Whole Front End Locked Up!

Something locked. Here?s the sequence of events. I drove up the steep, unpaved entrance to my house, about a quarter mile, in four wheel drive in my 4x4 Mazda pickup. At the top of the drive I shifted out of FWD and pressed the dash switch which electrically disengages the front hubs. Then I pulled in to my dry cement parking area and reversed making a ninety degree turn and parked. The next day I started up the truck, shifted into first, started to let out the clutch and it wouldn?t move. At first I thought the parking brake had frozen for some reason and gave it some gas to break free. Then I realized the rear wheels where spinning in place and that it was the front end that wouldn?t turn. At this point I should have jacked the front end up so at least one wheel was free in the air but I didn?t. Instead I shifted the transfer into 4 Low and started to ease out the clutch. There was a loud clunk and it broke free. I shifted back into 2 High and went on my way. I later shifted into 4 High on some steep loose sections and the 4x4 system seemed to work as normal nor were there any strange mechanical sounds. So what happened? How could the front end have locked up solid or was it from the transfer case forward? All I can figure is the front hubs and 4x4 didn?t disenge during the short distance I was in reverse and the short ninety degree turn somehow bound up the transfer case. Any ideas?

I don’t know how the front wheel disengagement works on this rig. Do the axles electronically disengage at the wheel hub, or is there a mechanism in the differential / on the axle tube? I would guess that they were half in / half out and binding some how. That’s why I’m asking if they disengage the front differential from the axle shafts, because I’m having a hard time envisioning anything binding in front of the transfer case that would cause it not to roll. Could have been an object stuck in a u-joint or something?

My other thought would be that the transfer case may have been between 2 and 4 wheel drive AND the hubs weren’t disengaged, but if you were able to shift it cleanly from 2 to 4 and THEN it made the clunk, I don’t think that sounds right.

If it works, just drive it and keep your fingers crossed.

The transfer case stuck between settings. Who knows why or how? Tricky things happen with 4WD. Don’t use the 4WD unless you need it. If the rear wheels spin too much, try some weight in back. If the road is gravel and not mud, it is probably best to do it in 2WD. If a kill is too steep, there couldn’t be loose gravel on it. Some 4WD systems are only meant for snow and not for serious use.

(Quote) Some 4WD systems are only meant for snow and not for serious use.(Unquote)

Since when?

Since they put little buttons on the dash that say “engage/disengage”. When you push the button, you have to ready for anything or nothing.

I have a '91 PowerWagon (W-250 Dodge) that, when you move the transfer case lever, a Rube Goldburg vacuum switching mechanism hopefully engages or disengages the front axle buy moving a shift dog built into the front axle assembly. If it ever craps out, I’ll just scrap the truck rather than attempt to repair it. Give me manual Warn hubs anytime. Simple and reliable. All this nonsense so the driver doesn’t have to get out of the truck and engage the hubs…“Automatic” front hubs have ALWAYS been a crap-shoot. They seem to fail when you need them most. That BANG you hear usually costs AT LEAST $1000 to make right again…Then there is BANG, clank clank clank clank…That’s $3500…

You know, they sell a $30 cable actuator kit that gets rid of the vacuum engagement on that thing.

While I am usually hesitant to agree with the “more technology is bad” crowd, I have to say, the least reliable parts of most modern 4wd systems are the transfer case shift motors, and the front axle engage/disengage motors. When people need reliable 4wd systems, they usually bolt on manual hub lockouts and find a transfer case with a manual shift lever. My F-100 has a divorced NP205 and a Dana 44 with manual hubs, and even though you have to get out and freeze your butt to lock in the hubs, and you can’t “shift on the fly”, when you want it in 4, you know you’re in 4.