I managed to hit my rear brake pedal on a stump the other day and bent it out a bit. Who can tell me the procedure I need to follow to bend it back into shape? It's aluminium and I'm assuming it will be better heated a bit first, but how hot, and quenched afterwards or not? It's a 315R one if that makes any difference to anything.

You lucky sod......My 315 rear brake snapped like a carrot (a replacement was

Edited May 6, 201016 yr by HAM2

im not 100 % sure but i think you put soap on ally and when it turns black its warm enough

be steady theres a fine line between it bending and snapping

Aluminum work hardens as in... when it is bent it gets harder. Hard metals want to break rather than bend so you need to soften it prior to bending. You heat and then allow to cool prior to bending. I have used two methods to get the correct heating temperature. One was to coat the area with a black magic marker (it probably has a different name in the UK). The other was to coat with acetylene soot. (I suspect that the soap trick is similar.) Heat until the marker or soot is burned off. I straighted a Beta cast brake pedal that was bent into a full U shape. Since it was such a sever bend, I did it in three steps stopping to soften the metal in between steps.

If it's only a bit, you'll be fine with it hot......if it's folded in half, you're screwed !

Never heard the soap thing before.

Don't need to get it glowing, just " spit rolling off " hot !

You can do the soap trick when heating it up and then keep it hot for a while, but you must let the Ally cool as slow as possible (Don't quench it) this is refered to as 'Normalising'

When you bend Ally it will 'Work Harden' so when I have straightened brake and clutch levers I normalise them again so they are more likely to just bend and not snap off

Soap turns brown at the annealling temprature, think its 560 degrees (but it was 30 years since I read it). If the material is cast it has different properties and any amount of softning won't necessarily work.

Here is a good web site to check out concerning alluminium,.

http://www.tinmantech.com/html/aluminum_alloys_continued.php

You will see that different types of alluminium require different procedures. Some need to be softened by fast quenching whilst others require a different approach.

Let us know how you get on.

Pete

Thanks for all your help, guys. It's not bent too much so hopefully I'll be able to straighten it OK. I will let you know how it goes.

For those about to bend

We salute you.

Mr Ham, Sir, you are The Man.

I pressed the bearing and seals out, stuck it in a vice and heated it gently with a Propane torch, whilst keeping a bit of pressure on it with a big spanner. It resisted and resisted and then slowly bent a bit. Then stopped. I heated it a bit more and it gently went again. Repeated a couple more times and it's now better than when I got the bike. Looking good.

The only probelm I can foresee is that I'll miss it the first few times I need it until I get used to it being further in.

Cheers, mate.

That's good to know, well done

Wahey.. like the ACDC reference.