Hey everybody,
Here goes with another non-F150 question. I just recently got a '99 Explorer with a 5.0 V8 with AWD. My question is, are the front wheels always under some amount of power or do they just know when to kick in without me telling them. I know there has to be some allowed slippage between front and rear wheels because of the difference in distance traveled. I was just curious about how this system works and what I might expect as far as drivetrain problems or concerns. I've never owned a 4x4 before and don't know a lot about their maintenance (I guess some would argue whether I've actually got a 4x4 or not). Anyway, thanks for the help.

 

It's me again. I just forgot to add in the fact that I still have my F150, in case some of you thought I'd totally fell off the wagon. We got the Explorer to replace the wife's '99 Mustang, which is not a practical family car in any stretch of the imagination. Our family will have a fourth member on April 5 and we had to have something to start making trips in. Thanks again for any suggestions.

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1997 F150 SC Lariat 4x2 Styleside
Oxford White/Prairie Tan Metallic
4.6 auto, 3.55
17" ORP wheels w/ 275/60R17 Goodyear Eagle GTII's
Extang soft tonneau cover
Kenwood 7003 CD head unit w/ remote, Sony 2x25W and Clarion 2x100W amps, Ultimate 10" pickup boxes
Powerdyne 6 psi supercharger, Autometer boost gauge

To come:
Ford Motorsports headers
Ford Motorsports 9mm plug wires w/ plugs?
Autometer fuel pressure gauge
Superchip
4.10 rear w/ 23-tooth speedo gear (gotta read right!)

Wishful thinking:
SVT 18" Lightning rims (painted Prairie Tan to match two-tone) w/ 285/55R18 Yokohama AVS's

 

OK, I'll try to tackle all of this and try to make it simple, so I don't get confused myself. Here goes:

First, the front wheels should be at about 5% power at all times, unless conditions call for them to engage more. How do they engage? Well, first off, there is viscuos fluid in the transfer case, somewhat like ATF, this fluid "connects" the front and rear driveshafts to the engine and to each other. But, it's a fluid connection, like auto transmission. Some AWD systems use a low range hard connect. Which just means that when in 4wd lo, the transfer case connects the two driveshafts together mechanically. There is also the same viscous fliud in both the front and rear differentials. Now, for the cool part. When the rear wheels slip, reletive to the front wheels, the fluid in the transfer case gets hotter and more viscous due to the added friction of the slipping wheels. When the fluid heats up and gets more viscous, the torque is then transfered to the front wheels because the higher viscosity fluid turns the front drive shaft. The same type of actions happen in each indiviual wheel, ie. left front slipping reletive to right front.

I hope this makes sence, and helps you out. It's really a cool idea. Much like automatic transmission was a cool idea when all that was available was standard.

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2000 Silver F-150 XL Sport
Reg. Cab, Reg. Bed, 4.2L V6, 5-speed, 4x2

mods:
Tailgate lock, Generic bedliner
285/75r16 BFG AT ko (33.1x11.4)
Sony CD player, Blaunpunkt 5.25" speakers
Crimeguard alarm, Power locks
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Never let your schooling interfere with your education --Mark Twain

[This message has been edited by r0land (edited 03-07-2001).]

 

Wow, I am impressed!! I would have given an answer like "The tires turn"