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Borg Warner 1356 transfer case problems

The Borg Warner 1356 transfercase is used in the '80's in Ford fourwheel drive trucks. It has been a fairly reliable transfercase, but is not completely without problems. The most common thing I see with the1356 transfercase, that ulitimately causes transfercase failure, is wear within the pump-stop area of the case, ("highlighted" with my black inkpen) allowing the oil pump housing to begin to spin freely, instead of being held stationary, as it should be. This pump-stop area begins to show extreme wear, typically, at, or around 100,000 miles, and, although there are no external warning signs, it can be quite a savings to tear the transfercase down, at the 100k interval, simply to repair the case, and do a "seal job" (replace the external seals, and renew the glue sealing the two transfercase halves). I have found many shops that overlook this area of the case, choosing to overhaul a 1356 without any regard to the problems inherant within the 1356 design.

Worn Lugs, Common to the 1356
(Figure 2) Repaired Lugs
(Figure 3)

The 1356 transfercase relys, completely, on a crude oil pump, mounted on the output shaft, turning, obviously, with the output shaft, to provide all of the lubrication needed to keep the transfercase properly lubricated in 2 wheel drive (the chain can provide "splash lubrication", but is not used in 2 wheel drive). The pump is turned, as I stated before, by the output shaft, but the pump housing must be held stationary. The housing is held stationary by a crude steel plate, bolted to the pump housing, and then indexed in between two lugs cast into the transfercase housing (within the front half of the case); it is these lugs, cast in the magnesium housing, that wear, and become unable to hold the pump housing stationary.

Ford describes transfercase housing replacement as the cure for this problem, but at our shop, we send the front case half to a machine shop, capable of welding on cast magnesium. We simply have them weld up the worn lugs (figure 2 and 3), and then carefully file them down to factory height. In addition to repairing the case half, the steel pump-stop steel plate must be replaced.

Borg Warner 1356 Transfer Case Overhaul

You will need a T50 torx bit to work on a 1356 transfercase. During overhaul, make sure that both the case halves are completely clean, and free from oil residue (use a good quality carburetor spray to clean glue surfaces). Also, make sure to flat-file both glue surfaces carefully (don't actually remove much material, just run a fine flat file over the surface to remove any scratches, nicks, or other high spots), to make sure that there are not nicks, that could cause the case halves to be held apart. Clean all bearings and check them for wear (bearings do not typically fail in a 1356, unless the pump-stop completely wears and the pump housing spins, causing lack of lubrication; if this happens, chances are that you may have to replace MOST of the parts within the transfercase, at a substantially higher cost than a "seal job"). Replace the shift fork plastic inserts and all of the seals (use #271 red lock-tite on the seals, to keep them from popping out). I also prefer to apply #242 blue Lock-tite to all of the torx bolts, holding the case halves together.


Worn Lugs, Common to the 1356 (Figure 2)	Repaired Lugs (Figure 3)