Brand new tacoma with the button-engaged 4WD. (where have you gone lever engaged 4wd?)

Well I was out looking for the dog, who had run off again, and was slipping a bit on snowy roads in 2WD.

I stopped the truck, turned the 4WD button to engage and the 4wd light started blinking, but didn't wait long enough and pressed the accelerator too quickly when the light was still flashing.

Long story short, rear wheels started slipping and then it ka-klunked into 4WD.

I read in the owners manual to never engage 4wd when the wheels are slipping, and of course I managed to do it right off the bat, ha. Of course I blame this on the damn button engaged electro-fandagled 4wd.

Regardless,

A) Why is engaging 4wd with spinning wheels bad for the transfer case?

and

B) Did I just hurt my transfer case somehow?


Thanks!

 

With the back tires spinning and the front tires not spinning, you are putting a lot of torque to the drive shaft, transfer case, axle shafts when it engages.

You ever used a drill into a steel plate and then all of a sudden it get a good bite and the bit stops turning and the drill jerk your hand or twist your wrist? When a lot of power all of sudden comes to a stop, something has got to give. Depending on how much it was revved, if the front tires could slip and release some of the power and several other things, you may have lucked out and nothing happened or you could of damaged the transfer case.

That is a lot of weight of the truck sitting on your axle shafts and transfer case to all of a sudden to try and get moving all at once.

 

A: To elaborate on what Terry said, the transfer case is not synchronized like the transmission and there is no clutch to slowly bring the two together. Between 2 and 4 wheel drive the front and rear drivelines are either connected or disconnected, no in between and no soft transition. In order to shift into 4x4 the front and rear drivelines need to be spinning at the same speed whether that be stopped or driving without tire slip. The reason for this is because you're coupling two spinning parts together. If they are spinning the same speed no big deal, but if they are spinning different speeds it's a large shock load when you force them to engage with each other.

B: I would guess no damage resulted from one mistake, but I wouldn't suggest doing it again.

 

Definitely will be more careful next time, its obviously something that is a little different from the lever engaged transfer cases I'm used to, where you don't have to worry about lag time for engagement.

I was at low RPMS around 2k I think and the front wheels were on snow too so maybe that helped ease the stress on the Tcase.

Hopefully I didn't do any lasting harm.

 

Sounds like you are going to be ok. The thing with push button 4 wheel drive is it is not engaged right off the bat. Sometimes it takes a little movement to get things in sync. As nice as it is to just push a button and get 4 wheel engaged, you really should engage it before you get into a sticky situation. The newer trucks are built so that push button/turn the knob is what engages 4 wheel and in some cases not much you can do about it.

My 3rd gen runner is something I am very careful about what sticky situation I get into just because of the slow response to engaging 4 wheel. My older trucks, you manually engage the hubs and transfer case so I might actually get stuck first before engaging and can get out. Not so much with my 3rd gen.

Pros and cons to how each truck is set up whether push button or manual engagement.

 

About as simple as I can put it .

The push button style made for the new style SUV crowd that find it unfashionable to push a lever or let alone get out and engage hubs.

 

That ka-klunk could have been a ka-SNAP.

But it wasn't, so you're good! THIS TIME.

But hey, any part can break at any time, even in t-cases with levers, right? So don't worry too much about it.

Make sure your fluid levels are full. Drive patiently. Shiny side up. =)

 

Im wondering if you will shorten the life of the T case by doing this, or if it is more of a "as long is it didn't break its fine."

Does it strip any gears in there or anything, or is it just more of a it didn't break its fine?

 

After doing a test drive in 4 wheel, are you hearing or having any issues? If not I think you are going to be ok. Other then the ka-thunk, is there something else that has your suspicions?

 

No, nothing, more worried about long-term damage.

More of, Im concerned my transfer case will grenade at 60k or something.

 

Drain the fluid and strain through metal coffee filter if you want to confirm you didn't break bits and grind them up.

You should be fine though. If it ever fails, you replace it. But that's not today so drive on!

I've been waiting for my loud transmission to fail someday. I made a post about it here, YEARS ago! It still buzzes, but it's still going, so I'll drive it till it grenades. But im confident the fluid in there is fresh and full, so no worries until then.