How Can I Measure Rotor Temperature

[MrStabby]

Looks like the cheap infrared jobbies only go to about 400-500 deg c. Is there a cheap way (<$300) than i can measure rotor temps after track runs? Say up to ~800 degrees. Doesnt need to be too accurate, i just want to verify that i am within the deisgn spec of the rotors.

Cheers,

Kot

[djr81]

Cheap infra red jobbies DON'T WORK ON OTHER THAN MATT BLACK SURFACES. Sorry, but I have seen far too many people make that mistake. People who should know better.

Anyway, best method is to get yourself some temperature sensitive paint from your local race shop. There are usually three colours which go off at varying temperatures.

[MrStabby]

Cheap infra red jobbies DON'T WORK ON OTHER THAN MATT BLACK SURFACES. Sorry, but I have seen far too many people make that mistake. People who should know better.

Dont you just adjust the emmissivity to whatever is approriate for the material you're measuring? Or am i missing something?

Anyway, best method is to get yourself some temperature sensitive paint from your local race shop. There are usually three colours which go off at varying temperatures.

Yeah i've got the DBA4000s which come with that - does it work once only? Ie burns at a certain temp? Or must you view it when its hot? Either way its a bit crude, i'm really interested in a thermometer.

Rgs,

Kot

Edited November 6, 2006 by MrKotter

[djr81]

Some infra red thermometers have adjustable emissivity values, but that for bare metal is a long way from black surfaces.

Yes the paint works only once. That way it measures the peak temperature which is what you want. If you have to wait to get back to the pits you won't gather any data of any worth as the rotors will long since have cooled.

The only other effective way to do it is to check the colour of the rotor itself (ie what shade of orange/red) it glows at the end of the braking zone. Bit hard in the daylight, but if you can get out there in the gloom it works.

If you get yourself three jars of the paint you can check the temps any number of times.

[Sydneykid]

As djr81 said, race teams use temperature sensitive paint. For example the DBA 4000 series rotors come with temperature sensitive paint on the rotor edge. This is the DBA instruction sheet for what the temperature sensitive paint is going to tell you.

There are 3 colours (green, orange & red) and they change colour (white, yellow & white) at different temperatures. So I will be able to tell how hot the rotors have been. This tells me what pads and what brake fluid to use.

as you can see from the following picture, the green paint (458 degrees celsius) has started to change colour. And the orange (550 degrees celsius) is slightly more yellow. The red is still red, not white.

Looking at those colour changes, I would say I haven't had many brake applications that have resulted in spot temperatures over 500 degrees.

Hope that was of some help

Cheers

[djr81]

As djr81 said, race teams use temperature sensitive paint. For example the DBA 4000 series rotors come with temperature sensitive paint on the rotor edge. This is the DBA instruction sheet for what the temperature sensitive paint is going to tell you.

There are 3 colours (green, orange & red) and they change colour (white, yellow & white) at different temperatures. So I will be able to tell how hot the rotors have been. This tells me what pads and what brake fluid to use.

as you can see from the following picture, the green paint (458 degrees celsius) has started to change colour. And the orange (550 degrees celsius) is slightly more yellow. The red is still red, not white.

Looking at those colour changes, I would say I haven't had many brake applications that have resulted in spot temperatures over 500 degrees.

Hope that was of some help

Cheers

Not trying hard enough then....

[Sydneykid]

Not trying hard enough then....

Road car

cheers

[MrStabby]

Some infra red thermometers have adjustable emissivity values, but that for bare metal is a long way from black surfaces.

I have asked a thermometer vendor and he has said that the infrared will work with brake rotors, and supplied me with emmssivity values for rusty cast iron, polished cast iron etc. I think the "black surfaces" issue may no longer be correct. He suggested using a thermocouple to verify the correct emmissivity, and since its only an extra ~$65 i will get that as well to increase my confidence. Should only need to use it once to do the verification, then i'll just use infrared from then on. $220 for up to 760 degrees, $65 for the thermocouple, $15 delivery.

Rgs,

Kot