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which 2(or 3?) transfer case models are used in our trucks?

tc429

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need some clarification from a transmission guy/someone at ford...what exact model transfer cases are put in our trucks? a discussion came up about 4A mode- I had always assumed 4A had a open center differential in the transfer case PLUS a dog-type clutch to lock the diff in 4H modes, but where the XLT type cases(without 4A mode) had ONLY a dog type clutch only to lock in power to front driveshaft....

a ford guy said the 4A had no center diff, just the locking clutch came on as needed by wheelslip/power detection...this seemed wrong to me, so went out to see...started trucks (tried both the 19 and 22, both lariats with 4A) put in 4a to lock in the axle hubs, jacked up one front wheel off the ground and spun it...had expcted it to just turn until gear lash was gone, nope- it spun... spinning it quicker though- KLUNK. it locks in same as 4h... Let it sit a few seconds, click- it releases and can be spun again. feels to me like hes right, no center diff in 4A- but then if so the power split display is lying, as in 4A it always shows some power delivery to the front tires in 4A.

To me, this is still a head scratcher, but it sure seems to be freewheeling unless enough slip detected to klunk it in... I'd like to know what exact model xfer cases are in use and pick up the ATSG manuals for each just to really see exactly whats inside and fully understand how they function. the ATSG manuals have great diagrams, and are available cheap- many years ago was able to redo my TH700R4 in a couple evenings for a total of 85 bucks...50 soft parts, 15 used (29 element) forward sprag, 20 for the book... a buddy of mine had 3 times spent 1200-1500 to have his fixed each time, but they kept putting the same crappy 19 element or whatever 1985 sprag back in.

anyways, thoughts/comments appreciated, but still really need to know models and get a factual 'whats in the box' manual to know for sure...oldest son and I have 3 '4A' lariats, next oldest son has 4H only xlt- i just want to really be able to understand the differences without tearing one apart... have heard comments both ways from guys in the know, and someones wrong about 4A... from jacking up/spinning one wheel it sure looks like no center diff to me- so think that guy is correct, which is a bummer really- but that would mean dash display is lying in 4A about power delivery...
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Pedaldude

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4A uses a clutch pack to simulate a center differential. It’s been around since the mid 90’s and was developed to save weight and cost.

I forget what the manufacturer Borg-Warner calls it but Ford calls it Torque on Demand or TOD. There are some explanations on Wikipedia and SAE but it would be pretty cool to see actual diagrams and the parts in a manual.

It’s an active system, so it relies on data from the wheel speed sensors to engage or disengage the clutch pack.

At least on the previous generations, the 4A transfer case has to have its own module that has the computer that controls the TC as well as interface with the rest of the truck.

Go to parts.ford.com and input your VIN and search: transfer case

Then the part supplied with your truck should be displayed.

One of the things with Ford though is that they reuse the same part numbers for similar parts, so it’s really just a prefix and you will need the longer complete part number for the actual part.

Good luck!
 

Tomatoboy

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I’ve been under the understanding there are three transfer cases:

1) the standard electronic shift on the fly one, which mechanically locks into 4H/4L, but lacks any automatic features.
2) the automatic electronic shift on the fly one (which shows up on Lariat or greater), which has 4A mode that basically functions more like an AWD system on say the current RWD-biased Explorer platform, which can force the clutch closed into 4H/4L, but which doesn’t actually “lock” like #1 does.
3) the “high lock” or “hi-loc” which works like a hybrid of both, it has the 4A mode, but has a mechanical lock into 4H/4L. This is the unit in the Raptor that has occasionally been offered with certain trim/engine options elsewhere.

Therefore, the Lariat one doesn’t “lock.” There’s one caveat, if your Lariat was ordered with the snowplow package, that reverts you to the standard ESOF one That locks but lacks 4A. I’d expect a normal Lariat to behave more like an AWD system on a jack than an XLT, accordingly.
 
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Jesse-Infotainment

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The 4A transfer case is different it’s called TOD torque on demand. The internals are different for sure.

I am adding the 4A.. I have the transfer case, tccm and atcm ready it’s been too damn hot to do it .
 

Oxford_Powerboost

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4A uses a clutch pack to simulate a center differential. It’s been around since the mid 90’s and was developed to save weight and cost.

I forget what the manufacturer Borg-Warner calls it but Ford calls it Torque on Demand or TOD. There are some explanations on Wikipedia and SAE but it would be pretty cool to see actual diagrams and the parts in a manual.

It’s an active system, so it relies on data from the wheel speed sensors to engage or disengage the clutch pack.

At least on the previous generations, the 4A transfer case has to have its own module that has the computer that controls the TC as well as interface with the rest of the truck.

Go to parts.ford.com and input your VIN and search: transfer case

Then the part supplied with your truck should be displayed.

One of the things with Ford though is that they reuse the same part numbers for similar parts, so it’s really just a prefix and you will need the longer complete part number for the actual part.

Good luck!
I would add it’s a common misconception that it requires wheel spin to engage the front end. The modern system in our trucks uses much more such as steering angle, drive mode, accelerator pressure, speed of increasing accelerator pressure, windshield wipers, etc to determine if to send power to the front or not
 

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Badhabit

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put in 4a to lock in the axle hubs,
FYI, if the truck is equipped with the 4A transfer case it does not have electric/vacuum actuated unlocking hubs. They are full-time engaged.
 

Pedaldude

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I would add it’s a common misconception that it requires wheel spin to engage the front end...
I’d hope that wheelspin alone would be enough to engage the front wheels; a lot can happen fast and the time of exposition for the clutch pack alone to react is long enough as it is. I’d hate to spin out in an intersection because I didn’t have my windshield wipers on :p I would be interested though in seeing the tables for what the inputs are and how they are weighted. My guess is that most of the other inputs are used for off throttle applications like parking or corner entry to make things smoother. Maybe the yaw and axle height sensors could come into play but even then; I would be dubious of its effectiveness, since the surface traveled isn’t a billiard table but a 3D environment where all that really matters is where the tires meet (or don’t) the road, gravel, dirt or mud. Though hopefully, with all the extra inputs and technology they are able to make it to where the wheel speed sensors and wheel slip is minimal and anticipate the power demands of the axles. If anything, it would make a lot of sense for the front axle on an unladen truck to get more than half the torque on mild acceleration because that’s still where most of the weight is.

FYI, if the truck is equipped with the 4A transfer case it does not have electric/vacuum actuated unlocking hubs. They are full-time engaged.
I know that for my 2001 Lincoln Navigator, there are no integrated wheel ends but the transfer case switch has no 2H setting. The Expedition of the same year with the 4A TC has IWE’s and a 2H mode.

I thought that the F-150 would have the IWE’s if it has 2H. The IWE’s are primarily to get that extra few miles from the fuel tank for mileage standards. I would be super surprised if Ford didn’t do this for the newest generation of trucks. A quick VIN search, or look under the front of a 4A truck would confirm this.

I am adding the 4A.. I have the transfer case, tccm and atcm ready it’s been too damn hot to do it .
Please do a thread on this, LED headlights and the 4A TC are the two things that I couldn’t get on my regular cab. When the warranty is out on my truck in 18 months, the 4A transfer case and a front Torsen will be on the table. Thankfully that will be Feb./March, it’s too hot now to go to the mailbox during the day let alone R/R a TC!
 
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Oxford_Powerboost

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I’d hope that wheelspin alone would be enough to engage the front wheels; a lot can happen fast and the time of exposition for the clutch pack alone to react is long enough as it is. I’d hate to spin out in an intersection because I didn’t have my windshield wipers on :p I would be interested though in seeing the tables for what the inputs are and how they are weighted. My guess is that most of the other inputs are used for off throttle applications like parking or corner entry to make things smoother. Maybe the yaw and axle height sensors could come into play but even then; I would be dubious of its effectiveness, since the surface traveled isn’t a billiard table but a 3D environment where all that really matters is where the tires meet (or don’t) the road, gravel, dirt or mud. Though hopefully, with all the extra inputs and technology they are able to make it to where the wheel speed sensors and wheel slip is minimal and anticipate the power demands of the axles. If anything, it would make a lot of sense for the front axle on an unladen truck to get more than half the torque on mild acceleration because that’s still where most of the weight is.
Right - the point of my post was that wheelspin isn’t the trigger, the truck uses other inputs like throttle application to gauge intensions and hedge against the possibility of wheelspin. Just like you said - it anticipates it so it doesn’t have to engage once the wheels spin
 

Snakebitten

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Right - the point of my post was that wheelspin isn’t the trigger, the truck uses other inputs like throttle application to gauge intensions and hedge against the possibility of wheelspin. Just like you said - it anticipates it so it doesn’t have to engage once the wheels spin
Motor Trend describing Borg Warner Torque On Demand for Ford: (back in 2012 for the F150 Ecoboost)

The Torque-On-Demand system utilizes an ECU (electronic control unit) that monitors steering wheel angle and pedal position to predict slip and automatically deliver the precise proportion of torque to the front or rear axle.
 

Badhabit

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I know that for my 2001 Lincoln Navigator, there are no integrated wheel ends but the transfer case switch has no 2H setting. The Expedition of the same year with the 4A TC has IWE’s and a 2H mode.

I thought that the F-150 would have the IWE’s if it has 2H. The IWE’s are primarily to get that extra few miles from the fuel tank for mileage standards. I would be super surprised if Ford didn’t do this for the newest generation of trucks. A quick VIN search, or look under the front of a 4A truck would confirm this.
The F150 had vacuum IWEs up until 13th gen. 21MY changed to electric actuated vacuum IWEs except for 4A equipped trucks.
 

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Snakebitten

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The F150 had vacuum IWEs up until 13th gen. 21MY changed to electric actuated vacuum IWEs except for 4A equipped trucks.
I don't know if it was a typo, but the electric IWE doesn't have vacuum involved at all. That's a vent line routed up and open to fresh air.
The early press article called "deep dive" into the 2021 F150 was one of the first and unfortunately assumed that was a vacuum line and 2 years later it still gets mentioned as such.
 

Pedaldude

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The F150 had vacuum IWEs up until 13th gen. 21MY changed to electric actuated vacuum IWEs except for 4A equipped trucks.
https://static.nhtsa.gov/odi/tsbs/2020/MC-10181917-0001.pdf

Since this TSB involves capping off and disabling the vacuum IWEs on TOD/4A trucks, it’s possible Ford figures most owners will just stick their trucks transfer case switch to 4A and leave it there as long as they own the truck. If it’s true that they ditched the IWEs on 4A trucks, it wouldn’t say much about Ford’s confidence in the new electromagnetic IWE’s though if they have abandoned disconnecting the halfshafts and front diff. on the 2021+ 4A trucks.

I searched the VIN for a TOD equipped Tremor and the front wheel bearings are equipped with IWE’s but parts.ford has been less than stellar lately, so I’m still not convinced either way but they probably do have the IWE’s if it’s showing them.

Ford F-150 which 2(or 3?) transfer case models are used in our trucks? B34F3004-A028-4660-85C8-87A5D45A7466


Ford F-150 which 2(or 3?) transfer case models are used in our trucks? 2DDF70EE-B5B6-4475-BF2B-1B11E8F6E852
 

hotrodmex

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@tc429 This was said earlier by @Tomatoboy , but there's been a lot said between then and now so it might be good to bring it back.

I believe the standard ESOF Transfer case is the Borg Warner 4419. This electrically shifts between 2H-4H-4L, locking each speed with dogs.

According to THIS ARTICLE, the "4A" transfer case is the Borg Warner 4417. This is the Torque-on-Demand system illustrated here:



New for 2021 was the 4A-Hi-Lock in the Raptor, and the Tremor 402A. This is a blend of the 2 above cases, with 4a function using the clutch, and 4H and 4L using locking dogs.

21MY changed to electric actuated vacuum IWEs except for 4A equipped trucks.
This change actaully happened for 22. 21s were built with E-IWEs for some reason.

If it’s true that they ditched the IWEs on 4A trucks
100%, cuz I own one. Thread on another board about it. It actually came up because someone tried to install a TOD Hi-Lock and ran into...

I searched the VIN for a TOD equipped Tremor and the front wheel bearings are equipped with IWE’s but parts.ford has been less than stellar lately, so I’m still not convinced either way but they probably do have the IWE’s if it’s showing them.
...the fact that the Tremors and Raptors seem to still have them. He had to install e-IWEs and just has them up in his engine bay so the TCCM would stop throwing a code.

I asked someone who just took delivery of their Tremor what he saw when he just did his level, but he has yet to get back. The theory is there's something about the Hi-Lock that makes the E-IWEs important. Maybe to do with the T-Case needing to lock up before the wheel hubs, which you can't do if the wheels are permanently locked?

Please do a thread on this, LED headlights and the 4A TC are the two things that I couldn’t get on my regular cab. When the warranty is out on my truck in 18 months, the 4A transfer case and a front Torsen will be on the table.
There's a large thread on f150forum.com. It's actually really simple, about as plug and play as you can get. It's pretty spread out, though, so I'm sure Jesse will do a better job laying it out.
 
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Snakebitten

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^ Awesome post! Thanks for that information.

My 2021 Platinum Powerboost did have an E-IWE. My 2022 KingRanch Powerboost does not have any IWE.

My buddies 2022 Tremor does have the E-IWE.

Lines up perfectly with what the previous post explained. This forum is amazing!
 

notabot

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I am adding the 4A.. I have the transfer case, tccm and atcm ready it’s been too damn hot to do it .
I had a local, family owned transmission shop install mine for $225 in my XLT. Worth every single penny to have someone else do it...
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