pad surface area vs. performance?
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From: milwaukee, wi
been searching for a solid 2 days and think im going to go with some CL RC5+ pads. they dont sound horrifically noisy and it sounds like they stop great even dead cold, no warm up needed to get into a decent coefficient of friction which is what im looking for. even the ds25000's take a while.
http://www.essexparts.com/shop/brake...e-pads-65.html
http://www.essexparts.com/shop/brake-pads/fcp1334h.html
http://www.essexparts.com/shop/brake...e-pads-65.html
http://www.essexparts.com/shop/brake-pads/fcp1334h.html
What pads are you running in your car currently? A good set of pads for the proper application, brake ducts, and good fluid will do wonders. Im just running regular centric rotors with carbotech pads and I have no complaints with brake fade. At the track the car stops like your throwing an anchor out.
I would personally have the oem brembos vs the wilwoods imho.
I would personally have the oem brembos vs the wilwoods imho.
Imo, if you dont mind the squeal when they warm up, I feel the xp8s are totally driveable on the streets once properly bedded in.
I really love these pads. During the last track event I wanted to test the xp8s and the hawk dtc70s, I loved the xp8s so much I didnt bother swapping out to try the dtc70s. I still have them sitting in their box as part of my spares for the track.
To correct something you said though, pad surface has nothing to do with how hard a pad can stop the car. If all else remains equal and you simply increase the pad area, you reduce the pressure on the surface of the pad, but you still have XXX line pressure acting on the same piston area and your normal force goes unchanged. If the coefficient of friction is unaffected by pressure, then there would be zero change in brake force with the change in pad size. I have no idea if brake pads are sensitive to pressures though.
As for why people might be interested in aftermarket setups, there are numerous downfalls to the stock setup.
The stock brembos have aluminum pistons and dust boots. Not exactly the greatest items for a race caliper. Most aftermarket stuff is stainless steel or some other superalloy that has low thermal conductivity to reduce heat transfer to the fluid.
The brembos also look to be fairly weak based on some of the pictures that have popped up showing signs of caliper flex on the pads. Some aftermarket calipers offer substantial gains in caliper stiffness.
As mentioned, some calipers manage to stuff a much thicker pad in there so pad life isn't reduced. The stock pads measured out at 4.5 in^3 of pad material. There are numerous calipers out there that increase that by 20-30% or more.
There is also the weight. The stock calipers are like 10 pounds. AP makes a caliper with like 40% more pad volume while being under 4.5 pounds.
The rotors in a big brake kit can be lighter while using better materials.
There are lots of reasons for the upgraded kits out there. But you are also right, the correct pads and venting has shown to work very well with the stock calipers. If all you are interested in is 150-0, then yeah, the brembos can be made to work very well, MOST people don't judge the capabilities of a brake upgrade by their performance under one 150-0 test.
As for why people might be interested in aftermarket setups, there are numerous downfalls to the stock setup.
The stock brembos have aluminum pistons and dust boots. Not exactly the greatest items for a race caliper. Most aftermarket stuff is stainless steel or some other superalloy that has low thermal conductivity to reduce heat transfer to the fluid.
The brembos also look to be fairly weak based on some of the pictures that have popped up showing signs of caliper flex on the pads. Some aftermarket calipers offer substantial gains in caliper stiffness.
As mentioned, some calipers manage to stuff a much thicker pad in there so pad life isn't reduced. The stock pads measured out at 4.5 in^3 of pad material. There are numerous calipers out there that increase that by 20-30% or more.
There is also the weight. The stock calipers are like 10 pounds. AP makes a caliper with like 40% more pad volume while being under 4.5 pounds.
The rotors in a big brake kit can be lighter while using better materials.
There are lots of reasons for the upgraded kits out there. But you are also right, the correct pads and venting has shown to work very well with the stock calipers. If all you are interested in is 150-0, then yeah, the brembos can be made to work very well, MOST people don't judge the capabilities of a brake upgrade by their performance under one 150-0 test.
Good post.
While the AL pistons and dust boots aren't great - I think they are only the weak link when tracked hard with tire upgrade.
I think thew weak link in all of these OEM Brembo's - EVO, STi and several others that utilize the same pad is twofold.
It's big and heavy for the performance.
It uses an expensive pad shape that is on the thin side.
They freaking squeal at any pad even remotely over the 'street performance' level. This is a TERRIBLE OEM flaw. And when they squeal - it's like NO OTHER. We've all heard it.
I have a street 06 STi. With the Brembo's - omg HP+ were the WORST pad ever. Great bite - but at times the noise was simply otherworldly.
I installed a similarly sized Stoptech ST40/332/32 mm rotor front BBK w/ the same HP+. Awesome. The overall feel etc is about the same - but tthe noise reduction is like 90%. I get a bit of squeal at cold and certain times - but not even anything to complain about.
To the OP
Cl makes a good pad - but I suspect a sintered pad in an EVO Brembo is a tough call to have street manners. Same w/ XP-8's. I tried it a few times - users NOT HAPPY.
YMMV
-Ken
PS
The ST 332/32 kit has decent sized pads - reasonable replacement costs - and fits many wheels.
The AP kit is more a track kit.
WW kits depend on who made it and with what parts. They are one of the only brake manufacturer's too sell parts - so there are many 'kits' - some well engineered and some not engineered at all - just thrown together. Most use a WW Superlite or derivative there of. Definitely meh.
-Ken
The ST 332/32 kit has decent sized pads - reasonable replacement costs - and fits many wheels.
The AP kit is more a track kit.
WW kits depend on who made it and with what parts. They are one of the only brake manufacturer's too sell parts - so there are many 'kits' - some well engineered and some not engineered at all - just thrown together. Most use a WW Superlite or derivative there of. Definitely meh.
-Ken
I wish there was more information available from the manufacturers when it comes to caliper stiffness.
Wilwood particularly as their lower end stuff is all fairly similar in using 4 bolts with similar spacing and no bridge. I have to assume there are differences though or they wouldn't bother making different lines of calipers. Main reason I even look at Wilwood myself is I'm not after massive heat resistance as I'm building an Auto-X car. Having a good stiff caliper though will provide better brake feedback. I'd like to go as light and cheap (including pad replacement costs) as possible without sacrificing pedal feel.
FWIW though, it seems like the calipers Wilwood makes that would actually be very stiff are on par with pricing of the AP Racing calipers. At that point, it seems like AP has a lot nicer features.
Wilwood particularly as their lower end stuff is all fairly similar in using 4 bolts with similar spacing and no bridge. I have to assume there are differences though or they wouldn't bother making different lines of calipers. Main reason I even look at Wilwood myself is I'm not after massive heat resistance as I'm building an Auto-X car. Having a good stiff caliper though will provide better brake feedback. I'd like to go as light and cheap (including pad replacement costs) as possible without sacrificing pedal feel.
FWIW though, it seems like the calipers Wilwood makes that would actually be very stiff are on par with pricing of the AP Racing calipers. At that point, it seems like AP has a lot nicer features.
^Personally, I think you're over thinkin it for an autox build. Autox speeds aren't high enough to require super braking systems as with road racing/hpde. Autox braking is also not long enough to generate heat as you mentioned. I can see running the lightest weight rotor you can find, but putting money into the braking system, specifically calipers and bbk for an autox car is a waste of the budget that could be used elsewhere. Furthermore, consider you goal for the weight of the car (2620lbs), its unlikely for you to need more brakes, bot that its a bad thing. Thats just my honest opinion though, and should take nothing away from what you already have in mind.
Last edited by chu; Feb 8, 2012 at 07:49 AM.
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From: Charlotte, NC
N2oiroc,
You can read all about the results our customers are having with the Essex/AP Compeition system in this thread.
Our website has loads of details, and I'd be happy to answer any questions you have the system via phone, email, PM, etc.
Lots of other good responses here with regards to pad size/shape/volume. Stickier tires will get you further towards achieving a shorter stopping distance than anything brake related possibly can. Everything you do with your car is tire-limited. The fundamental rule is that more grip = more potential to accelerate, brake, and corner.
Big brake systems are about heat reduction...which leads to a wide array of benefits.
When AP designed the CP8350 caliper we use in our system, they benchmarked the Wilwood Superlite, which is the foundation for most of their popular systems. The AP caliper is far stiffer. The benefits include a firmer pedal, superior modulation, and a much longer service life (when calipers get old, they tend to fatigue and "clamshell" open). While we haven't had many Evo owners replace their Wilwoods with the AP's, we've had a ton of late model circle track guys do so. Every one of them says the same things when they make the switch, and they don't ever go back...firmer pedal, easier to modulate, less pad taper, and longer life of the caliper.
Generally speaking, it's more or less impossible to get publishable data from caliper manufacturers on their testing vs. competitors. Most view it in bad taste to directly attack or dismiss a competitor's product, and they just don't do it. It's probably better that way. Instead they focus on selling their strengths, which leads customers to rely on real-world feedback, brand history, technology, etc.
You can read all about the results our customers are having with the Essex/AP Compeition system in this thread.
Our website has loads of details, and I'd be happy to answer any questions you have the system via phone, email, PM, etc.
Lots of other good responses here with regards to pad size/shape/volume. Stickier tires will get you further towards achieving a shorter stopping distance than anything brake related possibly can. Everything you do with your car is tire-limited. The fundamental rule is that more grip = more potential to accelerate, brake, and corner.
Main reason I even look at Wilwood myself is I'm not after massive heat resistance as I'm building an Auto-X car. Having a good stiff caliper though will provide better brake feedback. I'd like to go as light and cheap (including pad replacement costs) as possible without sacrificing pedal feel.
When AP designed the CP8350 caliper we use in our system, they benchmarked the Wilwood Superlite, which is the foundation for most of their popular systems. The AP caliper is far stiffer. The benefits include a firmer pedal, superior modulation, and a much longer service life (when calipers get old, they tend to fatigue and "clamshell" open). While we haven't had many Evo owners replace their Wilwoods with the AP's, we've had a ton of late model circle track guys do so. Every one of them says the same things when they make the switch, and they don't ever go back...firmer pedal, easier to modulate, less pad taper, and longer life of the caliper.
Generally speaking, it's more or less impossible to get publishable data from caliper manufacturers on their testing vs. competitors. Most view it in bad taste to directly attack or dismiss a competitor's product, and they just don't do it. It's probably better that way. Instead they focus on selling their strengths, which leads customers to rely on real-world feedback, brand history, technology, etc.
JRitt, you can post factual data about your product without posting negative information about others. It’s just funny because stiffness is a very quantifiable value, yet the only information you can get as a consumer is opinion from people using the products. An effective spring constant to give a rough idea of stiffness for small bending deflections across the bridge would do it. Of course, it does nothing unless the competitor provides the same info in a comparative manner.
Chu, my thoughts on an auto-x brake setup is the stock rotors are larger than needed. Downsize diameter and use a smaller calipers and drop a considerable amount of weight, both rotational and unsprung. I'd like to do it without getting a caliper that flexes like crazy and makes the pedal feel like crap though and that's where caliper stiffness comparisons come in.
Chu, my thoughts on an auto-x brake setup is the stock rotors are larger than needed. Downsize diameter and use a smaller calipers and drop a considerable amount of weight, both rotational and unsprung. I'd like to do it without getting a caliper that flexes like crazy and makes the pedal feel like crap though and that's where caliper stiffness comparisons come in.
Last edited by 03whitegsr; Feb 8, 2012 at 03:30 PM.
For kicks, here's a thread detailing problems with the really poorly made stuff:
https://www.evolutionm.net/forums/ev...-shacking.html
Stoptech sometimes shifts the bias slightly rearward via smaller pistons up front, which may shorten stopping distances a little. But that's not really the main goal with a BBK.
- Andrew
https://www.evolutionm.net/forums/ev...-shacking.html
Stoptech sometimes shifts the bias slightly rearward via smaller pistons up front, which may shorten stopping distances a little. But that's not really the main goal with a BBK.
- Andrew
That run-out in the video could be largely in the hub and not the rotor assembly. Also, with floating rotors, until they have had a few heat cycles on them, can't you expect some run out?
Their measurement of brake drag also has the hub bearing, axle and differential drag in it. Not to mention it's not an accurate torque value anyway as they were not applying the force through the axle centerline.
Now caliper flex on the other hand, that is exactly what I'm concerned about with the Wilwoods.
Their measurement of brake drag also has the hub bearing, axle and differential drag in it. Not to mention it's not an accurate torque value anyway as they were not applying the force through the axle centerline.
Now caliper flex on the other hand, that is exactly what I'm concerned about with the Wilwoods.
What Jeff Ritter said. Not only do you gain a ton of features/feedback from the pedal, but you also save a lot of rotational weight which is big in AutoX with all of the sudden accel/decell.
Last edited by Balrok; Feb 12, 2012 at 08:09 PM.
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