Victor,
The last one of these that I had to deal with was a real challenge. I was able to drill it out and install an easy out. Then the easy out broke off! I ended up with a larger hole and installed a HeliCoil insert. It worked but was a bugger. If I were a welder I think I would have ended up with a better solution...
Dale
Victor, I've been where you are right now. Here's what worked for me. First, grind out a concave "divot" in what is left of the bolt shaft with your bullet-shaped Dremel grinding stone as close to the center as you can. Next, with a fine center punch, hammer a "Starter hole" right smack dab in the middle of the cup-shaped indentation you ground into the shaft with your Dremel. This will help keep your cutting bit centered and get you some purchase. As it looks now, I'm sure your bit just bounces all over the irregular surface as seen in your photo. Then use your extractor as usual. A bit of penetrating oil won't hurt. Also, if you are using one of those double-ended extractors, remember that both cutting and extracting operations require the drill is set to run in reverse (anticlockwise). Don't laugh - I wrecked one that I've used for 20 years trying to drill the pilot hole with the drill in forward mode. I use an impact drill/driver for the "shock value" but a regular drill/driver also works well. A little thread cutting oil will help with drilling the pilot hole. Also, if you still have the broken off head, check to make sure the DPO didn't decide to use that Grade 8 bolt he had sitting around. If that's the case, you might need someone with a no-$h!t mill to get through it. Good luck!
i will try and put this in to something thats some whats understandable. since it looks like the tank mount is in kinda rough shape how bout grinding it down , or a cut off wheel in a 4 inch grinder. trying to leave the bolt proud of the surface so you can tack weld a nut on through the hole of the nut and when you get it out you can use some flat stock ,drill and tap to the correct size and bolt that piece on the tank mount and weld it on so to replace what you ground off, clean it off with said grinder and a spot of paint .. a lot of monkeying around but some things just get complicated look at it as a skill building exercise might help it go easier......albert
I find that most of the bolts broken off in this tank mount location were not broken in trying to take them out, but trying to tighten a tank bolt that was too long and grounding it at the back of the hole. Once you drill the hole for the extractor, remember not to do the same with the extractor. If you attempt to use a regular tap, drilling all the way thru into the steering head will keep you from breaking the tap by bottoming it.
I would wire weld the jagged hole you made, file it flat, and start over using some of the mentioned drilling, tapping or insert methods on a new surface. I have drilled the hole large enough to spot weld a 6mm nut inside the hole. Looks good and is hidden by the tank mount.
My problem is the bolt is acting like it’s a #8 hardened bolt even though that’s not what it is.
I’m going to try a carbide bit today and see if I can drill into it. I’ll probably have to weld the hole shut and re-drill & re-tap the threads.
But the broken bolt has been highly resistive to drilling. I even tried grinding a dish shape to keep the drill bit from wandering. Started to work until the grinding stone broke off! It’s just been very frustrating!
When I got the bike there was also a broken bolt in the same place. But it stuck out enough to grab that one with a pair of vice grips. Hopefully I’m over the frustration today! Victor
Just as the bolts come in different grades, so do drill bits. I has a tough one once and went to an industrial nut and bolt supplier. They has 3 grades of drill bits on display. When I asked the difference between the bits and 3 different prices, he said the level of cussing goes down as the price and quality of the bit goes up. Make sure you are using a electric drill with a low speed. I use an electric drill for hard steel and it somehow seems to work better than a cordless. Slow and steady wins the race.
That bolt looks like there’s already a broken drill bit in there, which would account for it being tough to drill. If so, I’d grind the tip of a larger diameter drill flat - so it cuts out the remainder of the hole to a flat area. Then very very carefully use smaller drills bit by bit and drill around the broken off drill bit until it is sitting proud and can be removed with long nose pliers in a twisting motion anti clockwise. Careful that you don’t drill too deep with the smaller drill bits as they’re prone to breaking if they strike the old bit with too much pressure. When you get to the broken bolt by itself use heat and penetrating oil for a while before attempting to withdraw it. I generally dislike easy outs as they’re brittle, fail to grip and usually break if they do grip and the bolt is stubborn.
Well, here’s what I did. I could not drill into this even with cobalt bits and a hammer drill! I figured if I couldn’t drill into it, I certainly wasn’t going to be able to run a hand powered tap into it.
So I decided to just weld a 6mm nut onto the place where the hole used to be. Maybe not the perfect solution, but at least the tank is mounted securely now, and you can’t see the mod unless you remove the tank!
Victor