Borg Warner 4405 transfer case issue explained
First I have...
1997 Ford Explorer
V6 Control Trac 4X4
I have had this problem before and repaired it and have it again. First before I give details on what I know about this issue let me make a clear statement of the symptoms of my problem.
1. loud spinning sound when "coasting", does no occur at very low speeds but does at speeds over 30 or so mph.
2. spinning sound volume is directly related to speed. If going fast it is louder that if going slower.
3. sound occurs in all gears, Drive, second and first.
4. sound occurs in 4 wheel high, 4 wheel low and auto mode. no matter what gear the transmission is in. Drive, second and first. The only exception is when the vehicle is in 4 wheel low in 1 st gear. This seems to be because the vehicle does not reach more than 30 mph easily.
5. reapplying the gas pedal makes sound go away and reengages the drivetrain. As long as you are on the gas it doesnt make sound. Sound starts 3-8 seconds after you left off the gas.
6. I can totally avoid this sound by using both feet to drive and instead of "coasting" I keep a little gas on while applying the brake.
7. If I "coast" in reverse the sound is present and reapplying the gas does not reengage the drivetrain. But the above 2 foot method can avoid this as well.
Now having said all of this I have had this problem before. It is the transfer case.
I had this problem a year and a half ago and bought a used transfer case from my local junkyard for $500 and replaced it myself. It solved the problem. I recently am experiencing the same issue again and have been told by 4 transmission shops that it is the transfer case and it will be about $1100- $1200 to replace it with a rebuilt one. I am leary about doing this if the problem is going to come back in 18 months or so. In fact the best warranty I can find on a rebuilt transfer case is 18 months. huh? A new one from ford is $2100 so that is out of the question and I am not sure but I think it only has 1 year warranty.
The transfer case in question is the 4405-008 made by Borg Warner. The ford part number is f77a-7a195-ga. I called Borg Warner and was told I can only buy it new from Ford. I have done a lot of research on this problem since this is the second time I am going through this.
I was able to find an interesting article published by the ATRA, Automatic Transmission Rebuilders Association, that was printed in a magazine that they publish called "Gears". It can be found in the September 2002 magazine. In an article entitled, "Diagnosing the Borg Warner 4405 Transfer Case" by Mike Weinberg, President, Rockland Standard Gear Inc. I copied the important info here.
---This unit is prone to certainmechanical problems that are beyond the scope of most shops to repair. The most common mechanical failure is acomplaint of a loss of drive accompanied by a ratcheting noise coming from the transfer case during coast or deceleration or when in reverse. Careful questioning of the driver will reveal that this condition was preceded by an occasional thump from the transfer case at a constant road speed of 40-60 MPH.When you disassemble the transfer case you will find that the range hub and range fork will be damaged, but replacing these items will not solve the prob-lem. The range hub is helical cut gearing and will stay in mesh under load, but will move out on coast due to thethrust loads generated by the helicaldesign. Adding power will cause thegear to return to the correct position.The bottom of the teeth get chewed upand the constant pressure on the forkcauses it to burn up. The real cause ofthe problem is an offset in the centerlinedistance, putting the shift rail at anangle, which allows the range fork tomove out of position. The cases aremagnesium and we do considerablemachine work to correct this problem,which is beyond the equipment found inthe average shop. If you see units withthis damage, you will usually seeoblong holes in the cases where theshift rail rides. It is cheaper and moreefficient to buy a unit that has this problem corrected than to tackle it yourself.---
This article basically says its a known issue and has a fix. I personally believe that if its an engineering flaw it should be covered by a recall of some sort. I will be contacting Ford about such a claim.
I also found a site that seems to be selling a fix that should minimize costs associated with repairing this problem. Omega Machine and Tool, Inc. is selling rear case halves that their website seems to indicate fix this problem comkpletly. Do your own research though first. Here is the link ---http://www.omegamachine.com/html/BW4405_rear_case_repair.html---
Anyways I know this is a long post but I thought I would try and summerize everything I have learned through this process. Too bad its winter time or I would have torn mine apart already and look at it myself. Hope this helps someone else out there. Please respond if you have any other info that I didnt include that may be useful.