Opened transfer case - stupid idea

[Opera House]

Well I opened the 4405 transfer case on my 97. Know what your thinking, can't get it back together. Not at all, doesn't look bad at all to put back. Just a lot of work for nothing.

Took it out because I had a lot of up down play on the rear output shaft. I was wondering why I did't have much side to side. Bought a master rebuild kit with all the bearings. The bearing holder for the rear is a split configuration. The mount surface on the bottom is worn. Bearing seems in ok shape. Do have wear on the flat clutch actuator surface (the one the balls rotate on) and the clutch backing plate it rides against.

Looks like I'l put in the easy bearings and put some dimples on the bearing mount surface to tighten things up. Can't say that will last that long. The frame is not spread. Above snap in groove it is still tight. Thought sure it was the bearing because when I bought it the case was almost empty with metal in the fluid. I doubt rear cases are available.

 

[Rhett]

Well, maybe it's not all for nothing. You know more now than you did before you did it, right? I know I would--I've never cracked open a t-case before, it would be educational.

 

[Opera House]

Beer cans cheaper than bearings

Well I polished down the clutch end pieces and I used two 3/4 inch folded over strips of aluminum can as shims to get rid of the housing play. At least it is soft metal that will easily chew up when they get loose. Lot of empty space in the transfer case. Think most of the damage was done before I bought it. You're right, sometimes you just have to do things for science. You can get at all the bolts to remove the transfer case without lowering the transmission. Just takes forever.

 

[Adam Berger]

Can you post some pics of the inside so we can all see? I've always been curious as to what's inside. Mine's perfect, so I'm not pulling it apart.

 

[macanudo56]

Opera House,

I have the same wear on the output bearing holder, plus the groove for the snap ring has virtually disappeared . I found a safe-looking way to repair this and am currently rebuilding the rest of the transfer case. If wear on the housing is moderate, with play up to 0.02" = 0.5 mm then you can use Loctite 660 to mount the bearing and it should hold fine. This is not to be considered a temporary fix. Knowledgeable people told me they have succesfully used it on applications up to 0.03" = 0.8 mm bearing play (but on a whole holder, not a split one like ours). Casing is magnesium, so you must spray Loctite Primer "T" on it before mounting.
I am sure rear half cases are available as replacement parts. I had one quoted ten days ago through a local Ford Parts shop, so if they can bring one to Argentina from the USA, you can get one too. The quotation was in Argentine Pesos, but deducting international freight, taxes and shop fee, I estimate it may be around $ 400 in the USA.

Adam,

I plan to post photos and a write up on rebuilding the t-case as soon as I finish and see some results.

Best,

Luis

 

[Opera House]

I haven't researched it further but was told a rear half case was available form Omega Manufacturing for about $140. Not sure this is new or just a remachined case with a sleeve. Chain force and the mount being split doesn't give me much hope for a sleeve let alone a filler. You probably noticed that the mount is chemically hardened. I think the best thing you can do is to disconnect the clutch wire to reduce the torque on this bearing.

To add to the unpleasantness, I tried putting the cover on when it was on the floor in a cramped position instead of on the table. This caused the shift shaft to bend and that snapped the 1/8 inch hardened dowel pin. I had to EDM the stuck pin out. I have access to machine out the housing for a sleeve if it ever needs to be. More likely a cheap transfer case will fall into my path in the next year.

 

[dogfriend]

I found an article about a year or more ago that indicates that the case damage is fairly common. They describe remachining the case, but don't give any details or pics.

Control trac problem caused by case deformation

I would also be interested in some pics; I have looked at the manual procedure for disassembly/reassembly but pics would be more enlightening.

 

[macanudo56]

Opera House,

Sorry about pin, shift rail, etc . If the BW4405 is not very reliable as a transfer case, it is a most effective torture instrument instead (for the unfortunate owner).

I think your doubts about the fix are 100% justified. However, I'm in the hope it will behave well in 2WD, when the chain is not stressing the bearing mount. I didn't think of leaving the brown wire disconnected, it is a good way to be sure the chain won't work.
Once I had the case apart, my first thought was to insert a sleeve, but it had to bee so thin walled... Anyway, if Loctite 660 doesn't do the trick, installing a sleeve is still possible.
If NEW rear half cases are available for $140 here's a good candidate for one. Will do some research on it and keep you posted.

Just an idea... have you thought of electric weld filling the housing, then remachining? Case is the most common magnesium alloy (AZ91) and there are welding rods available for it. As far as I know, welding magnesium procedure is quite similar to aluminum, so I think any qualified welder could tackle the job.


Dogfriend,

I have read that article some time ago and it motivated me to repair the case myself. When you see what I made to mine you will find out what the author means when he says: "the problem is an offset in the centerline distance, putting the shift rail at an angle, which allows the range fork to move out of position. The cases are magnesium and we do considerable machine work to correct this problem".
Now, machine work to correct this problem is anything but considerable. I did it myself in half an hour, true that I have access to machining equipment. On the other hand, correcting the teeth on used gears for them to stay in mesh is a specialty work although not an expensive one (at least, in this part of the world).
You can count on the pics, I will post them whatever the result.

Best,

Luis

 

[Glacier991]

Opera House writes:

"More likely a cheap transfer case will fall into my path in the next year."

PM me, I may have what you need and we can work something out.

Chris

 

[Opera House]

Just wondering if you found any wear on the flat surface of the magnetic drum (not the clutch). Memory is pretty poor on this. This was a piece that didn't look like it was ever supposed to touch anything and thought it might be rubbung because the shaft was angled a little bit from the bearing. I cleaned it up a little and just put it back. I'm thinking of retiring the 97 to my better half who only drives 5 miles a day. Thinking about getting a pickup again. Probably won't buy another Explorer for a couple of years since I would be stuck with a SOHC.

 

[macanudo56]

Yes, I found wear and did the same. Polished it to some extent and plan to put it back in. I found coincidental wear on the clutch back plate also (seems like both have been rubbing). At first I thought this parts shouldn't rub against anything but now I'm not so sure. If you take a look at the exploded view of the t-case, the magnetic drum we're talking about (#26) and the clutch back plate (#21) have matching slots. I think these slots act as an outlet for fluid from the clutch which at the same time lubricates the contact surface between both parts. Such contact is the only way I see pressure could be exerted on the clutch for it to engage but I'm guessing here, so ideas are welcome.
Also, I still can't explain why the front shaft is driven by the chain even when no pressure is on the clutch (the transfer case is still half disassembled).

 

[macanudo56]

Transfer case is re-assembled. Few details left to finish, hopefully this monday afternoon I'll be bolting it back on the transmission. On the workbench and rotated by hand, everything seems to be OK, but road test will probably have to wait until tuesday afternoon. Will let you know at once how things come out.

 

[checkedout]

I haven't had a chance to open my case yet but I don't have any up and down play. Instead, I can move the rear output shaft in and out a great deal. Any ideas on the offending part? It would be nice to have the part on hand before I open her up.

 

[macanudo56]

Not easy to guess without opening the case. Many parts are mounted on or rotating with the main shaft, so you could find damage in any of them. I would say output bearing and the same bearing mount on the rear half case, in which you can attempt a fix (I did).