[subiesailor]

Its a subaru not a 4x4 lol

 

[subiesailor]

OK, so a few more facts. No part of the chassis was resting on the ground. The right rear wheel was not hanging freely, but certainly without sufficient weight and contact to get traction. The vertical face of the rock showed I left quite a bit of rubber trying to get out. The front wheels were not on loose gravel and did not spin when trying to engage (and burning up) the clutch. I couldn't rock the car as the rear bumper was pushed up against (but not caught on) even larger rocks in the back. I've attached another photo showing how I got out after sliding the jack under the frame and lifting the entire car enough to push some rocks and large branches under the real right wheel and putting an old blanket over the stuff and the rock. With that help, the car pulled right out with little problem.

So, my question is exactly how does the center differential work on my car and how much torque is shifted to the front wheels or to the LR wheel in such a situation? I didn't get any sense that the front wheels were pulling at all.

As to the FWD fuse "solution", I'll go back to the mechanic about the fuse working only for a 4 speed auto. If I'd had an automatic would it have pulled out on its own? Why? Thanks for the comments. LRV
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AT would have been better MT the gearing is way to high to tackle this type of technical surface. You couldn't spin the front wheels because you couldn't get enough power to them with the MT ie your gearing was too high and you had to slip the clutch to keep from stalling the car. MT the AWD system is very basic there really isn't anything to fail other than the viscus coupler but that won't matter in this case given you couldn't get enough power to the wheels to start with due to the MT and slipping the clutch.

Not to mention if the rear wheel was spinning enough to put some rubber on the rock - the viscus coupler was working given thats what sends power to the rear of the car. Again your issue would be lack of low gearing in the MT which is why the hard core off road guys in the outback prefer the AT the torque Converter makes up quite a bit for not having low gearing.

The only other possibility is a CV joint which has failed on the front end as a result the axle is turning but the front wheels are not. I highly doubt this though.

 

[subiesailor]

too much for it to pull over, but like was said it is surprising the wheels didn't move.

the rear viscous type LSD's degrade as an open rear differential with age fairly often. so that both rear wasn't spinning doesn't surprise me. the fronts though that is strange.

Not really - block a tire good and give the rest decent traction add MT with tall gearing and you just do not have enough power to spin two tires or three regardless. My guess is that the aWD system is just fine and the reason why he didn't spin the fronts, simply didn't have low enough gearing to get power to the wheels.

 

[subiesailor]

OM: Thanks for the further response and sorry for the delay. When trying to get the car out, yes, I released the clutch peddle as far as I felt I dared with the engine revving. The car would lurch ahead just a tiny bit each time, but no front wheels spun. With the clutch burning, I felt certain that fully releasing the clutch would have just stalled the car. Yes, I understand that a lot of torque going somewhere would be needed to pull and lift the RR wheel out of the hole. So, then, would the "fuse solution" have worked? By putting in a fuse into the "FWD" fuse slot, would that have disengaged the center VC (or whatever it's called) so that the engine power would have gone only to the front wheels? If so, then that should have pulled me out since the chassis was not stuck and the LR wheel was firmly on the ground, correct? Someone else has suggested that with a MT, that the gearing can't get low enough to work in that situation and that an AT has lower gearing. Would that have made a difference? Also, exactly how does the center VC send power to the wheels with more traction, when the system is working properly? Thanks. LRV

Clutch never released ='s not enough power sent to wheels. Turning the car into front wheel drive would have done nothing if the rear of the car was hung up enough where the front wheels would have simply just spun - assuming you had released the clutch all the way.

In this type of situation you need to let the clutch out and see if the car has enough gearing and power to hop out of the hole. Given you never did that - you have no idea if the gearing was beyond way too tall with zero hope of powering the car out of the hole. Having zero initial roll makes it very difficult to simply let the clutch all the way out but that really was the only option and if the car died without ever getting close to getting out of the hole - then you were simply lacking the right gears ie low gears to do the job. Hence why the AT is preferred by the OB guys who do pretty technical off road stuff over the MT.