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DY85262

How To Repair A Stretched Headstock

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I just received my JMC XL and note the headstock is slightly stretched. It makes sense as the repaired forks and stretched headtube must = a pretty hard nose dive into some whoops at some time

Now I can save this baby I am sure just wondered if anyone has done it and How.

Did you build up inside the stock and then hone out?

Maybe one of you is a metalsmith or fabricator and can advise.

They are not to bad to visually show ovalisation but I can push the headset cups in with my hands. Not a regular pastime believe me.

 

Cheers Guys/Gals :25:

 

Clint

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I think what ruins a head tube fast is running your headset loose. If the cups are not real loose you may be able to have the end of the cups knurled at a shop. This would tighten them a little.

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common problem w/JMCs .... allot of people insisted on running higher end hs's thinking they were more worthy of the prestige of the f/f, in reality JIM always suggested the better of the lower end basic chromed steel loose bearing hs's -- the Tange/Tioga MX-2 which actually inserted deeper into the headstock and helped in deter the problem

 

 

unfortunately to remedy (fix) the problem you either have the shave a few cm/mm off the top and bottom (if needed or just the effected area) and then go from there like regular (find a road repair specialist as that too is a regular problem with older road bikes, ask a vet. road mechanic, as he would know how to do the fix correctly, there's a special tool just for that type of repair, but I can't remember the name)

 

or

 

you have to go with a full headtube replacement

 

 

can't unstretch the metal - so you have no choice - shims will only further continue to damage the frame and may cause a crack, tapping and hammering will not give you a smooth circle no matter how much time you put in so its either one or the other of the above choices --- which will result in a need for a refinish/rechrome after the repair

 

 

 

good luck

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Cheers

Just MC (JMC)

I will put that on hold until the bike is ready for riding. I won't be and no siblings yet so it wont hurt for standing there.

I know a good frame builder in the UK and will ask a few questions from these guys.

Will update if anything else found out.

Cheers

Clint

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need to hold back on the smoking Will .... like i said .... you can't unstretch stretched metal and tapping hammering or crushing won't give you a proper circle- or even straight enuff center to rebuild it properly (especially if you have intention of riding the said frame) :blink:

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Yeah stressed metal has to go somewhere and if you try to put it back to where it came it will bulge somewhere else. So here is what I did.

I took ten headset cups and measured them with my vernier. They varied in both roundness and OD (outside diameter) The largest I could find was 32.8mm some were as small as 32.65mm. Again that was at its widest point as it also was not round. That was enough to make it a tighter fit that results in no fore and aft movement. I need to tighten these up and see but with some Threadlock in place to stop the cup rotating it might just do the trick.

 

Sure its right on the border and it will need to be watched.

 

So anybody out there with a headset that has a larger OD bottom cup than 32.8mm (Tioga Beartrap2) let me know it might help my cause a little more.

 

Cheers for your help

 

Clint

HeadsetCup2gif.GIF

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"Also, hasn't anyone heard of metal shrinking? You can shrink the metal. Just heat it up not to cherry red and quickly hit it with cold water or an ice cube. It will take a little strength out of the material. After getting it close, You can heat it up one more time then dunk to end in motor oil to quench the metal. This will harden it and give it some strength."

 

This was told to me by someone far smarter then me.

 

I was also informed to "tell JMC Mark to blow it out his A$$"! LOL

 

So Mark :Special Salute:

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Hey Corky just about anyone born within the last 24 hrs is smarter then you .... so lick it as i blow it out my sweet cuban ass - matter of fact why don't you smoke it like those cuban hand rolleds' you so desire to lip - beotch !

 

 

:nobull:

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

:lol:

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ive repaired a badly stretched headtube, by cutting a slot in it (only to the depth of the flared part) with a cutting disc on a grinder, hammering the gap closed with an old cup inserted as a dolly, then mig welding it. filed it back. 

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