Even bigger brakes...

[DLC]

So last week my new brakes arrived, but I haven't had a chance to put them on yet. It's been over 100F here more often than not in the past week, and a west-facing garage doesn't help.

The stock brakes on the car were the standard LGT/RS 10.7" front with much larger 11.3" rears. I did the natural thing and went for a WRX upgrade a few months after purchase, and 11.4" was good enough.

The newest set are the stock 12.3" fronts from an 05 GT. I looked at the rotors last night and they're pretty much huge. They only have about 10k miles on them, so I'll probably use them and the stock pads for a while.

Install will probably happen sometime in August after I get back from a trip.

[Legacy777]

Cool!

[THAWA]

Those brakes are pretty much unfadable until you REALLY push it. Assuming you have half way decent pads. They're also heavy as all hell!

[DLC]

The shippind weight of the front brakes was 82lbs. Now I'm sure that the ones on there right now are reasonably heavy, but geez. I hope I'm not undersprung/dampened just for brakes!

[THAWA]

The calipers will be about the same weight, but the rotors are much heavier.

[DLC]

Maybe my next brake upgrade will be pads and lighter rotors then.

[THAWA]

Eh, If the weight concerns you, yo ushould just go with brembos, lighter calipers and two-piece rotors a plenty.

I'm not sure if anyone even makes two-piece LGT rotors.

[Legacy777]

Yeah....two-piece would be the way to go. I'm sure someone on the LGT forums would know whether there are two piece rotors out there.

[BAC5.2]

Racing Brake makes a 2-piece rotor. Some $560 a set too. Not a horrible price.

The Brembo's are nice. I'm looking to source a set. If only I can find a 16" wheel that will clear them. Hardy, any finds?

[Bane]

interesting thread... with the bigger turbo and intercooler, i really am starting to look for something bigger and better in terms of brakes...

if i go with Brembo's or something similar in stock size... i can get thicker rotors that will hold up to warping better, but the car won't stop any faster.

which means i can keep my current winters and the original turbo rims and tires for rallying or something similar.

has anyone found really good rotors stock size?

I know there was a post regarding the SR rotors... but i'm just checking my options at this point.

or at this point with the extra power, would you guys suggest a real upgrade for more stopping power?

[BAC5.2]

Well, I would hold that thought James.

The way the brembo caliper is designed, you can't really use a smaller rotor. The rotor is 32mm wide though, which is nice and thick (compared to the WRX's 26mm width).

Brake diameter has very little to do with stopping distances when compared with tires. Tires make the car stop. The benefit to big brakes is the ability to fight off fading from over-heating the brake pads.

To be perfectly honest, pads and OEM rotors are the only way to get good performance out of the stock brakes. Otherwise, upgrade to stock WRX brakes and that should be suitable for 97% of drivers out there. The WRX has some good hardwear under it.

I just want a 16" wheel that fits on an 04 STi.

[evolutionmovement]

The best resistance to warping comes from cryo-treating. I can't say enough about it.

[Legacy777]

The best resistance to warping comes from cryo-treating. I can't say enough about it.

DITTO....I will never run another rotor that is not cryo-treated.

[BAC5.2]

**** PROPERLY CRYOTREATED ****

While no rotors I know of are manufactured using a cryo process, many aftermarket cryo treaters are pretty good.

I did some research and onecryo.com seems to be one of the best aftermarket cryotreaters.

[jake15]

I did some research and onecryo.com seems to be one of the best aftermarket cryotreaters.

i just used them to cryo treat some stock pistons to see how much stronger it makes them seeing as i cant affored forged pistons at the moment.... it's nice that they're local to me too.

[Bane]

To clarify a couple of things (just to make sure we're all on the same page)... i didn't mean diameter of the rotors... i mean the thickness.

ie... are some afttermarket rotors thicker then stock? wouldn't that resist warping more? more material means stronger?

by Brembo's i didn't mean STI brakes... but rather, Subaru Legacy Turbo rotors made by Brembo... different materials, better quality then OEM etc, etc...

There had been a post here about SR crossdrilled rotors, visited the site and found they are A. Local and B. Cheaper then NAPA... but they also sold Brembo cross drilled rotors which were marginally more expensive then NAPA.

SR - $90 tax in for the pair
NAPA - $120 +tax for the pair
Brembo's - $160 tax in for the pair

Had a few emails with the company, who indicated that the SR's were better then OEM and that the Brembo's were better then the SR's (referring to anti-warping) especially if you were tracking the car. They indicated they were a better made rotor with different materials.

then i found this website:

http://performance.thepartsbin.com/bran ... &partid=78

I was looking at the PowerSlot Cryo rotors...

guys in the toronto club have done group buys on this stuff in the past. Seemed to give good reviews.

at $125 each, they surely are more expensive, but if as you all say, that cryo treating is the way to go... i have no issues with the expense.

What kinds of pads are you guys running with your cyro treated rotors? standard, ceramix, racing pads... what gives the best bite?

these would let me keep running the stock rims and winters i already own...



then again, there is a person selling the Group N 4 pots/2 pots calipers, rotors and pads for $1100 in the for sale forum.

[ej22t]

Hi James, nice to see you here, I also a TSC member.
I has to do my brake upgrade on my Legacy turbo, I suggest you to get a set of SS line first then get a set of Bermbo front and Eurorotor to the rear(bermbo don't make rear rotor for our car!!) I cyro all 4 rotors and now my car is sitting in front of my driveway but I could see those vent slot still frash and rust just build up and shows on the outter surface.
I use PBR pads and it do gives good performance, I use them to RallyX, winter rallying and some track use.
The last thing you better do is swap a single stage brake booster and it will give you a good feeling on the paddle since our turbo peddle always feel soft.
I would like to upgrade to 4pot front caliper, but the problem is I have 3 sets of stock 15" for my summer, winter and rally tires, so I don't have too much choice!

Now my car is wait to put a EJ20H engine since I blown my engine in the track day. I would like to ask you about the turbo that you using and hope to get back to the road soon and lets have a meet before snow fall.

Good luck!

Ben

[Bane]

Ben i was thinking about the ss lines... where did you get yours from... or are they just taken from a WRX?

i remember you saying something about the upgraded brake booster... as it stands now... mine isn't spongy grabs great... but if it's something straight forward enough, i'm up for it.

now where did you have your rotors treated?

how much did you spend on the rotors and then on the treatment?

if i can get cyro fronts and rears from the manufacturer i'd be interested in comparing price.



sorry to hear about your engine... what turbo were you running? you have a v2 angled intercooler right?

I would DEFINITELY be up for a meet when your up and running again!

[Legacy777]

**** PROPERLY CRYOTREATED ****

While no rotors I know of are manufactured using a cryo process, many aftermarket cryo treaters are pretty good.

I did some research and onecryo.com seems to be one of the best aftermarket cryotreaters.

Thanks for the clarification Phil.

Yeah, cryo-treatment is done after manufacturing, and I've had all my rotors done by onecryo.com. I've been really happy with them.

[ej22t]

Hay James, Just reailize that we did meet before at the RallyX or Subaru meeting, since I remember your Scooped BD wagon.
I could get a touch on the shop who selling me the treaded rotors from front and rear.
They also has the SS brake line for sell too.
Let me give them a call on monday and see how much will this combo cost and if possiable, I could try to ask them to give you a better deal

Yep I have a V2. intercooler in my car, and I am running the Stock JDM First Gen Legacy EJ20G turbo it should be a VF 10 or VF12(sorry I don't remember)
I would like to know hows the feeling in your car with the VF34... I may as a ride when we meet.

Remine me or PM me next week so that I could ask the price for you!

Ben

[BAC5.2]

Another thing to note about Cryotreating, is that you really shouldn't get your hopes up.

When a piece of metal is heat treated, it hardens while it cools (if you have a stud stuck in a turbo you can cut it and drill it out. But if you heat it cherry red first, and let it cool down, it's almost impossible to drill out. Really basic, but you get the idea). The long and short of it is this. You machine the metal to form a product. You take this product and heat it (for steels, expect just below 2000 degrees), then you quickly (as quickly as possible) quench the metal. Oil is most often used, but what you use depends on the steel. Air can be used for low carbon steels. The oil used is very thin with a very high flash-point. You quench the product down to a certian temperature (ambient is OK). Once cooled, you have an extremely hard piece of steel, but it is extremely brittle. So you reheat the product (to a lower temp, usually 400 degrees or so, sometimes more or less. Some metals (high carbon steel) can be reheated to 1400 degrees for tempering). You let it sit at this temperature for a few hours to ensure that the whole material is the same temperature. Then you VERY slowly cool the product back down. 20 degrees per hour cooling rate is normal, but some metals require slower or faster cooling. This is called tempering. It reduces hardness a bit, but it also reduces brittleness of the material significantly.

This is where cryo-treating comes into play.

One way is taking un-treated steel, and exposing it to liquid nitrogen cold temperatures (cooling at ~4.5degrees per minute) until the steel reaches minus 320 degrees or so. It stays here for 24 hours or so. Then the steel is warmed up to room temperature, and then is tempered as normal. This cryo-treatment process takes the place of the standard heat treating process.

Some of the research has shown that you can do what I said above, or you can heat and then quench and then continue to cool to sub-zero temperatures and bring back up to ambient for tempering. I want to do more research and find out which way is the correct way.

The basis is simple. When things get cold, they contract. Particles move more slowly and objects become more dense. The theory is that when this happens with steel and super-cold temperatures, it "squeezes" the carbon more towards the surface. This increases the dimensional stability of the steel, by creating a more uniform microstructure. By doing so, internal stresses are relieved.

I believe the benefits most experience from cryotreating brake rotors, is a decrease in wear from the pads. Not necessarily an increase in strength. Cryotreating can increase harness, but not necessarily strength. That's the rub on cryo-treating. Many people think that something cryo-treated WILL be stronger, and that simply isn't true. The metal may show an increase in it's Rockwell Hardness, but it may or may not actually show a significant (or proportionate) increase in it's lewis form score (the formula for determining bending strength of a metal is called the lewis formula). Hardness and resistance to wear don't equal strength. If cryo-treated DURING production, I can see significant benefits, but none of the research I did has told me conclusively that a metal can be cryo treated to the same level after it's been heat treated and tempered as to when it is cryo-treated during production. I did read in an ASM article, which basically said that if a part is heat-treated for high hardness, cryo-treating may have little to no effect. It may prolong the life, but it won't change the properties gained from the heat treatment. I assume this was geared towards cryo-treatment after a full heat-treatment/tempering process was completed.

I did read a report of cryo treatment during production increasing tool hardness between 200 and 600% (variations based on material).

Take this information for what it is worth. Expect a return on your investment for cryo treating, but don't expect a significant strength increase, as you may or may not get it.

[evolutionmovement]

The observed benefits of the cryo process that I've seen are extremely higher resistance to warping and slight increase in resistance to rust. The last set of rotors I had were worn nearly through to the vents and still worked. They pulsed a little, but about as much as you get from a set of regular rotors with minor warping. So, it would appear the benefit is in an increase in dimensional stability and, perhaps metal uniformity. From what I read there are several types of cryo processes and the type employed by any one firm is considered proprietary information. As a note, I also have heard that this process can work on ceramics and some plastics (!) to good effect, but have not tried it.

I'll alos vouche for onecryo.com

[BAC5.2]

I know that you can cryo-treat Nylon, and get extreme benefits from doing that.

I want to know more about what onecryo does. Do they just super cool and then slowly reheat the product, or do they re-temper, or do they anneal then super cool, then re-temper? There are a lot of ways you COULD do it, I would think.

[Legacy777]

Phil,

To add on or comment to your above post. The stuff you posted is exactly why cryo-treating everything really may not be cost effective or produce any gains. You need to look at the material in question, and make a judgement from there.

One cryo uses a deep cryo-treating process where they slowly bring the temp down and hold it for 24hrs, then slowly bring the temp back up, and do an annealing process on the material at the end to put some toughness back in it.

There's two main things that occur at least in cast iron rotors that improve their durability & wear resistance. The alteration of the crystaline struction to a smaller/denser structure, and the phase shift from retained austinitic iron to matinsitic iron.

Martinsite is a stronger crystaline structure, but is a little more brittle, which is why the tempering process must be done. When the tempering process is done, the grain structure should look similar to before tempering, except that the area between grain boundaries will be a little larger.

[Legacy777]

BTW, www.onecryo.com has some pretty good links on their site for info about cryo treating.