legacycentral bbs

My brake pedal is annoyingly mushy right now. I've bled the system several times but it kind of hit a plateau after five or six rounds of bleeding.

I'm going to be doing a huge brake job soon (putting in 11.4" front rotors with Axxis Ultimate pads, new OEM vented rear rotors with Metal Masters, stainless steel lines, and single stage booster), as soon as I find a reasonable place to have the rotors cryo-treated.

I would expect that these upgrades alone will firm the pedal up quite a bit, but I also kind of suspect my master cylinder. When I got the car the brake fluid was really really yucky so I have no idea what kind of crap has gone through the system. A worn master cylinder could have excessive clearance between the piston(s) and the housing, right?

Does anyone have experience with rebuilding a master cylinder? I looked around and it seems like I could get a master cylinder kit for around $60. The weird thing is, though, a rebuilt master cylinder can be as cheap as $35 from autopartsgiant.com. I'm a bit confused about that, and unsure about rebuilding... Any advice?

Oh, also, the same web site seems to differentiate between 4EAT and 5MT master cylinders. I thought the only difference was between ABS and non-ABS cars. Does anyone know what difference the type of transmission makes?

A worn MC will cause the pedal to slowly go down to the floor if you hold your foot on the pedal. It's possible there might be some small grooving in a certain area which may not cause the pedal to go all the way to the floor, but it's probably not as likely.

The normal test for the MC is to apply pressure to the pedal, if you hold your foot there and the pedal slowly goes to the floor, MC is bad.

If your brakes a just mushy, it's possibly your lines are worn. I'd see how upgrading to stainless steel lines helps things.

Check out www.onecryo.com Was $25 per rotor.

Honestly, I'd probably just buy a rebuilt one. the one I'm putting in mine is a rebuilt unit.

There's no difference between the 4EAT & 5MT trans, only ABS & non-ABS.

Legacy777 wrote:The normal test for the MC is to apply pressure to the pedal, if you hold your foot there and the pedal slowly goes to the floor, MC is bad.

Huh. I'll try that out. Thanks.

If your brakes a just mushy, it's possibly your lines are worn. I'd see how upgrading to stainless steel lines helps things.

Yeah, I do expect the stainless lines to help quite a bit.

Check out www.onecryo.com Was $25 per rotor.

Yeah, that price sounds good, except I'd have to ship the rotors across the country... I was hoping to find a place here in upstate New York, or maybe somewhere in Eastern PA or in the DC/MD/VA area to do it. That way I could just drop them off and then pick them up.

I contacted a few places that specialize in heat treating in the area (the ones with web sites and email addresses) but they either never emailed me back, wanted a huge amount of money, or said, "Yeah, we do have the facilities to do cryo, but we usually don't use them."

Honestly, I'd probably just buy a rebuilt one. the one I'm putting in mine is a rebuilt unit.

Heck yeah, if a rebuilt one is half as much as a rebuild kit! I'm just puzzled by it.

Do rebuilt units come with reservoirs, or would I have to transfer my reservoir over?

There's no difference between the 4EAT & 5MT trans, only ABS & non-ABS.

Okay, cool, that's what I thought. ABS ones have one line per circuit and a 1 1/16" bore, and non-ABS ones have two lines per circuit and a 1" bore. I wonder why autopartsgiant.com lists AT and MT ones separately.

Yeah, that price sounds good, except I'd have to ship the rotors across the country... I was hoping to find a place here in upstate New York, or maybe somewhere in Eastern PA or in the DC/MD/VA area to do it. That way I could just drop them off and then pick them up.

I contacted a few places that specialize in heat treating in the area (the ones with web sites and email addresses) but they either never emailed me back, wanted a huge amount of money, or said, "Yeah, we do have the facilities to do cryo, but we usually don't use them."

You're finding out what I basically went through......there is very few places that do cryo-treating for under $50-$60 a rotor, and the places that do automotive stuff is a lot less.....I looked locally, and there wasn't any. You should have better luck in your neck of the woods, but don't expect them to be plentiful.

Do you already have the rotors?

Do rebuilt units come with reservoirs, or would I have to transfer my reservoir over?

My rebuilt one came with a resevoir.

I wonder why autopartsgiant.com lists AT and MT ones separately.

Probably just stupid.....hehehe

Legacy777 wrote:You're finding out what I basically went through......there is very few places that do cryo-treating for under $50-$60 a rotor, and the places that do automotive stuff is a lot less.....I looked locally, and there wasn't any. You should have better luck in your neck of the woods, but don't expect them to be plentiful.

Yeah, I'll have to see... Shipping all four rotors together two ways would probably add up to more than the difference in cost.

I've only tried contacting the ones with email addresses. I should call all of them up on the phone.

Do you already have the rotors?

Yes, I do. I bought them at random times, not all together. I guess if I had planned this all out I could have done better by having the rotors delivered directly to a cryo treatment place. But at the time (a year ago) I wasn't sure whether or not cryo treatment was snake oil. I'm still not certain of the supposed "scientific explanations" which don't at all jibe with any of my understanding of metallurgy, but you and other people have had good experiences with cryo-treated rotors. And since I'm using ceramic and metal brake pads I ought to take as many precautions as I can with my rotors.

Hey you're doing just about all the things I'm doing right now. I got some WRX calipers, brackets, lines, & pads off e-bay for $40 . Oh, and they only have 4000 miles on them. I have ATE Super Blue fluid & SS brake lines sitting in my room. Just need to buy new rear vented rotors/pads and front 11.4 rotors.

On the rotor work, you need to consider how hard you are on them. And how much longer you think they will last with cryo-treating. If you are really hard on them... then you are going to shorten the life significatnly anyways and might be better off getting $40-60 OEM ones. Otherwise, if you're not really a heavy-braking kind of guy, stockers would hold up fine for a long time. I personally don't see spending the huge chunk of change and time to ship/treat rotors for . If it was cheap/close, go for it, otherwise....

Brat4by4 wrote:Hey you're doing just about all the things I'm doing right now. I got some WRX calipers, brackets, lines, & pads off e-bay for $40 :D :D . Oh, and they only have 4000 miles on them.

Yeah, it just seems like a logical cost-effective upgrade.

Nice deal on the eBay auction. How much did shipping cost you? =)

I have ATE Super Blue fluid & SS brake lines sitting in my room.

Cool... is the main advantage of ATE Super Blue a higher boiling point? Is that really a concern? Like, could my current brake fluid be boiling? I thought that if your brake fluid boils you're screwed anyway, so I would think I would know if my fluid didn't have a high enough boiling point... am I mistaken?

I guess one other very cool advantage of a different colored fluid is that you definitely know when you've thoroughly bled the system and replaced all old fluid.

Just need to buy new rear vented rotors/pads and front 11.4 rotors.

Exeter Subaru (subaruwrxparts.com) has got good prices on OEM rotors. I was emailing back and forth with Mike Shields at SPD Tuning when figuring out my rotors, though, and he matched their price for me... I don't know if he usually does that or not.

On the rotor work, you need to consider how hard you are on them. And how much longer you think they will last with cryo-treating. If you are really hard on them... then you are going to shorten the life significatnly anyways and might be better off getting $40-60 OEM ones. Otherwise, if you're not really a heavy-braking kind of guy, stockers would hold up fine for a long time. I personally don't see spending the huge chunk of change and time to ship/treat rotors for :?: . If it was cheap/close, go for it, otherwise....

Well, my rear pads will be organic, so they should be pretty easy on the rotors, but my front pads will be ceramic, so they will be pretty hard on them. A kid I know with a WRX got the same pads on his front brakes and really grooved up his rotors. He's probably braking pretty hard, but I expect that I will too. I'm doing engine mods and with higher speeds and acceleration comes harder braking.

I guess the question is whether the cryo treatment will pay for itself. If it costs (for example) as much to treat as the rotor cost, then it would be worth it if it doubled the rotor's life (and there are many claims that the treatment more than doubles the life span). But that's not factoring in performance... if the brakes work better, then they could be worth it regardless. Especially considering they could save a life. But it's very unclear whether or not cryo-treated rotors work better.

I figure I'm being thorough with the rest of the job, so I may as well try the treatment. At the end, the worst case would be that I lost some money and learned a lesson.

By the way, if anyone knows anything about the science behind the cryogenic treatment and wants to explain it to me or debate it with me, please do...

Good point, safety is always worth it. If indeed cryotreating actually helps you stop better. But I guess you'll find that out soon enough.

Shipping was not bad for the rotors and it was all the way from the West Coast. Just took a while to get here.

And the Super Blue... what can I say? I'll have blue brake fluid . It has a boiling point and statistics on par with Dot 5 but is for Dot 3/4 systems. It is also less hygroscopic, absorbing less moisture over the long run than typical Dot 3 fluid.

Huh, cool... Is the fluid expensive? Where do you buy it?

$10-14 a liter.

http://search.shopping.yahoo.com/search ... +blue&did=

This is how I got mine, just order from whoever is cheapest with shipping and everything. I think I paid under $30 for 2 liters when all was said and done. I have no idea whether this is expensive or not, but it didn't seem bad to me.

I don't have time to type out the science behind cryo-treatment, but I can. Believe me, it's 100% valid. Have you tried searching for articles on google yet about the science behind it?

If you don't find anything or anything to your satisfaction I can try and do a write-up.

Fluid, for daily use, you won't boil a good DOT 4 brake fluid. I'd recommend Valvoline synthetic. It's boiling points are very similar to ATE & motul. The cost is less, and availability is more easily attainable.

The issue with the blue stuff is as follows. Brake fluid is normally a light amber color when new. When it get's old and absorbs moisture/dirt, it turns darker in color to help let you know it's time to replace the fluid. With dark blue fluid, you can't tell by a visual inspection that the fluid should be replaced.

ATE has stopped making the blue fluid. They have a comparable fluid called ATE super gold, which is the same thing as the blue fluid, except a normal amber color.

Personally I have had better results with OEM rotors. What are you current rotors, are they slotted/drilled or anything?

If you want cryo-treatment, just sell the rotors you got, buy a set of OEM, have them cryo-treated, and move on.

With a harder pad, the cryo-treatment will definitely improve rotor life.

Like I said I'll try to write up something when I have time if you don't find anything else online.

The cryo-treatment definitely works. Not sure about better braking, but I've had my rotors now for ~70K mi. and three years and the're still excellent. They don't even seem to corrode as bad. Previous rotors lasted ~6 mo. before they would start pulsing like mad. Also, my brother-in-law swears by cryo-frozen knives for cooking as they take much longer to dull.

Steve

Legacy777 wrote:I don't have time to type out the science behind cryo-treatment, but I can. Believe me, it's 100% valid. Have you tried searching for articles on google yet about the science behind it?

Most of what I found was pseudo-scientific literature from companies that sell the service.

What bugged me was that half of them seemed to call the process cryogenic annealing and the other half called it cryogenic hardening. Annealing and hardening are almost opposites, aren't they?

Or is this really in fact neither, and both terms are dumbed-down explanations of what's going on?

If you don't find anything or anything to your satisfaction I can try and do a write-up.

Fluid, for daily use, you won't boil a good DOT 4 brake fluid. I'd recommend Valvoline synthetic. It's boiling points are very similar to ATE & motul. The cost is less, and availability is more easily attainable.

Cool, that's the stuff I've always used.

The issue with the blue stuff is as follows. Brake fluid is normally a light amber color when new. When it get's old and absorbs moisture/dirt, it turns darker in color to help let you know it's time to replace the fluid. With dark blue fluid, you can't tell by a visual inspection that the fluid should be replaced.

Oh... but, if you regularly change your fluid anyway, a different-color fluid could be helpful as it can tell you when you've gotten all the old fluid out. Too bad they don't make the blue stuff anymore... if they did you could alternate between gold and blue each time so you'd always know when you had gotten the old fluid all out.

Personally I have had better results with OEM rotors. What are you current rotors, are they slotted/drilled or anything?

Me? I've got OEM-replacement Brembo rotors on the front and God-knows-what on the rear (if the fronts that the previous owner left on where any indication, my rear rotors are probably as thin as they can legally be).

If you want cryo-treatment, just sell the rotors you got, buy a set of OEM, have them cryo-treated, and move on.

Well, the rotors I have right now are all OEM. But it could end up costing me less with regard to shipping, though, since the buyer would pick up shipping on the rotors I have. That's an interesting idea...

With a harder pad, the cryo-treatment will definitely improve rotor life.

Like I said I'll try to write up something when I have time if you don't find anything else online.

When you have time I think I would appreciate that. Or maybe you could just respond to individual questions. I guess I just don't really understand it...

They say that basically you're converting austenite into martensite. But I thought austenite only existed above the transition temperature of the steel in question (thousands of degrees).

I understand martensite is the hardened form of steel. But I thought the way to get a piece of steel to be primarily martensite is to heat it well above the transition temperature (so it turns into austenite) and then quench it. The resulting mishmash of carbon and iron is known as martensite. I thought it got its hardness from being all disordered.

So... was I given the little-kids' explanation of metallurgy? Is austenite really retained in steel when it's below the transition temperature? How can austenite be slowly turned into martensite without becoming pearlite?

Don't worry about responding to this right away or anything, Josh... I just wanted to get some of my questions up on the board so anyone can comment and so I don't forget.

I do believe that the treatment will improve longevity, since many people (like you guys) have told me about their successes with it. Even taking into account the potential "I paid $50 for it so it must be good" syndrome, it's too much to ignore. Steve, I've also heard that the treatment improves knives (both for the kitchen and otherwise) and tools in general. So I will try to find a place to do the treatment for me.

Legacy777 wrote:ATE has stopped making the blue fluid. They have a comparable fluid called ATE super gold, which is the same thing as the blue fluid, except a normal amber color.

REALLY? Damnit! whenever I do my fluid changes, I go back and forth between the two. Gold one change to blue the next, back to gold for the next one.. The swapping colors letcha know when your fluid is completly changed over.

that's what I've been told about the ate super blue from a distributor. You'll probably still be able to get a hold of it for a little while, but if he was right, supplies will probably diminish.

And yeah, alot of people do what you guys said, and switch back and forth between the blue and gold to know they have all the fluid out.

I usually just suck out what's in the MC, pour new fluid in, and then bleed everything.

What bugged me was that half of them seemed to call the process cryogenic annealing and the other half called it cryogenic hardening. Annealing and hardening are almost opposites, aren't they?

Actually the process consists of both, they will slowly bring the temp down to a certain point....don't remember exact temp. I believe there is also hold temps in between, they will hold temp at a certain point for x minutes/hours. Once they reach final temp, they will hold for x hours, then slowly raise temp back up. At this point the metal is going to be much more brittle. A final annealing process is done to put toughness & durability back in the metal.

You will probably get some phase changes in the metal, as for how much, and where you end up, I'm not really sure. I would need to look back at my mat. science text. You also need to remember that not only would the type of metal change slightly, but also the individual grain structure/size, as well as voids or porosity in the casting will be affected.

I think if I write something up, I'm going to do a good one....thorough. Time is unfortunately not on my good side. I'll let ya know when I got something written up. But I'll try and do my best to answer any specific questions.

Thanks for sharing the knowledge... Yeah, I thought it was something more complicated than the explanations I've found. Good point about changing grain size and stuff.

So basically it's a more careful and refined version of the standard heat treatment process, and it goes to further extremes to ensure that transformations happen completely?

In any case, I'm going to have the treatment done anyway, and learn why later. :)

hehe.....cool. You won't be dissapointed.

It may take a little bit for you actually to notice a difference in how the rotor surface wears.......but the treatment really isn't something you can see.

The only downside I've heard is it makes the rotors slightly more "slippery" basically a finer grain structure lowers the coefficient of friction of the metal. Or at least that is how I would explain it.

Huh, really? It would decrease the coefficient of friction?

That would hurt braking performance, wouldn't it?

Wait, let me think this through. Lower mu means higher N for the same F. So you'd need to press the brake pedal harder for the same deceleration. But the amount of work done by friction would be the same so you'd get similar amounts of heat generated.

So I guess it wouldn't hurt braking performance but it could affect pedal feel. It's not clear to me whether it would be a better or worse feel. Then again, it might not even be perceptible.

it's so minute it's not worth worrying about.

Just thought I'd bring it up though

You know what I found out......there is a difference between "some" MT & AT master cylinders.

The MT equipped vehicles that had the hill holder have a different MC.

I am pretty sure that the turbo models did not have the hill holder though. So for your application....shouldn't matter.

Yeah, there are little lines that run from the front bottom of the MC, I believe, to the hill-holder. I'd think you could just plug 'em up somehow though.

But yeah, the new Forester XT is the first turbo Subie ever to get the hill-holder...

P.S. My XT has a hill-holder, when I didn't think it did

Oh yeah... I forgot about the hill holder. It vanished when the hydraulic clutch appeared, and the hydraulic clutch first appeared on the BC turbo.

The Forester XT has a hill holder?! That's awesome!

All new MT Foresters do. Subaru is re-introducing it starting with the Forester...