4WD reliability vs 2WD

[Ridgerunner665]

I didn't realize the 44-45 also had a clutch until now... thank you for that bit of education.

I like the 44-44 just fine for my uses, as I've said on here a few times before.... I'm not someone who can hard core offroad a truck this expensive.

The 44 isn't a bad T-case, not at all... but it isn't the one I'd want for rock crawling either.

I've had my truck (2018 CC) in some pretty sloppy mud getting into and out of the cow pasture, and a pretty dang rough road up the mountain to go deer hunting (as rough as this truck will ever see), and driven it on snow/ice covered east Tennessee back roads through this past white Christmas.... the T-case does great, the OE tires are the weak link... but used within their limits, even they aren't terrible.

If I wanted a stump jumper truck.... I'd build one from a much older truck.

Lastly..... the clutch "might" prove to be a good design for a T-case....I know I broke the front shaft on more than a few T-cases in my younger days.... seems to me replacing the clutch might be less expensive than a shaft, and on parts shelves for longer.

Forged and machined metal parts are costly and time consuming to make... little clutch packs, not so much.

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[kurek]

So I'm a bit disappointed in my Ram now knowing that there is a clutch pack in my T-case.Just another unnecessary failure point.Not that I've had an issue with this one or my 15 SLT but neither have a lot of miles either.Doesn't leave me feeling all warm and fuzzy.

Some kind of slip engagement is necessary to make shift on the fly possible..

The front axle disconnects the passenger side wheel from the differential while in 2wd to prevent the front driveshaft and the bottom half of the transfer case from spinning all the time.

That saves gas and wear and noise. But it means when you are driving forward the passenger side of the differential is spinning backward, so if the axle disconnect would try to engage you would just get glitter and grinding noise out of it.

That means something has to bring the front driveshaft and front differential carrier up to speed before the axle disconnect can engage. I had not previously given much thought to how this was accomplished, in the back of my mind knew it needed some sort of slip engagement but before now had not considered any specifics.

As long as the clutch has ample size and clamping force for the torque it will see I don't consider it a likely failure point, it should not experience wear at any point other than during shifts and if you make the choice to only shift into 4wd at low speeds or stopped that wear should be very close to zero.

 

[Brandon-w]

Some kind of slip engagement is necessary to make shift on the fly possible..

The front axle disconnects the passenger side wheel from the differential while in 2wd to prevent the front driveshaft and the bottom half of the transfer case from spinning all the time.

That saves gas and wear and noise. But it means when you are driving forward the passenger side of the differential is spinning backward, so if the axle disconnect would try to engage you would just get glitter and grinding noise out of it.

That means something has to bring the front driveshaft and front differential carrier up to speed before the axle disconnect can engage.

As long as the clutch has ample size and clamping force for the torque it will see I don't consider it a likely failure point, it should not experience wear at any point other than during shifts and if you make the choice to only shift into 4wd at low speeds or stopped that wear should be very close to zero.

GLITTER! [emoji1787]

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[CVX20]

Some kind of slip engagement is necessary to make shift on the fly possible..

The front axle disconnects the passenger side wheel from the differential while in 2wd to prevent the front driveshaft and the bottom half of the transfer case from spinning all the time.

That saves gas and wear and noise. But it means when you are driving forward the passenger side of the differential is spinning backward, so if the axle disconnect would try to engage you would just get glitter and grinding noise out of it.

That means something has to bring the front driveshaft and front differential carrier up to speed before the axle disconnect can engage.

As long as the clutch has ample size and clamping force for the torque it will see I don't consider it a likely failure point, it should not experience wear at any point other than during shifts and if you make the choice to only shift into 4wd at low speeds or stopped that wear should be very close to zero.

Not true.You've always been able to shift on the fly to 4wd Hi without adding a clutch pack.My old GMC New Process T-case went 300 K miles with no clutches,just not necessary.I fixed t-cases,trans and diff's for a living for 15 years at a dealer so I have a pretty good understanding of how they operate.The only way to destroy the frt diff is by not getting off the power and giving it time to engage/dis-engage or by running it out of oil.

As far as the clutch pack in my t-case,it may never fail but you have to admit it is just another unnecessary failure point.

BTW My 4wd gets used daily in the winter up here in the North.On a 20 mile trip to work(one way) it might get shifted in and out of 4wd 6 or 8 times at hiway speeds(50 to 60 mph).No clutches,no issues.

 

[Ridgerunner665]

Shift on the fly had been around a while... but those older ones had all the front end stuff rotating forward all the time.... and they were noisy...I had a 79 Chevy full time 4x4, best truck I've ever owned... bought it used for $800, replaced a spindle bearing, put an engine in it that I rebuilt myself when the one that came in it threw a rod.... drove that truck for 13 years.

It had the NP 208 T-case, the one most everybody hated, never gave me an ounce of trouble.... but it ate front tires like candy (BFG Mud Terrain tires on it didn't help that any).

They all have their quirks.

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[Quyonmob]

Not true.You've always been able to shift on the fly to 4wd Hi without adding a clutch pack.My old GMC New Process T-case went 300 K miles with no clutches,just not necessary.I fixed t-cases,trans and diff's for a living for 15 years at a dealer so I have a pretty good understanding of how they operate.The only way to destroy the frt diff is by not getting off the power and giving it time to engage/dis-engage or by running it out of oil.

As far as the clutch pack in my t-case,it may never fail but you have to admit it is just another unnecessary failure point.

BTW My 4wd gets used daily in the winter up here in the North.On a 20 mile trip to work(one way) it might get shifted in and out of 4wd 6 or 8 times at hiway speeds(50 to 60 mph).No clutches,no issues.

agreed, as long as the front and rear driveshafts are spinning at the same speed, powering the front shaft is seamless.

I shifted my 92 k1500 np241 with a firm pull at at any speed, even after installing a cable front diff actuator. Never a grind. Even shifting the range side was smoother at a 3mph roll.

the auto function does require a clutch, as it waits for the abs sensors to tell it a wheel speed difference front to rear (losing traction) then applies the front output of the tcase to regain traction

 

[kurek]

Not true.You've always been able to shift on the fly to 4wd Hi without adding a clutch pack.My old GMC New Process T-case went 300 K miles with no clutches,just not necessary.I fixed t-cases,trans and diff's for a living for 15 years at a dealer so I have a pretty good understanding of how they operate.The only way to destroy the frt diff is by not getting off the power and giving it time to engage/dis-engage or by running it out of oil.

As far as the clutch pack in my t-case,it may never fail but you have to admit it is just another unnecessary failure point.

BTW My 4wd gets used daily in the winter up here in the North.On a 20 mile trip to work(one way) it might get shifted in and out of 4wd 6 or 8 times at hiway speeds(50 to 60 mph).No clutches,no issues.

Think it through man... there is a splined disconnect in the front axle which separates the passenger side output of the differential from the passenger side CV shaft. Since the front differential is open this means when you are driving 60mph your wheels are spinning around 630rpm, the driver side axle shaft is spinning 630rpm forward, the passenger side axle shaft is spinning 630rpm forward, the differential carrier itself is stationary and the passenger side stub shaft from the differential is spinning backward at 630rpm.

That means if you didn't bring the front driveshaft and front differential carrier up to speed before engaging the axle disconnect there would be a 1260rpm difference between the passenger side stub shaft from the differential and the passenger side CV. Splined engagement is either 100% or 0% so an attempt to engage that while the front driveshaft is stationary would either produce grinding (and failure) or it would produce an extremely violent bang as 40 lbs of steel suddenly went from 0 rpm to hundreds of rpm in 0.000 seconds.


On the transfer case side it's a similar story, at 60mph with 3.92 diff gears and ~33" tires your transmission output shaft is spinning around 2470rpm and your rear driveshaft is spinning around 2470rpm but in 2wd the lower half of the transfer case, the front driveshaft and the front differential are all going 0 rpm. If you had exclusively interference engagement with no clutch it would be necessary to bring all that steel up from 0 rpm to thousands of rpm in 0.000 seconds. It would either grind or it would slam with extreme violence.


If you don't have some kind of slip engagement either in the transfer case or in the axle there is just no way to smoothly accelerate a bunch of stationary steel to full operating RPM. It's not about whether or not you're transmitting torque (pressing the gas or letting off) it's about the difference in speed and how you make up that difference.


My previous 4wd vehicle had a 4 position transfer case, 2wd/AWD/4H/4L with no clutches and it was always possible to shift back and forth between AWD and 4H at any speed, because in AWD the front axle disconnect was engaged so the front driveshaft and differential were already up to speed, as long as you're not at that moment also doing burn-outs there is 0 rpm difference between the front and rear driveshafts so there's no drama in locking the center differential. It was also always possible to shift from AWD into 2wd at any speed because there's no drama involved in letting spinning parts coast to a stop on their own time. But you could not shift from 2wd into any of the 4wd modes while moving because you can't just accelerate all that metal from stationary to fast in zero time.

Sure you can have shift on the fly at any speed without a clutch if you just leave the front axle engaged all the time because then the front driveshaft is always spinning. Our trucks don't do that.

 

[pacofortacos]

So I'm a bit disappointed in my Ram now knowing that there is a clutch pack in my T-case.Just another unnecessary failure point.Not that I've had an issue with this one or my 15 SLT but neither have a lot of miles either.Doesn't leave me feeling all warm and fuzzy.

 

[CVX20]

Shift on the fly had been around a while... but those older ones had all the front end stuff rotating forward all the time.... and they were noisy...I had a 79 Chevy full time 4x4, best truck I've ever owned... bought it used for $800, replaced a spindle bearing, put an engine in it that I rebuilt myself when the one that came in it threw a rod.... drove that truck for 13 years.

It had the NP 208 T-case, the one most everybody hated, never gave me an ounce of trouble.... but it ate front tires like candy (BFG Mud Terrain tires on it didn't help that any).

They all have their quirks.

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Not talking strait axle frt ends.88 and up with the CV axles had no noise.

 

[CVX20]

Think it through man... there is a splined disconnect in the front axle which separates the passenger side output of the differential from the passenger side CV shaft. Since the front differential is open this means when you are driving 60mph your wheels are spinning around 630rpm, the driver side axle shaft is spinning 630rpm forward, the passenger side axle shaft is spinning 630rpm forward, the differential carrier itself is stationary and the passenger side stub shaft from the differential is spinning backward at 630rpm.

That means if you didn't bring the front driveshaft and front differential carrier up to speed before engaging the axle disconnect there would be a 1260rpm difference between the passenger side stub shaft from the differential and the passenger side CV. Splined engagement is either 100% or 0% so an attempt to engage that while the front driveshaft is stationary would either produce grinding (and failure) or it would produce an extremely violent bang as 40 lbs of steel suddenly went from 0 rpm to hundreds of rpm in 0.000 seconds.


On the transfer case side it's a similar story, at 60mph with 3.92 diff gears and ~33" tires your transmission output shaft is spinning around 2470rpm and your rear driveshaft is spinning around 2470rpm but in 2wd the lower half of the transfer case, the front driveshaft and the front differential are all going 0 rpm. If you had exclusively interference engagement with no clutch it would be necessary to bring all that steel up from 0 rpm to thousands of rpm in 0.000 seconds. It would either grind or it would slam with extreme violence.


If you don't have some kind of slip engagement either in the transfer case or in the axle there is just no way to smoothly accelerate a bunch of stationary steel to full operating RPM. It's not about whether or not you're transmitting torque (pressing the gas or letting off) it's about the difference in speed and how you make up that difference.


My previous 4wd vehicle had a 4 position transfer case, 2wd/AWD/4H/4L with no clutches and it was always possible to shift back and forth between AWD and 4H at any speed, because in AWD the front axle disconnect was engaged so the front driveshaft and differential were already up to speed, as long as you're not at that moment also doing burn-outs there is 0 rpm difference between the front and rear driveshafts so there's no drama in locking the center differential. It was also always possible to shift from AWD into 2wd at any speed because there's no drama involved in letting spinning parts coast to a stop on their own time. But you could not shift from 2wd into any of the 4wd modes while moving because you can't just accelerate all that metal from stationary to fast in zero time.

Sure you can have shift on the fly at any speed without a clutch if you just leave the front axle engaged all the time because then the front driveshaft is always spinning. Our trucks don't do that.

Don't know where you got the idea I was talking about locking hubs.Unless you're into off roading strait axles they are a thing of the past,ancient history.You are way over thinking this set-up.There is absolutely no issues with the frt axles locking together if you get out of the power and let it do it's thing.No grinding and no noises.I've been into enough of these things to know.

 

[Ludville1]

Shift on the fly had been around a while... but those older ones had all the front end stuff rotating forward all the time.... and they were noisy...I had a 79 Chevy full time 4x4, best truck I've ever owned... bought it used for $800, replaced a spindle bearing, put an engine in it that I rebuilt myself when the one that came in it threw a rod.... drove that truck for 13 years.

It had the NP 208 T-case, the one most everybody hated, never gave me an ounce of trouble.... but it ate front tires like candy (BFG Mud Terrain tires on it didn't help that any).

They all have their quirks.

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I had one of those that I bought brand new in 1979. Had it for 20 years...great truck!

 

[Ludville1]

Have owned 4X4 vehicles since 1979...never an issue with the 4wd systems. Personally, would never even consider a 2wd truck.

 

[kurek]

Don't know where you got the idea I was talking about locking hubs.Unless you're into off roading strait axles they are a thing of the past,ancient history.You are way over thinking this set-up.There is absolutely no issues with the frt axles locking together if you get out of the power and let it do it's thing.No grinding and no noises.I've been into enough of these things to know.

I never mentioned hubs.

The front driveshaft is stationary while in 2wd. Explain how that gets up to 2000+ rpm from 0 instantly without a clutch.

 

[Quyonmob]

I never mentioned hubs.

The front driveshaft is stationary while in 2wd. Explain how that gets up to 2000+ rpm from 0 instantly without a clutch.

the front diff actuator shifts first, then the transfer case. My understanding is that the connection of the diff actuator is usually related to a side gear in the differential.

My np241 was chain, no clutches. I could pull the hammer at any speed with the oem diff actuator. When i switched to the cable actuator, I could engage the actuator anytime (had to be first) then the transfer case any time.

 

[kurek]

the front diff actuator shifts first, then the transfer case. My understanding is that the connection of the diff actuator is usually related to a side gear in the differential.

.

The front diff carrier is stationary. The passenger stub shaft is going 630rpm backward. The passenger axle shaft is going 630 rpm forward. How do you reconcile that in 0.000 time without a clutch.

 

[Quyonmob]

The front diff carrier is stationary. The passenger stub shaft is going 630rpm backward. The passenger axle shaft is going 630 rpm forward. How do you reconcile that in 0.000 time without a clutch.

I don’t know, I’m just saying that’s how it worked in GM trucks of that era, Ram used a similar Cnetral Axle Disconnect for a while as well.

maybe parts 4-6 on the front output? But it is a load bearing clutch, so I dunno


EDIT- had it backwards, sold the truck 9 years ago... shift tcase then diff. No clutches.

 

[ram1500rsm]

I'm not really sure i care how this TC operates. I got 97k miles on my truck, 50k of them on 35's or 37's and the TC shift smooth as butter and that thang has never slipped knocking on wood. I shift into 4hi as needed i don't slow down other than to engage 4lo.The only thing i hate about this particular trasfer case is the waiting for the actuators to do their thing though but other than that it's been a very reliable transfer case considering i use it every other weekend and have been doing so for almost 3 years now. Don't need auto anything function and haven't in the 20 years i have offroading everywhere so you could tell i have a black belt in offroading hahaha. 44-45 here and again, change the oil every 30k miles with your choice of ATF+4, no sneak or mistery oils and you can buy the fluid in your local supermarket store if you wanted.

 

[kurek]

NP241's have a synchronizer which is likely the "clutch" surrogate that brings the bottom half of the transfer case and the front differential carrier up to speed so that the axle disconnect doesn't have a speed difference to deal with.

Presumably an electrically actuated transfer case could have that - I had a S10 Blazer with an electrically actuated transfer case but I don't remember the specifics of when it did or didn't permit 2wd>4wd shifts.

My other vehicle is a Jeep Patriot and it uses an electrically operated clutch a bit like the 44-44 except it's located in the rear axle and I read somewhere it's rated for 1800 ft-lbs which is way more than the vehicle can produce even when multiplied through the 1st gear of the transmission (165 ft-lbs from engine times 4.21 first gear is <700 ft-lbs) - so it's as good as a mechanical lock as far as I'm concerned.

 

[Narg]

More "cogs" in the machine will of course need more maintenance. But overall, 4wd systems are crazy reliable these days. Check the owners manual for more info: Official Mopar Site | Owner's Manual

 

[thebuilderman]

So, I've always had 2wd trucks and live in the south. We got plenty of mud holes and swamps but I don't like getting my truck dirty. haaha

I want a new Ram and found a good deal 4x4 Ram in the color, year, miles I want.

Is there any more maintenance or reliability issues with 4WD?
I did read on here that the front diff, transfer case and rear diff use THREE different fluids. That's kinda crazy.

Who knows, maybe I might get this one muddy a few times. lol

Thanks

I’ve had 4 wheel drives all my life. It’s the only thing I will buy. I’m not a mechanic either. I do keep my trucks well maintained and I use them hard. I’ve never once in any of my trucks or my jeep had issues with any of my 4 wheel drive trains. Nothing.