3rd Gen front wheel lock-up in 4wd? Anyone had this happen?

Looking for some advice from the experts here.

Scenario:

While blinded by the sun, that long 3rd Gen front hood, and some long grass I stoved my front end into a dry drainage cross-cut (water bar) on a deactivated logging road. I was running in 4lo as the grade was quite steep. The truck did not come to a full stop, and it rode through and up the other side dragging the hitch receiver. Air bags did not deploy and truck was outwardly undamaged, I just hit the ditch way harder than I would have had I known it was there.

After inspecting the truck for damage, I drove the truck another 50 feet forward up the road and came to another cross-cut which I stopped to have a look at and decided I could roll through at a safe speed. When I stopped this second time and went to roll forward, one or perhaps both of my front wheels were locked up and the rear wheels just kicked up gravel. I had a look under the truck and could not see anything out of sorts, so I tried again (convinced I was imagining it).....same thing....just rear wheels spinning (and possibly one front....didn’t think to check at the time). A little bit of panic is now setting in as I am quite a far ways out in the wilds. So I reversed the truck (not wanting to inch forward any more and drop into the second cross cut) and the problem resolved itself and has not returned. I cycled the transfer case, tried all modes of 2WD and 4WD and all gear selections and can not replicate the problem. I have also jacked up my front end and the front wheels spin smooth separately, and properly counter-rotate with 4wd engaged.

So thinking this through it seems possible I either had a rock stuck in one caliper, or I’ve damaged my front diff and whatever chunk I took out of it is free of the assembly and maybe laying on the bottom of the housing. I don’t think the transfer case could be a problem as I think I would have still rolled forward with transfer case issues. Also I can’t see it being the front brakes as in 4wd clamping both front wheels would also stop the back wheels.

Anyways.....this issue has left me a bit baffled. I’m going to drain the front diff and transfer case oil this weekend and look for debris, I was just wondering if anyone else had any advice or thoughts on this, or had experienced anything similar?

 

Ok, well I guess I’m the only one. That’s normal for me.....uughhh.

 

Probably everyone is busy with outdoor fun stuff, height of the Summer and all.

And....bump- hope all is good when you change out the fluids.

 

Yes thanks! This situation has me puzzled. I wish I had taken more time to fully figure out what was going on at the time, but just a tad of panic stopped me from being more methodical. I will update if I find anything in the diff or transfer case fluid. If not, I’ll assume I had a rock in one caliper and was just fighting that one jammed wheel.

 

When the original condition occurred, you said you were in 4Lo. I didn't see in your post, was MTS/A-Trac engaged when you first encountered the issue, or were you just running open?

 

Just running open.

 

I can tell you I did effectively did almost the identical thing, running into a deep washout hidden by weeds at about 15 mph. I swear the nose flew at least a foot in the air, freaked me out, but didn't break anything that I have seen. Seat belt definitely got used that time, seat covers luckily did not...

It is pure speculation, but with you running in open diffs when it happened, I would bet on a single jammed brake and only one front wheel was jammed and the other was spinning. And don't feel bad about not being super observant on every little possible detail when in the midst of this type of thing. In similar situations, my mind instantly jumps to problem solving to getting out of there, and doesn't think so much about logging exact data for root cause.

Just don't think the transfer case could have allowed the front axle (or both front tires, or front diff) to be jammed while the rear turned in 4Lo, without self destructing at least. So front diff would have had to have jammed on one side only it seems to be. So I think a single wheel jammed, which seems likely to just be debris in brake or wheel.

But that may me just being optimistic...

 

Hey..... I appreciate very much you taking the time to respond. Thank you. You are absolutely right about ones mind jumping to problem solving. Kinda a “fight or flight” takes over. I hope you are right about a jammed wheel. I got a bit waylaid today with other chores so will probably tackle the fluid on Tuesday night. Will post the results.

 

I know how things go, but any update yet?

 

I'd say check fluids. Pull diff plugs and see if any big chunks.

I personally think it was just glitchy brakes.

 

I called out of town on a job, so taco is sitting in the driveway. Will do the work this weekend and update if I’m not waylaid by something else.

Maybe a quick question:

How badly do I need new sealing washers for the transfer case and diff if I change the fluids? Are the washers single-use?

 

washers are single use based on factory service manual.

For the cost would you really want to risk it?
how fuckin shitty would it be if your diff or T case ran dry and seized up all for a what $5 part?

 

My vote is on binding of some type.

 

I wasn’t looking to skimp, just trying to coordinate getting to a dealer to buy a washer kit if they are not open when I return from my job.

 

Ok, so I changed my front Diff and transfer case fluids today. I’ll do the rear diff over the weekend.

No chunks, no shards, no debris or chunder in there so that was a huge relief. Both fluids were fairly dark and fairly sparkly with minute metal particles from the break-in period, but not cloudy.

I’ve put about 4000km (2500M) off-road, in 4WD, on this truck, so the fluids were what I expected from the factory fill. Both cases were filled to the exact right level from the factory so the Toyota Texas boys were doing a good job they day they built up my Tacoma.

So the mystery of what locked up my front wheel or wheels remains for now.

This picture is of the magnetic plug out of the front diff before cleaning. Not too bad. Mostly very fine particles.

 

Glad to hear transfer and front diff look ok. Thanks for the update.

 

Could have been a hard enough hit to throw something out of sync. Which resolved itself once you reversed, as it seems to have been put in a bind while going forwards.

 

Drained the rear diff tonight. Also just dark and sparkly as you would expect for factory fill. Nothing obvious. Minimum fine particles on the magnet. Actually less magnetic schmoo on the rear magnet than the front magnet which surprised me.

This has me stumped. Hope it’s a one-off.


Unrelated, while I was under the truck I greased my front propellor shaft (no zerks on the rear). The u-joints were not dry, but filled with a very dark stinky factory grease. Incredibly slippery and tacky stuff, and lots of it in there. Felt like an ass for forcing it out with new grease, but what’s done is done. It was nice to see that the u-joint seals were working so well as I did a lot of off-road driving this winter, and the bottom of the truck got caked in silt many times. Gives me hope for the fully sealed, zerkless rear U-joints.

 

I wouldn't stress it too much. If everything appears fine, and is acting fine, then just chalk it up as a one off. Just be more mindful of any noises that may emanate from the front end.

 

You did all the due diligence inspections that are reasonable at this point. So the only thing left I think is to put together a plan should (heaven forbid) it happen again. Not sure what the plan should be...
Maybe keep a GoPro or cell phone camera in the truck to set on the ground or under the truck to see if one front wheel is spinning, or neither.
Or if front drive shaft is spinning... etc. I haven't climbed under to see how hard it would be to actually film it.
Or hook up techstream and save a log of wheel speeds. Not sure, just brainstorming.
(Techstream is pretty effective at data logging in my experience, but it takes time to set up the parameter list, so its something to do ahead of time ideally)