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Clean up rusty pitted forks - sort of...


Stray

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Hello everyone, 

 

This is is a quick how-to for those with crappy rusted forks. It's not a cure-all but might help reduce the amount of pitting and help your seals last a bit longer. The only ways to ultimately tackle rusty forks is to re-chrome or replace. This is just a temporary fix and doesn't work on heavy corrosion 

 

You will need: 

 

1. Cola (any brand as long as it has Phosphoric acid in the ingredients)

2. Piece of aluminium foil

3. Protective oil of your choice (I use ACF50)

 

Method is very simple: splash some cola on the forks and swish it about so it gets into the rust. Apply some cola on to foil sheet also. Now rub the soaked foil across the rust until it is completely removed.  

 

You can actually feel the rust reducing as you rub. Go gently to avoid scratching the chrome - it works just as well gently. Best to rub left-to-right as this will create microscopic ridges for fork oil to dwell and protect the fork (same principal as honing a cylinder for piston rings). Up and down would create microscopic tears in the seal's mating surface, shortening its life. 

 

In reality it it doesn't really matter  which way you rub - just go gently. 

 

When you're satisfied simply wipe off the cola and apply some sort of lube protectant. 

 

Lots of rumours on the internet suggest the phosphoric acid "converts" rust and the tinfoil chemically fuses bits of itself to the pitted area. I'm not a chemist and cannot confirm-or-deny this but I feel there is not enough Phosphoric acid in cola for this. 

 

My my gut feeling is that the tin is harder than rust but softer than chrome. It removes the former without harming the latter. But the acid and chemistry might help things along. It creates a grey residue which might suggest the acid is working. 

 

The only thing I know for sure is it works well. 

 

You can can see from the pics how much of an improvement there was, although some deeper pits remain, although  they are much smoother and kinder to the seals.  

 

One old-timer told me he seals the pits with flexible superglue and builds them up to match the surrounding surfaces. Normal superglue it too brittle. Sounds like a good idea but really time consuming. 

 

This is process took less than 5 minutes and cost less than half a pound. 

 

Hope it helps someone out. 

 

Best, 

 

 

stray

 

 

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  • Member Contributer

You can actually use just water, and save yourself the sticky residue. Next time, try it before the cola method and see if it's as good.

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Just water? I'll try that next time - thanks. Just goes to show the phosphoric acid does nothing. 

 

Firgot to say in the last pic the left fork is still rusty whereas the right one has been cleaned. It's not perfect but you can see an appreciable improvement. 

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  • 5 years later...

I appreciate that this is an old thread but though I might reply for interest of future users.

 

So a couple of comments, phosphoric acid does passivate steel surfaces. Leaving a layer of iron phosphate, however the theory behind this method is mainly using it as an electrolyte. 

 

The tinfoil, doesn't actually contain any tin. It's aluminium foil. Contact between the aluminium metal and the iron oxide rust in the presence of the acidic electrolyte, in theory sets up an electrolytic cell, where the iron oxide is reduced to iron metal and the aluminium is oxidised to aluminium ions. Does it work ? Well it looks as if it's somewhat effective, but iron oxide is also somewhat soluble in phosphoric acid so there could be a process of rust removal there. You could do the same thing with other sources of phosphoric acid, but you would have to dilute the acid down to a sensible concentration. 

 

Coca Cola is also useful for some other cleaning applications but it's generally a more expensive way of doing things although it is sometimes readily available where other cleaning products are not and it's safe to handle, although whether it's healthy to drink is another question ;).

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