'02 WRX Cobb stage 2 w/ Helix DNA coilovers and Advan A048's on track. Brakes consist of DBA slotted rotors, goodridge lines, Motul fluid, 3" cooling ducts from fog openings to center vented portion of front rotors, and Carbotech XP12 pads on track.

Cracked both front rotors last season @ Road America, but mainly due just to age. Bigger problem is melting front wheel studs and lugs from the heat and having to break them off.

I am considering going to DBA 5000 2pc. rotors that should help w/ heat a little and upgrading lugs and maybe front studs. Would Rays or Work alum. lugs on stock studs be enough or maybe ES lugs from rallispec? Are ARP studs longer or just more durable?

Anyone know if this will be enough or is a true BBK in my future? Also considering Stoptech 332x32's, but not too excited about having to sell two sets of rims due to fitment.

Thanks,
Pete

Do you have a pic of your brake duct outlets? 2-piece rotors will definitely help save your studs/wheel bearings, but properly designed brake ducts are key. A Stoptech BBK or even STi Brembos will be able to handle heat more effectively, but proper cooling is incredibly important.

I had pics, but no more. The ducts slam air into the central vents of the rotor right between where the caliper bolts up . When we tested them out in the shop with an air hose they forced a lot of cold air through the rotors. Maybe too much ice cold air when I was at Road America in Oct contributing to my cracked rotors?

Unfortunately, the track I go to most frequently is a go-kart track (basically like an autocross) that I am probably hitting half the top speed of the bigger tracks and thus not drawing in nearly as much cold air with the ducting. That track is where I usually have wheel stud/lug melting problems.

I had pics, but no more. The ducts slam air into the central vents of the rotor right between where the caliper bolts up . When we tested them out in the shop with an air hose they forced a lot of cold air through the rotors. Maybe too much ice cold air when I was at Road America in Oct contributing to my cracked rotors?

I would put my money on that. With low ambient temperatures, the thermal shock of heavy braking and then stuffing the rotors full of cold air could definitely cause some cracking. I would get an idea of what sort of rotor temps you are seeing before you start looking for more cooling. IIRC the DBA's have temperature sensitive paint on them... did you check that out?

Unfortunately, the track I go to most frequently is a go-kart track (basically like an autocross) that I am probably hitting half the top speed of the bigger tracks and thus not drawing in nearly as much cold air with the ducting. That track is where I usually have wheel stud/lug melting problems.

I'm not sure how you could be "melting" studs or lug nuts... what sort of problems are you actually having? breaking off studs when you go to remove the lugs?

Aluminum lug nuts are definitely not going to help you there...

You may want to invest in some heat sensitive paint to get an idea of just how hot the rotors are getting. Additionally, if you don't thin you're getting enough forced air from the go-kart length straights, maybe a couple of 3" muffin fans should be installed?

Fitz

Wow. I've never heard of melting studs/lugs. If things are getting that hot, you're wheel bearings should be toast. What lugs are you using? What are they torqued to? When are you trying to get them off, while things are still hot, or later when things are all cooled down?

Question: Why slotted and not just huge chunks of blank rotor/metal? Are they cracking along the slots?

--kC

I had run the 4pots with the oem size rotors for a few years on the wrx and using xp12s (on tracks not autox). Im not at all surprised at your symptoms, even with good cooling. A lot of good stuff has already been said. the only way you can get better cooling (cold days notwithstanding) is to build a clam shell duct around the rotor to force the air thru the rotor instead of just blowing it at the rotor.

As for the cracking rotors.. thats just gonna happen especially with huge thermal shocks. Hard to say from here the magnitude of it, but the root of the matter is that the OEM size rotor just doesnt have the thermal mass to handle the kind of energy being dissipated at the rate its dissipated.

If you are limited to this setup, rotors will be consumable items just like brake pads, probably at the same rate of usage. I had gotten to a point where i was going thru rotors as fast a pads, so i kept buying dirt cheap ones. If your melting wheel studs, then id say you've probably got bigger issues. im surprised your hub didnt just totally fall apart! those wheel bearing are also not designed to take this kind of heat load, those are probably junk by now. I think ARP studs would be your only bet, they are of a stronger steel alloy with a higher tensile yield, but at some point (temp) all steels structurally change to a weaker composition. If you can find out what alloy this is you can look it up.

Other option, is to go to a less aggressive pad which in turn generates less heat. At least you'll be able to finish a (race?) weekend.

Im surprised you didnt boil your fluid, but yet 'melted' wheel studs. fluid boils something like <600* while phase change in the crappiest steel happens at 1200+ (this includes your rotors btw.. which also contributes to a rotor's demise)

I am surprised your wheel bearings are still there - esp if your wheel studs suffered. I would be curious to know just how old these rotors were... (IMHO) As an FYI there are a lot of rotors that are not well suited for the stresses of racing, but as JoBoo pointed out - if you treat them as consumables than you will minimize your problems...

Properly cooling these are a PITA...

Ray
Ray

Good questions. I believe the rotors cracked more from age than heat issues. I used them for more than one season of track days. The wheel bearings are still good as far as I can tell which surprises me too.

I cannot exactly be sure if the stock wheel studs were failing or if it were the stock lugs as they would bind together and the only way to get them off would be to break them off. I tried taking them off after they cooled, when they were hot, on the ground, in the air, etc, but nothing seemed to work. I tried torquing them to the rec. 70-72, 85, 100 and still had issues. It was my understanding that the best thing to do for track days would be to overtorque a bit to 100 so I would not have to retorque between sessions when they were warm and take them off cool with very little weight on wheels. Is that correct?

I have heard people have success with Ray's alum lugs, but I thought that might actually cause more problems since the wheel studs are steel. Are the ARP studs longer or just stronger? Would the heavy duty steel ES lugs from Rallispec be a better option? Am I ultimately screwed even with better lugs and studs as well as stock sized 2pc. DBA's and should just consider the Stoptech 332x32 BBK?

Do NOT over torque the Subaru lugs - they WILL snap. Keep them at the ~75 ft-lbs they are rated for and DO NOT torque them once they are hot.

My guess is that the rotors were just worn out, view them like brake pads and fluids as consumable and you should be all set. I would also suggest you view the wheel bearings the same way...

The ARP studs are both longer and stronger...

HTH

Ray

...should just consider the Stoptech 332x32 BBK?

If you can swing it, go for it. I had the Stoptech kit on my WRX and after 30+ track days, I never had problems with the studs and/or lugs. The wheel bearing didn't do so well, but I think that was a combination of abuse and heat, and pretty typical for a regularly tracked WRX.

Do NOT over torque the Subaru lugs - they WILL snap. Keep them at the ~75 ft-lbs they are rated for and DO NOT torque them once they are hot.

My guess is that the rotors were just worn out, view them like brake pads and fluids as consumable and you should be all set. I would also suggest you view the wheel bearings the same way...

The ARP studs are both longer and stronger...

HTH

Ray

Speaking of overtorquing, the ratings according to the service manual for a WRX is 65.7 ft-lbs. ;)

Does anyone think the 2pc. DBA rotors with different wheel studs and lugs will work or am I just putting a band-aid on a bullet wound and need to move up to a true BBK?

my understanding that the best thing to do for track days would be to overtorque a bit to 100 so




Holy carp! 75-80 max and don't touch them until they've cooled.

I've stress cracked OEM and Brembo blank rotors after two days on the track with 255 Azenis and 225 RA-1's with Blues and Xp8's with ducts.

Just the nature of the beast.

My advice, instead of buying expensive rotors to crack, I've had good luck with Autozone rotors. Duralast 34203. $31 each. :eek:

They haven't shown any stress cracks yet after 4 days and seem to still be large hunks of iron. At $31 a piece, I keep a couple sets with me just in case.

Just start using cheap blanks... I can't tell the different in wear/etc. over rotors costing 5X the price, and on the track, you're just killing them anyway. NO SLOTS!

Keep them at the ~75 ft-lbs they are rated for and DO NOT torque them once they are hot.



Actually OEM spec is more like 65 or so.

Edit. someone beat me to it!

Are your wheels hubcentric? Are you using wheel spacers?

Not using wheel spacers. Track wheels are Kosei K1 TS. I had the exact same wheel stud problem @ 65-72ft/lbs, but at that rating they were coming loose by the end of sessions. Not very confidence inspiring when your lugs are finger tight at the end. Tried to re-torque them between sessions, but ended up with the same problem.

I have cheap blanks on the car right now. I am more concerned about the heat that is causing the studs and lugs to go bad and will probably ultimately fry the wheel bearings. Does anyone think the 2pc. DBA's would dissapate enough heat or will I ultimately need to go up to a true BBK with the much improved heat sink in the larger rotors?

Are your wheels hubcentric? Are you using wheel spacers?

Definitely a good place to look... where are the studs breaking? At the face of the lug nut, or closer to the hub? If the wheel is not hubcentric and the lugs are bearing the load of the wheel, that can fatigue them and also lead to problems with them loosening.

torque to 65ft-lb WET! lube with anti-seize that will definitely help your problem. Do not over torque, or undo them while hot, you will snap the wheel studs..

Definitely a good place to look... where are the studs breaking? At the face of the lug nut, or closer to the hub? If the wheel is not hubcentric and the lugs are bearing the load of the wheel, that can fatigue them and also lead to problems with them loosening.

The studs are NOT breaking by themselves. They are melting or binding with the nuts due to the heat. I have to break them off because they melt together with the heat.

The studs are NOT breaking by themselves. They are melting or binding with the nuts due to the heat. I have to break them off because they melt together with the heat.

You need to broaden your search for causes of your problems here. Lug nuts or studs melting is just not something that happens. Frankly, I've never heard of that happening- and if your studs were getting hot enough where they were starting to fuse with the nuts, the integrity of the stud would be so compromised that it would probably break on its own while you were driving the car.

If you aren't using hubcentric wheels, it's also possible that your studs are getting bent due to the loads you are imposing on them, causing the lug nuts to bind on them when you try to remove them. That's much more likely than your theory about lug nuts melting.

I just think you need to be cautious about being 100% sure of what the cause of the issue is, as it can lead you down the wrong path for quite a long time. I know I've done that more than once. :)

Double post

The studs are NOT breaking by themselves. They are melting or binding with the nuts due to the heat. I have to break them off because they melt together with the heat.


I'm with everyone. If you were "melting" studs, you'd see other signs, and have to be at 1500-2500 F depending. Really sounds load related and then deformation.

What size A048's on what wheels/offset.

Sorry about the wrong torque value - should have checked first. I use 72 for the STi...

Read the manual - sometimes they call for dry sometimes they call for a light oil...

Ray

The manufacturers will never write in their manuals to lube the studs with anti-seize because they are afraid of the liability when morons use motor oil instead of anti-sieze.

Put some high-quality anti-seize on - the kind that looks like ground up copper in thick grease. Start with the lugs and studs perfectly clean with NO grit anywhere. Use steel lugs on steel studs. Torque to the factory figure in the right pattern in two stages. Use hubcentric wheels. If you drop a lug into the dirt don't reuse it until you've thoroughly cleaned all of the grit out (carry some clean spares along). You'll be fine and never break a stud again.

--Kevin H.
(no broken studs in 5+ years)

The wheels I was using for track days are Kosei K1 TS in 17x7 w/ 225/45 Advan A048's. They have hub centric rings like all my other wheels.

65 is the torque spec w/ anti-seize? I remember a big debate about using anti-seize on wheel studs because the torque numbers would not be accurate due to the anti-seize making it easier to twist the lugs. Any truth to that?

So no one seems to think that this issue is heat related even though I cannot touch my lugs for about an hour after a session due to the heat? The XP12 pads are good up to 2000 degrees and there have been times when they flake white from the heat. The rotor vanes turn permenantly red. I have not used rotor paint yet, but guys using these size rotors even with street tires melt off the paint for 1200-1300 degrees.

+1 Certainly aluminum lugs would be a bad idea as far as heat is concerned.

I just can't imagine the the threads are deforming from heat alone, and not additional loading from an incorrect bore etc.etc.

The wheels I was using for track days are Kosei K1 TS in 17x7 w/ 225/45 Advan A048's. They have hub centric rings like all my other wheels.

65 is the torque spec w/ anti-seize? I remember a big debate about using anti-seize on wheel studs because the torque numbers would not be accurate due to the anti-seize making it easier to twist the lugs. Any truth to that?

So no one seems to think that this issue is heat related even though I cannot touch my lugs for about an hour after a session due to the heat? The XP12 pads are good up to 2000 degrees and there have been times when they flake white from the heat. The rotor vanes turn permenantly red. I have not used rotor paint yet, but guys using these size rotors even with street tires melt off the paint for 1200-1300 degrees.

I have similar "heat issues". I've run XP8's, 10's, and blues. 225 and 255 Azenis and 225 RA-1's. Certainly can't go near the studs for a good hour or so, and the rotors get stress cracks after an hour or two or hard use.

I've never had the stud issues though. One would think you'd have bearing failures and things of that nature before deforming wheel studs.

The only time I've ever heard of that is tightening them, or taking them off, while still hot.

Tough problem...sorry no help here.

I'm running a similar setup (4/2 pots)- sans the R compunds (relatively sticky "street" tires though) and have experienced no problems w/ studs or lugs. I have slowly upped my torque and have settled on 74 ft lbs (no lube). I'm careful torquing my lugs w/ just enough weight on the tires to keep them from spinning, star pattern and slowly get them up to spec.

I've used aluminum lugs (same set for four years) w/o any problems (knock on aluminum :))

I've got a decent duct setup, but will be going w/ a better one this year- RCE's (not as convient as my leave on setup, but more efficient at delivering air to the rear center of the rotor)

Also running two piece rotors, not sure how much they are helping, but certainly not hurting :)

Could possibly be that your trying to swap your wheels out too quickly- not cooled down enough????

No one will argue that we have relatively fast cars that weigh a lot- brakes take a beating no doubt.

I think it would be good to get some temp paint or a decent IR temp gauge to get a handle on the actual temps your seeing.

BIGSKY, thanks for your help earlier on the DBA 2pc. rotors (got your pm's). I wait to swap wheels until the lugs are cool enough to touch, but still mildly warm...usually about an hour. I am usually one of the last ones to leave the track because I have to wait so long for the lugs to cool. Maybe I'll try some portable fans this season to speed up the cooling process after the cool down lap. Also, where is a good place to pick up temp paint or an IR temp gauge that does not cost an arm and a leg and goes beyond 1500 degrees?

Maybe the additional heat and cornering loads produced by the race pads and R compound tires combined with the studs being original was enough to roach them. I have replaced nearly all the original front studs now. Hopefully, I will have better luck this season.

In regard to torque specs, I should shoot for somewhere between 65 and 72 dry and not re-torque them between sessions for fear they are still hot? Any ideas on the anti-sieze/overtorque debate of previous discussions?

Pete- try here http://www.raceshopper.com/temperature_paint.shtml

IR gun in the 1500 range are $100+ (I want one :))

I check my torque between sessions- right before I go back out- usually close to an hour- occasionally one or two might be a little loose. I wouldn't feel good about going back out w/o checking the lugs.

I've never used anti-seize on the studs as you had mentioned- I've always read that influences the actual torque?????

I saw the paint, but where is the IR gun?

There are a bunch of different ones out there- this is the one I've been eyeballing

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&pid=03450499000&cat=Mechanics+Tools&subcat=Automotive+Specialty+Tools&vertical=TOOL&ihtoken=1

Most specs I have seen call for no lubricants, clean surfaces or perhaps a bit of light oil. Anything more than that and you change the torque values (they would need to be lower). The manufacturers publish the values dry because of the inability to provide a consistent spec between available lubricants.

In addition, be VERY careful about retorqueing when things are hot (studs are longer and you have effectively dramatically increased the cold torque value) - studs break when this happens.

I tend to not use anti-seize because I am changing wheel so often, I tend to keep things dry and clean.

Ray

In addition, be VERY careful about retorqueing when things are hot (studs are longer and you have effectively dramatically increased the cold torque value) - studs break when this happens.


Ray

This sounds like it could be very likely the problem Pete's encountering

That IR gun looks pretty sweet. I just hope I would never go over 1500 degrees or it would be kind of pointless. I think rotor temp paint may be the answer.

Fortunately, I only torqued lugs between sessions once last season. Maybe it has to do with my upped torque specs to keep from having to re-torque lugs in the first place.

That IR gun looks pretty sweet. I just hope I would never go over 1500 degrees or it would be kind of pointless. I think rotor temp paint may be the answer.

Fortunately, I only torqued lugs between sessions once last season. Maybe it has to do with my upped torque specs to keep from having to re-torque lugs in the first place.

The temp paint is definitely a better solution as far as finding peak temperatures go, since that will be on track at the end of your longest braking point. It's hard to lean out the window and shoot the rotor with a pyrometer at that point. :D The disadvantage to the rotor paint is having to re-apply it.

As far as checking temps in the pits, 1500 degrees is plenty of leeway. For steel, that's the point at which your rotors are glowing "cherry red" and flaking off metal due to rapid oxidation. Some rough estimates:

900: faint red glow
1000: dark red
1250: cherry red
1500: BRIGHT red

It's hard to lean out the window and shoot the rotor with a pyrometer at that point. :D

You've got to try out group 4! :lol:

The temp paint is definitely a better solution as far as finding peak temperatures go, since that will be on track at the end of your longest braking point. It's hard to lean out the window and shoot the rotor with a pyrometer at that point. :D The disadvantage to the rotor paint is having to re-apply it.

As far as checking temps in the pits, 1500 degrees is plenty of leeway. For steel, that's the point at which your rotors are glowing "cherry red" and flaking off metal due to rapid oxidation. Some rough estimates:

900: faint red glow
1000: dark red
1250: cherry red
1500: BRIGHT red

The higher temp paint is 1250 F - you will most likely go well past that - I did and I am SLOW w/ street tires.

torque specs are generally based on the following
material, diameter, thread pitch.

for the oem suds, in the diameter of the bolt, and material grade of the steel, the DRY torque is around 120 or so.. depending on the various lubricants you decrease your torque spec anywhere from 10-50%.

you can look up this topic by searching the intarweb and any ASME/ISO standards. This is widely used in everything fastener related.

This concept has to do with bolt elongation to reach an ideal preload on the bolt as to prevent nut loosening. over tighten and snap the bolt, under tighten and have the nut come off. lubricants affect the static friction you have on the threads to reach said preload. The less friction you have to overcome to tighten the nut, the easier it is to reach desired preload. (a secondary effect is to decrease your contact resistance for more uniform heat transfer from stud to lug nut, this avoids hot spots that may affect material properties and may lead to seizing)

hope that sheds some light on things. from what im hearing pete, your studs might be siezing to the lugs, heat will cause metals to bind together. this will happen on aluminum quicker than steel. use anti-seize! and keep all FOD outta there. its like holding a string taught and having the smallest grain of sand snap it.

So if using anti-seize, what should you torque the lug nuts to?

I am more concerned about the heat that is causing the studs and lugs to go bad and will probably ultimately fry the wheel bearings.

Not to worry, you're wheel bearings are already toast. The heat breaks down the grease, then it just a matter of time before your bearings wear into the hub and ultimately disintegrate. They are probably already far along in this process.

You said those Kosei's have hub centric rings - what are they made of? Aluminum? Plastic?

A good copper high-temp antiseize will do wonders to help your lug studs live longer.

Also sounds like you're not doing cool down laps.

torque specs are generally based on the following
material, diameter, thread pitch.

for the oem suds, in the diameter of the bolt, and material grade of the steel, the DRY torque is around 120 or so.. depending on the various lubricants you decrease your torque spec anywhere from 10-50%.

120!?! Everyone was freaking out about going over the factory spec of 65 dry and you are suggesting 120ft/lbs??? Am I missing something here?

Not to worry, you're wheel bearings are already toast. The heat breaks down the grease, then it just a matter of time before your bearings wear into the hub and ultimately disintegrate. They are probably already far along in this process.

You said those Kosei's have hub centric rings - what are they made of? Aluminum? Plastic?

A good copper high-temp antiseize will do wonders to help your lug studs live longer.

Also sounds like you're not doing cool down laps.

Good to hear my wheel bearings are in excellent shape. I actually do a ton of cool down after sessions. I am usually one of the last cars back in the pits.

120!?! Everyone was freaking out about going over the factory spec of 65 dry and you are suggesting 120ft/lbs??? Am I missing something here?

My guess is because the rest of the post was spot on, technically speaking, everyone was cutting him a break (get it? break!).

As he should have noted though, ideal preloads for threads aren't what the manufacturers go off of to determine wheel stud torque.

You can have a wide vairety of torque specs for any given size thread across different manufacturers, inspite of the fact that there is only one true "theoretical" preload. The torque spec is usually much less that the theoretical preload based on material, thread pitch, diameter, etc.

You should in no way shape or form be running anything near 120, or going to a machinist's handbook for stud torque.

120!?! Everyone was freaking out about going over the factory spec of 65 dry and you are suggesting 120ft/lbs??? Am I missing something here?

im not suggesting that you torque them to that. Im simply stating that for a grade 8 equivalent (in metric is actually closer to the grade 10 spec) material for this size of stud thats what the torque would approximately be. I dont know what grade steel the OEM studs are made from, so I cant say what the dry torque spec would be. I guess i should have clarified a bit so its not misleading...

From all those that have contributed here, I think the take away is put some anti-seize on your studs and torque them to 65-70 ftlbs. I dont think it matters as long as your in the 65-75 range or whatever makes you warm and fuzzy inside, experience will tell you. Make sure your wheels are not bending your studs, and dont do anything while theyre hot. If I were you, I would replace your wheel bearing asap. If they seize or blow apart, bad things will happen especially if your are on track.

FYI in my wrx i had new wheel bearings replaced before 1 season and pulled them at the end, they were all heat checked.. even the rears. it would have been only a matter of time till they blew up.

As for torquing, I will usually retorque the nutz just before going out on track when they are coolest. do this a few times and you'll figure out when you need to torque them and when you dont. hope this helps..

My advice, instead of buying expensive rotors to crack, I've had good luck with Autozone rotors. Duralast 34203. $31 each. :eek:


Thanks for the tip. I checked them out today and they have jumped up to a whopping $51/ea. Not bad. They even come with a two yr. warranty. You think track days are covered in that warranty?:D "Yeah, I just drive it on the street. What did you say about the rotors being bright red?" :lol:

Thanks for the tip. I checked them out today and they have jumped up to a whopping $51/ea. Not bad. They even come with a two yr. warranty. You think track days are covered in that warranty?:D "Yeah, I just drive it on the street. What did you say about the rotors being bright red?" :lol:

Really?

I JUST bought a 2nd set TODAY for $31 each, $64 OTD in PA.

www.autozone.com still lists 30.99!

http://autozone.com/selectedZip,19422/initialAction,partProductDetail/initialpartType,00854/initialR,APP1048918/initialvehicleId,2880601/shopping/selectZip.htm

Not like $51 is bad (cheaper than every other parts store around me), without having to pay shipping, but $30 is a horse of a different color (always wanted to say that :o )

Let me know how you like them if you ever run a set. Again, I haven't used 12's (yet ;) ) but I imagine they can't hold up that differently.

Maybe your autozone guys are reading this thread and the jig is up?

I'll bring them back stress cracked in 2 months and report on the look they give me... :lol:

(runs to store to buy out $31 supply before price increase hits....)

Jeez, and I thought I was getting a deal when I was buying $60 generics a few years back!

now, having to replace the brembo rotors are a whole nother beast...

I'm getting gipped. When I punch in my zip code online it comes up 51.99. Son of a....

Really?

I JUST bought a 2nd set TODAY for $31 each, $64 OTD in PA.

www.autozone.com still lists 30.99!

http://autozone.com/selectedZip,19422/initialAction,partProductDetail/initialpartType,00854/initialR,APP1048918/initialvehicleId,2880601/shopping/selectZip.htm

Not like $51 is bad (cheaper than every other parts store around me), without having to pay shipping, but $30 is a horse of a different color (always wanted to say that :o )

Let me know how you like them if you ever run a set. Again, I haven't used 12's (yet ;) ) but I imagine they can't hold up that differently.

Maybe your autozone guys are reading this thread and the jig is up?

I'll bring them back stress cracked in 2 months and report on the look they give me... :lol:

(runs to store to buy out $31 supply before price increase hits....)

I think the wheel bearings are still ok at this point. No noise and no play in the hub with the car in the air. On a WRX is there just one wheel bearing per side and can you replace that by itself or do you have to replace the whole hub?

Just one bearing, and yes, you can change it yourself.

Making a home-made $10 Home Depot "Hub shark" works wonders and makes wheel bearings a quick job, provided you have a place/press to get the outer race off the hub.

Just one bearing, and yes, you can change it yourself.

Making a home-made $10 Home Depot "Hub shark" works wonders and makes wheel bearings a quick job, provided you have a place/press to get the outer race off the hub.

Well that is good news. I have access to a shop so the tools should not be an issue as long as it is not some exotic tool needed like the titanium/carbon fiber muffler bearing puller. I hear those are hard to come by.

The rotor vanes turn permenantly red.


If you have DBA 4000's or 5000's, they have that Temp Monitoring System built in. Its stripes placed on the vanes.

Red is 630+ C.

I'm going to briefly summarize some of the good ideas and add a couple.

I didn't see what your rear brakes are anywhere (maybe just missed it). H6 swap will bring just a bit of bias towards the rear, increasing your overall straight line braking power and reducing the work done by the fronts. Cheap, easy upgrade.

Front: Blank non-slotted rotors. You need the thermal mass and you need the surface area.

Lugnuts: steel only. I saw something about you considering....or using aluminum. Just don't.

During cool down lap, don't even touch the brake pedal. Once off the track, drive around for 5 full minutes without touching the brake if possible. After parking the car, after 5 minutes, push the car to rotate the wheels 180 degrees. I know these are very basic instructions, but I've seen others with experience forget about the basics. In over 20 years on the track in a bunch of cars, I've yet to crack or warp a rotor using this method.

You also didn't mention boiling brake fluid (that I saw). I can't believe you're getting things that hot and not boiling the crap out of any fluid.....even the exp600 I use. Fitz had a great basic suggestion of getting some heat paint on there to see how hot it's getting.

You're not mixing pad compounds....are you? You noted the carbotechs. If you're sticking to one compound on the rotors always, ok. If you're mixing them (swapping just the pads for street, for example), don't. Some compounds don't do well with others. I had some nice caliper seal melting experiences that taught me never to mix anything with Hawk blues.

Good luck, sounds like a tough one.... jack

Jack,

Thanks for the good advice. I upgraded the rear brakes at the same time to the matching 2pot Subaru rears with larger vented rotors. I was having an issue with brake fluid as well until I switched to Motul RBF 600.

I had gotten some advice on alum lugs and that is why I was questioning it since it seemed stupid to have alum lugs w/ steel studs since they will react to heat differently.

I do a lot of cool down after the track sessions, but I forgot about moving the car forward after it sits for a few minutes. Good point. Fortunately, I have not had any hot spots on the pads or rotors. The time the rotors cracked I was actually out driving around trying to cool them down. I think they were just at the end of their life.

As per Carbotech's advice I am only swapping between Carbotech Bobcats and XP12's. They said it was ok to swap between their compounds, but bad to go to a different pad type (ie. semi-metallic). I thought it was just some marketing on their part, but I have kept true to Carbotech and have not had any problems.

One thing to check is your torque wrench. If it's reading low you may be overtorquing the lugnuts - which could lead to the nuts seizing on the studs. It's a longshot, but worth checking.