For those than have ventured down this path, can provide any insight that will make this job easier. I have a 1995 Ducati 900ss and have spent a little time watching videos on youtube. I have a MIG welder with Argon gas. I was planning to build up the bolt, since it broke below the surface, and then weld a nut to aid in removal. I am guessing I should heat up the aluminum block a bit, but not sure how much. Any other gotchas I should be aware of? The bike has been dismantled and the engine is in a separate stand already. Hopefully I can get this extracted before the bolts get here from Italy.
Did you break it or was it broken before you got to it? I don't know what kind of clearances you have to work with around the hole as far as damaging threads etc, but that's likely how I'd be going about it. Drilling is a last resort for me usually. You're better off keeping as much of the bolt intact as possible. I'm assuming the bolt is in aluminum, that's great and not so great. The great part is your weld wont stick to the alumn. if you screw up, the bad part is it will melt it if you screw up. That's why I wondered about clearances and what may get damaged.
It was broken when I bought it. The case is aluminum and the bolt is hardened steel. That is why drilling the bolt out is not really working. But you are right...weld should not stick to the aluminum threads on the case since it is steel. I have a ton of clearance since the motor is out of the frame.
How or why did it break? If it was sheared during installation by over-torque, the threads are pooched and it will be very difficult to remove even with a built up head. Was it sheared off by a crash? If so, then it's probably bent inside the threads, and the threads and possibly the head are pooched. Cross threaded and the head twisted off during the removal attempt? Again, it will be difficult to remove. last possibility (in my mind) is corroded and the head sheared off, which means best chance for success with the heat from the welding operation. You may want to drill the bolt just to see about relieving the thread stress (assuming it was over-torqued or sheared off), or maybe even using a reverse drill in incrementally larger steps to see if it will twist out.
The bolt broke while riding and from what I hear this was a common problem. Especially if you reused them. I plan to replace all of them.
Fatigue, that's good. Or, better than the options I listed. The welding should work, with the heat helping to loosen it in the aluminum.
I understand this isn't possible for everyone but to increase your chances of success you could after welding the nut on toss it in an oven (assuming it's just the block as this point) and try to pull it at just the right time. The aluminum will expand way quicker then the steel bolt/nut will. Best of luck, this is a nightmare to me.
Awhile back I had a similar issue. I soaked it really good in pb blaster for days, hit it with a chisel to make a deep groove, heated it up real good and then attacked it with a impact drill with a flat head bit on it (slow on the trigger). Good luck
MIG is a bit messy. It's easier with a TIG, it is easier to place the filler where you need it. Oil often boils up out of the cases as well and contaminates the weld. Take a torch and heat up the cases to drive all the residual oil out of the hole before you weld. Tricky operation.
I'm with Rick. That mig will make a mess of things. Post up a pic if you can so we can see what you are working with.
Since it broke while riding it should come out easily with a left hand drill bit. There is no longer any tension on it. Go buy a carbide one for $20 and be done with it.
Definitely if the head just popped off on it try a good sharp left handed drill bit, one that's nearly as large as the bolt (you want as much torque on it as you can get). Go really slow with a lot of pressure, you want a heavy chip to start as that's what's going to be turning the bolt.
