Straightening A Bent Lever?

[mokwepa]

Hi guys

My pops has a 2013 beta 300 and took his first minor tumble the otherday, hes still getting used to the vicous power of a trials bike. Anyway my dad stood back and watched the bike cartwheel out of his hands. In the multiple 360 degree process, the bike bent its clutch leaver. He says its a minor bend and he could leave it but i know my dad and his other bikes, itll drive him nuts. Can a alu leaver be tweeked straigh with a block of wood and a rubber mallet or will it crack?

Any body have any tips on this?

PS: I know he could just buy one but if it can be straightened, why spend the money + my mom will kick his @ss.

[shercoben12]

yes your idea should work. we did the same with dads brake lever on his gasgas 2011 300. with original levers. you do need to give it a big hit though.

ben

[billyt]

"The Vicous Power Of A Trials Bike"

Heat the lever gently before bending or hitting with a block of wood and mallet.

[0007]

I don't know about the heat thing, I'm sure it works but there is likely a proper temperature that helps

I just put it in a vice and smack it, shock is the way

And you only get one of them, it's weaker after this

[billyt]

The heat is needed as it has already been smacked and the aluminium is altered in the area that took the hit i.e. stress.

If you just wack it again without heat it may straighten out but it will be very weak and will break the next time is sees any stress on it.

Edited June 18, 2013 by billyt

[dadof2]

I agree with Billyt. The alloy will have work hardened by being bent and you need to anneal it to soften it before straightening.

Rub a bar of soap on it and heat it until the soap chars black, then quench in water.

Cheers

[charlie chitlins]

I agree with Billyt. The alloy will have work hardened by being bent and you need to anneal it to soften it before straightening.

Rub a bar of soap on it and heat it until the soap chars black, then quench in water.

Cheers

This is good advice.

The soap will turn brown first, but wait for it to go black.

Equally good:

If you have acetylene, light the torch with acetylene only and cover the piece with soot, then bring in the oxy until the soot flakes off and quench.

Now you can bend it.

[0007]

Ahhhhhhhh, there's what I was looking for

I am of the belief that you cannot manage what you cannot measure, soap or soot huh

That's good old school stuff there

[copemech]

Fact is, a good hair drier works. Get some heat init to relax it a bit. If it is not bad, it will take back to the bar with minimal pressure from a pipe or wrench slid or the end without removing anything, just but a block in between good part of lever and bar. Easy Peasy, but be gentile!

If it breaks, you prolly needed a new one anyway!

Edited June 19, 2013 by copemech

[lee_28]

put the leaver in a saucepan and fill with boiling water from the kettle, leave to stand and you can bend them back easily enough

[dadof2]

http://www.mlevel3.com/BCIT/heat%20treat.htm

Suggest you have a look at this link - Water usually boils at about 100 C. Too low to affect the alloy

[0007]

Ya I was going to say the water trick would work for plastic but not metal

It takes 450 - 500 F to temper steel

[richt]

Quenching aluminium will work harden it, It should be heated and kept hot for a while to normalise, then let it cool slowly. When you've straightened it repeat the normalising again so it will be ductile and next crash it should just bend instead of snapping.

I have managed to do this 4 times on the same lever (Brembo) before it eventually gave up.

[dadof2]

This is now maybe getting a bit complicated. Quenching to harden is hardening by heat treatment not work hardening.

If we knew exactly what alloy the levers were made of it would be possible to know exactly how to anneal them, in practice we don't.

In practice although quenching may make the aluminium slightly harder than slow cooling it results in a much finer crystal structure which is less prone to cracking during bending and more than offsets the slight increase in hardness.

Really its a case of finding what works best for a given make of lever and sticking to that. Some cheap pattern cast levers (as opposed to forged OEM items) cannot be straightened because of the high level of impurities in the metal.

Cheers

[charlie chitlins]

Whatever the theory, I've been doing it just as described for all kinds of levers for many years.

That kind of heating/quenching would make some metals more brittle and, for annealing steel, slow cooling works best.

We blacksmiths anneal steel last thing of the day and leave it in the coals to cool over the course of hours.

But for cast aluminum, heating to the right temp and quenching works fine.