4x4 question

While driving in to work this morning I noticed the Jeep next to me had the front drive shaft spinning while he moved. My initial thought was "Why is he in 4-wheel drive?". Then I wondered if maybe my front shaft was spinning too.

My understanding is that in 2-wheel drive the front hubs are not locked (whatever that means) and the transfer case is only spinning the rear shaft. Shifting into 4-wheel drive locks the front hubs and engages the front shaft.

Is that right?

 

It all depends on exactly how the 4x4 is configured. On a stock Gen 1 Tacoma the front hubs are fully engaged and never unlock. The front drive shaft disengages at the transfer case and the front differential. When in 4x2 the tires will spin the front CVs but the front drive shaft should be stay still. Many other setups have lockable front hubs. If the front hubs are left locked the front tires will spin the entire front drive line.

 

Was it an older Wrangler? I know that some of them had issues with the vacuum switch for the front differential, so the cheap fix was to disconnect the switch and allow the front driveshaft to engage the diff. It is still disconnected at the transfer case from what I understand. Mind you, I am recalling from a conversation years ago with a friend who has a '97 Wrangler.

 

Dodges jeeps pretty much all new trucks solid axle you can see the u joints spinning in the knuckles. Unless they have manual hubs.

 

It was a Cherokee. Maybe about as old as my truck. It sounds like maybe it's right for that truck.

If I understand the answers correctly, on my truck the front diff is always spinning because the wheels spin the CVs which turn the diff, but the front shaft only spins if I'm in 4-wheel?

 

My 98 4x4 taco has manual hubs. When they are disengaged nothing up front moves. That's if my xfer case is in 2hi. When I'm in 2 Hi and hubs free I can go underneath and spin the front driveshaft by hand which in turn spins the CV axles freely. When hubs are engaged the driveshaft and cvs spin. Just have to lock in the xfer case to xfer power.

 

Front locker. Ideally the torque from the spinning wheel will travel through the axle, diff then through the free axle, leaving the drive shaft untouched. If you're locked all 3 outputs will be spinning together.

Jeep and Tacoma 4wd work similarly. If you have ADD (not manual locking hubs) 2/3's of all your shit's going to be spinning all the time.

 

Yup, with ADD front end your driveshaft will most likely always be spinning. The driver front wheel is directly connected to the cv which is directly connect to the diff. which is directly connected to the front shaft. Only thing that dis engages is the tcase to driveshaft and diff to pass. wheel. So if the tires are spinning most likely the shaft is spinning. This is how most 4x4s work now days, but some I.e. Dodge and jeep have no axle disconnect so nothing dis engages but the tcase so the front shaft will always spin. With manual hubs you break the connection from tires to diff so the spinning wheels will not spin the diff which spins the shaft. This is why manual hubs are supposed to net you better mpg, you get less drag from not spinning all the extra components

 

manual hubs are good on 1st gen Tacoma's for less wear on the cv boots that tend to rip all the time. Lifted application of course.

 

the other day I had my 2000 up on my buddy's alignment rack so i could inspect it for wear/damages. i grabbed the front axle and spun it freely while it was in neutral. i guess i was able to do so cause the front e-locker and transfer case were not engaged.