drill bit ?'s

[briyenkieth]

not related to my gs but motorcycle none the less. I'm fighting with my buell currently and need to drill out two broken exhuast studs. Problem is they are hardened steel. Is there a bit made for this material? Otherwise I have to pull the head and have a machine shop deal with it. Help me please!!!

[doctorgonzo]

Somebody else may chime in, but I'm swapping a head for that very reason right now, not even every machine shop can do it. Not saying it isn't possible, but betting it's at least gonna take a trip to machine shop.

[Big T]

Start with Cobalt bits - they're pretty hard and widely available. Home Depot, Ace hardware,etc. Get several sizes and start with the smallest to get a properly centered hole going.

If cobalt doesn't work, then you have to go to carbide bits. About $20 each and brittle. Available only at tool stores in cities. You'll want to call around for these.

Don't ask me how I know, but one of the rear shocks on my minivan is hanging from the upper bolt only.

[briyenkieth]

I know of a guy that has shop with a electric disentagration machine. So I know where to go, I just don't want to. This has been a 26 step procedure just to get the header off. If I can get the studs out in my garage it's a $30 fix. If not I'm not sure how much it will run. I'll need a top end gasket set and the $50 min. at the machine shop. I admit I'm cheap and lazy !

[Griffin]

I drilled out two broken off stock GS exhuast studs with a carbide bit on my wife's 550L. It wasn't nearly as difficult as I thought it would be, but great care must be taken to properly align the bit with the existing hole, or the angle will be wrong and it will be next to impossible to mount the exhaust once the new hole is tapped.

[Planecrazy]

I recently saw this tip on an automotive TV show. I have no idea whether it'll work in your situation, but it might be worth consulting with more knowledgeable people than myself to see if it's worth a shot.

Assuming that the broken studs are flush with or sticking out of the head, I watched a procedure where a steel nut of the correct proportion was centered over the broken stud and a mig welder was used to weld the nut to the stud through the center of the nut. then a socket or wrench was put on the nut and the stud came out with little trouble and no damage whatsoever to the head or threads.

The theory is that the heat used to fuse the stud to the nut also helps break the bond between the stud and the head. I have no idea whether this technique would be dangerous to the aluminum head, but they claim that because aluminum is such a good conductor of heat there is little danger of damaging the aluminum.

Obviously you'd need access to a MIG welder to try this, but it certainly sounds feasable if the stud isn't broken below the surface of the head.

Any more experienced opinions are welcome!

Good luck, and

Regards,

[Clone]

Save yourself the hassle of buying bits, having them break off, and then going to the machine shop. Just go there directly or mig weld a nut to the stud and take them out that way.

[Planecrazy]

Save yourself the hassle of buying bits, having them break off, and then going to the machine shop. Just go there directly or mig weld a nut to the stud and take them out that way.

Hmmm ... I see great minds think alike, hehe, and within a minute of each other!

Regards,

[rapidray]

Actually, a GOOD machine shop that KNOWS what they are doing will LASER a broken stud out! Ray.

[jed.only]

broken flush or do you have stud sticking out?

[Planecrazy]

Actually, a GOOD machine shop that KNOWS what they are doing will LASER a broken stud out! Ray.

You just wanted to include the word "LASER" in your fifteen hundredth post, didn't you, Ray?

But seriously ... wouldn't the preferable thing be to avoid a trip to a machine shop if possible? Assuming your answer is "yes," would you agree that the MIG welding strategy is a good one or is it too risky?

Regards,

[GQROD]

If you don't have a welder you can heat the surrounding alluminum with a mapp torch or oxy acetelyne this expands the alluminum faster than the steel stud can expand and with the extractors you can pull the stud out.

Otherwise all the advice above is excellent and will work.

[briyenkieth]

man you guys are great. I posted this like four hours ago and already lots of replies. Saddly I'm broke off about three threads deep so I don't see the nut trick working. I see a machine shop in my future!

[Road_Clam]

Somebody else may chime in, but I'm swapping a head for that very reason right now, not even every machine shop can do it. Not saying it isn't possible, but betting it's at least gonna take a trip to machine shop.

The only reason a machine shop could not extract a broken GS head exhaust stud is because they suck, and are lazy.

The reason the 25 year old studs are difficult to drill is because the studs are "seasoned" or another term is "tempered" from thousands of "heat cycles" . Yes they are hard, but totally machinable with a standard Bridgeport milling machine (and a patient operator).

[bucketsofgs1000]

I just did this operation in my garage on a '78 XS400 exhaust stud, also "tempered". I used standard HSS bits with a TiN coating. As long as YOU are patient, you can save yourself the expense of going to the machine shop (and pulling the head and buying a new gasket set, and taking the time to rebuild the whole top end). I used a hand drill, a steady hand, and started it very carefully. These studs are not that hard to drill. I drilled mine planning to helicoil it when I was done. I don't remember if I had to or not and I sold the bike so I can't go check on it. It worked great and took about 2 hours.

You can use carbide if you want (It is much harder than HSS, but far less forgiving), but when the bit gets half way in and you twist your wrist just slightly, blowing up that brittle piece of carbide inside the stud, even the machine shop will have a very difficult time removing the carbide pieces, let alond whats left of the stud.