anyone know about fwd based 4x4s?
 

I've gotten into a few heated discussions with a coworker over the device that fwd based vehicles use to make it 4wd (Ridgelines, Escapes, etc) it hasn't come to blows but neither will back down either. It connects the transaxle to a driveshaft to an independent rear differential.

He tries to claim its a front differential, which I know it isn't due to it has a transaxle and the front wheels will keep working if it should run dry but the back wont or driveshaft were to break etc. I say its a transfer case, which he says its not since it doesn't work like the ones you'd see on a "traditional" 4x4. He also says he found it in some book but has never shown it for proof.

I've tried looking up online for a blow up of the underside of one and didn't find anything real useful. Mostly I want it for my own info.

It's a transfer case. If some car company wants to give it another name like electronic coupling unit, it's still a transfer case.

SaturnSdn good to see you, stop in more often.

I think he found it in some book he used for the school he went to.

I'll try and stop in more but no internet at home and my computer was stolen a while back.

There are a number of different transfer-case variations to bring something into a all wheel or 4 wheel drive mode. Some are mechanical, others are viscus materials and the ruggedness or design of them depend in part on the designed usage of the vehicle. Not only do the names very from brand to brand but the functional characteristics will too. Something that is basically a front wheel drive car or truck which the rear wheels switched in and out will be light duty. Something like a 3/4 ton pick up that is rear wheel drive will be heavy duty mechanics
Something like a Suburu which is light duty and cheaper will be different than a Mercedes which will be expensive and light duty.
Dunno? I am not sure it is worth the argument, there are way to many variables involved to give things a one size fits all answer.

I do understand but its that I work at a lube shop and when we put down the fluid levels on the front diff/transfer case/rear diff on said vehicles that the arguments can begin. I say no front diff (since its a transaxle), transfer case level if we can check it, and rear diff level if we can check it. We don't argue if its a rwd based 4x4 or a Subaru style awd. If we worked any field outside of auto I agree it would be a totally pointless argument like the whole Ford/Chevy/Dodge argument.

Well, under those circumstances, yes there is a front wheel drive differential. There has to be in order for the front drive wheels to work as they should. The difference as you it is part of the Transaxle. Not a separate or stand alone piece. If you were to diss-assemble the transaxle you will find the differential pieces in side it. That is why the thing is called a trans-axle. It COMBINES the function of the transmission (shifting gears) and differential ( allowing one wheel to turn at a different speed than the other while turning)

Right and that is my point to this guy, if the driveshaft is disconnected the front wheels still drive the car due to the transaxle. The "front diff" is usually checked with the transmission check since its generally all 1 unit, thus the transfer case is NOT the front diff. but he swears its a front diff. If you look at most of the 2wd version you can see where the transfer case would bolt up to the transaxle.

Of course it is! If it is not a separate unit mounted some where between the transaxle and the drive shaft that drives the rear axle.
What I am saying is this:
The function of the transfer case is to supply power to the non engine driven differential. If the car in question has a trans-axle thus the engine supplies power to it to move the car, than the trans-axle's function becomes one to also supply power to the rear wheels. If the trans-axle is the source of that power it very well could have been built on to the case of the trans-axle or it could have been built in to the trans-axle function thus becoming part of the trans-axle.

Again look at the function of the vehicle. If the vehicle is built well enough to go off road with 4WD than the odds are it will be a something that had originally had a rear wheel drive 2 wheel drive configuration and the transfer case (the item that transmits engine power to the rear axle) will be modified to fit onto or become part of the transmission. And then would be used to transfer some power used to drive the rear wheels to the now added front wheel differential.

But if the car in question is a light duty vehicle than the primary axle drive will be the front axle as driven by the engine through the trans-axle. It now becomes the source of power for now added rear axle. Thus the transfer case will become added to the mechanics of the front drive-axle thus becoming part of it. It could be added on the trans-axle becoming part of it or built into the trans-axle also becoming part of it. And it will now be the source of power to the rear axle and thus the trans-axle becomes the source of power for the rear axle and uses the built into or added onto transfer case function to do it with.