Brake lathe?

[Tufbusa]

Has anyone ever had a brake rotor polished up with a lathe to take the imperfections out? One of my colleagues ran his BMW rear rotor til the metal roughed up his disk a little. He ask me if it could be turned down on a brake lathe and still be useable. I have no idea. I have never thought about polishing up a used rotor on a lathe. Maybe someone on here has some experience at this?

 

[mike04busa]

I guess if you were to chuck it up and polish it with scotch brite or sand paper, that would be ok. Cutting it on a lathe would probb. cause it to flex while cutting and warp it more. I don't think there is too much material to work with anyway.

 

[Karl_1052]

I doubt there is enough material to work with. He is probably looking at replacing the rotor and checking his pads more often.

 

[RedBusarider]

One rear rotor can't be that much $$$ so I would just replace it.
I replace rotors on my 4 wheel vehicles and do not ever get them turned - even if there is enough thickness that they could be.

You asked about "imperfections" I assume these would have to be high spot on the rotor.
I would take a fine FLAT file and put the rotor on a pad with a hard surface under it and file out any high spots - IF I COULDN'T AFFORD A NEW ONE.

 

[StrtRac3r]

Generally you don't want the directional swirls that sounds like it would do. And with the thickness and cross drilled I wouldn't want to try any bits or even files IMO. If you do try I would finish it up by flipping it and doing a little in the opposite direction to give it an even surface to seat the new pads on.



But I still would prefer a new rotor on my bike.

 

[dadofthree]

They turn them all the time for the cars, but I don't know about the bikes. Two different animals.

 

[dwilson]

You want to get them Blanchard ground. Unlike a car I believe they are flat . The Blanchard grind will be able to grind hatch marks and remove the heat spots which are sometimes trouble with turning on a lathe. Not to mention grinding remove less material at a time .

 

[RedBusarider]

You want to get them Blanchard ground. Unlike a car I believe they are flat . The Blanchard grind will be able to grind hatch marks and remove the heat spots which are sometimes trouble with turning on a lathe. Not to mention grinding remove less material at a time .

I know what Blanchard grinding is and that has to cost more then buying a new rotor, unless you knew/know someone that can do a government job for you.
That is why I suggested that you run a flat file over it if all you wanted to do is clean up the "metal roughed up his disk".

Since the OP's "colleague" has to remove the wheel and rotor before anything can be done (if it hasn't already) then the easiest thing would be to
just bolt on a new rotor and be done with it. Like dadofthree said not sure if anyone "Normally" does turn bike rotors. Maybe there is a reason for that.......

I could be wrong but it appears the vote is for a new rotor.....Let us know what your colleague decides.

 

[sixpack577]

I've turned many car/truck rotors over the years, and more and more places are getting away from it.
Reason being, in most cases replacement rotors are cheap, fast and easy(time is money); and more importantly, the thinner you cut the rotor the faster it heats up(as there is now less material to heat, but subjected to the same conditions). The faster it heats up(and therefore heat cycles hot to cool)the quicker the rotor will warp in the future.
The same applies to bike rotors, and the main reason you never hear of them being turned.
Not to say it couldn't be done, but unless you can do it yourself(and still plan on replacing it soon), it's not worth doing.

 

[Dscahill]

I actually tried to turn a spare set of rotors for the Busa, and it didn't end well.. I think they may be made from a different material because they didn't have little shavings like a car or truck, it was more like brass and came off in swirls. You can put a non-directional finish with a polishing wheel, but given what Ive tried...its really not worth it.. truly.

-D

 

[Professor]

I had an automotive combo drum/disk brake lathe for many years. When working on race cars and when I had a small bike shop, I worked with quite a few disks. The big problem I had was that the standard tooling, rotation rates and feed rates were set up for automotive cast iron. When turning steel and aluminum rotors the game changed. I had some machine shop connections and with a bit of help I was able to place some decent cuts on most rotors using some cutting fluids, different types of cutting tools, and speeds. I would then work it with a dual action sander while still turning on the lathe to get desired finish.

It was not a quick and easy chore but I had more time than money. Anyhow, the rotors will have a minimum thickness on them and it rare the damage is within the limits to allow them to be cleaned up. As mentioned Blanchard grinding would be the preferred method. With my contacts I did clean up a few. But it was done on the side as a favor and would have exceeded the cost of replacement if they had billed me.

 

[GsxrBots]

Tuf, Tuf, Tuf..... You are the guy that comes in here and CRUCIFIES people for putting Chinese levers, etc on bikes for being cheap, and you ask THIS?



Tell him to buy a new rotor. And tell him all angry and stuff like you do us..

 

[sixpack577]

Tuf, Tuf, Tuf..... You are the guy that comes in here and CRUCIFIES people for putting Chinese levers, etc on bikes for being cheap, and you ask THIS?



Tell him to buy a new rotor. And tell him all angry and stuff like you do us..

 

[Tufbusa]

Tuf, Tuf, Tuf..... You are the guy that comes in here and CRUCIFIES people for putting Chinese levers, etc on bikes for being cheap, and you ask THIS?



Tell him to buy a new rotor. And tell him all angry and stuff like you do us..

Thanks for that input bots. I'll take that as an "I don't know s h i t about the subject but I'm happy to take every opportunity to share my antipathy for you"!

 

[GsxrBots]

Thanks for that input bots. I'll take that as an "I don't know s h i t about the subject but I'm happy to take every opportunity to share my antipathy for you"!

Nailed it!

 

[Tufbusa]

Thanks for the all the input guys. That question has never crossed my mind and I didn't have an answer. I wouldn't think it to be a wise choice.

 

[Tufbusa]

Damn bots, I don't know if I can sleep tonight knowing you don't love me anymore!:cry:

 

[StrtRac3r]

I have chazzos, and not only were they cheap, they were free! I feel a bit like an azz because I can't remember who they were from here. But that was a long time ago, still using them, and still work great. Anyways, there wasn't really a point to that....

 

[GIXERHP]

Seriously here,, when you are talking about an item on a 2 wheeled vehicle, that one person is riding, Isn't safety the number one priority?
Now for the thought process, of this,, you are dealing with a piece of metal that is no more than 5.5mm thick.
If it it damaged,, it is most likely warped, and if not, there is no extra surface material, to machine, thus why the OEM manuals tell you to measure the component, and if not in spec, replace it.
SIMPLE, just spend more $$$$$