I have a 205 in my 78 bronco. there is a mount on the drivers side frame rail and that mount is bolted into the Tcase with 3 rather small bolts.

Well it seems like someone left 1 out (previous owners) and the other 2 have sheared off. Now I need to drop my Tcase and drill them out. I need to know if I can step up to a bigger bolt in diameter without toasting the tcase. I do a large amount of offroading so everything I do must be strong.

 

Since they sheared off rather than broke off while being removed, I would try a left-hand twist or "reverse" drill bit. Sometimes this is enough to remove them. If not, then an "e-z out" or screw/bolt extractor. If they still won't budge, then drill just below the size and see if you can clean out the threads-I know, this is extremely difficult to say the least but worth a try if your to that point. I don't think you'll have a problem going up in size, although I may suggest tryin' to drill with bias to the bottom of the 'case, in other words, try to stay from away from taking any more material from the top of the 'case. This area above them is what holds the weight (or will be the most prone to crack or break-out from stress), the other thing to keep in mind is the plate that the bolts go thru, should try to favor the lower if possible not only for strength (the weight is pushing down towards the "L" and bushing) but more importantly to keep everything in line. One last thing, might want to take a look at the rest of the mounts, engine and trans, if these are weak they would have allowed the 'case to move a lot more than it should contributing to the problem and if you have to oversize the bolts, good mounts elsewhere will help keep the twist torque off the 'case/'case mounting bolts.

 

Should add...I assume you have one that can still be the correct size, the missing one? If not, then I would try very hard to remove at least one so not all three have to be oversized. I don't recall there being a lot of material around them and they kinda have a "lip" sticking out from the side of the 'case rather than in the 'case itself. Sorry if I'm wrong on this, been a while since I had mine out!

 

one bolt is completely missing. it is exactly the same size as the bolts that hold the whole bracket assembly to the frame rail. I am going to either step up to a size that is just a tad bigger so when I drill them out I have fresh threads to tap.

Now I do not know if the motor mount was broken before or after this all happened.

For all I know someone could have sheared these off from not putting in all 3 bolts, then the motor mount gave loose, it is truely too hard to tell the exact reason it broke, but it needs to be fixed.


Any idea where I can get some reverse drill bits?