Bent levers

[gggGary]

I've mentioned this before but a new to me bike has a bent clutch lever.

This ones not real bad but bent for sure.
Heat gun, block of wood, piece of pipe.
Gotta be a heat gun, hair dryer ain't doing it. If you don't care about the finish on the lever a propane torch works also. Propane can melt aluminum if you leave it on there too long. I hear that some ivory soap smeared on aluminum acts as melt gauge, if the soap turns black melt is close. Wear gloves or you WILL get burned. Once GOOD n hot apply pressure with the pipe slow and steady, no jerking. If it doesn't want to bend under light medium pressure add more heat and try again.

I used some aluminum tube from an old lawn chair, filed sanded flared end with a ball peen so it doesn't cut or mar the lever. Steel pipe is fine too it just has to fit over the ball end. and no sharp edges.

There I fixed it. I have straightened levers where the ball was bent completely around facing in. Slow and steady, check, reheat a couple times as you straighten. My theory: You want to give the aluminum molecules time to flow and rearrange themselves, not start to separate from each other (crack, snap) Didn't even mar the black finish!

lever clutch brake bend bent straighten heat repair fix gun torch propane pipe tube fix

 

[Jim]

I hear that some ivory soap smeared on aluminum acts as melt gauge, if the soap turns black melt is close.

Soot from a candle (or oxy-acc rig) also works. When the soot just starts to disappear, you're at the annealing temp.

 

[Mailman]

Very nice tip Gary! Was that your new Buell? You didn’t drop it on your icy driveway did you? ( Just kidding )

Soot from a candle (or oxy-acc rig) also works. When the soot just starts to disappear, you're at the annealing temp.

Boy that was a memory from the way back machine! I totally forgot about sooting up a piece of metal with a torch.
I used to do that to gauge a proper pre heat when welding certain metals.

 

[xjwmx]

Don't fix it, sell it.
http://www.xs650.com/threads/custom-clutch-lever-100.9728/

 

[Camilo]

My theory: You want to give the aluminum molecules time to flow and rearrange themselves, not start to separate from each other (crack, snap)

Good theory Gary, not far off our current understanding of metallurgy. When you deform a metal you introduce "dislocations" which are places where rows of atoms are sliding past each other. The more you deform a metal, the more dislocations you introduce. They can pile up in one spot, get knotted around each other, or get stuck on inclusions / grain boundaries. Eventually the rows of atoms can no longer slide past the pile ups, the metal can no longer plastically deform, becomes brittle, and snaps. Heating up the metal indeed allows the atoms to rearrange themselves into more favourable positions, removing the "pile ups" of dislocations.

Heating up too much can cause recrystallisation which might slightly decrease the strength of small grain size metals like forged or rolled steel. Can also mess up the heat treatment of fancy heat treated alloys / tempered steels.

 

[xjwmx]

Good theory Gary, not far off our current understanding of metallurgy. When you deform a metal you introduce "dislocations" which are places where rows of atoms are sliding past each other. The more you deform a metal, the more dislocations you introduce. They can pile up in one spot, get knotted around each other, or get stuck on inclusions / grain boundaries. Eventually the rows of atoms can no longer slide past the pile ups, the metal can no longer plastically deform, becomes brittle, and snaps. Heating up the metal indeed allows the atoms to rearrange themselves into more favourable positions, removing the "pile ups" of dislocations.

Heating up too much can cause recrystallisation which might slightly decrease the strength of small grain size metals like forged or rolled steel. Can also mess up the heat treatment of fancy heat treated alloys / tempered steels.

Could bending it back cause it to be too weak, esp. in the case of a brake lever?

 

[Mailman]

Good theory Gary, not far off our current understanding of metallurgy. When you deform a metal you introduce "dislocations" which are places where rows of atoms are sliding past each other. The more you deform a metal, the more dislocations you introduce. They can pile up in one spot, get knotted around each other, or get stuck on inclusions / grain boundaries. Eventually the rows of atoms can no longer slide past the pile ups, the metal can no longer plastically deform, becomes brittle, and snaps. Heating up the metal indeed allows the atoms to rearrange themselves into more favourable positions, removing the "pile ups" of dislocations.

Heating up too much can cause recrystallisation which might slightly decrease the strength of small grain size metals like forged or rolled steel. Can also mess up the heat treatment of fancy heat treated alloys / tempered steels.

That is a great explanation, I’ve never heard it said like that but I can envision it. If you take a length of copper tubing for instance. You can easily bend it around a few times , then it becomes increasingly difficult until it will eventually just fold flat.

 

[gggGary]

Could bending it back cause it to be too weak, esp. in the case of a brake lever?

Suppose it's possible, but got a lot of miles on "rebent levers", no issues so far. Guess if anything it'd be more likely to break in the next crash....
There are shops that straighten aluminum wheels with heat and bend back techniques.

 

[gggGary]

That is a great explanation, I’ve never heard it said like that but I can envision it. If you take a length of copper tubing for instance. You can easily bend it around a few times , then it becomes increasingly difficult until it will eventually just fold flat.

Copper work hardens and can be annealed by heat and quench. Early vehicles used copper fuel and brake lines with disastrous results, vibration work hardens the copper then it cracks. Vehicle codes forbid copper lines.

 

[gggGary]

Just did a couple more when Allison had period piece flop over in a wind gust.
Being crude here not protecting the aluminum from pliers jaws. but with a gentle touch no marring. Trick is to load up the bending force then apply heat and wait for the lever to yield and start to bend, so you never FORCE the bend, and add just enough heat to do the work, keep moving the torch to the sections that need to be straightened. The lever will be bent AND twisted along much of it's length, need to work all along the lever. to get a good final shape. Don't overbend the thin sections, creating a snake. Good idea to mess with a broken lever to learn and understand the process.

 

[peanut]

thats the way to do it....thats the way to do it ...(Punch & judy voice )
Apparently one way to tell when you have sufficient heat in aluminium is to spit on it . When it sizzles its hot enough. I usually get some heat into aluminium first by putting things in the oven especially large items like crankcase covers because its difficult to keep the whole of a large item hot enough that it doesn't act as a heat sink for the part you are welding bending brazing etc

 

[fredintoon]

Soot from a candle (or oxy-acc rig) also works. When the soot just starts to disappear, you're at the annealing temp.

Hi Jim,
Mr. Bodger's aluminum annealing temperature gauge is the tail end of a wooden match.
When it leaves a sooty trail on the aluminum the metal is annealed.
Note that pure aluminum STAYS annealed but most aluminum alloys "creep" back to their pre-annealed condition a day or so later.

 

[gggGary]

The thing is if you use steady pressure on the pliers, piece of pipe etc. you don't have to worry about the temp, the aluminum starting to yield answers the question. Play the torch to the areas that need "unbending" most keep it moving in, out, around so the aluminum moves but doesn't turn into a puddle. LOL