Cleaning rotors

PB Forum :: Mechanics' Lounge
Cleaning rotors
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flag biscuito
Posted: Mar 4, 2009 at 12:21 Quote
boiling water and a clean/new rag. Does the job for me, only takes a few minutes, boil the kettle and pour it on as soon as possible. Then repeat whilst rubbing away with the rag/cloth. Won't damage the rotors cos water is gonna be at boiling point max- pretty sure steel can handle 100 celcius..........
flag Graphxxx
Posted: Mar 4, 2009 at 12:23 Quote
biscuito wrote:
boiling water and a clean/new rag. Does the job for me, only takes a few minutes, boil the kettle and pour it on as soon as possible. Then repeat whilst rubbing away with the rag/cloth. Won't damage the rotors cos water is gonna be at boiling point max- pretty sure steel can handle 100 celcius..........

Yeah it can. They heat up ALOT more when doing downhill.
flag awais
Posted: Mar 4, 2009 at 12:24 Quote
Graphxxx wrote:
biscuito wrote:
boiling water and a clean/new rag. Does the job for me, only takes a few minutes, boil the kettle and pour it on as soon as possible. Then repeat whilst rubbing away with the rag/cloth. Won't damage the rotors cos water is gonna be at boiling point max- pretty sure steel can handle 100 celcius..........

Yeah i can. They heat up ALOT more when doing downhill.
very true!!!
flag dh-pete
Posted: Mar 4, 2009 at 12:28 Quote
If only people used the search feature....

But since I have nothing to do, here goes:

Cleaning a brake disk should be done in 1 way, and only 1 way. That is with isopropyl alcohol and sandpaper. The rotors don't generally soak in much of the contaminants, but it is possible and they can glaze, so that's the reason for the sandpaper. This should work with rotors. Well.

A blowtorch should never be used because you gain heat warp and any glazing on the disk is left there. Making it an OK method since it does burn off surface contaminants, but not ideal, and risky if you want your rotors to last.

Cleaning pads should be done only if that is your last resort. A set of pads will never perform as well as before once they've been contaminated.

There are few ways of cleaning pads, you can sandpaper a little off the surface and wipe what you can off with alcohol. But once they wear you're back to oily contaminated pads.

You can burn them with a blowtorch, but this dramatically weakens the pad material. And can cause the material to simply crumble away. Depending on your technique etc. Generally I'd just avoid it at all costs.

You can boil them, but this requires a new pan to burn them in, and 5 or 6 repetitions so you can wipe off the surfaced oil each time they've been boiled. This has been known to give pads a glazing, so to make sure you should sandpaper them off after this.

You can use specific brake cleaner, this is a pretty good method, but unless you're made of money, to properly clean the pads requires a good flushing, enough to consume a whole can of brake cleaner for 2 pads.

The ideal method for me, though. Is to just grab a nice handfull of dirt, the grittier the better. Then get it into a big bottle, fill the rest of the bottle with water and get on the bike with the bottle of gritty water. Start riding with your brake slightly on so it's feathering. Then, start pouring the gritty mixture onto your caliper whilst still holding the brake and riding. Spend about 10 minutes doing this and the grit & water should remove as much of the contaminants as possible, aswell as removing any sort of glazing. This method is free, and is more reliable than the others, with no damage other than a little pad wear.
flag biscuito
Posted: Mar 4, 2009 at 12:28 Quote
that was a bit of sarcasm on my part, but cheers for the clarification- no offense intended btw.
flag albertadiablo
Posted: Mar 4, 2009 at 12:31 Quote
ya i wouldnt be too keen on the gritty water ill stick with the brake clean lol free from work but hey it may work ive never tried it but great reply nice to hear the facts and i agree on most of them
flag wanabe
Posted: Mar 4, 2009 at 12:36 Quote
given the cost of pads why even clean them
flag albertadiablo
Posted: Mar 4, 2009 at 12:37 Quote
i agree i always carry 4 or 5 sets with me in my vehicle. they are 20$ canadian a set here so thats not worth my time trying to fix some
flag jonbikes
Posted: Mar 4, 2009 at 13:44 Quote
Graphxxx wrote:
Themaninthenorth wrote:
albertadiablo wrote:


thats a nice way to weaken metal

Best not ride your bike when its cold then...

What? Okay you clearly don't know what hes talking about. I'll explain, when you heat up a metal and then cool it very quickly into cold water, it will in a way weaken the metal by alot. Try this with a plate. Heat it up VERY hot and then put it in snow. There will be high chances that the plate will crack or brake. Thats cause by such a quick change in heat.

When you do that to metal, it plays with the caracteristics of the metal, thus making it alot weaker. Only time you cool down metal is after welding it.

If you heat it up and then cool it in very cold water, you could warp you disc due to heat torquing and quick heat change.

Shit i was beaten BIG time to it Razz Oh well.

As others said, heat plays with the molecules and will screw up the metal.

You aren't going to hurt the rotor taking it from boiling temp of water to room temperature, there just simply isn't enough of a change there to do anything noticeable.

Also, warping is caused by uneven heating and cooling, not just heating and cooling. I could heat up a piece of plate to the point of it being red hot, then return it to room temperature and have it come out flat as a pancake.
flag Graphxxx
Posted: Mar 4, 2009 at 13:57 Quote
jonbikes wrote:
Graphxxx wrote:
Themaninthenorth wrote:


Best not ride your bike when its cold then...

What? Okay you clearly don't know what hes talking about. I'll explain, when you heat up a metal and then cool it very quickly into cold water, it will in a way weaken the metal by alot. Try this with a plate. Heat it up VERY hot and then put it in snow. There will be high chances that the plate will crack or brake. Thats cause by such a quick change in heat.

When you do that to metal, it plays with the caracteristics of the metal, thus making it alot weaker. Only time you cool down metal is after welding it.

If you heat it up and then cool it in very cold water, you could warp you disc due to heat torquing and quick heat change.

Shit i was beaten BIG time to it Razz Oh well.

As others said, heat plays with the molecules and will screw up the metal.

You aren't going to hurt the rotor taking it from boiling temp of water to room temperature, there just simply isn't enough of a change there to do anything noticeable.

Also, warping is caused by uneven heating and cooling, not just heating and cooling. I could heat up a piece of plate to the point of it being red hot, then return it to room temperature and have it come out flat as a pancake.

Okay, then why don't you do that and film it? If you believe that heating a rotor at high temps and then cooling it back to room temp in about 1 sec won't damage it, then you need to learn some things. I won't even bother arguing, go do some research on google before talking. Why do you think people TAC weld first? Because if they weld it straight, the metal will torque and warp. Heat can easily damage metal, as long as you let it cool correctly. If you cool it by dumping it in cold water, now you will damage the metal. When metal is ver hot, the molecules aren't the same, they aren't position the same either.

Just a pointer, www.google.com
flag jonbikes
Posted: Mar 4, 2009 at 14:09 Quote
Listen buddy, I haven't spent a year and a half in a welding shop and come away with nothing. I'm 9/10th the way done my first year of a welding diploma. The reason you tack weld is because you are unevenly heating the metal, thus causing distortion. The reason a rotor warps is because it is generally cooled unevenly, ie you come to a stop and then do not release the brake, causing it to cool slower where the pads are touching. Repeated abuse like this will eventually cause distortion in your rotors. As for boiling them and then cooling them off, you aren't going to hurt them in that small a temperature range. Riding in the rain causes much greater changes in temperature at just as fast a pace as going from boiling to room temperature.
flag Graphxxx
Posted: Mar 4, 2009 at 14:15 Quote
jonbikes wrote:
Listen buddy, I haven't spent a year and a half in a welding shop and come away with nothing. I'm 9/10th the way done my first year of a welding diploma. The reason you tack weld is because you are unevenly heating the metal, thus causing distortion. The reason a rotor warps is because it is generally cooled unevenly, ie you come to a stop and then do not release the brake, causing it to cool slower where the pads are touching. Repeated abuse like this will eventually cause distortion in your rotors. As for boiling them and then cooling them off, you aren't going to hurt them in that small a temperature range. Riding in the rain causes much greater changes in temperature at just as fast a pace as going from boiling to room temperature.

The guy was talking about heating the rotor with something like a tourch, not boiling it in water. 100 degres for metal is nothing.
flag lafalot
Posted: Mar 4, 2009 at 14:16 Quote
the person who posted the idea of splashing water on a hot rotor is not talking about "water boiling" temperatures..He was saying to bike around with the brake pulled or GO DOWN A HILL. i'm sure most of us have experienced that it does not take much for the rotor to go beyond 100 celsius, so this is why people are saying its a bad idea.

As for cooling metal, yes blacksmith take iron out of the furnace red hot, smack it around, then dip in water to cool instantly, so yes, that is fine, but we are talking about Splashing water on a rotor that is still on your bike, so this isnt the same as dunking the whole rotor in water very quickly - it isn't going to cool evenly, and rotors have so many cut aways so they are delicate, and temperature stress CAN cause cracks. There has already been a recall on Ashima rotors in the past where some of them developed cracks after going red hot during downhill run, and then getting water/mud splashed on them.
flag jonbikes
Posted: Mar 4, 2009 at 14:21 Quote
Graphxxx went on a nice little tangent based on my "You aren't going to hurt the rotor taking it from boiling temp of water to room temperature, there just simply isn't enough of a change there to do anything noticeable." comment, I responded to that. That entire thing started due to someone talking about boiling water, putting the rotor in, then putting it in cold water and wiping it off, which someone else responded to with the whole distortion thing.

This is why pb gets such a bad rep, too many people commenting on different things and thinking they are all talking about the same.
flag biscuito
Posted: Mar 4, 2009 at 14:26 Quote
this thread has turned bad....

 


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