1924 chief fork legs

[hairynob24]

G day everyone, I have a question about the 1925ish fork legs/ droppers, both of mine have a slight bent in them and would like to know if anyone has straighten these before, not sure of what metal they are made , hence do it cold or heat them up, thanks for any response, Rob

[Jerry Wieland]

G day everyone, I have a question about the 1925ish fork legs/ droppers, both of mine have a slight bent in them and would like to know if anyone has straighten these before, not sure of what metal they are made , hence do it cold or heat them up, thanks for any response, Rob

They straighten very easily cold. Jerry

[T. Cotten]

Heat destroys the heat-treat memory, Rob!

Cold, they want to go back to 'straight'.

....Cotten

[exeric]

I've had to straighten the spring connecting links on pre '20 Excelsiors, and a '22, '24, '32 and '40 Indian. I was fortunate to have a connection to a company that did shot blasting, and shot peening. which takes a lot of the stress out of a bent piece of forged steel. The links are easily straightened but an acute bend can crack when carelessly forced. A good sandblasting works just as well on lesser bends. As said above; don't use heat.

[T. Cotten]

.. I was fortunate to have a connection to a company that did shot blasting, and shot peening.....

OK Eric,.. I'll bite.

What's the difference?

Thanks in advance as always,..

...Cotten

[exeric]

I believe shot peening is more aggressive, with steel shot, with the intention of strengthening the steel it's blasting. That's my 1st grade knowledge of the world of metallurgy.

[T. Cotten]

I believe shot peening is more aggressive, with steel shot, with the intention of strengthening the steel it's blasting. That's my 1st grade knowledge of the world of metallurgy.

Did your connection charge more for one than the other, Eric?

Askin' for a friend.

....Cotten

[exeric]

It was free, that's why it was a good connection

[hairynob24]

Glad I asked the question, another indian enthusiast here told me to use heat, ok . Thanks for the reply you guy's, n no heat, Rob

[gharper]

OK fellas, I'll throw my 2 cents in.... I straightened my 24 Chief forks decades ago using heat and a home made fixture. Since then,15,000 miles plus, with a sidecar and the Cannonball. I've straightened 6 Excelsior frames and forks, using heat and fixtures. 3 of these X's made our 3500 mile Lindbergh ride in 2022, no problems. Since then, we straightened Stuart's wrecked X frame and fork, again with heat and fixtures. I've never had any issues with these parts being soft, and I ride them! I'm no metallurgist, but my simple mind tells me these frames were sweat brazed together, so why can't they be heated and bent again?

Let the debate begin.......

[T. Cotten]

One thing for sure, Gene,...

You were lucky. My contention is; cold gives easier results without introducing risk.

This Hen frame still knew how to return to straight....

HENFRAM2.jpg

Frames and forks are tempered springs: the primary suspension to absorb shocks. Applied force is distributed appropriately, whereas heat makes one spot move disproportionally, losing the advantage of heat-treatment, often permanently.

If it got bent cold, bend it back cold.

....Cotten
PS: A jiffy stand taught me the hard way: Straightened with a torch, it laid me and the machine on its side in slow motion the first time I tried to kick.

[RichO]

Gene, I've been working with metal for some 60 years cold and hot. Class A fitter, welder (certified all types), blacksmith, fabricator (structual and sheetmetal), foundry worker. Not bragging it just has been one of my life's work. I compared notes with the metal working professor Emeritus at Washing State University who wrote a paper on flame straightening. He and his team ( when he was plying hs trade) straightened the Seattle space needle and a giant hanger for the Air Force in the Dakotas after a fire. It was cheaper than building a new one. and many bridges. It confirmed what I had been taught and practiced since I began working in the trade. Applied heat works but has to be in the right place and properly used. When damage is introduced to a metal frame work or weldment it causes an energy transfer that is absorbed an has to be released. I could go into the many Zen like issues with metal graining and cell struture, and such but I'd rather not. Cold is cool if possible but heat if used properly is the proper technique in most cases. Just sayin' for me.

[hairynob24]

Well I am taking all this in , appreciate everyone input , Rob

[T. Cotten]

[QUOTE=RichO;n326101...straightened the Seattle space needle and a giant hanger for the Air Force in the Dakotas after a fire...[/QUOTE]

If the barn burns down around it, Rich,..

Nevermind 'memory'!

....Cotten

[RichO]

"If it got bent cold, bend it back cold" It didn't get bent cold. When it was impacted there was an absorbing of energy. Force or energy if you will creates heat even if it's in the abstract. Frames and forks were brazed which also stress relieved the weldment. They were never tempered as that is a whole different process. The reason the early forks and frames were so tough was in their design of bracing, lamination, etc.So heat is usual applied to relieve the energy that was absorbed upon inpact.