How to: - The Borg Warner 4405 Transfer Case Rebuild Diary | Page 3 | Ford Explorer Forums - Serious Explorations

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How to: The Borg Warner 4405 Transfer Case Rebuild Diary

Prefix for threads which are instructional.
Sometimes you could pop it out with a narrow screwdriver. There is a tool with a dimple (indented notch) on both sides for grabbing ends of snap rings without any holes. It has a spring grip, and it's made to expand when you squeeze it.

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I have read through your very detailed thread on breaking down a t-case. I am trying to avoid removing mine but it is stuck in 4WD.
I have checked the motor, the switch, the coil wire going to the magnet gets power when the switch is on 4high or 4Low, but not on 2WD.
I have disconnected the motor and it moves along with the swithc in 4high and 4low. I have disconnected the wire harness and the vechicle still remains in 4WD.
Anything i might have missed before pulling the t-case?

Popping noise on hills after a transfer case rebuild


My problems began with the T-case....and with all of your collective knowledge, I'm sure that you can tell me what I'm missing....Thank you in advance.

I own a 1998 Explorer with about 170,000 miles on it. My problems began with a high speed whine. The noise occurred when above 40 mph and your foot was removed from the accelerator.

Stegall's Transmission Shop in Greenville, SC rebuilt the transfer case. They did a great job and answered tons of questions about it and my other 4WD. The problem was a bad shift motor which damaged the range hub.

Well, after the transfer case was rebuilt, the Explorer began to make a popping type of noise when climbing a hill (under load) - 30+ mph. The noise has not occurred except for climbing a hill.

The majority of the time, the noise occurs when you lift off the gas then get back into the gas hard … like climbing a hill with a curve (in the throttle, out for a sharp curve, and back into the throttle and POP - as if something is snapping back into place).

Sometimes, the noise occurs when you are in the throttle the entire time on a hill (ie, no lifting off the throttle then back into it. It doesn't seem to matter what gear the transmission is in. I have never heard the noise while driving downhill or on flat terrain.

The Transmission Shop (Stegall's) completely rebuilt the transfer case again (replaced all of the guts at no charge to me), but the noise still occurs. Then they replaced the transfer case with another rebuilt transfer case to rule it out the transfer case as the problem (again at no charge to me). They checked the transmission, changed the filter, adjusted it and flushed it. No problems were noted.

The rear diff was checked satisfactory with no issues, the front drive shaft was pulled and the mechanic thought that the front diff was the problem…well, $450 later, the popping noise is still occurring…

The explorer seems to steer just fine and is not a suspension issue - I think. However, I did put new shocks on it this past summer (after the transfer case rebuild)...but I don't remember if the shocks were installed before or after the popping noise began...

Alignment was done just before transfer case broke to begin with and suspension check sat at that time...

Lower balls joints were replaced about 30,000 miles ago...

Thinking about pulling front driveshaft again and driving it myself to see if noise still occurs (I know the vehicle better than the shop and know how to make it "do" the noise...).

Any thoughts?

First and foremost, keep that trans shop. If only all mechanics were so helpful. Diagnosing a noise on the internet can be hard but not impossible. My first thought was a TC staying in 4WD and causing binding but a second rebuild and TC swap should have ruled that out.

Next, make sure the TC functions properly. Does 4WD actually engage? More importantly, when in auto, does the TC engage and disengage as it should? Then I think you should pull the front drive shaft and see if anything changes. This will help, but not absolutly, rule out the front differential.

Finally, take a good look at the universal joints, front and rear. Your discription sounds like the noise only occurs under load. Is this true? Try these "tests" and get back to us.

Divepro99, if you start a new thread in the TC section, you will probably get more response. Since this is a rebuild diary, most of the people that can help you seldom scan the responses to this thread.


Already have a post in several other forums with no real help...


I pulled the front driveshaft, checked a lot of bolting tight (one skid plate bolt was loose), sprayed WD-40 on the ends of the torsion bars. However, the darn thing still makes the noise.

Also another gentlemen, MikeHart, is having the same problem with one interesting commonality ---- "....has been doing this for about 3 weeks just after I put a different t case in it after a year of driving it without the shaft in."

Any thoughts? At this point, I see no reason to keep the front driveshaft out, so I plan to reinstall it tomorrow, unless someone can think of a reason to keep it out and test something else...

glacier, where can i find an exploded view of the BW 4405 like you have but with names of parts? i cant find one anywhere.

i have mine apart and was also wondering the "shift rail bore issue" is that pin that holds the shift collar? should there be no free play when it sits in the housing? i got a little bit of a play and when i look at the hole it sits in it looks a bit oval-like. thanks alot for you help GREATLY APPRCIATED

also when people describe the whhhrrrrriiinnngggg noise when explaining a shift rail bore issue what exactly is causing the whhhrrrriiiinnngggg noise? thanks alot

Thanks IZWACK. And I will throw in my 2 cents... that snap ring is a HUGE PITA and requires patience, ingenuity and a willingness to open it WAY farther than you think ought to be necessary.

I'm glad this Diary has been helpful.
thank you for taking the time to put all this together,the pics and documentry was a huge for the snapring under the planetary set.I used a needlenose pliers stuck it between tabs on the ring, spread the handles - pop out the plant set

I have read through your very detailed thread on breaking down a t-case. I am trying to avoid removing mine but it is stuck in 4WD.
I have checked the motor, the switch, the coil wire going to the magnet gets power when the switch is on 4high or 4Low, but not on 2WD.
I have disconnected the motor and it moves along with the swithc in 4high and 4low. I have disconnected the wire harness and the vechicle still remains in 4WD.
Anything i might have missed before pulling the t-case?
ours was doing the same thing, turned out it was a broken spring,think glacier called an accordian spring , anyway with that spring broke there is no tension to keep the actuator balls center in the ramp,centrifical force takes over with no spring tension to hold it back thus ingages the clutch pac whenever truck is in motion. spring cost 6 bucks 30 for a new seal kit

front transfer case drive shaft seal leak

I have a 2003 explorer AWD and have a transfer case front drive shaft seal leak.I would like to know if the seal can be replaced on the vehicle without pulling the t.c.? I don't see how the " cup yoke " is retained from the pictuces. Is the cup yoke part of the front output shaft?

Thanks !
Richard A. Ringenbach

nope gotta yank it out, tear down clutch pack & remove chain, remove snap ring & pull out shaft...should replace the other two as well, same seal 11.99 at autozone

Can Anyone tell me if this BW 4405 transfer case will work in a 91 explorer? that's what I was sold and told would work? I have had a trany Mechanic here in Peru tell me the A4ld had to have a compatable 4x4 gear??? IS IT?? Help!! anyone..

It will bolt up but you wont be able to control it - internally, the BW-1354 and the BW-4405 are different. In addition, there's a good chance that the front output flange will be different. So yes you can install a 4405 into a 1st gen, but you wont have the 4wd capability.

Thanks, It was installed but the 4X4 is not working that's probably why...
I really appricate your help..

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I am going to try and put this entire thread together much as I did the 4R70W Diary, so those just needing basic info do not have to sift through a lot of chatter throughout the thread. I will create and link another comment thread for those comments - which is here:

and until at least the first half of this Diary is done, lock this thread. (unlocked for now as the first half is done)

Much of this initial info came from the FORD manual, with some edits. While the initial part might not make a lot of sense to some, once the pictures start coming in I hope to try and explain what this all means in 3d nuts and bolts inside the TC. I always think theory of operation is essential to any component you are working on, and this is no exception. This first stuff is important to understand how this TC works though and I recommend reading and at least trying to comprehend it... even without pictures. I admit it is not easy.


The Borg-Warner Control Trac 44-05 transfer case was used in the Explorer (4WD) vehicles starting in 1996. The transfer case transfers power from the transmission to the rear axle, and also to the front axle when electronically activated.

Mechanical Operation

In the 4X2 mode, torque from the transmission is transferred to the input shaft which, in turn, drives the rear output shaft that drives the rear axle assembly. Though the input shaft and the rear output shaft are independent of one another, there is a mechanical gearing interconnect that locks them together as a unitary assembly during normal operation. That through power from the transmission is transmitted to the back wheels for a 4X2 engagement. Shifting to 4WD is done electronically by energiizing the electromagnet, which in turn actuates a very interesting electromechanical ball ramp clutch assembly. (More on this later)

The electromechanical ball ramp clutch assembly drives the drive sprocket after the generic electronic module (GEM) activates the clutch coil. The drive sprocket turns the chain which rotates the front output shaft and front driveshaft. In other words the input shaft and output shaft are locked, and the eledctromagnet actuates the gearing (through a clutch) that adds the sprocket attached to the chain drive, which then adds the front output shaft to the equation. (Confusing enough?)

The high-low shift is accomplished when the reduction shift fork moves the reduction collar to lock the planetary gear set to the output shaft. Torque from the input shaft is then transmitted through the sun gear, which then turns the front planetary gear set front planet The front planetary gear set front planet which is now engaged provides transfer case speed reduction.

Transfer Case Functions

There are three modes on the transfer case, Auto, 4WD Low, and 4WD High. Neutral is only available as a dealer installed option.

C-Trac Function

This is the interesting part. The C-Trac transfer case transmits torque to the front wheels through an electromechanical shift assembly after a predetermined change in speed between the front and rear driveshafts is detected. These driveshaft speeds are determined by two Hall effect sensors which send a signal to the generic electronic module (GEM). If the GEM detects a change in speed between the front and rear driveshafts, it activates the transfer case clutch coil with a varying current to minimize the change in driveshaft speeds.

Low Range Function

In 4WD Low Range, the transfer case electromechanical clutch locks the front and rear driveshafts for maximum 4WD traction. The transfer case motor also rotates the shift cam to move the reduction fork to the 4WD low range position. This low range shift is accomplished through a planetary gear set which changes torque to the driveshaft from 1:1 to 2.48:1 ratio.

This is the transfer case being rebuilt in this thread.


The all-wheel drive (AWD) transfer case is a two-piece aluminum, chain driven, viscous clutch type unit. This produces a system in which all-wheel drive is always activated. All-wheel drive transfer case is automatic and has no external controls.

The viscous clutch is a non-repairable, torque distribution device. The internal construction of the viscous clutch consists of alternating plates that are connected to the front and rear outputs of the transfer case. The viscous clutch is filled with a high viscosity fluid which flows through slots in the plates. The resistance to shear causes the plates to transmit torque at the needed ratio. The ratio that torque is transmitted at is approximately 35% front and 65% rear.

A front differential compensates for the difference between the inner and outer wheels. However, when one driveline component travels farther than another, there will be driveline or torsional windup that must be released.


Torque is transmitted through the input shaft to the planet carrier assembly. Torque flow continues through the gear ring to the rear output shaft. Torque also flows from the planet carrier assembly to the sun gear shaft, which is splined to the drive sprocket. The drive gear is connected to the driven sprocket by the drive chain. Torque continues through the driven sprocket to the front output shaft flange. The viscous clutch provides the connection between the gear ring and the sun gear shaft.

The AWD is not being rebuilt in this diary.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Initial note: Some changes occurred in 98 when the Vehicle Speed Sensor was moved from the transfer case to the rear differential. For that reason a 1998 4405 will not provide a necessary VSS input to a 97 or 96.\ model year vehicle.

como eu faço para arrumar uma t-case desta para minha explorer 96 cambio manual?:::thumbsup: