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Wednesday, August 10, 2011

How to remove old rusted crank arms

Every once and a while you'll come across this mess. A rusted crank arm that needs to be removed on a bike that's been sitting out in the elements for years. The odds of an easy job are 50/50 but with a little preparation, that goes up 95/5.

Hope of an easy job is for amateurs. Taking these simple steps will save yourself time, frustration, stress, bloody knuckles and some money out of the swear jar. Another benefit will be a longer life for your tools, read on.

The first step is removing that crappy little plastic cover that hides/protect/prevent access to the 14mm lock nut on the axle. Use a big coin in the slot and unscrew it. This will give you better torque control and the larger surface will distribute the energy more evenly (I'm sure there's a special tool for that but you probably, like me, already have this freely available in your pocket.).

Did it work? It came off no problem? If the answer is yes, buy a lottery ticket. These damn things usually explode in pieces because they get brittle over time. You didn't win the jackpot then? No worries, just jam a very small flat head screwdriver between the plastic and the locknut. Then slowly pry the remains of the cover off.

Second, using a 14mm socket wrench, remove the axle locknut.

Third, prepare! Before going any further you need to do a few things. Get yourself an old toothbrush, again free, and clean the thread inside the crank arm nut housing. Next use a lubricant (NOT WD40) and lube those threads. You would be surprised on how one grain of sand can ruin your day here. As far as lube goes, anything but the aforementioned fish oil stuff will do. I use Duralube engine treatment, 1 quart goes a long way on everything and it's like liquid bearings.

We're still not done. Apply oil on all the threads of your puller and on the end of the shaft that will push off on the axle. While using your puller, the friction creates a lot of heat and that's what can damage your investment in the long run. Be cool, lube your tool.

Click on image for full size

Click on image for full size


Now you can go ahead and use the puller and the crank arm should fall right out as it did in this case. Hope you found this useful.

Don't forget to check out the how-to articles post
and download my free bike maintenance book if you haven't already.

Until next time, ride safe and free.

Gerry :)

3 comments:

Ken Davidson said...

Hurhur, easy. Now do a tutorial on rusty old //cottered// crank removal! ;))

(step 1. go straight to hacksaw; step 2. grab a beer)

Anonymous said...

Why not use wd-40. I love that stuff and it smell good.

Gerry Lauzon said...

WD40 is not a very good lubricant.

Gerry