Removing bolt with stripped thread

I am in the process of removing my transmission for repair and have a bolt that connects the transmission to the engine which has stripped threads. It just turns in the hole and the bolt head is flush against the case. I was thinking of drilling it out but it may be a hardened bolt which would make this harder.

Any suggestions/tips of how to deal with this.

A) Hammer+Punch/Drift from opposing end of the bolt head. The threads are already destroyed, and you'll need to oversize the hole, rethread with a tap and replace the bolt anyway. Or B) you could attack at the head side of the bolt by drilling a hole, wedging in an easy out type of bit in the hold, and using a small slide hammer, pull the bolt from the hole. Either method may result in pulling the bolt back enough to cath enough damaged thread to use a tradition socket or wrench to fully extract the bolt. Good luck.

MechanicMatt

Could you use those clamping type of pliers used in welding?

Grab onto the bolt head and pull while turning?

Maybe slide a wood chizel under the bolt head to pry it out a ways while turning
it with the wrench - so you can get a hold of it better...

Why would it be stripped out that badly?

Did the previous owner or some mechanic reef on it too hard? Must have taken
some real brute force to strip it out like that!

I hope the bolt isn't broken a few millimeters further down inside the case....
how long were the other bolts that you removed?

DoctorBill

Actually it is much easier than I thought to drill into it. However it is hard to drill straight as the transmission is preventing me from holding the drill straight. I'll see if I can pickup one of those close quarters drills tomorrow. I do have a right angle drill - a Milwaukee - which I got for drilling through framing to install some copper water pipes - bit it is not really suitable for this job.

Doctorbill - I was the person who worked on this transmission last. I had to remove it 2 years ago as the second brake band had broken. I rebuilt it at that time but having more troube with it lately. First missing reverse and second due to a jamming 1-2 shift valve which I fixed but how it seems like the direct clutch washer has broken (found a small bit of it at the bottom of the pan). So no third and reverse now.

I actually wanted to replace this washer 2 years ago but for some reason Transtec does not include it in their gasket kit. I was told that it does not fail very often. It would seem mine has failed LOL. They do include the thrust washers that separate the front and rear planets - maybe they are prone to failure.

Any back to the bolt - I did not recall doing anything to cause this.

This may not be the case here but a while back I had an old chainsaw that would rattle itself apart when the chain got dull. One of the bolts holding the muffler on came loose and since it was a steel bolt in an aluminum case, it basically filed off the threads with the vibration of the cutting. Perhaps that's what happened here, if the bolt wasn't torqued? Not trying to place blame here, just thinking what might have happened. And as we all know, sh*t happens.

OK so I stopped off at HF today and got one of their close quarters drills. Had to remove the radiator fan and the range switch on the transmission for better access but I was able to drill straight. I drilled the bolt head off first and then drilled a smaller hole all the way through the bolt. This resulted in being able to push back the bolt the other way to the point where the transmission should be able to be slid out. Once it is out I will push the bolt back and cut the protruding end with a cut-off wheel and then use a punch to knock it out of the other end.

No sure what has happpened to the threads but I will try and repair it with my repair taps. If that's not possible I will drill a larger hole and retap for a larger bolt.