Auto 4WD to 2WD

[Guest]

Greetings. I have a 99 XLT that is used on paved, dry road at least 99% of it's miles. I would like to have 2WD mode available as well as A4WD, 4HI and 4LO. The quick way would be to pull the fuse for the transfer case clutch but then you need to stop and plug back in to activate 4X4. Anybody else done this, have a suggestion?

 

[Guest]

See following link to thread. It has been discussed in length.

http://www.ford-trucks.com/forums/showthread.php?s=&threadid=197105&perpage=25&pagenumber=1

 

[Guest]

Thanks for the thread. Seems my idea wasn't as hairball as it first seemed. I thought this out on a long highway trip pulling a heavy trailer without load leveler bars. The difference in tire rotational diameter was enough to trigger the A4WD and make some rude noises and handling. Pulled the fuse and bingo! no more noise. Now I will just do what the rest of the group suggests and wire in an inline 30 amp and heavy duty switch.

 

[Guest]

More research and what is probably the ultimate solution has surfaced. Remove the 30 amp fuse, wire in a relay with 30 amp high current protection and actuate the relay from a toggle on the dash. No more worries about high current through a toggle inside the truck, corosion on the terminals etc.

later

 

[Guest]

Back again with my hopefully last post on this subject. Installed the relay and switch as described above. During normal driving I engaged A4WD a few times just to see the difference if any on dry pavement, no load, highway cruising. Significant steering feel change and driveline noise in A4WD. My truck has 120K miles on it. Off to my transmission shop buddy and he said "Oh! another one. I didn't know you had an Expedition, pull into bay 3 and we'll fix you right up." The problem seems to be the clutch in the transfer case gets a little agressive when the fluid gets old. Solution, drain and fill with synthetic fluid. Noise gone, steers like new. Do your transmission a favor and fill with synthetic as well.

Happy Expeditioning.

 

[Guest]

Other fourums, people haven't seen an increase in MPG.. Since installing your switch, have you noticed any?

 

[Guest]

Too soon to tell but I doubt that you could actually document a positive change in fuel economy. You have to know that the drivetrain is more efficient now so fuel economy will be better. The original purpose was to make it steer better, ride quieter. Accomplished, anything else is a bonus. Oh yes, cost of the mod was 22 dollars for parts and about an hour of my time. The synthetic fluid was significantly more expensive ($85) but worth every penny.

later

 

[Guest]

MX Oldtimer

I think I'm going to do this mod too. What parts did you purchase to do the job, and where did you get them (Autozone, NAPA, etc.)

Thanks

 

[Guest]

First a little update. We have documented a small fuel economy increase over the last 4 fills. This truck is used 90% highway and 10% city so the mechanical efficiency has a relatively large impact on fuel economy. 1.4 mpg isn't much but it is about 8% so no complaints.

Parts: 10 feet of 14 gauge wire, 50 amp relay (rating isn't important, just more than 30 amps), 30 amp inline fuse, toggle switch. assorted connectors.

Simple installation. Remove fuse, wire 2 ISULATED female spade connectors into fuse location and connect to relay with the 30 amp fuse on the power side. Please note the relay is just a switch, not a power supply. Run a wire through a grommet into the truck. I located my switch on the right side of the snap off panel that contains the 4X4 switch. Connect relay wire to one side of the toggle and SWITCHED 12 volts to the other. NOTE: if your relay is mounted on a body panel that is grounded, it should now work. If it is mounted on plastic somewhere, a ground wire is needed. That is one of those don't ask lessons.

If you need A4WD, switch on, otherwise switch off. No way to disconnect front diff. Yet. Manual hubs would be nice.