is eliminated. In the 4WD more, the clutch is engaged 100% of the time (i.e., locked).

The 4x4 Escape does not have "All Wheel Drive." It has "Automatic 4 Wheel Drive." Explorers offer both types as an option.

Ed

Actually, it's the other way around. The Escape is basically a front-wheel-drive, transverse-engine vehicle with a viscous clutch to the REAR wheels.

In "Auto" mode, the front wheels are always engaged, and the clutch diverts some power to the rear wheels when FRONT slippage is detected.

In "4X4" mode, which isn't a true 4x4 because of the viscous (rather than direct, locked mechanical) coupling, the clutch is engaged full-time, but still allows some slippage. This is an advantage on dry roads, because there's no drivetrain bind, and you can makes turns without shutting it off. But it also means that its four-wheel-drive traction is lower than that of a true mechanical 4x4 connection.

Whoops - I got this completely worng -

See

an explanation of how the system really works. It is not like eitherExplorer 4WD system, despite the similar advertising name for the system (Control Trac whatever). Here is a quote from the article -

"For four-wheel-drive versions of the Tribute and Escape, a power-take-off unit bolted to the transaxle spins a two-piece driveshaft connected to a device called a Rotary Blade Coupling (RBC), mounted to the nose of an otherwise conventional rear differential. As long as the front wheels don't slip, the rear half of the driveline is merely along for the ride. When there is a rotational velocity discrepancy (resulting from diminished front-wheel traction), interleaved blades inside the RBC begin churning a silicone fluid. The heat so generated rapidly raises the temperature and pressure of the air also sealed inside the chamber.

"This pressure rise forces a piston against a multi-plate clutch pack. When so engaged, the clutch pack completes the link between the spinning prop shaft and the rear differential, dispatching engine torque to the rear wheels. As soon as front and rear wheel speeds get back in synch the process reverses and the operating mode reverts to front drive.

"A second mode is also available. For off-road or "get-unstuck" use, the driver may press a "4x4 On" button on the dash of the Tribute, or turn a switch on the Escape. Each sends an electrical current to an electromagnetic coil adjacent to the RBC. This engages a small multi-plate pilot clutch in the RBC unit, which in turn applies the main clutch though a ball-ramp thrust-amplification device. The drive torque available in this mode is nearly seven times greater than the maximum torque available in the on-demand mode."

Regards,

Ed White

"C. E. White" wrote:

Absolutley correct...

Not quite. Agreed there is a viscous coupling, when in 'lock' mode a electromechanical lock "locks" the front and rear drive shafts. It doesn't allow any slippage, and can cause binding and 'winding up' of the driveshafts when on a smooth surface.

Essentially it uses the same "set-up" as a Range Rover in that it has a viscous coupling and electromechanical lock. You wouldn't call a Rangie a pretend 4WD would you?

Cheers Dave.

Yes....

Er, that's not what I remember reading in Car And Driver. They said that although the "locked" "4X4" position does put the coupling in a "locked" mode, it still allows for slippage, and that an Escape stuck with alternately-spinning wheels (such as left front and right rear) would NOT be able to get unstuck, and I believe the end quote was "That makes the Escape NOT a true four-buh-four [sic]".

My sister has an Escape---I'll ask her what the owner's manual says. I'm pretty sure I recall that you CAN use the "locked" mode on dry pavement, like any other AWD (not 4WD) truck.

But any other 'true four-buh-four' without some sort of limited slip differential will do exactly the same.

Oh, I'm not disputing THAT. My sister's 2001 has something like 65,000 miles on it, and all they've done is change the oil, coolant, and tires, AFAIK.

But it's NOT a 4WD. It's an AWD.

OK...but again, my point was that in the Escape's "locked" mode, you can drive it on dry pavement without driveline bind. In other words, you can go through turns on dry pavement.

An Explorer with "4X4 on" is NOT designed to turn on dry pavement.

Well considering it is one of the most capable 4WD's built for the passenger markrt I'd say you'd need to reconsider your definition of

4WD.

I'll stop now. I ALREADY think the Escape is one of the best car-based SUVs out there.

I guess people just don't read and comprehend posts before replying.

Go read

I used to think like you, but after reading the above article I believe that in

4x4 mode, extra force is exerted, but it is still not a solid lock.

From the article -

"A second mode is also available. For off-road or "get-unstuck" use, the driver may press a "4x4 On" button on the dash of the Tribute, or turn a switch on the Escape. Each sends an electrical current to an electromagnetic coil adjacent to the RBC. This engages a small multi-plate pilot clutch in the RBC unit, which in turn applies the main clutch though a ball-ramp thrust-amplification device. The drive torque available in this mode is nearly seven times greater than the maximum torque available in the on-demand mode."

Ed

Well, with all due respect to Automotive Journalism and their descriptions of systems and the vehicles themselves, they know Jack!

I can quote a prominant 'Journalist' by the Name of Paul Glover in one of our National Newspapers writing that the "Escape is a rebadged Mazda Tribute". I attempted to point out that he was wrong and the only external things they share are the roof, front passenger and driver glass and windscreen and rear mirrors.. I did concede that underneath they are the same. I received a reply advising that I was wrong and that I should look at one..... I own one and I should know the difference! So this little experience has taught me that when a motoring journalist writes something, it's generally not quite correct!

As an aside I have to agree that the ESCAPE/TRIBUTE cousins have to be one of the best passenger SUV's out there! Now if only Ford could persuade Land Rover to ditch the current Freelander and base the next one on the Escape/Tribute - they'd actually have a nice car!

Cheers Dave.

Last week I test drove an Escape immediately after test driving an Explorer at the dealer's lot. There wasn't a suitable terrain near the dealer's location for me to try to get the vehicles stuck in mud. So I resigned myself to just doing 2 simple tests of the drivetrain for *both* vehicles:

1) Listen for how much noise the drivetrain (mostly the transfer case) makes while in locked 4WD mode; compare noise for both vehicles. Normally, locked 4WD mode makes quite a bit of noise compared to 2WD mode for such 4x4 vehicles that have push-button 4WD. 2) Test to make sure the panel switches actually are turning on the 4x4 locked modes, and that the switches are able to get the vehicle out of the locked modes. This has been a problem with my old '91 Explorer. Moreover, a mechanical problem that has something to do with lubrication/rust can seize the locking/unlocking in old Explorers, Blazers and other 3+ year-old push-button 4x4 models so that (sadly) some owners actually revert to using aftermarket hub locking kits.

The 2004 Explorer, with V-8 has a drivetrain that makes about the same amount of noise in both 4WD-high and 4WD-low that of my '91 Explorer (V-6; manual; 4x4) made when it was new. OTOH the locked 4WD mode of the 2004 Escape V-6 was so unbelievably quiet that (by ear) it was very difficult for us to be able to say for sure until we got the vehicle above 40 mph.

A second test that I did on the 2004 Escape to prove the locked 4WD actually was engaged was to deliberately make a creeping U-turn on dry pavement while in locked 4WD mode. The vehicle had *very little* "rear axle hop" (Is that what it's called?) due to the failure of the rear to slip freely. The rear wheels hopped just slightly enough for me to be able to confidently say "Yep, it's in locked 4WD mode." However, when I did the same test test in the 2004 Explorer I got the big thumping of rear wheel hop that I expected. So there's something obviously different about the Escape's locked 4WD performance on dry pavement; it sure doesn't lock rigidly. That's nice on dry pavement, but why would anyone normally be operating the vehicle that way? That "ability" of the 2004 Escape in locked 4WD mode is a disadvantage if you should get stuck in gravel or with a rear wheel down in a hard surface hole.

Another questionable characteristic of the Escape; when in "auto" mode. When I took a sharp 90 degree corner of a residential neighborhood road at 27 mph (faster that anyone would normally drive a SUV on such a corner) in order to test the flatness of its cornering. In the turn I felt a slight bumpy drift in the rear, with no squealing of tires. A little unnerving. Wasn't used to it; didn't like it. Couldn't be sure whether the rear wheels had hopped or whether something had instantaneously changed in the drivetrain. What's your take on this, guys?

To summarize, I like the extremely low drivetrain noise of the Escape's locked 4WD mode. But that locked 4WD mode did not prove to be very rigid during a creeping U-turn on dry pavement, so what can be expected of it if you should get stuck on a rigid surface? Also I felt that the 'auto' mode interfered with the handling of a brisk but unchallenging paved turn, so what will happen during an emergency swerve?

Ed, it's definitely *not* a solid lock; based on the dry pavement creeping U-turn that I described in my earlier reply in this thread to JohhnnyCab. And that's not a good thing.