Broken exhaust stud removal procedure

steph

steph

Hero member
Location
Torgny, Belgium
I made a forum search on that subject but was unsuccessful.

1. Is there a good procedure to remove the remains of an exhaust broken stud ?

2. Same question but for an intact exhaust stud ?

Thanks a lot

St?phane




 
How much is left sticking out?
If not enough for a stud extractor maybe you could weld a bar on to it and free it that way?
I would think heating the head in any case will help.
 
Don't even think about using stud extractors. They're worse than useless.

If there's sufficient stud poking out, you might be able to get a grip on it with mole grips, but it's probably siezed in there reasonably tightly by products of galvanic corrosion (mostly oxides of aluminium) otherwise it would have unscrewed rather than breaking in the first place. So unless you loosen it with heat and gentle impacts, the mole grips will probably only chew the end of it up without shifting it.

Rather than weld a bar onto it, place a nut over what's left of it and weld the inside of the nut to the broken stump. It's a bit of a fiddly weld, especially if the head is still on the bike, but do-able. I find the nut works better than bar because it contains the weld pool, you get a stronger connection to the stud, and you can get a spanner on it when it's done. If it's broken off close to or flush with the alloy head, you can bore a countersink into the nut to make the access for welding a bit easier. You could do it with a stick welder using a small welding rod, but best to use MIG, TIG or oxy welder to avoid filling up the inside of the nut with slag. It's worth the time investment to do a good weld if you end up with a successful outcome. As grant said, the heat from the weld will break down the corrosion oxides that have caused it to sieze, and subsequent shrinkage when it cools will more than likely loosen the stud and it will come out easily.

I've had 100% success with the above method, but if it fails, you may need to take the head to an engineering shop to have it spark eroded out.

Good luck
Cam
 
Is the head still on the bike, or already off?  If it's on the bike and there is some shank poking out then weld a nut on (TIG is the best option) as Cam suggests.  More likley the stud has sheared at the base of the thread and there is nothing to grab or weld on to.  At this point it is infinitely more likely to make a much bigger problem if trying to fix it in-situ or on the bench with typical shed tools.
While it might be possible to drill out using an appropriately made guide and a skilled hand, the best and safest fix is to put the part in question in a milling machine so the hole can be accurately set up, centre drilled, then progressively drilled out till you reach the base of the thread, at which point you can pull the remains out like a spring. Which ever way you go it's best to enlist the help of an experienced machinist/engineer to avoid compounding your misery.
Cheers
SteveB
 
I've had success by heating with a butane torch then cooling with a blast of penetrating oil, repeating 3-5 times. Then using a pair of flush cutters to grab the end to twist it out while still hot.

You need to break the corrosion bond, then it should twist out e-z.

Wayne
 
If all the at home stuff as above fails spark erosion is the go - cheap, quick and leaves the original thread perfect.
 
Under NO circumstances use an Easi-Out.
Then you really need the spark erosion to get out the end of the Easi-Out as well as the broken stud.

DAMHIK...
 
+1x2 - slow learner

Easy outs now safely filed in the rubbish tip.
 
Yogi said:
You blokes are obviously not using the Ezi-Out correctly - do you have much experience with working on bikes? :D :D :D :D :D
Click to expand...
Tsk!  You little ...

shit+stirrer.jpg


:P :-*


Mind you, it was a bit ...

shooting-fish-in-a-barrel.jpg
 
breganzane said:
Is the head still on the bike, or already off?  If it's on the bike and there is some shank poking out then weld a nut on (TIG is the best option) as Cam suggests.  More likley the stud has sheared at the base of the thread and there is nothing to grab or weld on to.  At this point it is infinitely more likely to make a much bigger problem if trying to fix it in-situ or on the bench with typical shed tools.
While it might be possible to drill out using an appropriately made guide and a skilled hand, the best and safest fix is to put the part in question in a milling machine so the hole can be accurately set up, centre drilled, then progressively drilled out till you reach the base of the thread, at which point you can pull the remains out like a spring. Which ever way you go it's best to enlist the help of an experienced machinist/engineer to avoid compounding your misery.
Cheers
SteveB
Click to expand...

The head (Jota) is still on the bike.
A friend of mine (not on the Forum) is facing that problem and I was curious about a good solution to help him to solve it.

Thanks to all of you guys, Steve, Grant, Cam, Ernesto, Wayne, Yogi ... for your interesting comments !

Cheers,
St?phane
 
Find a toolmaker to fabricate a drill jig that fits in the port and over the remaining stud. It will help if you have a spare head to het the dimensions from.

This will exactly align the drill with the centre of the broken stud.

Then drill out to the thread root diameter and pick/punch the remains out.

However, this might be more expensive effort than removing the head and taking it to the toolmaker to burn the stud out with an EDM.

Cheers,

Rob
 
if you do weld or get welded a nut onto the stud, dont just try to undo it ,but undo it maybe 45 degrees and then wank it back and forth the same 45 degrees untill you are bored shitless and get some penetrant in there as well, the best one I have come accross is made by La-Co and is a derivative of the self cleaning flux used thes days by plumbers on copper tube and fittings , a by product so to speak, it is called rust buster and comes in a little non aerosol bottle with a telescopic spout, it is very economical, and I have found particulary good on steel in alloy, but you must get that nut on first, and you must at least move the stud a smidgeon .
CLEM
 
CLEMTOG said:
... undo it maybe 45 degrees and then wank it back and forth
Click to expand...

The words of a true wanker :D

Good onya Clem, you're absolutely right. I should have said so in my earlier post.

Should be a general rule of engineering: If something feels like it's tightening up, back it off and wank it a bit.
 
I saw that.. but if you have to wank away until you're bored shitless.. ;)
I prefer to give it a couple of wanks.. bit of release and away we go.. :LOL: :LOL:

8)
 
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