Power distribution in AWD auto

[RamMe]

Flipped to awd auto in heavy rain the other day and noticed the truck felt like it put more power up front and pulled vs a balance distribution. Honestly it was the first time I used AWD in the truck so it was a new feeling vs being pushed in 2WD. I've had full time awd in my past and current cars -bmw, audi and range rover. They all felt more balance with slightly more rear biased power. Not sure what the RAM power distribution is for AWD vs the other brands. I know Audi & BMW is 40:60, Range Rover 50:50.

 

[millerbjm]

Flipped to awd auto in heavy rain the other day and noticed the truck felt like it put more power up front and pulled vs a balance distribution. Honestly it was the first time I used AWD in the truck so it was a new feeling vs being pushed in 2WD. I've had full time awd in my past and current cars -bmw, audi and range rover. They all felt more balance with slightly more rear biased power. Not sure what the RAM power distribution is for AWD vs the other brands. I know Audi & BMW is 40:60, Range Rover 50:50.

The owner's manual (and other discussions here and my experience) indicate that 4WD auto keeps the truck in RWD unless a loss of traction is sensed at which point it sends power to the frint wheels. This makes it different than AWD which as you mentioned has a defined split between front and rear axle power. If you felt a distinct difference in the feel of the truck I would say either something is off with your truck's system or you are way more sensitive to the change than I a because I've never noticed a difference in the 7 years I've had a Ram with 4WD auto.

 

[kdoublep]

Never noticed this either

 

[Scap]

On mine, the truck feels like it's got less power for the same throttle input when I put it in 4WD A.

I assume it is due to the front end being engaged, even if the xfer case isn't sending power up there.

 

[Neurobit]

I really can’t feel a difference. I used 4WD Auto when it rains for added traction and to keep everything operational.

 

[Richard320]

Auto four wheel drive is not the same as all wheel drive.

Auto four wheel is plain four wheel drive that is engaged by a computer instead of you. When it kicks in, it's no different than if you picked 4 HI. When it's engaged, the two driveshafts are locked together, so the power split is 50-50. All wheel drive has a center differential so the power split can be uneven.

 

[IvoryHemi]

Auto 4WD is basically Full Time 4WD.

The transfer case clutches need to detect slippage between the front and rear axle, in order to redistribute power. So yes there is power being routed to the front axle in 4A, how much I don’t know.

While there is no center differential, the electromagnetic clutch packs can distribute an uneven power split and vary power sent to the front axle.

 

[dearchristopher]

the only time i notice 4wd auto is when i’m in reverse and have the front wheels turned (e.g. backing a trailer). i can feel it pushing me a little bit. other than that, its a pretty seamless system. only notice it kick in off road.


Sent from my iPad using Tapatalk

 

[LouNY]

On mine, the truck feels like it's got less power for the same throttle input when I put it in 4WD A.

I assume it is due to the front end being engaged, even if the xfer case isn't sending power up there.

I would expect the front end to feel heavier and different,
when 4wd auto is selected the front axle disconnect engages.
The front axle engage is what replaced free wheel hubs many years ago.
When disengaged it disconnects one axle shaft from the differential, engaged both axle shafts are connected to the differential.

Auto four wheel drive is not the same as all wheel drive.

Auto four wheel is plain four wheel drive that is engaged by a computer instead of you. When it kicks in, it's no different than if you picked 4 HI. When it's engaged, the two driveshafts are locked together, so the power split is 50-50. All wheel drive has a center differential so the power split can be uneven.

The power is not split 50-50 in these transfer cases.
I have not seen a good breakdown diagram of these t-cases but there has to be a mechanical assist to the electric clutches.
There is no way that a straight electrical clutch can handle the amount of torque going thru the t-case.
The electric clutch is controlled by the computer in any mode.
At one time I had seen a chart that showed the amount of torque that the 44-44 was supposed to apply with perfect disc's

 

[RamMe]

On mine, the truck feels like it's got less power for the same throttle input when I put it in 4WD A.

I assume it is due to the front end being engaged, even if the xfer case isn't sending power up there.

This is the same feeling I get. RPM shift points are a little different as well.

 

[IvoryHemi]

The power is not split 50-50 in these transfer cases.
I have not seen a good breakdown diagram of these t-cases but there has to be a mechanical assist to the electric clutches.
There is no way that a straight electrical clutch can handle the amount of torque going thru the t-case.
The electric clutch is controlled by the computer in any mode.
At one time I had seen a chart that showed the amount of torque that the 44-44 was supposed to apply with perfect disc's

Yes, power is indeed split 50/50 in these transfer cases when in 4H or 4L. Yes, the clutches can handle it

“4WD High enables the clutch pack to fully engage, locking the vehicle in a 50/50 torque split between rear and front axles. This range is suitable for use only off road or on snow- or ice-covered dry pavement, where there is some wheel slip available to stop driveline windup and crow hop. 4WD Low does exactly the same thing as 4WD High but adds a 2.64-1 gear reduction and likewise should be used only off road or on snow- or ice-covered pavement.”

BorgWarner 44-44 Transfer Case from the Electronic Side - Transmission Digest

Discover the inner workings of the BW 44-44 transfer case and its electronically controlled active full-time operation in Ram pickups.

www.transmissiondigest.com

 

[TruckDriver]

Saw this video a while back - great visualization of AWD vs Locked vs 2WD in our 5th Gens in particular

 

[kdoublep]

He's brave doing that with those wheels and tires

 

[LouNY]

Yes, power is indeed split 50/50 in these transfer cases when in 4H or 4L. Yes, the clutches can handle it

“4WD High enables the clutch pack to fully engage, locking the vehicle in a 50/50 torque split between rear and front axles. This range is suitable for use only off road or on snow- or ice-covered dry pavement, where there is some wheel slip available to stop driveline windup and crow hop. 4WD Low does exactly the same thing as 4WD High but adds a 2.64-1 gear reduction and likewise should be used only off road or on snow- or ice-covered pavement.”

BorgWarner 44-44 Transfer Case from the Electronic Side - Transmission Digest

Discover the inner workings of the BW 44-44 transfer case and its electronically controlled active full-time operation in Ram pickups.

www.transmissiondigest.com

That article is on the 44-44 T-case and it is pure and simple BULL.
Those clutches and RAM's programing could not handle the torque applied to them.
I had that case in my 2015 Eco-diesel and I know for a fact how poor it was when hard work was expected of it in low traction conditions.
My trucks use 4wd every day climbing my driveway year round in the dry months so as not to churn up and loosen the gravel and in the winter months for enough traction to make it to the house.
And then throw in some mild to moderate off road use in differnt farm situations.
The 44-44 was the absolute worst t-case I have ever had the misfortune to have in a truck I owned.
The auto function was nice in the spring, summer and fall pulling any kind of load out of field roads and onto dirt or paved roads,
that is the only time that it was worth a damn.

With a 4.71 transmission low gear and a 2.74 t-case low gear times the torque avilible from the engines:
with the eco-diesel you would end up with over 5000 pound feet of torque.
There is absolutly no way that the little multi disk electricaly activated clutch could handle that,
which is why that t case has a ball and ramp to compress the clutch plate when the rear axle is getting traction.
It doesn't do anything with no traction at the rear.

The video of the newer Rebel was interesting it shows what the traction control can do in high traction conditions.
Because that was what was making that truck move not the t case but the traction control.

 

[IvoryHemi]

That article is on the 44-44 T-case and it is pure and simple BULL.
Those clutches and RAM's programing could not handle the torque applied to them.
I had that case in my 2015 Eco-diesel and I know for a fact how poor it was when hard work was expected of it in low traction conditions.
My trucks use 4wd every day climbing my driveway year round in the dry months so as not to churn up and loosen the gravel and in the winter months for enough traction to make it to the house.
And then throw in some mild to moderate off road use in differnt farm situations.
The 44-44 was the absolute worst t-case I have ever had the misfortune to have in a truck I owned.
The auto function was nice in the spring, summer and fall pulling any kind of load out of field roads and onto dirt or paved roads,
that is the only time that it was worth a damn.

With a 4.71 transmission low gear and a 2.74 t-case low gear times the torque avilible from the engines:
with the eco-diesel you would end up with over 5000 pound feet of torque.
There is absolutly no way that the little multi disk electricaly activated clutch could handle that,
which is why that t case has a ball and ramp to compress the clutch plate when the rear axle is getting traction.
It doesn't do anything with no traction at the rear.

FCA used the MP3023 transfer case with the EcoDiesel in the WK2, which also uses clutches and had a 50/50 power split with a 4.71 first gear

Also currently use the MP3010 case with the 6.4L, 4.71 first gear and 50/50 split with clutch packs in WK2, WD and JL

 

[Mountain Whiskey]

Man, I can see that video going up on the Jeep forums and those guys rolling around in hysterical laughter.

 

[LouNY]

The older cases did NOT split the torque evenly using just the electrical side of the clutch,
on my 2015 installing a kit to give it full voltage it did considerably better.
In low traction surfaces it never came close to doing a 50/50 split.

I hope that the 2019 with the different BW case does better. I know that it feels better
in normal operation so far. I just picked up the 2019 this spring so it hasn't been on ice
for me yet.

And to put it as plainly as possible untill I see this t-case working better in very low traction conditions
I will have my doubts.

By my calculations the chart you posted with 1600-1800 NM so 1180-1327 foot pounds,
so that is along way from handling any where near the torque that could be sent to that case.

I have not seen a parts breakdown or power flow schematic on the newer cases and it was hard to find
on the 44-44. So whats BW trying to hide.

The BW 44-44 would split the power equally to both the front and rear driveshafts with the truck in the air and no drag what so ever on the axles,
which would be minimal power.
If the front axle was on the ground and the rear in the air at low rpm the front tire would just sit and quiver, it would not spin,
if it rotated it was in partial revolution jerks.