How to: Rebuilding a Borg Warner 4404

[gavin]

I found the culprit of the noise.

oil looks a little dirty to only be a couple hundred miles old.

can you see what went wrong?

shavings all over my hand.

what's that down there?

something looks... hmmm... wrong?

that doesn't belong there.

it fell apart as I was removing it.

 

[99SportX]

Oh boy, that looks like a mess. You will have to do some serious cleaning to make sure you get all the metal put of that case. Do you have any idea why that bearing failed?

 

[gavin]

nope, no clue why it failed.
nothing was apparent.

and yes, I used up atleast 2 cans of brake parts cleaner.
along with a LOT of air.

it's now back together, and back in the truck.

one bolt left to tighten, the d-shaft, and fillin' her up with fluid.

All teeth and splines looked good.... no abnormal wear from the pieces.

One other bearing looked bad, so I replaced it also. The rear-most bearing for the front output. There were also brown marks on it, from the looks of it, caused by heat.

I ended up re-using the bearings I removed from those 2 spots, for 2 reasons.
#1 - so I could get it done tonight.
#2 - I cleaned them good, applied some ATF, and verified they spun smoothly.


edit: I do have 1 idea as to how/why it failed... although I'm not 100% certain. If you look at the destroyed bearing, there is a clip on it. The original did not have this clip. I MAY have put the bearing in upside down, with the clip nearest the outside of the shaft, which would have caused the set of gears to not sit correctly. This would also cause abnormal pressure on the bearing, which could have caused it to fail. This is just a guess, though, as I do not remember if the clip was nearest the inside or outside of the shaft.

 

[gavin]

updated post #2 with some more pics and my little write-up on "how it works"

 

[gavin]

well, she's buttoned back up, filled up with fluid, and ready to go.
Haven't done any more driving than moving forward and backward in the driveway.

No noise is apparent.

Hopefully she's ready for another 170k miles with no more problems.

 

[Neilk]

just FYI, I just put a 5.0 with a Mazda 5speed and a 4404 xfer case in my 98 ranger (all 98 parts), the 4404 I have has the rear drive after the viscous clutch in other words the output isn't directly connected to the input as a result the clutch failed this morning and I had no drive at all, really sucked too....Neil

 

[pubenemy]

Thanks for the writeup Im reading all the 4404 posts I can. Im looking to rebuild mine cause when I removed the front driveshaft I had no drive! I thought the chain drove the rear but I guess the chain runs the front? With the front driveshaft on I can drive around fine. So whatever powers the rear is shot. And how much fluid do you fill it up with and what kind atf?
Thanks!
-Mike

 

[watts]

viscous coupler BW 4404 transfer case

I have 96 AWD Explorer with symptoms of load clunk at moderate to hard acceleration, and going from reverse to drive. Checked all CV and u-joints all were good. I pulled the transfer case and expected to find a bad gear, chain or bearings that would cause such a load noise. After opening the case I found nothing really wrong. That is how I came to this sit looking for some help. After finding several threads with similar complaints I found this one on the workings of the viscous coupler. I toke my TC to a transmission shop told the owner my symptoms he pointed to the viscous coupler and said he was 99 percent sure that was my problem. I found a used TC for $300 instead of rebuilding mine. The coupler it self new is $350 not including new chain seals and bearings.

 

[gavin]

it's very possible that it could be the cv-joint at the t-case end of the front driveshaft.
those are notorious for causing noises under load when they start to go bad, then they start to cause a heavy vibe.

that would be the next place to look if the used viscous coupling doesn't solve the noise.

 

[CDW6212R]

Ditto, that CV joint is the most common part to go bad in the front drive system.

 

[watts]

viscous coupler 4404 transfer case

In my search to trouble shoot my transfer case I found this link explaining the workings of an AWD with a viscouse coupler. It is not a WB 4404 TC but is similar and gives a test procedure for the viscous coupler. Do not see why it would not work for BW TC. Could not copy the link with the drawings but here is the text NVG 149 Transfer Case Description and Operation




The RPO NP3 is a single speed, single mode transfer case. The mode is full-time all wheel drive. It has a planetary differential gear set that splits the torque, normally 38 percent to the front wheels and 62 percent to the rear wheels.

The NVG 149 utilizes magnesium housings. Proper fasteners, brackets, and fill/drain plugs must be used to prevent galvanic corrosion. The planetary differential uses the carrier (6) as the input. The annulus gear (4) connects to the rear output shaft (5) and rear wheels. The sun gear (3) connects to the front output shaft (7) and front wheels through the chain (8) and sprockets. The viscous coupling (2) consists of a sealed housing filled with a high viscosity silicone fluid and thin steel plates alternately splined to the inner and outer drum. The inner drum is connected to the input shaft (1), and the outer drum to the sun gear (3). Whenever there is a speed difference between the front and rear wheels, the inner and outer plates of the viscous coupling spin relative to each other and the silicone fluid provides resistance. The resistance was tuned to be high enough to bias power quickly to the wheels with traction, and low enough to prevent binding in a tight turn on dry surfaces. This is the most common way the viscous coupling is activated, the shear mode. If the speed difference is high, the coupling can lock or hump. This "hump" occurs when the heat generated, expands the fluid inside the housing, changing the fluid dynamics between the plates. This results in pressure between the plates, forcing them into contact with each other, similar to a clutch pack. In the hump mode, the coupling can bias torque 100 percent to one axle, if required. Situations requiring this are extreme such as backing up a steep gravel grade or climbing over off-road obstacles. The viscous coupling is not serviceable; it must be replaced if defective. This is because each viscous coupling is calibrated for optimum vehicle performance for both the shear and hump modes. If the viscous coupling is in the "hump" mode too long, severe damage will occur. To prevent damage to the viscous coupling, DO NOT:

Tow with only two wheels down
Drive without one propshaft
Drive with a "donut" spare tire for an extended period of time

Power Flow - No Wheels Slip



During normal operation, 100 percent torque is delivered to the input shaft (1) from the transmission. The torque is split to 62 percent to the rear output shaft (2) and 38 percent to the front output shaft (3), by the planetary differential. Because there is not a loss in traction or slip in the front or rear wheels, the viscous coupling is locked in place and there is no "shear" mode or "hump" mode involved.

Power Flow - Front Wheels Slip



When traction is lost at the front wheels, the viscous coupling works in conjunction with the differential to bias the torque more to the rear wheels. The rear torque goes higher than the 62 percent, and up to 100 percent torque to the rear output shaft (2). The torque at the front output shaft (3) is lowered from the 38 percent, to as low as 0 percent torque.

Power Flow - Rear Wheels Slip



When traction is lost at the rear wheels, the torque is biased to the front wheels. The torque to the front output shaft (3) goes higher from the 38 percent, up to 100 percent torque. The torque at the rear output shaft (2) is lowered from the 62 percent, to as low as 0 percent torque.

Customers may have concern that the transfer case is not operating properly because one set of tires spun for a brief period. It is normal for one set of tires to spin until the viscous coupling engages.

Turning off the traction control switch, if equipped, enhances the function of the viscous coupling. The viscous coupling, as described above, engages by heat. Allowing one set of tires to spin or slip for a brief period will generate heat in the viscous coupling. The engine speed should be kept at a constant speed during the brief spin of the tires. Pulsating the engine speed or hard acceleration will not allow the viscous coupling to operate properly.

© Copyright General Motors Corporation. All Rights Reserved.

Document ID # 873908
2003 Chevrolet/Geo Chevy K Silverado - 4WD


******************

Transfer Case Viscous Coupling Test
Tools Required
J 45382 Transfer Case Tester





To determine if the viscous coupling is operating correctly, use the following test procedure. Testing the viscous coupling operation by removing a propeller shaft and driving the vehicle will cause the viscous coupling to fail. The test will determine if the viscous coupling is faulty from a totally locked up failure, or if the viscous coupling fluid has leaked out from being severely humped.


Important
The Viscous Coupling Test is very sensitive to the temperature of the transfer case. If the transfer case is very hot, the time to turn will be faster. If the transfer case is cold, the time to turn will be slower.


1. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.
2. Set the parking brakes for the rear wheels.
3. Position the transmission in NEUTRAL.
4. Raise the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
5. Remove the front propeller shaft. Refer to Propeller Shaft Replacement - Front in Propeller Shaft.
6. Install the J 45382 into the transfer case front output shaft.
7. Using a torque wrench at 11 N•m (100 lb in) on the J 45382 , turn the front output shaft 90 degrees.
8. Note the length of time it takes to turn the front output shaft the 90 degrees.
* If the front output shaft turns slow, and takes at least 10 seconds, the viscous coupling is operating correctly.
* If the front output shaft will not turn, the viscous coupling or the planetary carrier assembly could be locked-up.
* If the front output shaft turns easily, and the 11 N•m (100 lb in) cannot be obtained, the viscous coupling is faulty.


© Copyright General Motors Corporation. All Rights Reserved.

 

[watts]

BW 4404 transfer case viscous coupler

Well I just installed a used transfer case $250 (thought I got a pretty good deal) and so fare all my problems are gone. I bought this 96 explorer 5.0 AWD for my daughter at a discount because it had problems. Which was loud clunk at acceleration from a stop our going from reveres to forward. I also had grinding noise when making turns. I actually though I had two different problems. Turns out this was all from the viscous coupler. From what I have read they either lock up (think that was in my case) or it leaks the fluid out, not sure what symptoms you would have then, seems like you would have no drive at all. So I hope this helps someone else in diagnosing there problem. I am new to this site came looking for help with my problem as per above and it has been good help taking some of the guess work out. Not sure if I have been posting right

 

[CDW6212R]

Very good, and thanks for the reference material. The TC's are getting a lot more miles on them these days. They will be going bad more and more, plus the used parts are worse too.

 

[gavin]

Well I just installed a used transfer case $250 (thought I got a pretty good deal) and so fare all my problems are gone. I bought this 96 explorer 5.0 AWD for my daughter at a discount because it had problems. Which was loud clunk at acceleration from a stop our going from reveres to forward. I also had grinding noise when making turns. I actually though I had two different problems. Turns out this was all from the viscous coupler. From what I have read they either lock up (think that was in my case) or it leaks the fluid out, not sure what symptoms you would have then, seems like you would have no drive at all. So I hope this helps someone else in diagnosing there problem. I am new to this site came looking for help with my problem as per above and it has been good help taking some of the guess work out. Not sure if I have been posting right

honestly, sounds more like a stretched chain to me.
yes, if the VC essentially "blew up" and drained all the fluid out; for one, the t-case would most likely then be overly full (although, possibility of it not, depending on how the fluid leaked). And yes, if that happend, you would have absolutely no drive (there's a thread around here where that WAS the case).

the clunking sounds more like a loose chain issue; as you start moving, there is an excessive amount of play before the gears "mesh" with the chain, causing the noise.

although the grinding when turning... no clue? possibly again chain related (maybe slipping or something?)

 

[watts]

4404 transfer case viscous couler

Not sure if you have seen my other posts but as I said earlier I did split the TC expecting to find bad chain, gears, bearings which could cause the noise I was hearing. But none of this was the case. The used TC I put on has the same amount of back-lash from front output to rear output as my old TC had. As far as what is actually making the noise when the viscous goes bad hard to say. In my case I believe the viscous was locked up and would be like driving a manual 4X4 on dry pavement, you get torque bind and something has to give. I am sure as the viscous starts to go first to last symptoms change a little. I know the previous owner complained of bad vibrations above 35 MPH this was on an inspection report from a shop she had it at before I bought it. I never experienced this symptom. As fare as the grinding or whining noise when making turns again I think it was torque bind going on because the viscous was lock up not allowing any release in torque from front to rear drive. The best way I can explain what I was feeling when making a turn (going forward or in reverse)is as you inter the turn it was like driving in sand there was drag and on a level surface you would have to give a little gas to complete the turn. I finished the install late last night and only drove the car a few miles but as I said all symptoms are gone no clunk at acceleration and I immediately noticed the difference in making a turn, no noise and the car would complete a turn backing up or going forward with my foot off the gas. Having said all this if I would have known for certain that this was the problem I would have spent the $600 to rebuild the TC. The viscous coupler itself was $350. Not easy to find either only found two places on line that would sell them.

 

[Fordified1]

Thanks Watts!
Finally a diagnosis that makes sense. I have a 98 with 5.0 and AWD and have been nursing that popping noise in my transfer case for close to two years. At first it would only clunk or pop when you really gassed it from a dead stop while turning. Progressively this popping has been easier and easier to generate until finally the other night at about 50 mph and 10 miles from the house, I started to hear a soft squeeling (sounded like a bearing going down or starving for oil) and a vibration that made the whole truck sort of shimmy or shudder until I came to a stop. I turned around and went home and changed cars. The noise and shimmy has not come back, but I have only driven the truck to the store and back a few times and never for a long distance because I don't want to get stranded or totally destroy what's left of my transfer case. I checked the fluid just to make sure it wasn't low because of the squeeling I was hearing and it is still full although is very black looking considering I changed the fluid a couple months back and the old 170,000 mile fluid still looked pretty clean.

At first, I too figured my chain and sprockets needed replacing. A local tranny shop even diagnosed it as that a few weeks ago. But I found that hard to believe for 3 reasons... A morse chain rarely slips unless it's stretched a whole lot and the sprockets are worn down to almost nothing, and that If it were stretched much at all, it would have eaten up the chain guide strips a long time ago and made noise rubbing metal to metal. And the oil was very clean when I changed it.
In the trans shop's defense they had never rebuilt an AWD TC before and hadn't ever heard one make noise like mine. Here in south Texas there aren't many.

In my mind that left the viscous coupler, but nobody could tell me if they make noise when they go bad, or even how they work for sure.

I was under the truck today contemplating splitting the case and just looking at the chain and sprockets, but decided to search on the internet one more time before I dove into it.

That GM diagnosis is enough proof for me.

Not sure what I'm going to do, but either converting to 2wd or getting a part-time 4wd tc is looking attractive considering the cost of the viscous coupler.

The truck has almost 180,000 miles on it, but other than the tc, still looks and runs great, uses no oil and dammit... I'm hell-bent on making it last 300,000 miles. Getting rid of it is not an option due to funds, as I've been off work recovering from surgery for going on 3 months. Finally felt good enough to crawl under it today.

.

 

[CDW6212R]

The viscous coupler is the key in these TC's. There have been a few references in these threads to buying them for under $200. For the cheapest repair I'd rebuild the TC, the other parts are easy to come by. I'd hunt the viscous coupler by the suggestions from this forum. If you can do that feasibly, then rebuild it.

 

[gavin]

I recommend Six States (http://www.sixstates.com) if you have one near.
By far the least expensive place to get one, as I have stated somewhere in this thread (I believe). Although all their stores are pretty much mid-west.

Boise
2138 Century Way
Boise,
83709
(208) 377-9393
Toll free ( only): (800) 632-2006
Toll free: (800) 635-3702
FAX: (208) 377-9437
8:00 A.M. to 5:00 P.M. Monday through Friday
Closed Saturday
Closed Sunday

Cedar City
2173 West 850 North
Cedar City,
84721
(435) 867-4666
Toll free: (877) 867-4666
FAX: (435) 867-6332
8:00 A.M. to 5:30 P.M. Monday through Friday
Closed Saturday
Closed Sunday

Evanston
113 Commerce Drive
Evanston,
82390
(307) 789-5700
Toll free: (800) 669-1884
FAX: (307) 789-5703
8:00 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

Orem
841 Industrial Park Drive
Orem,
84057
(801) 224-1155
Toll free: (800) 574-1155
FAX: (801) 224-1194
8:00 A.M. to 6:00 P.M. Monday through Friday
Closed Saturday
Closed Sunday

Salt Lake City
247 West 1700 South
Salt Lake City,
84115
(801) 488-4666
Toll free ( only): (800) 662-3712
Toll free: (800) 453-5703
FAX: (801) 488-4676
8:00 A.M. to 6:00 P.M. Monday through Friday
8:00 A.M. to Noon Saturday
Closed Sunday

Alaska
Anchorage
1884 East Third Avenue
Anchorage, Alaska
99501
(907) 278-6622
Toll free: (888) 933-6622
FAX: (907) 278-6625
8:00 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

Soldotna
44113 K-Beach Road
Soldotna, Alaska
99669
(907) 260-9177
Toll free: (877) 925-9177
FAX: (907) 260-9194
8:00 A.M. to 5:30 P.M. Monday through Friday
Closed Saturdays
Closed Sunday

Idaho
Twin Falls
1920 Kimberly Road
Twin Falls, Idaho
83301
(208) 734-2855
Toll free: (800) 464-1952
FAX: (208) 734-3072
8:00 A.M. to 5:30 P.M. Monday through Friday
9:00 A.M. to 1:00 P.M. Saturday
Closed Sunday

Nevada
Elko
4290 East Idaho Street
Elko, Nevada
89801
(775) 753-3993
FAX: (775) 753-3995
8:00 AM - 5:00 PM Monday through Friday
Closed Saturday
Closed Sunday

Oregon
Portland
6011 NE Columbia Blvd.
Portland, Oregon
97218
(503) 249-1010
Toll free (Oregon only): (800) 452-9365
Toll free: (800) 547-7024
FAX: (503) 249-279
8:00 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to 2:00 P.M. Saturday
Closed Sunday

Salem
1800 Mcgilchrist St SE
Salem, Oregon
97302
(503) 363-3159
Toll free: (800) 423-2094
FAX: (503) 371-1438
8:00 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

Utah
Logan
1077 West (1400 North ) RSI Drive
Logan, Utah
84321
(435) 753-9191
Toll free: (866) 753-9191
FAX: (435) 753-4464
7:30 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

Ogden
1112 West 3300 South
Ogden, Utah
84401
(801) 621-8772
Toll free: (800) 371-5547
FAX: (801) 621-8775
8:00 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

SLC Service Center
1388 South 300 West
Salt Lake City, Utah
84115
(801) 488-4677
Toll free: (800) 960-4677
FAX: (801) 488-4641
8:00 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

Exchange Parts/Clutch Remanufacturing Center
232 West 1700 South
Salt Lake City, Utah
84115
(801) 485-2474
Toll free: (800) 486-3051
FAX: (801) 486-3051
8:00 A.M. to 5:00 P.M. Monday through Friday
Closed Saturday
Closed Sunday

St. George
1260 West Red Hills Parkway
Washington, Utah
84780
(435) 673-9620
Toll free: (800) 570-9620
FAX: (435) 673-9580
7:30 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

Washington
Pasco
2251 North Commercial Ave.
Pasco, Washington
99301
(509) 545-4511
Toll free (Washington only): (800) 572-9694
Toll free: (800) 635-5014
FAX: (509) 545-4225
8:00 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

Spokane
3711 East Trent Avenue
Spokane, Washington
99202
(509) 535-7671
Toll free: (800) 541-4320
FAX: (509) 535-9105
7:30 A.M. to 5:30 P.M. Monday through Friday
Closed Saturday
Closed Sunday

Wyoming
Rock Springs
425 Mohawk Drive
Rock Springs, Wyoming
82901
(307) 382-6894
FAX: (307) 382-6897
8:00 A.M. to 5:30 P.M. Monday through Friday
8:00 A.M. to noon Saturday
Closed Sunday

 

[Fordified1]

Well, I bought one off eBay in Denver for $220.00 to my door. It has a 60 day warranty. Wish me luck. The cheapest I could find one local was $350 with 110,000 miles on it. Later this year I'll rebuild the original TCase and have it on the shelf ready for when the ebay one starts giving trouble.

.

 

[gavin]

ohhhh you just bought a whole new(used) case. gotcha.

yeah, they are spendy. All the junkyards up here want $700+ for the 4404, regardless of miles.

which is why I ended up rebuilding it myself, saving ~$300 and having all new parts and writing this thread :