I've got an 89 f150 with the 351 and C6 trans combo. I've got a BW1356 transfer case that I swapped onto it when my previous one took a crap. I've had problems with the mounting bolts backing out of the case. I've ALSO had problems with stripping the bolt holes out with just a normal sized 3/8 ratchet. I was wonder what the actual torque recommendation is for the mounting bolts? I'd rather not lose my transfer case due to stupidity.

 

If there is a torque spec, I don't know it, and it would be pretty hard to get an accurate torque reading as some of the bolts are only accessible using a box-end wrench. I've never stripped one out myself, and I get em pretty tight. Perhaps you could back up the stripped ones with a nut on the other side?

 

The case you easily stripped likely suffered from galling, as 20 year old never removed steel-to-aluminum bolts often do. It should be very hard to strip them with a 3/8 ratchet, considering how deep the threads are.

Before you put the case on, inspect the thread chases to be sure they are in tact. Apply anti seize to the bolts, go good and tight.

 

The threads are intact and don't appear to be corroded or anything like that. I'll just have to do like y'all said and put some anti seize on them. I'll just be careful not to use my apparent super human strength lol.

 

the bolt thread (just measured mine and replaced a couple) is M10 x 1.5, i would try a standard torque for that thread.

i lost a case due to this. Before install i ran a wire brush down the holes, not sure if that was the issue but maybe that and corrosion, i test fit the bolts and they dropped freely in a couple threads. The bottom of the holes seemed okay, so i assembled them with loctite. Checked it after a drive, then a trip, then another trip; no movement so i forgot all about it.

fast forward one year and i had a terrible vibration and i recall it popping outta 4 lo, after inspection I found the TC had loosened all the bolts, lost one, loosened the dowel, and probably would have came off the tranny if the drive shaft didn’t basically have it captured.

I went back in with a new case and good threads. Obviously i regret not putting helicoils in the first time, or Over sizing the holes.

with the good case i went really tight with a wrench and a little cheater on most of them. I also put a few in with a long 3/8 ratchet, and did have to stop short of as tight as i could have, or some damage may have occurred.