help broken stud

Post by **voyageur** » 20 Nov 2005, 16:49

Managed to break 2 studs in turbo while I was separating it from exhaust pipe .question now is there any magical tool or treks to extract them?
Or is there any shop can do that for me ?
Help please

Post by **Kermit** » 20 Nov 2005, 19:42

Are the studs still proud in the manifold? or have they sheard off flush?

kerr

Post by **NOT ANOTHER LEAK** » 20 Nov 2005, 20:43

https://www.frost.co.uk/default.asp
you can get stud extractors from here

Post by **voyageur** » 20 Nov 2005, 21:20

Unfortunately sheered off flush soaked them in penetrating oil over night and managed to drill one about 3 mm in debt but it looks messy
As it's not easy to keep the hole in the centre

hass
http://www.wanafin.co.uk

Post by **HarryMann** » 21 Nov 2005, 00:21

First clean the whole area up so that:-

a) you can see the extent of the stud and estimate it's true centre
b) there is reasonably flat face at it's centre (file, rotary burr)

With wickedly sharp pointed centre punch...
Centre punch stud face spot bollock centre - VERY LIGHTLY
If looks dead centre, go a bit harder in same place or move the centre pop to true centre by angling punch and then finally righting again for last pop. Inspect and be happy it's as good as you can do...

Very sharp (newish) quality 1/8" (3mm) drill unless stud/bolt is smaller (those new boron ones are great)....

Drill in as far as bottom of stud (estimate) - dead straight - keep stopping and checking drill angle in both planes - don't rush - spit on drill to keep it cutting and cool. Paraffin is a good cutting agent, nearly as good as spit!

Then open out in small stages until you are about out to the thread core diameter - at which point, you should be able to pick the thread out/collapse it/get behind it or a screwdriver in there and actually unscrew it! [whatever method appeals]*

With the one you've gone a bit off centre on - spend time trying to correct it with angles drill (and flanks of drill), then as you go up in size each time, try to re-centre the hole as best you can...
then, as soon as you see the threads first appearing at one side of hole, stop, and see if you can either unscrew it (jamming sharp screwdriver in there) or collapse thread inwards and pick it out.

Trick is to have a good range of quality HSS drillbits and when you get near thread core size, open out in very small stages (unless you've done it dozens of times before, when a bit of derring do gets the better of you!)

* can use centre pop to tap it around anti-clock to see if it will loosen. It's a matter of breaking it's seal, so as it starts to collapse it should start turning - usually have to pick out some bits left in there - a scriber is good for this, failing that a long oboe nail held in mole grip jaws.

Oh, and luck, confidence and perserverance! Don't rush, keep inspecting -change technique if going wrong - rushing is deadly!

Post by **voyageur** » 21 Nov 2005, 08:44

That fantastic it sound very good already bought a set of
Titanium coated drill bits, punches and booked a day off work to tackle
Them and hopefully I'm going to accede something to be prod of

Post by **HarryMann** » 21 Nov 2005, 10:46

Good stuff!

Don't break a drill off in the job - if you have to angle to re-align, gently does it, modern drills just don't seem to be able to be bent like good old Presto HSS.

If you do, it may still be possible to loosen and wiggle it out - but don't count on it!

Approx. thread core sizes (= tapping drill):-

Metric Thread (AF) - drill size mm
M4(7) - 3.3; M5(8) - 4.2; M6(10) - 5; M8(13) - 6.8; M10(17) - 8.5; M12(19) - 10.2; M16(24) - 14

Good luck...