This problem has got me so ticked right now I don't know what to do!

My truck ('88 F-150, 302, 5spd, BW 1356 manual shift) is eating range forks! It worked fine for a couple of months when I first got it before it ate it;s first one. I chalked it up to age and use and replaced it along with the oil pump, I also welded a tab on the pump to keep it from spinning. Somewhere around six weeks later it ate the replacement, so I dropped put another one in. Now today, just another six weeks have passed and it has ate the replacements replacement!

What gives? I'm using aluminum forks, not plastic. They have the nylon inserts in them. The last time I put it back together I used all new snap rings, and everything felt fine. What could it be? A blocked oil passage not allowing the for to be lubricated? Possibly a bearing worn out allowing the output shaft to come out of alignment wearing the fork?

I'm at a loss. Buying a new to me T-case could present a new set of problems, and I don't want to keep dropping the case every six weeks!


ETA: I did not change the range slider when changing forks. I do remember that the front of the teeth were rounded a little bit, maybe 3/32", and just on the corner of the gears.

 

When you take it apart again check the bore in both case half's where the rod that supports the shift forks sits. I know the 4406 TC wears them in a egg shape and that movement causes the forks to wear, we have to machine the cases out and insert a steel sleeves to keep that rod from moving around.

 

I looked at where the rod sits on both ends, it wasn't wallowed out and the rod fit in it well. It wasn't tight but it fit with no sloppiness.

So far so good, all new bearings and bushings in the case plus a new range slider. We'll see how it does.

ETA...

I just used my 4wd for the first time since the rebuild, I had to move my camper around my soggy, hillside yard. Because of the extra weight and the slope I decided to use 4-LO. The first thing I noticed was that the T-case was much harder to shift into low than before. I didn't have to force it, but before it pretty much would shift with no effort at all. Not sure if this is a good sign, but I'm keeping my fingers crossed.