Originally Posted by wwest (Post 204558)

We have been here before.

The FEH is F/awd. FWD only, except with moderate to hard acceleration at low speeds or if front wheelspin develops due to too much drive torque being used for roadbed conditions.

And as I have said before, I would have thought that the initial, first, action, ONLY action, upon detection of front wheelspin/slip would be to fully engage the rear drive in order to distribute the drive torque over a larger CSA. But the Ford Fusion documents plainly put the lie to this. According to the Fusion documentation front wheelspin triggers both actions, enagagement of rear drive AND TC.

Given the hazards of FWD associated with loss of directional control due to front wheelspin/slip, loss of traction, I can understand both remedies being applied simultaneously.

Shame, that..

You can believe that the fusion F/awd/TC technique does not apply to the FEH if you wish.

As everyone clearly knows I don't own an FEH...MMH or Tribute hybrid. If I ever do own one of these the very first modification will be to add a switch to make it TRULY 4WD. The switch will be used to supply 12 volts directly to the rear drive clutch so the rear drive can be manually engaged in wintertime adverse roadbed conditions. If TC engages "then" it will be only since the traction of all FOUR tires isn't enough, even with throttle "feathering".

So, why doesn't Ford supply a "switch" as they did with the earlier FE's..??

Because they are of the firm belief that "you" can't be trusted..!!

Originally Posted by wptski (Post 204562)

The '09 FEH operates like the Fusion AWD only because it has TC.

It doesn't even take moderate acceleration to generate rear wheel torque. I might even impossible not to generate some rear wheel torque.

There's no switch because there's no TC.

Originally Posted by wwest (Post 204604)

In this day and time Ford would not be so stupid as to build a FWD or F/awd vehicle without TC functionality, the ambulance chasers would get rich.

The description of AdvanceTrac (Ford's term for ESC) and the TCS subset begins on page 205 of the 2009 Ford Escape Hybrid owners manual and indicates that there is an ESC, Electronic Stability Control, OFF switch.

Originally Posted by Bill Winney (Post 206286)

In '06 Escape, the rear differential is an open, non-limited slip type differential.

In other words it will send power to the wheel with the least traction.

No, it will continue sending "power" to all drive wheels, just that the level of engine torque available is now limited by the tractionless wheel. Think of trying to torque a lugnut with the wheel free to turn.

There is no mention in the shop manuals of a limited slip option rear axle for the hybrid.

It may be there, a "virtual" LSD, just not directly mentioned as a part of TC. Once you have TC "on board" LSD's are cost free.

I can find no mention in the shop manuals of TC, if someone has a reference for it let me know.

It appears that the Intelligent 4wd system capability exists solely in the system that controls & engages the power transfer unit when wheel slip is sensed. (...And the info on that is darn short, I was disappointed in Ford on this.)

Originally Posted by Bill Winney (Post 206286)

In '06 Escape, the rear differential is an open, non-limited slip type differential. In other words it will send power to the wheel with the least traction. There is no mention in the shop manuals of a limited slip option rear axle for the hybrid.

I can find no mention in the shop manuals of TC, if someone has a reference for it let me know.

It appears that the Intelligent 4wd system capability exists solely in the system that controls & engages the power transfer unit when wheel slip is sensed. (...And the info on that is darn short, I was disappointed in Ford on this.)

Originally Posted by Bill Winney (Post 206293)

According to the shop manual the rear differential is nothing but a standard, open differential. There is no mention of ITCC at all, nor is there any connection to anything beyond the driveshaft input and axle output.

...And of course the power transfer unit is always on.

Originally Posted by wwest (Post 206310)

Housed within the rear diff'l case, just forward of the pinion gear, is a "dual" clutch mechanism. An electromagnetic clutch used to control a frictional clutch that actually does the dirty work. PWM, Pulse Width Modulation, of the 12 volt power source is used to provide linear functionality to the rear drive, 0 to 50% coupling. Greater torque coupling, more than half, to the rear is provided if TC intervenes and brakes the front wheels to alleviate slippage there and thereby reduce the potential for loss of directional control.

The earliest versions apparently had over-heating problems/issues since there was an indicator light to advise the driver that it was time to pull over and let the dual clutch cool down.

Some implementations of this drive coupling arrangement have engine coolant flowing through the PTO case to keep it cooled down.