Front Diff Engagement

zaac · November 28, 2009

How exactly do the axles lock to the diff when in 4x4? Clutches/gears/splines? Never got a chance to look at it during the rebuild. Thanks.

Nytemare · November 28, 2009

They're always engaged. You put your truck in 4WD and you allow power to be transferred and drive the front diff via the Transfer case.

The axles are splined in to the carrier, same as a rear diff.

If you look at the drive shaft and the front axles while the truck is moving you will see that they all spin, whether in 4wd or not. Your just not sending power to the front if its not in 4wd.

zaac · November 28, 2009

What is the actuator for on the front diff? If I remove the front driveshaft I can spin the diff pinion when in 2x4. I also can spin the output shaft on the TC but with drag when in 2x4. I always figured the front driveshaft turns when in 2x4 because of clutch drag in the TC.

Nytemare · November 28, 2009

The TC is a chain driven part...

There is an actuator on the T-case...either handraulic....(operated by a shifter in the floor)

or an electrical actuator that pushes in a coupler that engages the front drive section on the TC, allowing power to be transferred to the front wheels.

There should be no actuator on your front diff.

Heres a pic of how everything goes together:

zaac · November 28, 2009

Thanks for the pic. I wish I could find an exploded veiw of the front diff. The front diff does have some sort of electric motor on it. When I push the 4x4 button I can hear it along with the one on the TC. If I jack up the front end and remove the driveshaft I can spin the yoke and the front wheels don't turn. Put it in 4x4 and spin the yoke and the wheels turn. So there has to be something in the front end that engages and disengages. The motor on it looks much like the one on the TC. I'll try and find some pics.

Matt_ · November 28, 2009

the actuator on the front diff disengages the passenger side axle which results in only the spider gears spinning when in 2wd mode. the ring gear, pinion and front driveshaft do not spin in 2WD mode on these truck. I think this is an 03+ model year feature.... but could be wrong, it might be 99+ (edit, if your truck is a 2000 with this actuator, then it probably was a 99+ application)

zaac · November 29, 2009

the actuator on the front diff disengages the passenger side axle which results in only the spider gears spinning when in 2wd mode. the ring gear, pinion and front driveshaft do not spin in 2WD mode on these truck. I think this is an 03+ model year feature.... but could be wrong, it might be 99+ (edit, if your truck is a 2000 with this actuator, then it probably was a 99+ application)

Thankyou. Now for my question; what actually engages? Clutch/gears/splined. Found a pic.

http://www.monsterautoparts.com.bcentralho...otor_switch.htm

Nytemare · November 29, 2009

Heres an exploded view

Nytemare · November 29, 2009

My guess would be that 9 is what shuffles back and forth engaging the axle 61...and is driven off of 36.

looks like parts 13 through 17 are the actuator and actuates 11....to shuffle 9.

Matt_ · November 29, 2009

Thankyou. Now for my question; what actually engages? Clutch/gears/splined. Found a pic.
http://www.monsterautoparts.com.bcentralho...otor_switch.htm

On the exploded view posted above, #11 engages #36 via the actuator (which pushes the fork, #15)

Matt_ · November 29, 2009

My guess would be that 9 is what shuffles back and forth engaging the axle 61...and is driven off of 36.

looks like parts 13 through 17 are the actuator and actuates 11....to shuffle 9.

9 is stationary but has the same external splines as the #36 shaft. The internal threads of #9 mate with the output axle shaft #61. When the actuator engages it pushes for fork #15, which is connected to #11 over to link #9 and #36. When disengaged, #11 slides back fully onto #9, thereby breaking the 9 to 36 link.

Nytemare · November 29, 2009

My guess would be that 9 is what shuffles back and forth engaging the axle 61...and is driven off of 36.

looks like parts 13 through 17 are the actuator and actuates 11....to shuffle 9.

9 is stationary but has the same external splines as the #36 shaft. The internal threads of #9 mate with the output axle shaft #61. When the actuator engages it pushes for fork #15, which is connected to #11 over to link #9 and #36. When disengaged, #11 slides back fully onto #9, thereby breaking the 9 to 36 link.

Ahhhhh...seen now.

yeah...first I have heard of this actuator...I just haven't paid too much attention to front diffs really. We mostly work on cars at our shop..and older vehicles in need of engine rebuilds. Most of the time a newer truck comes in its for tire changes or oil.

Is it just me or does this look a lot weaker than it actually is.

zaac · November 29, 2009

9 is stationary but has the same external splines as the #36 shaft. The internal threads of #9 mate with the output axle shaft #61. When the actuator engages it pushes for fork #15, which is connected to #11 over to link #9 and #36. When disengaged, #11 slides back fully onto #9, thereby breaking the 9 to 36 link.

Thankyou, I understand fully now. Sorry for being such a pita.

Thanks for the pic, Aiden. You definitely have better internet search skills than me.

As for it being a weak or strong setup, it out lasted my G80 rear-end. The locking mechanism was fine but the clutches were completely wasted. Glad the front-end doesn't use clutches.