I used my 4x4 for the first time today in my new 97 F150 extended cab. Big snowstorm tonight. I drove all the way home and it didn't really feel all that stable. I pulled into my driveway, opened the door, held the brake down, and pushed on the gas in the snow and ice. the back drivers side wheel spun but nothing else would. i tried shifting into 4low, still no difference. Shut the truck off, put tranny and transfer case in neutral- front driveshaft spins freely. Put transfer case in 4x4, driveshaft has about a quarter inch rotational freeplay. Truck doesn't have manual lockouts. How does this whole system work, and what do you guys think is wrong? My last truck was a 91 with manaul lockouts, so this is all new to me. Thanks
aaron

 

Welcome to the world of SOF 4WD, with NO HUBS.

The '97 and newer F150's have no hub what-so-ever, it's a flanged axle like what's on the rear. They are basically a set of axles with the ring and pinion combined in the front by some sort of solenoid engagement when you shift to 4x.

By holding the brake down and checking for engagement doesn't seem to work with an open diff, that's probably what you have. The front is definitely an open differential in stock form. The rear will depend on what options were installed. Check your door sticker under "axle." A letter first in the two digit code indicates a limited slip rear.

Most people around the board seem to prefer to find an open area and checking for spin with a buddy. Guess that way you can get a tow if you get stuck?

Check, with the truck jacked up and running, if the front driveshaft will spin in 4HI, when you try to rotate the front tires. If it does, then you're system sounds like it's broke. Could be the engagement device on the front. If you have teh electronic shift **** for 4x, then it may be the motor in the xfer case or some other electrical connection with that system

The quarter inch of axle play may indicate something is worn...?

-Kerry

 

Thanks for the info. I'm learning alot about these new things. Who knew it could take 2 1/2 hours to change sparkplugs.
With an open differential in the front, shouldn't one wheel still spin if i have a rear tire spinning? If the front wheels won't spin when there's a force acting against them(such as brakes, or good traction), then what good is 4wd? Essentially it becomes 2wd.
aaron

 

It may be that engagement system up front isn't working right.

You also have to remember that the brake bias is set so that the forward brakes are probably going to lock (at a stand still the ABS disengaged), but the rear may spin. I don't know how hard you had the pedal pressed, just an idea.

I've had the free rear wheel spin, while the one getting traction didn't do a thing on an open diff.

You're going to have to jack that truck up and check the front for rotation again. It'll have to be with the engine running to rule out any vacuum or electrical problems.

-Kerry

 

starting in 97 the front axle is engaged by a vacumn motor. Crawl underneath and look along the passenger side axle tube, you will see a black plastic cover with the vacumn shift motor underneath it.
Rich

 

i took the cover off the vacum shifter, and when i shift into 4x4, it doesn't seem to move. There are two vacum hoses going to the axle. I tracked them up to two little black "things".

 

Does anyone know any procedures i could use to find the problem?
aaron