BW 4405 ratcheting
Hi Mike, I’m posting from Argentina, South America. This is my first post and I hope it could be of some help about the topic of 4405 transfer case ratcheting. I found an article on the Web, written by Mike Weinberg (President, Rockland Standard Gear Inc.) which reads as follows:
“This unit is prone to certain mechanical problems that are beyond the scope of most shops to repair. The most common mechanical failure is a complaint 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 form 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 problem. The range hub is helical cut gearing and will stay in mesh under load, but will move out on coast due to the thrust loads generated by the helical design. Adding power will cause the gear to return to the correct position. The bottom of the teeth get chewed up and the constant pressure on the fork causes it to burn up. The real cause of this 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, which is beyond the equipment found in the average shop. If you see units with this damage, you will usually see oblong holes in the cases where the shift rail rides. It is cheaper and more efficient to buy a unit that has this problem corrected than to tackle it yourself”.
My Explorer is a 1996 XLT, 4.0 V6, 5 sp. Mazda manual. Bought it on 1998 with 37,500 miles, now it has 100,000. Transfer case is a BW 4405 Control Trac. This failure has happened to me twice, and it is just like described above: loud thump when on the road at 50 mph, then ratcheting sound during deceleration and sometimes on reverse. The first time it happened I had to replace the range hub, fork, electric clutch coil and casing, oil pump, chain, bearings and seals. In your first post you asked for part numbers involved, here they are as per local Ford Parts Dealer invoice:
F77Z - 7100 AA - Hub Reduction
F57Z - 7289 A - Fork Assembly
1L2Z - 7G362 AA - Clutch casing
F57Z - 7G361 A - Clutch coil
XL2Z - 7A029 AA - Chain
F57Z - 7A149 A - Pump
F57Z - 7A098 A - Pump filter
E3TZ - 7025 A - Bearing
F57Z - 7025 A - Bearing
F57Z - 7127 A - Bearing
E3TZ - 7120 A - Bushing
F3TZ - 7B215 A - Seal
Now here it goes again: A loud thump, then the ratcheting. Knowing the drill, I changed the ATF as a preventive measure and took from the draining hole a little bit of aluminum (oil pump alignment tab?), another little bit of steel sheet (chain?) and some steel shavings. No copper residue so I hope the electric clutch is good, but range hub and fork are going in for sure. Well, now I’m facing the second repair and don’t want to waste money, time and expectancies anymore. I’ll consider alternatives carefully.
As far as I know, there are no rebuilts available down here, so my options should be:
1) Swapping to a brand new electric BW 1354: VERY expensive but perhaps definitive solution. However, I don’t know if it is possible to cheat the GEM since a 1354 has no front and rear Hall effect sensors and no Torque-On-Demand clutch. Seems like a high risk of diagnostic trouble codes popping up. Also, I’m not sure if the speedometer would work.
2) Repairing the 4405: If Mr. Weinberg is right (and I believe he is) it is useless to replace any parts if the hole offset in the casing is not corrected first. I have learned it the hard way. But he discourages about doing the correction yourself, because “we do considerable machine work... beyond the equipment found in the average shop”. I find it difficult to send my t-case to Mr. Weinberg for rebuilding, so I must imagine how to work this out. Two options come to my mind:
a) Redrilling the hole to a slightly larger measure (if casing thickness allows it) then inserting a thin bushing into it. This should be cheap and absolutely not beyond the equipment found in the average shop.
b) Filling the hole with electric arc welding, then redrilling it to proper measure. This could be a much better fix, but it is definitely reserved to a very qualified welder, since a wrong practice could create cracks that would render the casing unusable and this may be the reason why Weinberg warns “The cases are magnesium”.
Whatever the choice, one is still to figure out where the center point to redrill the hole is. Tough job without a blueprint of the casing. If it is not drilled in the right position, the shift rail would be at an angle again and everything back at the start situation.
Well, I’m still stuck on the ideas phase. I would really appreciate your comments on this failure and potential corrective methods. Thank you very much in advance and sorry for the long post.
Luis
