Advice please: removal of broken exhaust stud

[Henners]

Thanks everyone ~ wish me luck!

[dave the german]

John that I bought my exhaust off, asked at Williams, and the old hand there said run the engine and get it hot and they'll come off - want to take mine off to clean the pipes, but.....

[Archie]

If you want to do it yourself these type of extractors are a better bet.

[beachcomber]

John that I bought my exhaust off, asked at Williams, and the old hand there said run the engine and get it hot and they'll come off - want to take mine off to clean the pipes, but.....

That's the first step [ heat ] .......didn't work on SIX ocassions we tried !

Good luck.

[dave the german]

John that I bought my exhaust off, asked at Williams, and the old hand there said run the engine and get it hot and they'll come off - want to take mine off to clean the pipes, but.....

That's the first step [ heat ] .......didn't work on SIX ocassions we tried !

Good luck.

I know what you're saying - that's why there's a but. Really would like to get them off - maybe I'll leave it to someone else to do it

[beachcomber]

You need to go into the job expecting at least ONE to break off !

If you get someone else to do it - AND 1 or more break - you're still going to have to pay to have it / them replaced.

There's no guaranteed "special method" to remove them without breaking. If all come off without aggro - consider that a very lucky bonus.

In our 50 + years of speciality workshop practice - we've tried ALL methods known to man !

If it's a cosmetic issue - have the pipes soda blasted in - situ ?

[dave the german]

I was t clear access to the engineering. That "quality " finish BMW use is all skanky

[dysondiver]

heat , and sharp vise grips ,,, if they break , well , i could wright a book on stud repairs , forty years of owning a vintage boat will do that .. good luck

[Pete.]

I've never had to remove a cylinder head to cure this but I have better than average mechanical acumen. Beachcomber is quite right about using stainless bolts in ally heads it's a bad move. I once had all eight bolts shear off on an inline-4. Here's the account copied from anther forum:

I went to remove the headers on my 1996 Bandit yesterday, and all eight of the bolts sheared off at or just below the head. This is my third Bandit and I have removed the exhaust off all three for the same reason - rotted collector. Here is how I went about tackling those 8 broken studs. Forget easy-outs and stud extractors for frozen-in bolts, you will very likely only make things much worse.

There are a couple of tried and trusted ways to remove a stud that has some thread showing.

One way is to put a nut over the stud and weld the end with a mig welder getting it nice and hot, then un-doing the nut which should bring the stud with it. I don't have a mig welder - I have an arc welder but they are much harder to get good results with since the rod is fatter and for small diameter studs it's likely the arc will wander when you try to weld in the well of the nut.

The other way is to drill out the stud. This is no easy task, starting off on the end of a sheared stud is tricky and you must be dead centre to avoid having the drill wander off the bolt into the softer ally threads. This is how I have done it - by making a drill bushing.

First, take an old 12.5mm drill and chuck it up in the lathe backwards. Drill bits are not hardened at the shank so you can drill, file and cut them but they are made from hardenable steel which is what we want. Drill the tail-end 6.8-7mm which is tapping size for a M8 bolt.



Then drill it deeper with a 4mm drill, which will be the pilot for drilling out the stud.



Now I set up a M8 taper tap in the lathe using the centre to keep it perfectly in line.



And follow it with a 2nd tap and plug tap to get the thread right to the bottom of the hole.





After that I part it off.



Now I need to be avble to tighten this bushing, so I file two flats in it for a 10mm spanner.





Broken studs.



Bushing fitted



I used the drill rod so I could harden the bushing for use. This involves heating it up to cherry red and quenching. Here is what I did, but unfortunately I could not get it hot enough on my gas ring to lose it's magnetism (which is when it becomes hardenable) so it remained soft - so I used it anyway. Tomorrow I will take it to work and heat it with oxy-acetylene then it will be glass-hard.





As you see, the drill now takes a straight path directly dwn the middle of the stud.



Drill extension for those hard-to-reach ones. Just a bit of mild steel rod, grind four small flats on the drill you use to drill the rod with then poke it in and give it a little squeeze in the vice.



Holes drilled, spot on centre and right through each bolt - only 6 more to go.



Once all eight are drilled I will follow the pilot with a 1/4" or 6.5mm drill to allow me to pick out the remaining threads.

- - - - - - -- - - - - - - -

Did some more tonight. 6.5mm drill down the middle:





Too small as it leaves the thread intact, though it looks pretty cool. Tapping size is 6.8 but I wanted to allow a bit of extra clearance so I went for a 7mm drill. Tapped using a 1/4" socket extension backwards in the tap wrench to reach past the frame. You need a GOOD tap to do these:





Both done and bolts fitted:






Middle ones will have to wait until I get some more 4mm drills

[Pete.]

You can buy those drill bushings in sets if you haven't the facility to make them. After that it's a reasonably simple job.

[dysondiver]

nice job ,,, but have a rethink on your hardening procedure ,,, you have enough heat in the gas , heat quench then clean reheat slowly and gently to a blue temper , about 300 degrees , and it should be grand , wear well against the drill bit and not bind , yet still be tough enough to do the job nicely ,
but you are so right on the quality of the taps ,, somethings just have to be good , and taps are certainly one of them.

[dysondiver]

ah ,, another thought , instead of a nut when your welding over a broken stud try a bit of say 3mm or 4mm plate , and drill a clearance hole , you can then give your self a larger run off area , just bent a 90 on it some where to grip with vise grips, if you only get a fraction of a turn before you run out of clearance and then grind off the weld , its enough to get things started , just a few ideas .

[nab 301]

I've never had to remove a cylinder head to cure this but I have better than average mechanical acumen. Beachcomber is quite right about using stainless bolts in ally heads it's a bad move. I once had all eight bolts shear off on an inline-4.

I had the dreaded collector box failure on my '04 Bandit 600 at the weekend, I guess my glass is half full , all 8 header bolts came out intact without a fight Any closet bandit owners know if these stainless cap heads are OE and any suggestions as to whether I should reuse or substitute with something else ? ( I can't find much useful info on any Bandit forums I looked at.

[dave the german]

I have used some stainless into alloy and was told by fellow Trixter about Duralac - supposed to prevent the thingummy reaction and stock bolts seizing - about a tenner off the Bay

[nab 301]

Thanks.