Here's a short question. Is it necessary to pay extra money and get cryo treatment when ordering brak rotors? It's like $60.

 

Put the rotors in your freezer for a couple of days and save $60.

 

Are you being serious? Put the rotors in the freezer before installation?

 

 

lolz

 

Sure, provided your freezer goes down to -300 degrees F.

I think it's one of those things that has some basis in fact, but you could easily be scammed. There's no way you can tell if it's really been done, except by doing some really expensive controlled tests under lab conditions.

 

But it's not necessary to get it treated right? Since this car is just hard daily driving, it won't affect much

 

What would be the supposed reason for cryo treatment, besides bilking dupes outta extra $$$$ ?

 

Cryogenics is used to freeze metal parts at very low temps. It is supposed to cause the molecules to reslign themselves in a way that increases durability. For the street it is probably overkill.

 

Agree^
It's an extension of heat treatment used to improve durability, but it has to be done in a carefully controlled process to be effective. For street use, it's not worth the extra cost.

 

regular rotors will do just fine... even for track use..

 

For a street car cryo treating is of no value. For a track day and autocross car its generally of no value. For a race car, especially a car running endurance events, it help significantly with rotor wear. I used to race a ITS build Datsun 240Z (solid front rotors) and I could get 4 times the life out of the front rotors with cryo treatment, especially when I ran the CalClub 6 hour or one of the enduro races at Thunderhill.

 

Actually, tests have been done using really expensive equipment and controlled lab conditions. The result was that no discernible difference could be found. The metallurgists could not even tell which rotors had been cryo'd and which ones were not (it was a double-blind test using micro-photography at the molecular level).

Cryo works very well for many metal alloys, but cast iron does not have the grain structure necessary to benefit from it. Yes, I know, there is some random anecdotal evidence out there, but in real lab testing there was no improvement as there was none possible. It is not used in professional racing, at least by the teams in the top level series'.

The good news is that is doesn't look like it hurts cast iron, so do it if you want. Just make sure you understand you (nor anyone else) will not be able to tell if it has actually been done or not.

Chris

 

^^Wise words. IMHO OP NOT worth the $$$$$$$

 

I'm not a cryo treater and I don't sell the stuff. I've had some very positive experiences with cryo treated brake rotors and will always get them cryo'd for any race car I or my customers run. I've also run cryo treated stub axles but I can't report on any increase in service life because the race car was sold before the mean expected replacement for those axles. They did last longer then the "typical" stub axle used but that could have just been a fluke.

My very basic understanding of cryo treating is that its a stress relieving process (primarily for steel) which further transforms a percentage of retained austenite into martensite. This increases the abrasion and chipping resistance of the steel and increases its toughness (ductility).

Heat and vibration also do the same thing, over time, to steel - steel is a very ductile material despite what people think. What cryo treating does is accelerate this transition and stabilizes the metal so you see less part dimension change in use.

Items subject to cyclical stress tend to last longer when cryo treated with valve springs on top fuel drag engines being a great example. In the ITS racing world where you have to run stock valve springs I've seen a 500% increase in valve spring life (+/- 5% spring pressure change) in specific applications.

Cryo treating is real and cost effective but only in extreme racing applications where the incremental benefits outweigh the additional costs. Its of no value to a street driven car. And as stated above, proper cryo treating is not just dipping the part into liquid nitrogen for a set period of time. There's a lot more to it then that.

 

True, except for typical gray cast irons, which is what the OP's brake rotors are made of. This type of iron contains a random disbursement of graphite flakes, not an organized grain structure. Without a grain structure, no structural change or transformation can occur.

Improvements can be made in brake rotors by the precise selection of alloying elements and the cooling/heat treating techniques. Of course, the better the rotor and treatment, the more expensive it is to make (no surprise there!). When we hear someone say that "a rotor is a rotor", they are clearly ignorant of what goes into quality rotor production. Regardless, the effectiveness of cryo treatment is material dependent, not application dependent.

Chris

 

thank you all for answering my question. It really helped

 

As far as Grey Cast IRON goes......

Might wanna read this:

http://www.metal-wear.com/Myths.htm

*Myths* on Cryo

Cryogenic Processing Will Not Work On (insert material name here) because there is no retained austenite in it.
Metallurgists often pull this one. They were taught that the only use of cryogenics is to convert austenite to martensite. So obviously, cryogenics will not work on austenitic stainless steels, cast iron, non ferrous metals, and such. The trouble is that it does work on these materials. We have had customers who, while observing huge savings on downtime and part replacement, were ordered by the corporate metallurgist to stop using cryogenics because "It can't work on that metal." One of the biggest uses for cryogenic processing is for brake rotors which have a pearlitic microstructure. No Austenite, no martensite.

Cryogenics works on brake rotors because it turns the austenite into martensite.
I love this. Give the dummies (customers) something the think they understand. Look, the customers are not dummies, and some of you out there know that common brake rotors are made from pearlitic cast iron.....no martensite, no austenite. Yet we've proven beyond any doubt that brake rotors benefit greatly from cryo.

AND >>

http://www.mendeley.com/research/wea...e-disc-rotors/

Abstract
Cryogenic processing has the potential to significantly increase longevity in many automotive components, where friction and wear are major factors in their operation and eventual failure. Cryogenic treatment affects the whole cross-section of the component and is inexpensive compared to other treatment processes. Whilst numerous studies have been conducted on cryogenic treatment of tool steels since the 1970s, in many cases showing significant improvements in wear resistance, only minimal work has been done in cast irons. In this study the effects of deep cryogenic treatment (93K) on the wear resistance of grey cast iron (SAE J431 G10) brake rotors was assessed and related to changes in their microstructure using optical microscopy. A comparative analysis using pin-on-disc testing was carried out on brake discs having undergone deep cryogenic treatment and those that had not, using chrome steel ***** as the wear inducing body. The results indicate an improvement in the wear rate of grey cast iron of 9.1-81.4% due to deep cryogenic treatment where significant wear has occurred, although there was no significant change in the bulk hardness, matrix hardness or in the microstructure of the material under optical observation.

And finally this>>

http://www.eng-tips.com/viewthread.cfm?qid=145775

The article on cryogenic processing in Heat Treating Progress is the publication of a paper given at the ASM conference last fall. It is not an advertising blurb. Yes, the author is affiliated with a cryogenic processing company, but so are a lot of other people who know something about cryogenic processing. I find, however, that not many of its detractors know much about it.

I do not believe that the relief of residual stress has a whole lot to do with the increase in wear resistance in cast iron. And, as the microstructure is pearlitic cast iron, and there is very little or no retained austenite, it cannot be the austenite to martensite transformation either. So you have to look deeper.

We believe that the benefits of cryogenic processing are from subtle changes in the crystal structure. As the temperature drops, solubility of elements in the matrix changes, vacancies move or are eliminated. We have seen some indication of this in the electronics industry. In a project done for Honeywell on thin film magnetic memory chips, Honeywell thought that they detected the movement of atoms in the structure that healed vacancies in the chip layers. The program ran out of time and money before this could be confirmed. But the removal or moving of vacancies could explain the increase in sound acuity in stereo systems after cryogenic treatment.

We know for a fact that these effects are responsible for the formation of carbides in hardened steels. (See the work by Dr. David Collins.) Nobody that I know of has proven this in cast irons, but it is plausible that carbides are formed. There is also a theory that the atom to atom spacing in a crystal structure has an ideal distance where the bond energy is at a minimum. Reducing the temperature allow this spacing to become more even and closer to ideal, creating a better crystal structure. These are unproven theories, but the do give an explanation as to why pearlitic cast iron responds to cryogenic processing when there is little or no austenite to transform. It would also explain why cryogenic processing works on brass, aluminum, silver, titanium, etc.

Cryogenic processing consistently increases the life of brake rotors two to three times. There is no doubt to that. Why? Some day we will find out. Until then there is no reason not to use this amazing process to reduce costs and increase efficiency.

Stoptech/Powerslot does offer a Cryo option for slotted/drilled rotors.