AP Racing's own Competion Brake Kit. Feedback?

[Estragon]

Is anyone running the AP Racing Factory Competition Kit put together by AP Racing themselves in the U.K.? Any feedback?

http://www.apracing.com/product_deta...60-1001np.aspx

http://www.apracing.com/product_deta...02-1003np.aspx

Would like to know how this kit compares to the Essex AP Racing kit and others.

[MasterP]

It looks like AP took Essex's kit and basically made their own.

[Estragon]

Except that AP Racing's predates the Essex's version considerably. And there are notable differences:

The AP kit uses 368 x 36mm, 72 vane front discs and takes 25mm thick pads, while the Essex kit has 355 x 32mm, 72 vane discs and uses 18mm thick pads. So the AP kit will have significantly more thermal capacity and durability.

The rears have the AP kit with 352mm vs Essex's 340mm. Pad thickness is similar.

[8k3]

Goodness so many variants of AP; Stillen, Essex, AP themselves, ...

[JAJ]

The AP kit is a racing-only kit. The calipers take 25mm thick pads and there are no anti-rattle springs or dust seals. It's basically a direct competitor to the Brembo Race products. It's not a good choice unless you're actually racing.

[jritt@essex]

Here are the differences between the Essex Designed Competition Kit, and the AP Racing Factory Competition Kit. We'll focus on the front kit as an example (differences in the rear are similar):

Calipers

• The Essex version of the CP5X60 caliper uses an 18mm pad instead of 25mm thick.

• The Essex version of the caliper is roughly an inch narrower.

• The Essex version calipers have a more advanced piston design (domed-back, ventilated SS) vs. (standard SS).

• The Essex version calipers have a 4 lb. AKB spring rather than a 7 lb. spring.

• The calipers we're using weigh 1 lb. less each.

• Essex uses a machined logo rather than painted.

Discs

• Essex uses a 355mm x32mm disc rather than a 368x36mm

• Essex uses J Hook racing slot pattern vs. 8 groove

• Essex setup is float-in-disc rather than float-in-hat

• Essex disc weighs 2-3 lbs. less each

Brake Lines
Essex comes with Spiegler SS line. AP Factory comes with Goodridge.

Wheel fitment
Obviously with the smaller front disc and the narrower calipers, the Essex kit will have more wheel options that will clear it without a spacer.

Price/spares
I can import and sell the larger AP Racing Factory Kit, but it would be about $1,000 USD more per axle vs. our Essex version. Our spare 355mm discs cost about half of what the 368's cost.

Lead Time
Essex kits are in stock and ready to ship in the USA. AP kit is standard 6-8 week lead time.

Both kits are excellent options, and we took a long look at the AP Factory Kit specs before deciding on what we wanted to include in our package. As j.lecram mentioned, the AP Factory Kit will have more thermal mass in the pad and disc. Ultimately we decided that the slightly smaller and lighter package we are offering would be ample for our target customers' intended usage (typically 20-40 minute track sessions/sprint races). By going with the slightly smaller components we could bring down corner weights, reduce consumable disc costs, and substantially increase wheel fitment options. By domestically producing the hats, brackets, brake lines, and hardware, we were also able to knock a large chunk off the retail price and make the kit both more competitively priced against rivals and more attainable for the average enthusiast. During the process we also took the opportunity to tweak a few things, like upping the specification on caliper pistons, adding the J Hook slot pattern, and using the float-in-disc attachment mechanism (which tends to wear longer under heavy track use, requiring fewer long-term disc hat replacements).

I suppose I look at our Essex version Competition Kit as sort of a V2.0 of the Factory Kit...an evolutionary technological advance, wrapped up in a slightly smaller package, at a lower price, tailored more closely to the specific needs of our USDM customers. Who says we can't learn anything from Apple or Microsoft!?!

Again though, if anyone wants the larger Factory Kit, we are happy to import and sell it to you. Thanks!

[Estragon]

Originally Posted by JAJ

The AP kit is a racing-only kit. The calipers take 25mm thick pads and there are no anti-rattle springs or dust seals. It's basically a direct competitor to the Brembo Race products. It's not a good choice unless you're actually racing.

Both kits come without dust seals and are primarily track oriented kits that with proper precautions can safely be run on the street.

[rantarM3]

Originally Posted by j.lecram

Both kits come without dust seals and are primarily track oriented kits that with proper precautions can safely be run on the street.

Other than street pads, could you elaborate on what "proper precautions" would entail?

[The HACK]

Originally Posted by rantarM3

Other than street pads, could you elaborate on what "proper precautions" would entail?

Caliper pistons without dust shields should be rebuilt regularly. Service intervals on pistons without dust shield are typically much shorter than pistons WITH dust shields.

Race calipers that's used ONLY for the street should still follow the rebuild intervals. Unlike street calipers that has dust shields that probably won't need a rebuild for, mostly likely, quite a long time.

[jritt@essex]

Caliper rebuild intervals are purely a function of usage conditions. There is no inherent reason why a race caliper needs to be rebuilt more frequently than a street caliper when run on the track, or in mixed track/street use.

A race caliper will actually require far less servicing than a road car caliper if it ever gets driven on the track. Good race calipers have high temperature seals designed to handle the temps of track abuse. Most street calipers do not. As such, the seals in a street caliper are more likely to rot/crack/split with extreme heat. All else held equal, a proper race brake system is also able to run cooler overall on the track than a comparably sized street system. The discs are optimized for more airflow, which reduces temps. Stainless steel or titanium pistons in a race caliper also run cooler than the aluminum ones in a street caliper. That means less wear and tear on the brake components, as well as the components surrounding them (wheel bearings, ball joints, etc.). Finally, dust boots typically burn up very quickly under track conditions, as they're not designed for such. They crack and disintegrate. Once that has happened, they are completely useless. Dust boots and racetracks are not friends.

Dust boots come into play on a car that is never driven on the track, and commonly driven in inclement weather. If you drove around all year on the roads in southern California, there's absolutely no reason a race caliper would need to be rebuilt more frequently than a street caliper. If you're driving in Wisconsin winters, then yes, the race caliper will likely need more attention than the street caliper.

Originally Posted by The HACK

Caliper pistons without dust shields should be rebuilt regularly. Service intervals on pistons without dust shield are typically much shorter than pistons WITH dust shields.

Race calipers that's used ONLY for the street should still follow the rebuild intervals. Unlike street calipers that has dust shields that probably won't need a rebuild for, mostly likely, quite a long time.

[rantarM3]

Originally Posted by jritt@essex

Caliper rebuild intervals are purely a function of usage conditions. There is no inherent reason why a race caliper needs to be rebuilt more frequently than a street caliper when run on the track, or in mixed track/street use.

A race caliper will actually require far less servicing than a road car caliper if it ever gets driven on the track. Good race calipers have high temperature seals designed to handle the temps of track abuse. Most street calipers do not. As such, the seals in a street caliper are more likely to rot/crack/split with extreme heat. All else held equal, a proper race brake system is also able to run cooler overall on the track than a comparably sized street system. The discs are optimized for more airflow, which reduces temps. Stainless steel or titanium pistons in a race caliper also run cooler than the aluminum ones in a street caliper. That means less wear and tear on the brake components, as well as the components surrounding them (wheel bearings, ball joints, etc.). Finally, dust boots typically burn up very quickly under track conditions, as they're not designed for such. They crack and disintegrate. Once that has happened, they are completely useless. Dust boots and racetracks are not friends.

Dust boots come into play on a car that is never driven on the track, and commonly driven in inclement weather. If you drove around all year on the roads in southern California, there's absolutely no reason a race caliper would need to be rebuilt more frequently than a street caliper. If you're driving in Wisconsin winters, then yes, the race caliper will likely need more attention than the street caliper.

Pardon my ignorance but are there any other differences, apart from pad composition, lack of dust seals, and things of that nature, that constitute a "racing" only kit (i.e., not for street use)? For example, is the composition of the rotors different and better suited for track use such that a racing kit will not stop in as short a distance as a street or OEM setup during a cold panic stop?

[jritt@essex]

Originally Posted by rantarM3

Pardon my ignorance but are there any other differences, apart from pad composition, lack of dust seals, and things of that nature, that constitute a "racing" only kit (i.e., not for street use)? For example, is the composition of the rotors different and better suited for track use such that a racing kit will not stop in as short a distance as a street or OEM setup during a cold panic stop?

No worries. Some of the material composition is actually different. For example, racing calipers use stainless steel or titanium pistons typically. For an application such as F1, the actual caliper body is a special alloy that is stronger and lighter than a 'standard' aluminum alloy caliper'. In a proper racing disc the iron has special additives that make it more crack resistant, and better at withstanding high temperatures.

As for not stopping in as short of a distance, etc., no there aren't any factors that would make a racing/competition big brake kit any less functional or practical than a street system. Tires are what stop the car. The brakes are just changing the spinning energy of the disc into heat. Pad choice would have an impact on a cold panic stop if they were race pads designed only for high temp use. Sometimes that type of pad generates very little friction cold. The same would be true however, regardless of whether you put that pad into a stock caliper or a racing caliper.

To put it another way, no there isn't any magic going on with racing/competition brakes. They're simply designed to deal with heat better than street systems. They use advanced technology in terms of both design and materials to do so. They're no less effective when used in a pedestrian manner. They're typically more efficient, weigh less, and have a much higher performance ceiling when thrashed on the track since they were designed to handle that environment.

[dogbone]

@jritt@essex

Are the rotors on your kit AP-brand rotors? If not, where are they sourced from?

[jritt@essex]

Originally Posted by dogbone

@jritt@essex

Are the rotors on your kit AP-brand rotors? If not, where are they sourced from?

Yes sir. We only use authentic AP Racing heavy duty J Hook discs in all of our big brake kits. We buy them in large quantities directly from AP Racing in England.

[Estragon]

Originally Posted by jritt@essex

Here are the differences between the Essex Designed Competition Kit, and the AP Racing Factory Competition Kit. We'll focus on the front kit as an example (differences in the rear are similar):

Calipers

• The Essex version of the CP5X60 caliper uses an 18mm pad instead of 25mm thick.

• The Essex version of the caliper is roughly an inch narrower.

• The Essex version calipers have a more advanced piston design (domed-back, ventilated SS) vs. (standard SS).

• The Essex version calipers have a 4 lb. AKB spring rather than a 7 lb. spring.

• The calipers we're using weigh 1 lb. less each.

• Essex uses a machined logo rather than painted.

Discs

• Essex uses a 355mm x32mm disc rather than a 368x36mm

• Essex uses J Hook racing slot pattern vs. 8 groove

• Essex setup is float-in-disc rather than float-in-hat

• Essex disc weighs 2-3 lbs. less each

Brake Lines
Essex comes with Spiegler SS line. AP Factory comes with Goodridge.

Wheel fitment
Obviously with the smaller front disc and the narrower calipers, the Essex kit will have more wheel options that will clear it without a spacer.

Price/spares
I can import and sell the larger AP Racing Factory Kit, but it would be about $1,000 USD more per axle vs. our Essex version. Our spare 355mm discs cost about half of what the 368's cost.

Lead Time
Essex kits are in stock and ready to ship in the USA. AP kit is standard 6-8 week lead time.

Both kits are excellent options, and we took a long look at the AP Factory Kit specs before deciding on what we wanted to include in our package. As j.lecram mentioned, the AP Factory Kit will have more thermal mass in the pad and disc. Ultimately we decided that the slightly smaller and lighter package we are offering would be ample for our target customers' intended usage (typically 20-40 minute track sessions/sprint races). By going with the slightly smaller components we could bring down corner weights, reduce consumable disc costs, and substantially increase wheel fitment options. By domestically producing the hats, brackets, brake lines, and hardware, we were also able to knock a large chunk off the retail price and make the kit both more competitively priced against rivals and more attainable for the average enthusiast. During the process we also took the opportunity to tweak a few things, like upping the specification on caliper pistons, adding the J Hook slot pattern, and using the float-in-disc attachment mechanism (which tends to wear longer under heavy track use, requiring fewer long-term disc hat replacements).

I suppose I look at our Essex version Competition Kit as sort of a V2.0 of the Factory Kit...an evolutionary technological advance, wrapped up in a slightly smaller package, at a lower price, tailored more closely to the specific needs of our USDM customers. Who says we can't learn anything from Apple or Microsoft!?!

Again though, if anyone wants the larger Factory Kit, we are happy to import and sell it to you. Thanks!

The AP Racing kit, although it can be obtained with either 4 or 7lb anti knockback springs, comes standard without them. According to AP Racing, AKB springs are not really required in the M3 due to the inherent rigidity of its setup.

What are the repercussions, Jeff, of running calipers with AKB springs on a car that is also daily driven?

[jritt@essex]

Originally Posted by j.lecram

The AP Racing kit, although it can be obtained with either 4 or 7lb anti knockback springs, comes standard without them. According to AP Racing, AKB springs are not really required in the M3 due to the inherent rigidity of its setup.

What are the repercussions, Jeff, of running calipers with AKB springs on a car that is also daily driven?

The amount of knockback that occurs definitely varies by vehicle, and depends on the amount of deflection seen in the hub, bearing, spindle, etc. I personally don't know how exactly stiff the e92 M3 is in these areas relative to other sports cars and sedans. I have no hard data, only what I hear from customers. I tend to hear more about it from my Corvette customers than I do from my M3 customers. Many of them switch to the ZR1 spindles, SKF bearings, etc. to combat the issue. I will say that for the e92 M3, a 4lb. AKB spring should be more than adequate. The amount of cornering force also comes into play, which is why knockback isn't really an issue in street driving.

There are no major downsides to a light AKB spring as long as the caliper was designed for it. More specifically, the shape and material of the piston seal. The AP Racing competition six piston calipers used in both the AP Racing Factory Kit and our Essex Designed AP Racing Kit are designed to work with AKB springs. I posted about this the other day on a different forum, but it's applicable here:

As you're driving the suspension is constantly compressing, the disc is moving around laterally, etc., and the pads are being pushed slightly away from the disc. Think of the seals in the caliper as a spring or hinge attached to the side of the piston, rather than just a ring through which the piston slides. In the AP Racing competition calipers under discussion, the groove the seal sits in isn't a square cut groove. It has angles. When forces push the piston in or out there is friction between the outer piston wall and the seal. The seal distorts a bit...visually, think of it like this:

A caliper piston sliding out to the left would make the seal look like this (the slashes are the seals on either side of the piston):
/
---
---
\

As it slides back in to the right, the seal does this:
\
---
---
/

There is a certain amount of tension or friction that needs to be overcome before the piston even starts moving through the seal ring. That tension/friction keeps the piston from dragging on the disc once the pistons are pushed back into the bores by the disc/suspension movement.

When AKB springs are added, a little more force is required to push the pistons back into their bores than would be required without them, and the spring's unloading after being compressed pushes the piston back to 'neutral.'

So all you're doing with the proper seal and spring are trying to keep the piston in the 'neutral' position, not pressed against the disc. I think that's where a lot of the misunderstanding occurs. The piston is still able to slide almost freely in either direction, but a bit of friction or tension needs to be overcome initially to get it moving in either direction. The seal offers that first bit of friction to limit movement, and then the spring provides additional resistance. Therefore, AKB springs don't have much of an impact on a car being driven on the street, as long as the calipers have a seal designed to work properly with them. The brakes won't drag, create additional or unnecessary wear, etc.

Typically in street driving, the lateral forces aren't as great as you'd see on a racecar on slicks, nor are they sequenced as they would be on a track. If you go through a series of S turns on a track on slicks, you're quickly loading the disc back and forth, causing deflection in all of the components described above, and ratcheting the pistons back into the bores. That's when you usually see knockback. You go through a series of turns, hit the pedal, and have to take up all the slack to get the pistons back to the disc. In street driving, you take a slight left at low speed and lateral load...drive straight a while...make another left...come to a stop, etc. It's rare that you'd be going left, right, left, right at heavy lateral loads without touching the brakes.

All of that sounds nice 'on paper,' but the proof as they say, is in the pudding! To date we've sold hundreds of kits with AKB springs in our Essex Designed Competition Kits, and I've yet to have a single complaint about the springs, dragging brakes, excessive wear in any way related to the springs, etc. It's just not an issue. Since that's the case, I don't really see any reason not to use them if they're available. You get their benefit, without any major downside.

Hopefully that all makes sense and is helpful.