Anyone HAPPY with Borg Warner 44-44 / Auto 4WD

[Ken226]

This bw44-44 actually has the potential to be a really good transfer case.

I keep going back to that torsion spring as a source of trouble. If that spring had a significantly lower force/rate value and would allow the ball ramp to engage ANY time the rear driveshaft attempt to advance clock position beyond the front driveshaft, it might actually work well.

That spring seems, in the case of some trucks, to only allow ball ramp engagement when there's a significant force differential between the front and rear drive shafts.

In the case of a low friction surface, the rear drive system rotates against the torsion spring, and the torsion spring is strong enough to rotate the front drive system on the low friction surface, via the weak electromagnetic closing of the clutch, without allowing the ball ramp apply its own axial force through the clutch plates.

I'd love to try the system with new clutch plates and a torsion spring with about 10% the strength of the current spring.

 

[baydog]

So if anyone can tell me how to simply post a video, I will show you how badly this transfer case works............I'll email it if it's easier.......there is no excuse.

 

[hemipower95 2.0]

So if anyone can tell me how to simply post a video, I will show you how badly this transfer case works............I'll email it if it's easier.......there is no excuse.

When you post a new reply, click on the globe and paperclip logo and copy and paste the link

 

[WilliamS]

This bw44-44 actually has the potential to be a really good transfer case.

I keep going back to that torsion spring as a source of trouble. If that spring had a significantly lower force/rate value and would allow the ball ramp to engage ANY time the rear driveshaft attempt to advance clock position beyond the front driveshaft, it might actually work well.

That spring seems, in the case of some trucks, to only allow ball ramp engagement when there's a significant force differential between the front and rear drive shafts.

In the case of a low friction surface, the rear drive system rotates against the torsion spring, and the torsion spring is strong enough to rotate the front drive system on the low friction surface, via the weak electromagnetic closing of the clutch, without allowing the ball ramp apply its own axial force through the clutch plates.

I'd love to try the system with new clutch plates and a torsion spring with about 10% the strength of the current spring.

I see where you are going with this and I see an issue with it. As it would engage and disengage nearly all the time. In 4x4 High or 4x4 Low this would be ideal. In 4auto it would be banging and binding nearly all the time.

Although I would love a true lock, I use 4x4 auto more than I need 4-high/low. If there were an over ride switch to pull that clutch to full tightness, although a bandaid to the issue its a good solution. Or put in an open differential in the center with an electronic lock. Leave it open on 4auto, and lock it for 4-high/low

 

[Ken226]

Yea, your right. With a weakened torsion spring 4 lock and 4 low would work well, but, in 4 auto, if the rear wheels were already spinning when the computer commands the front to engage, it would be a hammerblow to the transfer case.

 

[WilliamS]

Yea, your right. With a weakened torsion spring 4 lock and 4 low would work well, but, in 4 auto, if the rear wheels were already spinning when the computer commands the front to engage, it would be a hammerblow to the transfer case.

Someone smarter than myself, which is everyone will crack it in HP tuners. From there its all over and they will command full power to that clutch system. Once they do that we should be able to make 4 high / low to lock the center diff fully.

 

[loveracing1988]

Someone smarter than myself, which is everyone will crack it in HP tuners. From there its all over and they will command full power to that clutch system. Once they do that we should be able to make 4 high / low to lock the center diff fully.

This system has been out officially for 4 model years, if they haven't gotten it already it isn't going to get done.

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[WilliamS]

This system has been out officially for 4 model years, if they haven't gotten it already it isn't going to get done.

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Ive seen new stuff come out many many years later in the past. Its just a matter of someone creating a file that looks for that system. It'll be found.

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[Ken226]

I haven't been sufficiently descriptive or articulate.

One of the things I've been attempting to state with all the parts descriptions is as follows:

Based on the parts inside the bw44-44 transfer case, and the way those parts interact with each other, electrical power to the tc clutch can not make the front wheels turn beyond about 20-30 ft lbs of torque. That system is simply way too week.

The computer can send power to the weak electromagnetic clutch. It's like a light switch, either sending power or not sending power. It's on, or it's off. There's no intermediate voltage settings. Just power or no power.

When the computer decides to make the front wheels turn, it turns on power to the weak electric clutch. (In 4 lock, this power is continuously on).

Keep in mind, this electric clutch is too weak to make the front wheels pull the truck. This electric clutch starts a reaction which allows the ball ramp (essentially a ratchet that also compresses clutch plates together), to start turning the output shaft.

So, what this means is that if someone reprogrammed the system to supply continuous power to the transfer case clutch system, they've accomplished nothing. 4 lock already supplies continuous power.

Regarding the 4x4 system only, disregarding traction control, Contrary to what has been previously posted by members, when in 4 lock there is no "sensing" of wheel slip, nor any "activating" of the clutch. In 4 lock, the clutch is continuously activated.

In 4 lock, the "slip" observed and hated by members here, is a mechanical function of the ball ramp. It takes some rotation (the input half of the ball ramp has to rotate about 180° past the output half) before the ball ramp can force the clutch plates together with enough power to drive the front wheels.


Older systems like the bw 44-05 worked similarly, but relied less on the ball ramp in favor of a much stronger electromagnetic clutch. They consumed alot of electrical power and couldnt handle the torque output of the hemi.

The bw44-44 uses a small electric clutch to initiate the locking reaction, and the (not electrically controlled, just a ratchet that both pushes and rotates) ball ramp to maintain that lockup.

When the torque passing through the ball ramp drops below around 20 ft lbs, The torsion spring unlocks the ball ramp.

 

[WilliamS]

I haven't been sufficiently descriptive or articulate.

One of the things I've been attempting to state with all the parts descriptions is as follows:

Based on the parts inside the bw44-44 transfer case, and the way those parts interact with each other, electrical power to the tc clutch can not make the front wheels turn beyond about 20-30 ft lbs of torque. That system is simply way too week.

The computer can send power to the weak electromagnetic clutch. It's like a light switch, either sending power or not sending power. It's on, or it's off. There's no intermediate voltage settings. Just power or no power.

When the computer decides to make the front wheels turn, it turns on power to the weak electric clutch. (In 4 lock, this power is continuously on).

Keep in mind, this electric clutch is too weak to make the front wheels pull the truck. This electric clutch starts a reaction which allows the ball ramp (essentially a ratchet that also compresses clutch plates together), to start turning the output shaft.

So, what this means is that if someone reprogrammed the system to supply continuous power to the transfer case clutch system, they've accomplished nothing. 4 lock already supplies continuous power.

Regarding the 4x4 system only, disregarding traction control, Contrary to what has been previously posted by members, when in 4 lock there is no "sensing" of wheel slip, nor any "activating" of the clutch. In 4 lock, the clutch is continuously activated.

In 4 lock, the "slip" observed and hated by members here, is a mechanical function of the ball ramp. It takes some rotation (the input half of the ball ramp has to rotate about 180° past the output half) before the ball ramp can force the clutch plates together with enough power to drive the front wheels.


Older systems like the bw 44-05 worked similarly, but relied less on the ball ramp in favor of a much stronger electromagnetic clutch. They consumed alot of electrical power and couldnt handle the torque output of the hemi.

The bw44-44 uses a small electric clutch to initiate the locking reaction, and the (not electrically controlled, just a ratchet that both pushes and rotates) ball ramp to maintain that lockup.

When the torque passing through the ball ramp drops below around 20 ft lbs, The torsion spring unlocks the ball ramp.

Ah so even a full power would only allow the system to activate, would not actually force the front wheels to turn. This sounds like the same system that BMW uses for xdrive. Also a system that uses rear slip to create front power.

Odd part is I can have 0 or next to 0 slip and get power to the front tires, its provable and repeatable.

Regardless there has to be a way.

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[Ken226]

Exactly! That's an excellent descriptive of what's going on. Rear wheel slip causes the ball ramp to force the clutch plates together.

And, mine is just like yours. Nearly zero slip. My front wheels start turning nearly the same instant as the rear. Indicates mine has a very tight ball ramp with tight clearances between parts.

The problem I have is that when I go from forward to reverse, I get at least a full rotation or two of the rear, before the front wheels start turning. When I go back into forward, the same. That's caused by the ball ramp design.

The more "gap" between clutch plates, pressure plates, etc the further the ball ramp has to "twist up" to close up the gaps. (Not a perfect description, but something we can visualize).

The delay is due to wear and tear on the clutch plates, shims, ball ramp, etc. The more wear and tear, out of spec, etc, the more the delay.

The more grip the front tires have on the road when the rear tires slip, the more instant and forceful the ball ramp engage.

It conceivable that if the clutch plates are worn out, the ball ramp wouldn't engage at all without some Delta of mass-moment-enertia (flywheel effect). Punch the throttle, rear wheels accelerate from motor torque and the mass of the front wheels delay their rotation enough that the torsion spring is overcome. With worn clutch plates, the electric part of the clutch may not provide enough drag for the ball ramp to overcome the torsion (disengaging) spring.

 

[Murphy Slaw]

I wonder who has the most miles, with one of the oldest 44-44's in use without any issues?

I seem to remember someone here living in Alaska and using their's all the time (as in, left it in Auto for like 6 months a year), and there was another member who did construction work with a Sport, and had quite a few miles on it.

 

[Ken226]

Mileage would be an indicator, but a small one.

Just one instance of someone holding the brake and throttle at the same time, or spinning all 4 wheels at high angular velocity then having the front only suddenly gain traction, could cause as much wear and damage as 100000 miles of normal use.

Also, as it's so sensitive to clearances, normal tolerances and tolerance stacking of as little as + - .001 inches per plate or shim could totally change the way it locks up.

Some aftermarket support allowing the purchase and installation of high quality clutch plates and custom clearance shim thicknesses would be all that's needed to solve most of the 44-44s issues.

I can't seem to find a single rebuild kit available anywhere for these cases. I could easily make my own shims in my machine shop, but not the clutch plates.

 

[Murphy Slaw]

Mileage would be an indicator, but a small one.

Yea, I know, that's why I mentioned the guy from Alaska, and the fellow with a Sport doing construction work. I meant high miles, and being used in a NORMAL manner, not doing burnouts in 4WD and such.

Although that might be considered normal for some members here.....

 

[WilliamS]

A clutch is a horrible idea in this type of vehicle based on weight. Again Im in Florida and it gets used in horrible weather, or when Im bored and take the long trails for fun. Regardless someone in the snow belt using the 4-auto would be comparable to 10x the wear.

Heat brazing would be an issue as well. Nearly every video on Youtube of someone complaining about the center diff they are full throttle without the front helping. If they torched what I would assume is a tiny clutch in there doing that type of driving/testing it would make that clutch useless. If you have ever cooked a clutch you know exactly what Im talking about.

In my use the wheels are commanded to all go the same speed without a huge difference so that clutch might get some wear but all the components would be already spinning at very similar speeds unless Im off road in full goofball mode. On ice, snow, or loose mud this would be a very different scenario based on the way its setup. You can get a lot of rotation speed then that clutch is trying to engage and pull the weight of the truck, and how small is thats poor thing. No wonder they overheat so easy.

My experience is a good one, but now actually seeing its operation is the same as my BMW's which are built 100% for performance not off road this is a bade setup for the snow guys. Im sorry I said otherwise earlier. For me its perfect, but as a 4x4 offroader its not great.

For anyone that wants to see this same style fail even better, Top Gear tested a BMW X6 and it couldnt make it up nearly any grade off road, and a Land Rover just idled by it many times. Again great for AWD performance not great for long term abuse needed to actual pull you out of a mess.

 

[VA10]

Best I can all of the links below are of Rams with 44-44 (auto transfer case) in them. Driving over some challenging terrain. I personally think they perform drastically better than most people say they do. These drivers also appear to know how to engage the TC properly using throttle control and patience haha. I realize sometimes throttle control and patience is not ideal in some situations. I doubt most of us flex our trucks like this on a daily basis. Based on these videos I think I will be happy with mine.

1. https://www.youtube.com/watch?v=8iQRewa8G2w

2. https://www.youtube.com/watch?v=tmiRVN01SFk

3. https://www.youtube.com/watch?v=NRLwEnz7cNE

 

[loveracing1988]

Best I can all of the links below are of Rams with 44-44 (auto transfer case) in them. Driving over some challenging terrain. I personally think they perform drastically better than most people say they do. These drivers also appear to know how to engage the TC properly using throttle control and patience haha. I realize sometimes throttle control and patience is not ideal in some situations. I doubt most of us flex our trucks like this on a daily basis. Based on these videos I think I will be happy with mine.

1. https://www.youtube.com/watch?v=8iQRewa8G2w

2. https://www.youtube.com/watch?v=tmiRVN01SFk

3. https://www.youtube.com/watch?v=NRLwEnz7cNE

With enough patience a 2wd truck could have done the same thing. Notice with the rear tire in the air how much that tire had to spin before the truck moved? The third video doesn't even have the 44-44 anyway. You can tell by watching the front tire start spinning at the exact same time.
Is it capable? Sure, but it is not something I would rely on when there was nothing wrong with the old auto transfer case or the 44-45.

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[Murphy Slaw]

Actually, those first 2 videos are pretty cool with the 44-44.

Not to mention, this thread is about people who are HAPPY with the 44-44.

There is ANOTHER thread that is a b!tchfest.......

 

[VA10]

With enough patience a 2wd truck could have done the same thing. Notice with the rear tire in the air how much that tire had to spin before the truck moved? The third video doesn't even have the 44-44 anyway. You can tell by watching the front tire start spinning at the exact same time.
Is it capable? Sure, but it is not something I would rely on when there was nothing wrong with the old auto transfer case or the 44-45.


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In the 3rd video- you are likely right. But at the 38 second mark the front wheels do not spin until the rears slip. but hey I could certainly be wrong. There a few additional reasons why I think you could be right as well. But there a few moments where the fronts dont pull until the rears slip a bit.

Anyways, I thought I would place the videos here to point out the 44-44 is still very capable (with some video evidence) - when used correctly. Sure you dont have the same control instantly as the 44-45.

 

[Ken226]

The 44-44 has a few advantages when it's working as designed, but then so does the 44-45.

The thing that's rubbing some the wrong way is that the 44-45 will pretty much always be working well. The 44-44 can be working well in some cases, or suck in some, depending on how the random accumulation of tolerances in your clutch basket.

If for example, your clutch plates are designed to each have a thickness of .125" with s tolerance of +/- .003,. And there are 30 clutch plates, then the nominal thickness of the plate stack would be 3.75".

But, because each plate can only realistically be manufactured to a thickness of somewhere between .122"-.128", the stack can never actually be 3.75" thick.

Were human, and our tools are made by humans, so .125" exactly, down to the very iron atom that would fall at the micrometers .125" line, would be insanely expensive.

Therefore, 30 clutch plates @ a thickness of .125" +/- .003 would make up a stack who's sum thickness from one individual stack to the next, from a minimum of 3.66 to a maximum of 3.84,. Or, anywhere can be anywhere in between.

The same is true of every single part of every machine ever produced by humans. The trick is to design it so the tolerances of the parts don't effect the function.

Example. You design a shaft to fit in a hole with a clearance of -0-. , Must seal and not leak air or water. The shaft spec is 1",. The hole spec is 1". So, you start making parts. You make 1000 of each, shafts and holes.

You start assembling them and find that about half the shafts fit loosely into the holes and are unusable. The other half are too tight and don't fit at all. So you consult an engineer.

The engineer changes your design an makes the shaft with a 1° taper. The holes are all also reamed with a 1° taper. Now, all the shafts fit all the holes and are airtight. A design that worked within the tolerances of the parts.

The bw44-44, I believe, is very sensitive to tolerances.

The 44-45 not so much.