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SOHC.co.uk Forums => CB750 => Topic started by: royhall on February 20, 2016, 04:37:47 PM

Title: Broken cylinder head stud
Post by: royhall on February 20, 2016, 04:37:47 PM
Just gone against the habit of a lifetime.

Read somewhere on here this morning to torque the head nuts dry. Well I have always used a drop of 3in1 oil and never ever had a problem.

Today I take advice and torque them dry, and guess what, a broken stud. My own fault, you should always go with what you know works.

Any ideas how to remove the remainder so I can fit a new stud. Any help would be greatly appreciated.

[attach=1]

[attach=2]

Am a little bit down hearted with this just at the moment. Sorry.
Title: Re: Broken cylinder head stud
Post by: Bryanj on February 20, 2016, 04:48:29 PM
Put a nut over the stud that's left and get the inside mig welded to the remains. that should warm it enough to help removal.

As to torqueing dry that's all I have ever done mate and for it to break it had to be either a bad stud or the torque wrench didn't work right
Title: Re: Broken cylinder head stud
Post by: royhall on February 20, 2016, 04:54:25 PM
Thanks Bryan. Torque wrench was only set to 2/3 torque as I do them up in stages. It broke with hardly any effort at all, is that something you've seen before? Got a TIG welder so will take your advice and have a go tomorrow after I calm down a bit. Many thanks for the advice.
Title: Re: Broken cylinder head stud
Post by: royhall on February 20, 2016, 06:08:51 PM
When you say dry threads, are they truly dry. If its a rebuild the threads will have soaked in oil for 40 years and unless it was all thoroughly degreased (like mine was for painting) the threads will still have old oil on them.
Title: Re: Broken cylinder head stud
Post by: AshimotoK0 on February 20, 2016, 06:22:37 PM
I tried to remove a 750K0 stud that had broken off flush with the crankcase for yonks, no luck. I tried welding a nut onto it, even etched away every trace of zinc plate on the nut and bead blasted it clean but the nut kept breaking off . Then I watched guy on a USA car programme doing the same and the same happened to him. So researched it a bit more and  read somewhere if you build up weld with no nut until you have large ugly looking blob of weld on top, then file a couple of flats and grip with a mole grip it came out dead easy. I think I also heated the weld blob up too but it worked a treat. You can reheat with a nother small weld on top . I used a MIG welder.
Title: Re: Broken cylinder head stud
Post by: Pops400 on February 20, 2016, 06:27:16 PM
Have you ever seen Irwin Bolt Grips? Extractors that bite into the exposed bit with a reverse spiral flute.

Worth a try. I've removed all sorts of rounded off crap with them.
Title: Re: Broken cylinder head stud
Post by: MarkCR750 on February 20, 2016, 07:46:04 PM
Bugger!, after you have welded it build a plasticine dam around it and fill it with plus gas or similar very thin penetrating oil,  leave it to soak down the threads, chin up it will come out!
Title: Re: Broken cylinder head stud
Post by: Trigger on February 20, 2016, 07:49:41 PM
Have you ever seen Irwin Bolt Grips? Extractors that bite into the exposed bit with a reverse spiral flute.

Worth a try. I've removed all sorts of rounded off crap with them.

Irwin bolt grips is for a rounded off head and if used on a stud, will chew it up more. Though you could get lucky.
Title: Re: Broken cylinder head stud
Post by: Pops400 on February 20, 2016, 08:55:17 PM
Each to their own, I guess, but I've used them on Yank cars and pulled sheared studs with them over the years.

Anyways, the weld option seems to be preferred, so shan't argue with that as it obviously works.

Best of luck with getting it out.
Title: Re: Broken cylinder head stud
Post by: royhall on February 22, 2016, 04:38:38 PM
Hooray its out.

What a job that was, don't wish to break another of those ever.

Tried the welding the nut onto the stub method, it didn't work. Tried three times and the welds held up okay but it kept snapping the remaining stud lower and lower. In the end I put a piece of copper sheet on the crankcase and welded a right angled piece onto the stud, and then shocked it out with a centre punch and hammer.

[attach=1]

[attach=2]

Worked okay but if you haven't got a TIG welder you will never do it this way as a Mig weld is just not strong enough to take the hammering.

Thanks all for the help, now onto the next problem.
Title: Re: Broken cylinder head stud
Post by: mike the bike on February 22, 2016, 04:52:27 PM
Well done 👍 we always like to hear of successes.
Title: Re: Broken cylinder head stud
Post by: Johnwebley on February 22, 2016, 05:01:43 PM
Well done 👍 we always like to hear of successes.


  Wot Mike says,


  when I have problems with the bike,I try to walk away,and sit and just think about it,
 sometimes a simple idea comes,

 it also clears the head,in my case there is not much inside anyway -))))
Title: Re: Broken cylinder head stud
Post by: MarkCR750 on February 22, 2016, 07:24:55 PM
Great result!
Title: Re: Broken cylinder head stud
Post by: Trigger on February 22, 2016, 07:26:50 PM
Well done 👍 we always like to hear of successes.


  Wot Mike says,


  when I have problems with the bike,I try to walk away,and sit and just think about it,
 sometimes a simple idea comes,

 it also clears the head,in my case there is not much inside anyway -))))

I thought you went to the pub when you had a bike problem John  ;D ;D
Title: Re: Broken cylinder head stud
Post by: UK Pete on February 22, 2016, 07:31:37 PM
Result
Title: Re: Broken cylinder head stud
Post by: Johnwebley on February 22, 2016, 07:33:25 PM
Of course. After  quite a few pints. the problem may look fuzzy.
But the cure is crystal! !


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