Exhaust Stud Removal Tips Needed Please

[pertonpc]

Hi There,

Have managed to shear the nut and top section of thread on one 8mm exhaust holder stud.

Still got 1.5cm of stud sticking out the head.

Here is my plan so far -

New stud ordered

Cleaned up the stud to head joint and soak with penetrating spray for a few days

Buying one of these impact stud removal chuck things - http://www.ebay.co.uk/itm/172380295992? ... EBIDX%3AIT

Apply some heat to the stud via paint stripper gun with nozzle

Air gun to tighten remover chuck if we can get access, if not socket/ ring spanner.

Then try and ease what is left of the stud out of the head.

*** Not done this before ***so anything I have missed or tips from those who have done it a few times would be great before next week when I attempt it.

Ta from Mark

[needaz1100r]

An air gun is not enough heat, and you need HEAT.

Either a proper blow torch, not even just a plumbers torch or oxy acetelyne, or mig a nut to the stud to get enough heat.

And hit it with a big hammer on the end.

Those stud extractors tend not to work on seized studs, they just take a layer of stud off, making it weaker.

My advice is, with 1.5cm of stud you have a good chance of getting it out, but do it right the first time, if you try the easy gentle ways first, you will gradually damage the stud making each more determined effort more difficult as you go and more likely that the stud will snap again.

If you try anything else I'll bet you a tenner you end up mig'ing ot tig'ing a nut on a stud broken off flush with the head or graunched up from various gripping implements.

[PAULJAC47]

Plenty of plus gas with heat,get hold of a set of left hand drills,get end flush center punch and work from small drill upwards hasnt failed me yet,usually it just twists them out..

[z1bman]

use a map gas gun if you can get hold of one much better than a normal blow torch

[needaz1100r]

Plenty of plus gas with heat,get hold of a set of left hand drills,get end flush center punch and work from small drill upwards hasnt failed me yet,usually it just twists them out..

He's got 15mm of stud left, it would be a shame to break that off, and a pain to drill straight through that much stud.

The heat from the left hand drill does often do the trick, but I'm too impatient.

[PAULJAC47]

Misread that as 1.5mm,of course it would be easier to work on that first,

[pertonpc]

Thanks for the input so far.

Why does heat help it come out ??

My very basic physics says that the two metals will expand and therefore tighten up when heated.

What am I missing ??

Ta

[PAULJAC47]

Are dissimilar metals so heat expands them at diif rates,plus gas or similar contracts them at diff rates hopefully after repeat applications breaks the bond.

[needaz1100r]

Thanks for the input so far.

Why does heat help it come out ??

My very basic physics says that the two metals will expand and therefore tighten up when heated.

What am I missing ??

Ta

Aluminium expands more than steel, so the hole gets bigger.

As Paul said, repeated heating/cooling helps as each time they heat and expand and cool each tiny part of contact moves, which gradually breaks the bond.

Put plus gas on it helps to cool it and it will tend to draw it into the joint.

Hitting it also creates tiny movements in all the microscopic bonds.

Shock and awe matey, no point tapping it!

I use one of these...

http://www.ebay.co.uk/itm/192022172466? ... EBIDX%3AIT

on one of these

https://www.calor.co.uk/shop/gas-bottle ... ottle.html

Works every time.

[needaz1100r]

Oh, and if there's Loctite in there, heat melts it..

[baz]

weld a nut to the broken stud, apply a direct heat ( oxy/act ) flame to the alluminium around the stud, with a spanner gently rock the stud left to right.
DON'T try and undo it in one go, it WILL pull the threads out of the head, Top tip ......if you don't have the means to do this take it to some one who has !!

[pertonpc]

Ok thanks
I get that alloy expands more than steel under heat.
I still reckon any expansion of the alloy will shrink the hole not grow it but it clearly works somehow.

I CAN see that the differing rate of expansion would tend to pull apart the stuck surfaces.

Ref Loctite it is a GOOD point.

I will start another thread for tips on how to fit the new stud - assuming the factory one can be budged of course

[needaz1100r]

Ok thanks
I get that alloy expands more than steel under heat.
I still reckon any expansion of the alloy will shrink the hole not grow it but it clearly works somehow.

I CAN see that the differing rate of expansion would tend to pull apart the stuck surfaces.

Ref Loctite it is a GOOD point.

I will start another thread for tips on how to fit the new stud - assuming the factory one can be budged of course

Ah, the hole in aluminium getting bigger or smaller when heated, quandary.

It was explained to me thus -

A piece of aluminium wire bent to a circle when heated will get thicker, so making the hole smaller, BUT, it will also get longer, making the hole bigger. There is more length than thickness so the hole gets bigger, it's the same with a plate or a casting.

If it didn't you couldn't heat a sleeve, eg a bearing, to fit in on a shaft, but you can. I often warm an aluminium wheel and put a bearing in the freezer to fit wheel bearings, they just fall in.

[pluto]

I had to undo the rear engine mount adjuster bolt on my Zxr750 recently, it is a large hollow steel bolt and was firmly stuck in the alloy frame. I heated (with a map gas blow torch) and cooled the area a few times then heated again and melted a candle on to the threads, the idea is the wax is sucked back into the join (found this on youtube). I then used my impact gun on forward then reverse a few times until there was a tiny amount of movement then more wax then out it popped. In your case weld a washer and nut to whats left, candle wax it while its still really hot, then slowly backwards and forwards with a socket til it lets go. I wouldnt use an impact/ air gun on such a small stud.

[PAULJAC47]

Wish i had only one stud stuck when i restored a Gs thou a few years back,bike had been standing in damp for some time,virtually every fastener was seized,took some time but every one came out its just time patience and different techniques...