4wd, or lack there-of

[irishboy02]

So last weekend, Foosh and I were out having a grand ol' time in the mud. All of a sudden foosh looses his 4wd. We shrug it off and keep wheelin. Then i get stuck in deep soft sand in 2wd so i go to switch into 4. Upon switching into 4, we heard the audible hum/wine of the tc engauging but then when i hit the gas you can hear a spinning almost slight grinding sound with no front wheel power.

It almost sounded like those wind up matchbox cars.

Then I turned off my truck and then when i started back up it worked fine. Once i got home it was working fine again...

Any ideas?

[The Roadie]

Your splined disconnect for the front intermediate shaft must not have fully engaged. The noise was some percentage of your splines being sanded off. It's probably weaker now. Why wait until getting stuck to engage 4WD? It's not a very robust system they designed for us.

Ahhhh, getting stuck was part of the FUN?!?

I can't recommend that. Your only other vehicle was running in 2WD mode, and you were the designated one to be able to tow HIM out of trouble! That's the time to slow it down and preserve your options. Did you try to engage it on the fly, or in neutral with no driveshaft RPMs? On the fly with significant difference of RPM from front to rear could break things. You can engage 4HI on the fly (at least there's no interlock) while running at any speed, but it's only safe for the transfer case and front drivetrain if the front and rear wheels are spinning at the same speed.

[bgwolfpack]

Roadie is this something you've seen a lot of before? Is it indicative of this system? That would scare the shit out of me and if it's more than rare, please comment. I personally would rather always be in 4HI when off road unless the conditions do not warrant it.

Was it a case of over zealous mud action and slamming the engagement or something else?

Glad you guys made it back OK. Time to look at the damage?

[irishboy02]

It was far from planned. It acted like quick sand and just sucked me in, so i tried to engauge 4 to get me out and bam no more 4. Once i turned the truck off for a little bit and then back on, i went into 4auto and once the rear spun the front caught and i just didnt stop untill i was well out of the way. But then my 4 worked after that point?

Weird

I have not gotten my 50k maintence yet and i am just shy of 52k. I have my extended warrantly untill feb 2010 or 63k, whichever comes first. However, i am going to need to powersteam my engine bay before i turn it over to them

[Trail X]

After you transition from 2 to 4, its a good idea to drive slowly and turn your front wheels left to right slightly. This will help align the splines in the front driveshaft.

If your splines weren't aligned, thus making the syncro activate, the syncro may not have fully seated into place on the intermediate shaft. If you apply a lot of gas in this condition, it may make the syncro skip across the splines without seating.

Sounds like you heard the TC motor humming... did you also hear the front actuator humming? If you don't hear the front actuator hum, it could be a non-mechanical issue.

I still haven't had time or a chance to pull mine apart. Having no garage, my window of opportunity is much smaller now than during the summer.

[irishboy02]

Tell me about it, dont you just love these 7hr daylight days

I was stuck installing my lift untill 145am under the street light, neighbors loved me that day

I dunno, im not too keen on dealing with transmissions. Ill do anything else, that ill leave to the pros.

James, did you expierence this same issue or was yours different?

[The Roadie]

It's rare, but I never engage the system in conditions that might trigger the problem. I'm normally in 4HI/4LO whenever I'm off pavement. Engages the clutches fully in the transfer case, reducing stress. Leave pavement, air down, engage 4HI/LO, pee by the side of the trail - good to go!

A4WD is a hateful invention and should NEVER be used offroad, IMHO. To wait for slippage, then expect the vehicle to do something on its own sweet schedule to keep you moving, is insane. The TC clutches will engage with a bang, could shear the torque-limiting tangs, and break the weak TC internal bearing mount that we (2005 and older?) are stuck with.

I can't stress enough that my tactic is to NEVER touch A4WD mode. I'm working on a TCCM replacement module that will skip that mode altogether in favor of the MUCH more useful 2LO.

If anybody has a defense of A4WD mode offroad, let me hear it. Otherwise, I really want everybody to take a pledge to shun the mode. And not speak of it again.

[irishboy02]

I use(d) a4wd during sleet conditions as well as very heavy rains. This was before my bfg mk2's.

In my defense, this was my first ACTUAL offroad adventure so i learned the ropes. After i got 4wd to engauge, i did not dis-engauge it and it worked properly from that point.

One scenario we thought is maybe the angle that the front axles were on, since we were not sitting on a flat surface, could have effected the engaugement of the teeth on the gears? Just some food for thought.