eostly

Cryo treated rotors are a complete waste of time and money. Never mind that the actual physics and metalurgy of it is complete BS, cryo-treating rotors just doesn't make any difference. They claim better rotor life, significant improvement in braking performance, and longer pad life. None of this is true in any way shape or form.

To prove this theory, I had 2 rotors treated and put them on 1 side of my car, yes a side not an end. Using PFC 93 and Pagid Orange, I ran the car for a two years this way. The car is a 914-6 with 86 carrera fronts and 83 SC rear brakes. I live in Northern California and this was 2 seasons of Laguna Seca (very hard on brakes), Buttonwillow, Thunderhill, and Sears Point.

The results were just as I expected. First, the car didn't pull to either side under any rate of braking. No one who ever tried the car could tell which side had the treated rotors and which side had the un-treated rotors. This completely invalidates their statements that cryo-treated rotors offer better braking performance. Second, after 2 years of use, the rotors from both sides had no visible difference AND measured within a couple thousandths in thickness. So much for better rotor wear. Third, in that time I probably went through 10 sets or brake pads. The pads never varied in thickness between the different sides.

Save your money and spend it on other things. Cryo treating rotors is just another scam.

Erik Ostly
Los Gatos, CA
1970 914-6 Track Car
1972 911E
PCA/POC
PCA-GGR Instructor

Bill Gregory

Erik,

That's an interesting test you did. The conclusion I draw from it is that cryogenic rotors didn't make a difference on a (guess, around) 2000 lb car. My experience has been that they can make a difference on a 3000 lb car. In my case, 'better braking performance' means the rotors last longer, hence I replace them less often. Of course there are a number of variables, including quality of the original rotor, individual braking style, vehicle brake bias, brake modifications, etc. that can vary benefits from vehicle to vehicle. I don't know enough about the cryogenic freezing process itself to know if there is more than one way to do it, thus whether how it's frozen makes any difference.

ColorChange

I agree with Erik. I do not believe cryogenic rotors make any difference at all. I know of no crystalline or other structural change in the steel as a result of cryogenic treating. Heat annealing, yes, carbon impregnation, yes, cold forging, yes, but not cryogenic treatment.

I have never seen hard data analysis that supports cryo treating and never seen supporting technical theory. If someone could explain what is supposed to happen in metallurgical terms, I would be very interested. Just my opinion and observations.

Joe Weinstein

Cryo treatment flies in the face of metalurgical science. Failure in metals is well diagnosed,
and is due to stress propagation along crystal boundaries.The solution is to either discover a
way to generate a monocrystaline part, which calculations suggest would yield parts that exhibit
100 times the currently observed strengths of manufactured parts, or to create a totally non-
crystaline part, as in metalic glass. This has been acheived in very small ribbons whcih can
be extruded and cooled instantaneously by contact with chilled rollers, but is impossible with
anything big enough to have a temperature gradient within it. This has also been obtained with
multimetal alloys whose mix of different atom sizes and proportions were caclulated to make
a mixture without a convenient crystaline organization.
As to cryo, you must first understand what you're starting with. The metal for a rotor starts
as a red-hot block, too hot for any crystalization. As it cools to room temperature, it crosses
the threshold for crystalization (on the surface at first) so crystals begin to nucleate randomly
all over the surface, and grow outward until the bump into each other, and because they are
mutually randomly oriented and irregularly shaped, they do not move, and cannot merge, so
they compete for the as-yet-uncrystaline atoms between them until there are so few of these
that they occupy the thin irregular gaps between the ill-fitting adjacent crystals. It is the
propagation of cracks along these alleys between crystals that makes metal weak. So, now
we machine the block into a rotor. The surface may benefit from some strain hardening, which
is when metal is deformed at low temperature. This causes the easiest shifting due to the largest imperfections to occur, so any subsequent load will have to be higher to get more deformation,
but making the part more brittle (closer to failure in terms of how much more deformation it will
take). Note that it takes lots of energy to move metal atoms, either from heat, or mechanical.
Now cryo steps up. What does it do? Lowering the temperature *removes* energy. It supplies
*no* impetus for atoms to realign. The metal is *already* frozen at room temperature. Cryo 'treatment' is like having a stack of randomly-shaped pieces of solid ice in Antarctica ,
and claiming that lowering the temperature even more for a while will make the shape of
the pieces of ice change magically to fit better together.
But it's worse! Please note that rotors especially, are repeatedly returned to a hot enough
temperature under normal use for the metal to pass back through the boundary where iron
crystalizes to martensite and austenite, so it is back to square-one and whatever magic you
believe you got by cryo is totally gone by the end of your first warm-up lap.
Joe Weinstein

sleder

I am buying Joe's story and I 'm stcking to it. It's been a long time since metalurgy class or chemistry for that matter, but I do believe in what joe stated...Thank you!

ColorChange

Joe I'm with you except for 1 thing, aircraft turbines are grown monocrystals. You could do this for rotors and they would perform much better, but you don't want to think about the price. It's just better to replace them.

Joe Weinstein

thanks Tim, I will look up how they make monocrystaline turbine blades, but I can't imagine
that any practical development of monocrystals would not have become mainstream, at least
in the top-budget Formula-1 teams. Just imagine the performance gains if reciprocating masses
could be thinned/lightened by 50%... And as to brake rotors, I am guessing they still get too
hot to hold any monocrystaline form on the surface, and would therefore not be able to
retain any abrasion resistance.
As a last shot at Cryo silliness, I would suggest that anyone do a Google search on Cryonic
treatments. The purveyers are like Carnies. They'll freeze anything for you and claim it'll make
your tuba sound better, and improve your golf game

http://www.nitrofreeze.com/golf.html

gt37vgt

it seems that all the cryo treatment industry has paid the money to get the page ranking .. when ever you type cryo anything into google you just get cryo treaters no independent engineering papers .

I'm still not convinced either way although the erics story is the strongest so far ..
I kind of worry that people who cracked rotors then changed to cryo's made other changes at the same time differnt pads more duct's no hot parking and these changes have made the differnce .

bgiere

If you are running cross drilled rotors they will crack quickly regardless IMHO...the longest life I ever got from a pair were slotted ,non-drilled and cryoed fronts from Frozen Rotors...They lasted a whole season using PFC 01 pads. I found that the cross drilled factory rotors would crack quickly, frozen or not. Slotted and froen were the best combo for my use on the 964.

333pg333

What about REM treatment?

magnetic1

Im glad someone here is onto the snake oil.

You also cant simply look at scenarios where "o I had this before, and this after". There are WAY too many variables inbetween uses, temperatures, track conditions, etc etc.

Dont waste your money guys. Spend it on more entry fees

mrbill_fl

FWIW,
when I was racing, (ITA rx7's) I bought a few sets of the cryogenic rotors. I think they were slightly better than brand new.

but hands down, the best rotors I ever used came off wreck lot cars. old and rusty... I figured they went thru thousands of heat cycles. whatever it was, they would last 3-4 weekends, when new ones would crack in 2 or less.

Matt Romanowski

I didn't believe in cryo treating until we used it at a machine shop I ran. We had trouble with a certain part stress relieving (read bending) on it's own after we machined it. After cryogenic stress relieving, the parts didn't stress relieve at all. It was pretty amazing.

I think it doesn't make a difference on rotors unless the braking system is on the line to begin with. A 914 with Carerra front rotor and calipers isn't using the brakes too much. Put stock brakes back on it and see if they make a difference.

kurt M

You have to cryo before machining fo it to have any positive value. IIRC the rotor sellers cryo after. Why try and remove stress after the metal is cut? I found a a well done paper on the making of moulds for plastic parts that went deep into stress removal. Regardless of method use heat, cold, vibration, peening or whatever, the work is done before final machining. Removing casting stress does not make the metal harder or stronger it makes it less likely to warp or distort from its intended shape. I don't see how it would help with cracking.

Matt Romanowski

^^Don't know how it works, but we've had good luck with it on brake rotors where the system was marginal. If everything is working fine, I don't think it's going to do too much. Obviously with brakes, if you can get them more air, it cures almost every issue.