Front driveline slip? Transfer case clutch pack.

[CallMeSyd]

A little info from everything I know about the way the transfer case works before my question... The transfer case shift motor and fork only shifts it between low and high at the planetary assembly and has nothing to do with the actual output locking mechanism, since the shifting is done before the clutch pack (output locking). The BWM (brown wire mod) directly disables the electromagnetic clutch on the output shaft, meaning that there is no output to the front drive shaft no matter how the case is shifted. All output to the front wheels must go through the electromagnetic clutch. The clutch pack is a friction disc type, and not a ball cam/sprag type, therefore it is not a true locking clutch. The amount of torque sent to the front drive shaft is controlled by the duty cycle of the magnet. In 4 auto, when the sensors in the transfer case detect a difference in speed between the front and rear shaft, it signals the magnet to engage in an increasing duty cycle, compressing the clutch pack in a controlled manner. When shifted to 4 high or 4 low, the signal is sent to place the magnet into 100% duty cycle, essentially "locking" the output shaft to the front drive shaft. However, it still relies on the clutch. If the clutch is bad, then it will slip. There is no direct (100%) locking of the front shaft. Larger tires also will put more stress on the clutch, causing it to slip/wear even worse. The 4411 case is an evolution of the 4405, so the mechanical function between the 2 is the same. I have talked to people with front lockers and/or larger tires and am getting a lot of talk about the front output shaft not locking to send enough torque to the front wheels. I also experienced this the other day while in 4 low attempting to pull a large stump on gravel. My rear wheels lost traction, but the front never spun either side. I know my 4x4 is working, but I plan to get front lockers as well as 33s vs the 31.6 tires on it now, (35s once i get new gears) but what would be the point if the transfer case allows slipping at the front shaft? Also, does the traction control or advancetrac system decrease the magnet duty cycle to allow the front shaft to slip? I would assume it does, however, mine was turned off when this happened. Is there any way to change the clutch pack to a locking sprag type? I have a friend with 35s and 4.63 gears with front and rear lockers and he is having this problem. He says that he already swapped in a new low mile transfer case and it didn't make any difference. Any help is greatly appreciated.

 

[Fix4Dirt]

A little info from everything I know about the way the transfer case works before my question... The transfer case shift motor and fork only shifts it between low and high at the planetary assembly and has nothing to do with the actual output locking mechanism, since the shifting is done before the clutch pack (output locking). The BWM (brown wire mod) directly disables the electromagnetic clutch on the output shaft, meaning that there is no output to the front drive shaft no matter how the case is shifted. All output to the front wheels must go through the electromagnetic clutch. The clutch pack is a friction disc type, and not a ball cam/sprag type, therefore it is not a true locking clutch. The amount of torque sent to the front drive shaft is controlled by the duty cycle of the magnet. In 4 auto, when the sensors in the transfer case detect a difference in speed between the front and rear shaft, it signals the magnet to engage in an increasing duty cycle, compressing the clutch pack in a controlled manner. When shifted to 4 high or 4 low, the signal is sent to place the magnet into 100% duty cycle, essentially "locking" the output shaft to the front drive shaft. However, it still relies on the clutch. If the clutch is bad, then it will slip. There is no direct (100%) locking of the front shaft. Larger tires also will put more stress on the clutch, causing it to slip/wear even worse. The 4411 case is an evolution of the 4405, so the mechanical function between the 2 is the same. I have talked to people with front lockers and/or larger tires and am getting a lot of talk about the front output shaft not locking to send enough torque to the front wheels. I also experienced this the other day while in 4 low attempting to pull a large stump on gravel. My rear wheels lost traction, but the front never spun either side. I know my 4x4 is working, but I plan to get front lockers as well as 33s vs the 31.6 tires on it now, (35s once i get new gears) but what would be the point if the transfer case allows slipping at the front shaft? Also, does the traction control or advancetrac system decrease the magnet duty cycle to allow the front shaft to slip? I would assume it does, however, mine was turned off when this happened. Is there any way to change the clutch pack to a locking sprag type? I have a friend with 35s and 4.63 gears with front and rear lockers and he is having this problem. He says that he already swapped in a new low mile transfer case and it didn't make any difference. Any help is greatly appreciated.

that is simply the nature of the beast, at least in the 4405. usually 35s or lockers are the breaking points where you find the limits of them. these were designed as i imagine light duty tcases, since iirc it evolved from the 1354 which was a light duty case. as such, they were designed for the boat ramp, or light backroading, and not with hardcore rigs in mind. your understanding of the case is right as i know it. for example, gerald (Gjarrett) had 35s and found the limits of his 4405. they just werent designed with this in mind. it works great in light duty conditions, when it can nearly immediately redirect some power to the front, hence the 4A function being very useful, and quite nice for light wheeling, etc as it works in the background. however, it does not cut it for heavy duty use like you describe. its just right tool for the job. no clutch will ever hold 100% and will always slip, and this is no different imo.

 

[CallMeSyd]

My next question would be, what could be done to solve the problem? I prefer to maintain the ability to use the electronic 4x4 system, but I just want it to lock when I need it. Anybody know a shop that might be able to make a locking clutch for it? I assume a design similar to what is used in electronic diff lockers will work.

 

[Fix4Dirt]

My next question would be, what could be done to solve the problem? I prefer to maintain the ability to use the electronic 4x4 system, but I just want it to lock when I need it. Anybody know a shop that might be able to make a locking clutch for it? I assume a design similar to what is used in electronic diff lockers will work.

not too sure. i do wonder if something like a 1354 could work? iirc those did not have the E clutch, might be wrong, though. many have used an advance adapters atlas in the 2g at least. i could find the specs again, maybe, if i rememebr where they were.

 

[CallMeSyd]

not too sure. i do wonder if something like a 1354 could work? iirc those did not have the E clutch, might be wrong, though. many have used an advance adapters atlas in the 2g at least. i could find the specs again, maybe, if i rememebr where they were.

I want to still be able to engage and disengage the 4x4 as well as high and low using the electronic system already in place, but just with a locking clutch.

 

[Fix4Dirt]

I want to still be able to engage and disengage the 4x4 as well as high and low using the electronic system already in place, but just with a locking clutch.

i see. maybe someone else has a solution! not one here, at least

 

[CallMeSyd]

I found a bunch of electronic locking clutches. I'm going to look into finding one that will fit and work when I have some time.

 

[imp]

I found a bunch of electronic locking clutches. I'm going to look into finding one that will fit and work when I have some time.

No electronic 4x4 system i've seen is satisfactory from my point of view, because they act after the fact of 4x4 need rather than before; sorry. Nonetheless, I still like Ford's electronic clutch.