<VV> Re: busted stud

[djtcz@comcast.net]

Message: 9
Date: Fri, 26 Nov 2004 12:33:01 -0500 (EST)
From: <monza65@localnet.com>
To: <virtualvairs@corvair.org>
Subject: <VV> NEED HELP

................One broke off at about three inches long. I've treated 
> it with penetrating catalyst hopeing for some luck.

>I need suggestions from someone who has had experience with the same 
 > problem.  One is a blind hole and one is a thru hole. BIG QUESTION:          can I put the halves backtogether, torque it down and apply some heat to the thread .....area, or is that a greatbig NO NO. Does anyone have any ideas????

Heat and beat, followed by some PB Blaster or Deep Creep.
For normal bolts seized by rust my theory is the rust must first be disturbed or crushed.  This is because iron oxide is less dense than steel, implying it swells up on the way from being steel to rust, making a press fit between bolt and threaded component.  Warming up the nut or housing to "expand" away from the rust >>sounds<< like a good idea, but in practice I believe a better result is obtained by heating the relatively small bolt red hot, ensuring it expands HARD, like a toad in a hole, and crushing the rust.  Another useful rust breaking technique is impact, not in the loosening direction, but but axially especially in the direction opposite the bolt was pulling, since that is where the thread space was, and is likely to be full of swelled up rust.
Studs by their design have interference threads, potentially complicating their removal. 
So, for my first attempt I would support the case (assembled or half) directly under the broken stud, on soft wood on a concrete floor, and with a 16-28 ounce hammer drive the stud stub "into" the case like it was a nail.  Maybe 10 good shots. Then I would heat the stub until it glowed with oxyacetylend or MAPP), hoping the threaded body was getting nearly as hot.
If by chance Loctite was used previously, the bond needs to get over ~ 400 F to loosen also.
After things had cooled I would apply PB Blaster, and let it soak for 10 minutes.  I would put 2 pairs of vice grips (HARD, with the stud deep in their jaws) on the stud, and twist them both together.  If the grips slipped, I would wail on on the stud/stub/nail about 25 times, re-heat, and soak for a few hours.  Then I would put on 4 big vice grips, and ask a pal to help twist the stud.
If that failed, I'd heat the stub and twist while hot.  That is dangerous because a glowing hot stud is very weak, and and a black hot stud is weaker than room temp.