4WD Lock or 4WD Auto?

[SyN]

Bad Weather is just around the corner.

This is my first 4WD with 4WD Auto.

For those who use their 4WD {Very Often}.

Is is better to leave the Pickup in 4WD Auto and let it decide when you need it?

Or Just put it in 4WD Lock=4WD High and have it all the time?

I have heard many horror stories about 4WD Auto. As well as many good stories about the benefits of 4WD Auto-->One being better fuel mileage compared to 4WD High.

I have not heard many stories about how effective the Ram 4WD Auto system is.

My Ram will never see hardly any off-roading--> Mostly Snow and Ice and the last few winters have been worse and worse-->Thus the reason for my question.

There will be a few instances of traveling over 300 miles in the snow and ice and I was really wanting to know the best position to put my 4WD System in---> 4WD Lock or 4WD Auto?

Thanks SyN

 

[BlackRamHemi]

I usually leave mine in 4-auto all year round, totally safe even on dry roads.
There are no negative side effects, the front only kicks in if your rear lets go.

I only use 4 Hi lock when Winter hits the hardest
like during a snow storm/blizzard with icy streets, snow drifts, low traction.

4Lo Lock ...only off road and only slow crawling obstacles (never for me)

 

[SyN]

BlackRamHemi--->Thank You!

 

[JinxCanada]

Personally in bad weather I have had my ass end slip out and THEN the 4WD auto kicks in...but it's scary at times. If the weather or roads are really bad I'd suggest 4WD Lock for those times.

 

[14hemiexpress]

I agree with the above statments. I would use 4wd auto if it's not bad out side, could save you on some black ice. But snow on the ground may as well keep it in 4hi. The way I picture it use 4hi when you normaly would with a truck that doesn't have 4auto as a option and if you would normally run your truck in 2wd but still iffy out use 4 auto.

 

[Flip-er]

I use 4 Lock if snow is on ground and traction is bad.
4Auto is nice too BUT go with your gut and how you feel

 

[HemiRoar]

When there's heavy snow or slush, lock that sucker up. I only have 4WD lock/low and 2WD. I remember getting stuck in a parking lot with bad potholes full of slush after a heavy snowfall..and 4WD acted like I was on dry ground. This was with the stock tires too.

 

[SyN]

Thanks for all the advice!

One more question is there any speed limit to using the 4WD Auto?

This sounds like the selection I would use if I was going down the interstate and it was just starting to drizzle during freezing temps or with just some what Icy roads--->Just before the heavy snow started to fall.

It just seems very hard on the system going 45-55 mph in 4WD Auto and hit a section of ice or hard packed snow and the front drive kick in.

But I do understand the best times to select either 4WD Auto and 4WD Lock! That part makes perfect sense.

 

[loveracing1988]

Thanks for all the advice!

One more question is there any speed limit to using the 4WD Auto?

This sounds like the selection I would use if I was going down the interstate and it was just starting to drizzle during freezing temps or with just some what Icy roads--->Just before the heavy snow started to fall.

It just seems very hard on the system going 45-55 mph in 4WD Auto and hit a section of ice or hard packed snow and the front drive kick in.

But I do understand the best times to select either 4WD Auto and 4WD Lock! That part makes perfect sense.

There is no maximum speed for any mode but 4 low. Four auto and four lock are essentially the same thing in these trucks so it doesn't really matter what mode you out it in. It will only use 4wd when it deems you need 4wd, that is in any mode including 4 low.

 

[fondupot]

My experience with GM trucks and 4 wheel auto setting is to only use it when you need it. Its able to shift on the fly.

I know its a newer feature on Ram and Ford truck starting to have transfer cases with the 4 auto feature. But I think they work similarly. Being able to shift on the fly, from 2hi to 4 auto or 4 hi.

Driving around in 4 auto year round is not needed. It will reduce your mpgs because the transfer case is engaged for when it needs to send power to the front wheels, so its adding parasitic loss as opposed to 2hi when its just being a pass thru.

Running 4 auto at higher speeds (aka interstate) is NOT going to help you when you hit a patch of ice. First off, you shouldn't be driving at normal highway speeds when freezing is possible. But even if you are, and you hit ice, not even the best 4 wheel drive system is going to keep you from slipping.

Normal dry conditions, use 2hi.

Slick roads/rain/light snow, use 4 auto.

snow packed roads/heavy snow/off road, use 4 hi

low speed off road, use 4 lo

 

[BlackRamHemi]

My experience with GM trucks and 4 wheel auto setting is to only use it when you need it. Its able to shift on the fly.

I know its a newer feature on Ram and Ford truck starting to have transfer cases with the 4 auto feature. But I think they work similarly. Being able to shift on the fly, from 2hi to 4 auto or 4 hi.

Driving around in 4 auto year round is not needed. It will reduce your mpgs because the transfer case is engaged for when it needs to send power to the front wheels, so its adding parasitic loss as opposed to 2hi when its just being a pass thru.

That's not how it works in a Ram,
and it's not new to Ram, mine is almost 5 years old already (2010 with New Venture Gear T-case)
I believe the new Borg Warner (44-47) T-case that came on line in 2012 operates 4-Auto the same way.

The transfer case is always "engaged" even in 2WD,
BUT The front drive shaft does not "engage" unless the rear tire slip is detected.

(in 4-Auto mode) When the wheel speed ABS sensors sense a significant speed difference from front to rear,
the solenoid triggers an electric clutch to engage the front shaft in the transfer case.
Once wheel speeds match up again the clutch is released, seamless operation.

There is zero difference in drag in 2WD vs 4WD Auto on dry pavement

Only 4 Lock is capable of sending power to the front end when its not really needed.


The only difference in operation in the new T-cases
is you can no longer get the tires to bind in a tight turn in 4lock on dry surface like the old New Venture T-cases.
It's almost as if Ram couldn't trust the average consumer to use 4Lock properly and put a protection mode on them to keep T-Cases from grenading.

The big disadvantage is that same protection factor now is a liability for off-road enthusiasts.

The new Borg Warner T-case is pretty much in 4 auto mode regardless of 4 auto or 4 hi lock is selected.

 

[loveracing1988]

That's not how it works in a Ram,
and it's not new to Ram, mine is 5 years old already

The transfer case is always "engaged" even in 2WD,
BUT The front drive shaft does not "engage" unless the rear tire slip is detected.

(in 4-Auto mode) When the wheel speed ABS sensors sense a significant speed difference from front to rear,
the solenoid triggers an electric clutch to engage the front shaft in the transfer case.

There is zero difference in drag in 2WD vs 4WD Auto on dry pavement

Only 4 Lock is capable of sending power to the front end when its not really needed.

Since 2013 any 4wd mode needs wheel slip to engage the clutch in the transfer case.
Yes there is more drag in 4 auto than 2wd, in 2wd the front axle is disconnected from the drivetrain. In any 4wd mode the front axle will be engaged at all times, so you will be spinning your front driveshaft in 4 auto but not 2wd.

 

[BlackRamHemi]

Since 2013 any 4wd mode needs wheel slip to engage the clutch in the transfer case.
Yes there is more drag in 4 auto than 2wd, in 2wd the front axle is disconnected from the drivetrain. In any 4wd mode the front axle will be engaged at all times, so you will be spinning your front driveshaft in 4 auto but not 2wd.

If the front drive shaft is always spinning, (4-auto)
what you are saying essentially is the auto 4WD "connection" is actually in the differential then?

Not in my 10', that's for sure.

I've taken highway trips and had no difference in fuel economy 2wd vs 4 auto,
I've also made several hundred passes at the local track (2WD, 4-Auto and 4x4Hi)
...the only ET that dropped 2 - 3 tenths was the 4x4 Hi runs

I've probably made 400 passes total over the last 5 years.

Before drag racing I was an avid off-roader and Jeep jamboree trail guide (since 1982)

I've torn open a few transmissions and transfercases,

I have not opened a new Borg Warner T-Case,
but it sounds like a **** from what I've heard so far.

If 4 auto and 4 hi lock operate the same now,
why even have two settings on the selector??

 

[Andy578]

Since 2013 any 4wd mode needs wheel slip to engage the clutch in the transfer case.
Yes there is more drag in 4 auto than 2wd, in 2wd the front axle is disconnected from the drivetrain. In any 4wd mode the front axle will be engaged at all times, so you will be spinning your front driveshaft in 4 auto but not 2wd.

for the auto yes but the part time case doesn't require slip and will still bind. tested mine a few times when i got it

 

[NYCruiser]

X2 - My part time 4WD without the Auto setting will bind and lock without slippage like I'm used to. Its a different T-case entirely than the ones with the Auto setting.

I had a 2005 Ford Expedition with the Auto transfer case, and it worked much the way the new Rams do. Required a little slip before engaging even in the lock position. I wouldn't have bought my Ram if it had that setting because of it.

 

[BlackRamHemi]

I have yet to find confirmation on the new Borg Wagner 44-47 T-Case..

But the old NVG 246 does not engage the front drive shaft on 4-Auto setting
UNLESS the clutch is engaged due a slip detection. It's not an AWD system.

Same T-case GM uses in many trucks

During normal driving situations, the transfer case can operate in the Auto 4WD mode. In the Auto 4WD mode, the transfer case shift control module monitors rear wheel slip speed, based on the inputs from both the front and rear propshaft speed sensors. When the vehicle experiences a rear wheel slip condition, the transfer case shift control module sends a pulse width modulated (PWM) signal to an electronic motor, which is the transfer case encoder motor. This motor rotates the transfer case control actuator lever shaft, applying a clutch pack. This clutch pack is designed to deliver a variable amount of torque, normally delivered to the rear wheels, and transfers it to the front wheels. Torque is ramped up to the front wheels until the front propshaft speed sensor matches that of the rear propshaft speed sensor. Torque is ramped down to the front wheels. The process would repeat if rear wheel slip is detected again

 

[NYCruiser]

That kind of says it right there. It's using inputs from front and rear prop shafts. If the front diff wasn't engaged, how would it get front data to compare to the rear?

 

[BlackRamHemi]

That kind of says it right there. It's using inputs from front and rear prop shafts. If the front diff wasn't engaged, how would it get front data to compare to the rear?

LOL, that was from a GM truck (but same model T-case)
Our trucks actually use wheels ABS speed sensors at all four corners too determine wheel slip.

Both drive shafts always turn on a Ram 4x4
even in 2WD, mount up a go pro camera if you don't believe me

The question is only whether the shaft is turned by the front axles
or driven from the chain in the transfer case.

Since we don't have lock out hubs on the front end,
there is nothing in the front axle to keep the ring and pinion from turning the front drive shaft.

I'm telling you that front drive shaft, although turning, is not from the transfer case,
the clutch pack is not engaged unless the electronics are told to transfer some of the rear torque to the front drive shaft.

I've played the 4x4 game for over 35 years, I can assure you this is not my first rodeo
I do not know for a fact that the new Borg Warner T-case is the same as the pre- 12' New Venture/New Process T-cases.
But I will do my best to find out.

 

[loveracing1988]

LOL

Both shafts always turn,
even in 2WD, Get a go pro camera if you want proof.

The question is only whether the shaft is turned by the front axles
or driven from the chain in the transfer case.

Since we don't have lock out hubs on the front end,
there is nothing in the front axle to keep the ring and pinion from turning the front drive shaft.

I've played the 4x4 game for over 35 years, I can assure you this is not my first rodeo

http://www.youtube.com/watch?v=4UoBCIjWIoU

Front axle disconnect. They've had them since at least 87 or so for gm. The front cvs turn but the front prop doesn't. In the BW 44-44 case the front prop does not turn unless the front axle is connected. In 2wd it won't turn.

 

[BlackRamHemi]

There is no front axle disconnect in my 2010 Ram 4x4,
if that's what they are putting in the new Ram 4x4 trucks to idiot proof them,
looks like I wont be rushing to trade mine in any time soon.