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      04-02-2013, 12:22 AM   #23
Drifty//
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First of all, thanks for the reply. I'm here to learn, and I appreciate anyone willing to share some knowledge.

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Originally Posted by JAJ View Post
Pad friction area is irrelevant.
Well, I'm no expert, but it seems to me that smaller pad friction area translates into higher temps, since you're using less area to apply roughly the same amount of torque. Whether by adhesion or abrasion, it still amounts to converting kinetic energy into heat. So, as long as two brake kits allow one to apply the same amount of torque, then the same heat is divided over a larger or smaller pad area.

And I'd guess higher temps would accelerate pad wear, if not also rotor wear.

Are you saying this somehow isn't true, or just that the amount of delta is too small to have a significant effect?
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      04-02-2013, 12:43 AM   #24
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Big thanks for that great testimonial. You've removed 95% of my doubts about this kit, especially since I don't plan to mod the engine.

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Originally Posted by dogbone View Post
With the rotor, you have a choice of slotted-only, or slotted and drilled.
I'm pretty sure the strap drive rotors are slotted, only. But, if you really care, just call AP and see what they can offer.

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Originally Posted by dogbone View Post
-You need to come up with a reliable way to remove wheels so that when you pull them off, the barrels don't come crashing down on the calipers and scratch them.
I use this:
Lug Bolt Guide Tools
I've also seen it referred to as a wheel hanger. The tire change kit for my Audi had a plastic one, and I liked it so much I bought this one for the M3. The only tricky part is to keep the front wheel from spinning, but I've gotten pretty good at using my toes (while sitting on my jack case) to help guide the wheels on and off. My first worry is about bending the dust guards.

Actually, it was traumatic experiences with the Audi's pinch welds that sent me searching for the correct tools to jack the M3. I made sure to have those in hand from day one.
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      04-03-2013, 12:45 AM   #25
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Quote:
Originally Posted by Drifty// View Post
First of all, thanks for the reply. I'm here to learn, and I appreciate anyone willing to share some knowledge.

Well, I'm no expert, but it seems to me that smaller pad friction area translates into higher temps, since you're using less area to apply roughly the same amount of torque. Whether by adhesion or abrasion, it still amounts to converting kinetic energy into heat. So, as long as two brake kits allow one to apply the same amount of torque, then the same heat is divided over a larger or smaller pad area.

And I'd guess higher temps would accelerate pad wear, if not also rotor wear.

Are you saying this somehow isn't true, or just that the amount of delta is too small to have a significant effect?
My point is that at the level of performance we're talking about, the difference will not be detectable. With the right pads, like PFC-01's, all of the top-end aftermarket kits at this level are more than capable of hauling an E9x down from top speed without a problem, lap after lap.
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      04-03-2013, 02:15 AM   #26
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Originally Posted by christopherchenm View Post
thanks for the advice, I will throw in AP . Btw whats the max i can go with the rotor? I got 19" and want an aggressive look
With OEM 18" 260Ms you would have to go with the 368mm rotors up front (or if you run 219Ms then spacers and the 368mm rotors), with the OEM 19s you can run the 368mm or the upsized 378mm. What rims you running?

http://www.apracing.com/product_deta...5555m1049.aspx
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      04-03-2013, 05:59 AM   #27
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Stillen is the distributor in the U.S. that puts these AP kits together. I would contact them with questions about rotor sizes, etc. Jim Hodgman is very friendly and quite knowledgeable. Interestingly, he was with Brembo for a long time as well.
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      04-03-2013, 07:04 AM   #28
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Quote:
Originally Posted by jonasaurus View Post
With OEM 18" 260Ms you would have to go with the 368mm rotors up front (or if you run 219Ms then spacers and the 368mm rotors), with the OEM 19s you can run the 368mm or the upsized 378mm. What rims you running?

http://www.apracing.com/product_deta...5555m1049.aspx
stock 19s
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      04-07-2013, 03:11 AM   #29
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Does anyone happen to have good info on whether the AP Racing kit fits Apex ARC-8 18x10 ET25 wheels? Those are my track wheels (both front & rear). I have a set of 18x10 ET25 EC-7's for street, but the BBK - Wheel Fitment Compatibility Database thread already tells me that fit works.

Saw so many Apex wheels at the last track event. Someone must know...
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      04-07-2013, 08:06 AM   #30
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Quote:
Originally Posted by Drifty// View Post
Does anyone happen to have good info on whether the AP Racing kit fits Apex ARC-8 18x10 ET25 wheels? Those are my track wheels (both front & rear). I have a set of 18x10 ET25 EC-7's for street, but the BBK - Wheel Fitment Compatibility Database thread already tells me that fit works.

Saw so many Apex wheels at the last track event. Someone must know...
I have AP Racing on all four corners and run ARC-8 wheels. I run 9.5" front and 10.5" rear. No problems. (My 9.5" wheels fit on the rear fine. I tested it out in case I had a flat in the rear at the track. I bring street fronts with me as a safety. So, if I have a flat in the front, then I replace the fronts with my street fronts. If I have a flat in the rear, I move my track fronts to the rear and put the street fronts on the front.)

I have been told directly from APEX, that all ARC-8 18" wheels with the M3 fitment fit over all brakes except Brembo 380mm. EC-7 is able to go around Brembo 380 as well. (I don't know if ARC-8 would go around that larger AP rotor though. I didn't even know about that rotor until I saw it posted above.)

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      04-07-2013, 11:11 AM   #31
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Quote:
Originally Posted by dogbone View Post
I have AP Racing on all four corners and run ARC-8 wheels. I run 9.5" front and 10.5" rear. No problems. (My 9.5" wheels fit on the rear fine.
Excellent! Thanks!

So, the 9.5" is ET22 and the 10.5" is ET27? If I can find some wheel templates, I can confirm that mine will fit.

I can't use any spacers, as my track wheels/tires (275/35) already rub (hoping new control arms and a good alignment will sort that out) and my street wheels (running 265/35) just barely clear.

Quote:
I have been told directly from APEX, that all ARC-8 18" wheels with the M3 fitment fit over all brakes except Brembo 380mm.
Apex also tells people that 275/35 tires, on 18" ET25 wheels won't rub on our cars. I know rubbing is far different from caliper clearance, but I'm just not going to assume that Apex had this BBK (which is still somewhat rare) in mind, back when they made that statement to you about the ARC-8.
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      04-07-2013, 02:05 PM   #32
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if you are tracking and switching pads, skip brembo.
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      04-07-2013, 02:52 PM   #33
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Quote:
Originally Posted by surlynkid View Post
if you are tracking and switching pads, skip brembo.
Why, because you have to remove the caliper? On my old e46 M3 track prep'd car I had AP calipers with a removable top bridge, and on my e92 M3 I have Performance Friction calipers with a fixed top bridge. It only takes me 5 min longer to swap pads on the Performance Friction calipers, however, a portion of the extra amount of time is due to having to swap four pads per caliper instead of two pads per caliper.
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      04-07-2013, 06:08 PM   #34
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Why, because you have to remove the caliper?
If AP and Stoptech are correct about 2-piece calipers being stiffer than monoblock, it makes me wonder what's the point of monoblock. Weight? Bragging rights?
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      04-07-2013, 07:29 PM   #35
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Quote:
Originally Posted by Drifty// View Post
If AP and Stoptech are correct about 2-piece calipers being stiffer than monoblock, it makes me wonder what's the point of monoblock. Weight? Bragging rights?
Monoblock calipers are used in F1 and top pro race series. AP uses a monoblock caliper on the M3 in the ALMS - if 2-piece calipers are better why are they using a monoblock caliper in the ALMS? StopTech is making a general statement about 2-piece calipers being stiffer than ALL monoblock calipers which is an absolute joke. Don't believe everything that you read...
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      04-07-2013, 10:41 PM   #36
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Originally Posted by M3SQRD View Post
Monoblock calipers are used in F1 and top pro race series. AP uses a monoblock caliper on the M3 in the ALMS - if 2-piece calipers are better why are they using a monoblock caliper in the ALMS?
AP has plenty of 2-piece racing calipers. I don't think the answer is so simple.
Brake Calipers
I think cost is one issue. In another thread, Chris B. (from AP Racing) described some of the differences between their racing calipers and their street calipers, when explaining why forging is not worthwhile, on street products. He explained that their racing monoblocks are machined, and this sort of production would be cost-prohibitive on their street products.

But that was all about forging and how it doesn't usually increase stiffness. He never directly explained the rationale behind 2-piece vs. one-piece. He did say that if AP thought forging (i.e. the forging techniques like those used by StopTech on their Trophy series) were worth offering in their street products, that they would do it. So, I take the same logic to apply to the 2-piece vs. 1-piece decision.

Sadly, he hasn't been active on here since Nov. 26 2012. Perhaps he's no longer with AP Racing.
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      04-08-2013, 01:07 PM   #37
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Quote:
Originally Posted by Drifty// View Post
If AP and Stoptech are correct about 2-piece calipers being stiffer than monoblock, it makes me wonder what's the point of monoblock. Weight? Bragging rights?
Quote:
Originally Posted by Drifty// View Post
AP has plenty of 2-piece racing calipers. I don't think the answer is so simple.


I think cost is one issue. In another thread, Chris B. (from AP Racing) described some of the differences between their racing calipers and their street calipers, when explaining why forging is not worthwhile, on street products. He explained that their racing monoblocks are machined, and this sort of production would be cost-prohibitive on their street products.

But that was all about forging and how it doesn't usually increase stiffness. He never directly explained the rationale behind 2-piece vs. one-piece. He did say that if AP thought forging (i.e. the forging techniques like those used by StopTech on their Trophy series) were worth offering in their street products, that they would do it. So, I take the same logic to apply to the 2-piece vs. 1-piece decision.
I gave you a "simple" response because your original statement was basically "what's the point of monoblock?" There are advantages to designing a monoblock caliper and not all bolted-together caliper designs are stiffer than monoblock caliper designs. All monoblock calipers - racing or street - have to be machined whereas most bolted-together designs are cast.

PFC only uses 4-piston calipers on the front of the e9x M3 kit - does that make it an inferior design compared to AP, ST and Brembo because they use 6-piston calipers on the front?
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      04-08-2013, 11:04 PM   #38
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Hah! There are no endurance racing "sprint calipers", and no sprint racing "endurance calipers".

Every racing caliper has a design goal - sprint calipers don't weigh very much but the cooling is epic. Endurance calipers are heavier, but changing pads is a priority, so they have removable bridges, if they even have bridges at all; many have spring clips and no bridges.

Before you can pick a caliper that works for your actual needs, you need to understand the differences and decide what your specific goals are. If you don't know how the real world works, you'll decide that you want a light-weight endurance caliper, and sure enough, some skilled marketer will realize how gullible you are and sell it to you at a staggering price. It won't actually deliver, but regardless, you'll put the stickers on your car and pretend it does.
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      04-09-2013, 12:09 AM   #39
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Originally Posted by JAJ View Post
Before you can pick a caliper that works for your actual needs, you need to understand the differences and decide what your specific goals are. If you don't know how the real world works, you'll decide that you want a light-weight endurance caliper, and sure enough, some skilled marketer will realize how gullible you are and sell it to you at a staggering price.
Well...

That's where you guys come in. I know I want to minimize weight, have easy pad changes, long pad & rotor life, good feedback & modulation, and low entry cost, but performance and reliability are both paramount and non-negotiable. So, I come to boards like this to read about others' experiences and try to get a feel for what tradeoffs can be made and how they weigh against my priorities.

I have a technical background, but I'm not a materials scientist and certainly not a brakes specialist. So, while I can follow technical discussions and arguments, I'm not & will never be at a level where I can make good decisions about braking systems & products in a vacuum.

Plus, I have a sneaking suspicion that most of what's known about brakes, and indeed many areas of automotive engineering, has been learned through trial and error. That's one reason I'm biased towards more experienced firms, especially in areas where it really counts. Likewise, I value actual firsthand experiences of real-world users far above spec sheets.
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      04-09-2013, 12:18 AM   #40
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Does anyone happen to have good info on whether the AP Racing kit fits Apex ARC-8 18x10 ET25 wheels? Those are my track wheels (both front & rear). I have a set of 18x10 ET25 EC-7's for street
I got a reply from APEX (I submitted this question to them, through the contact form on their website, Sunday). They said they tried the template on AP Racing's website (I included a link) and verified that it should clear both wheels.

I'm about 99% sold on this kit. So, I'll probably be trying it, myself, soon enough. I'll update the BBK - Wheel Fitment Compatibility Database thread, if/when I do (it already lists the 18x10 EC-7).

BTW, that's less than one-business day turn-around time from APEX. And I already own those wheels, so it's not like they had any direct incentive to be so prompt.
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      04-10-2013, 12:39 AM   #41
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Okay, now that I've verified wheel clearance and finished reading the entire "E92 M3 AP Racing BBK Review (long)" thread, I think I'm ready to pull the trigger. Between that and all the other posts I've read about it, I've seen nothing but praise.

Does anyone know of a reason NOT to buy the AP kit? Have there been any bad experiences with it?
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      04-10-2013, 08:28 AM   #42
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Does anyone know of a reason NOT to buy the AP kit? Have there been any bad experiences with it?
I have to say that the AP kit has been the most trouble free mod I've done to my car. They've gone on the car and just worked. And I've tracked them on 108 degree track days where the track surface temp is 130 degrees---no issues. 10 laps in and they feel the same as lap 1. Again, I'll say----don't screw around with cheap brake fluid. Get SRF. It's also interesting to see how an r-comp like Hankook TD can really work the brakes even harder with that extra grip. And again, the brakes don't care. They come in to the pits literally with the pads smoking hot!! Smoke is pouring from the brakes---still no change in performance. The consistency is pretty amazing.

I just want to say again that pad choice for the track can lead to a WIDE arrays of "feel". I can't emphasize this enough. If you don't like the "feel", switch to another pad. It's amazing how different an experience different pads can give you.

When you get the kit, make sure to do a proper bedding procedure for the rotors. btw, the front rotors are generically listed as 36mm thick when new, and there's a 2mm wear range. So, it's commonly said that the rotors are worn by 34mm. This is not quite accurate. The 368mm rotor is ACTUALLY 35.6mm thick when new. There still is a 2mm wear range, so you should replace them at 33.6. One might say, who cares about 0.4mm. Well when your front rotors are $900 and you only have 2mm of wear, 0.4mm is almost 25% more life from the rotor!! (Btw, what I'm saying has been verified by Stillen.) Stillen looked into this discrepancy. Hehe AP's response was basically, "hey, we're not on the metric system over here in England!" Turns out 35.6mm is EXACTLY 1.4 inches. Anyway, just thought you might be interested in that tidbit.

Good luck! I'm curious to hear what you think if you get them.
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      04-12-2013, 06:49 PM   #43
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Quote:
Originally Posted by M3SQRD View Post
Why, because you have to remove the caliper? On my old e46 M3 track prep'd car I had AP calipers with a removable top bridge, and on my e92 M3 I have Performance Friction calipers with a fixed top bridge. It only takes me 5 min longer to swap pads on the Performance Friction calipers, however, a portion of the extra amount of time is due to having to swap four pads per caliper instead of two pads per caliper.
yes, removing it over and over is a PITA, imo, versus just removing a bridge.
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      04-12-2013, 10:29 PM   #44
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yes, removing it over and over is a PITA, imo, versus just removing a bridge.
I have monoblock Alcon calipers on my A4. While I don't really mind removing them for pad swaps, I consider it to be an advantage if a design has a removable bridge (though it's really the idea I'm reacting to, since I've never seen or done a pad swap on such a caliper). My feeling is that it's probably a bit over-hyped, but probably does save a couple minutes and I've actually lost track time while swapping pads. That said, I wouldn't buy an inferior product just for that feature.

Basically, if the Brembo GT caliper had a removable bridge and the AP caliper didn't, it might be enough to have me leaning in that direction. But I wouldn't consider Stop Tech Trophy, no matter what. [Call me a ST hater, if you like, but I've decided they're not for me. Let's not start a flame about this.]
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