Anyone ever break a head stud?, Looking for ideas, tools success stories, horror stories, what cha got Options

[rick 918-S]

I'm building a 928 hybrid engine which is comprised of a 5.0L 32 valve short block with 16 valve euro spec "S" heads, spyder and CIS from the 4.7L "S" engine.

I stole some time from my busy work schedule to prep my 928 block for the machine shop. The head studs need to be removed for the boring process.

Now I've pulled studs before without incedent. But as Murphy would have it, this time I broke one of the studs flush at the start of the threads.

So I have the threaded section ( 1 1/4"long ) hardened head bolt stuck in the block. Normally this wouldn't be a problem, but the stud is free standing in a 3 1/2" deep hole in the block!

Here's a crude drawing of the problem I'm faced with.



Here's the stud.



Here's the stark reality of the stud in and out of the block. The stud slides down a 3 1/2" deep hole in the block before it starts to thread in.




I'm going to make a drill collet as a guide for a pilot bit. The problem is I need a long, reverse twist drill bit.

Most drill bits are approx 5" long. the hole is 3 1/2", the threaded section is 1 1/4" for a total of 4 3/4". See the problem?

Then, what the #$!! do you drill a hardened bolt with?

Anyone know of a good tool source? This is beyond most Mac and Snap on stuff I would think.

[Bartlett 914]

What is the size and pitch? How hard is it? You can see how hard it is by filing or grinding. Drill and tap on the section you have in hand to see how hard it will be to drill and tap.

[rick 918-S]

What is the size and pitch? How hard is it? You can see how hard it is by filing or grinding. Drill and tap on the section you have in hand to see how hard it will be to drill and tap.

I plan to chuck one of the studs up in a lathe and run the drill bit in the end of it as a test. It's a head stud. It's designed to hold tension and resist torsion during torque.

The left hand bits are extraction bits designed to drill hardened steel bolts and studs.

Cross your fingers for me. I wish you were closer. I'd bring it over to your shop and we could tag team it. (IMG:style_emoticons/default/beerchug.gif)

[Bartlett 914]

I plan to chuck one of the studs up in a lathe and run the drill bit in the end of it as a test. It's a head stud. It's designed to hold tension and resist torsion during torque.

The left hand bits are extraction bits designed to drill hardened steel bolts and studs.

Cross your fingers for me. I wish you were closer. I'd bring it over to your shop and we could tag team it. (IMG:style_emoticons/default/beerchug.gif)

With any luck the bolt will be a little softer in the middle. I am a little concerned about your getting the drill to start in the center. What would help the most is to use an end mill to machine the top of the broken stud. This would require another bushing for the end Mill. Long ones are expensive and a little hard to find (although I have a long .5" carbide one). After the stud is milled flat, center drilling would help. again the length would be a problem and that I don't have.

Yes its too bad you are not closer. I was thinking the same thing. (IMG:style_emoticons/default/beerchug.gif)

Lots of luck