First drive in snow handling report vs Chevy-Jeep-Porsche

[DANACO]

You sure about that? Typically letting things be partially engaged with clutches leads to overheating clutches. Just curious, where did you hear this?

I think the resistance is due to the front hubs being locked, not the transfer case being partially engaged. This means that the front axles, differential and driveshaft are engaged though no power is supplied to the driveshaft.

The 4A system is not an on off switch, it’s variable just like many AWD systems are. If it were not engaged you would not feel that resistance in the steering just like you don’t when in 2H. There are no locking hubs in this system in the front, it’s a Torsen differential, look it up and understand how they operate. The only elements of the system that can be locked in the are center transfer case between the front and rear (4H) and the rear differential in low.

 

[TurboTJ]

The 4A system is not an on off switch, it’s variable just like many AWD systems are. If it were not engaged you would not feel that resistance in the steering just like you don’t when in 2H. There are no locking hubs in this system in the front, it’s a Torsen differential, look it up and understand how they operate. The only elements of the system that can be locked in the are center transfer case between the front and rear (4H) and the rear differential in low.

I’m not sure what you’re saying.. the front hubs are always engaged? I don’t believe that is correct but I would have to check.

Traditional AWD systems have a center differential that sends power front and back. They don’t disengage when there is plenty of traction (like a Raptor does). They are always engaged. This is why they are different than a Raptor’s transfer case. I would suggest that you read up on conventional AWD systems and maybe the viscous couplings used.



The Front diff has little to do with this other than, with the hubs engaged, you can feel it in the steering wheel due to the limited slip (maybe) as well as the front axles and driveshaft spinning.

The wet clutches the t-case uses are to connect into 4WD while there is a front/rear speed differential. They cannot be used in a constantly slipping state or they will overheat.

edit: Upon looking into it further, yes, when you put it in 4A the front hubs lock up. This is likely what you feel in 4A since unlike 2WD, the front axles, differential and driveshaft is now spinning. The Torsen front will resist the speed differential associated with sharp turns even if not power is going into the front axle.

There is debate as to whether or not the clutches are always sending power to the front wheels. Best engineering practice is to not always slip clutches so I would bet they are only engaged when slipping is detected. Slipping wet clutches = wear and heat. Heat needs to be dissipated to function correctly. Think of it like driving a manual at full throttle and controlling your speed with the clutch pedal. You’d need a new clutch quick. Of course, this is a dry clutch which means it likes slip even less.


Of course, this is coming from Ford who is well know for their differential clutches over hearing on the RS so who knows if best engineering practices can be assumed.

 

[Okegg0]

I picked up my 18 Raptor in January of last year about a week before we started getting blasted with winter storm and blizzards after another here in ND. Can honestly say it handles awesome for most part. I pull a trailer with a snowblower and it really pulls the back of the truck around in deeper snow as the part of the town I am in gets plowed out last so I always have to go through whatever was dumped on us that day. I came from an F350 so a lot more weight I suppose. Without the trailer though there is nothing I wouldnt try with it in 4wd and traction control off. Noticed that was the key for a lot of the things I did just to be sure I got out of what I was going in.