AP Racing brake systems in development

[Ro_Ja]

I was actually researching information on rear brake upgrades today and found this:

http://stoptech.com/technical-suppor...brake-upgrades

I'm a noob when it comes to the technical stuff, but I found it an interesting read. Visually, it'd be nice to have a rear kit to balance it out, but in regards to function, you theoretically should be fine with lines and pads (and some kind of matching rotor? (so you don't go from seeing a nice j-hook or drilled setup in the front to a plain ol' blank disc in the rear lol). This kit maintains or is close to stock brake bias, so it seems there's no real need to offset any changes with a rear kit. Right?

[Matt Andrews]

Originally Posted by ImAwesome

for me upgrading the rears just helps keep the factory distribution, if you take into account total swept area, proportioning valves, piston sizes, etc.

I don't think this reasoning holds water. If you are changing the front brakes with a kit designed to keep the same stock braking proportion, then changing the rear would in theory need to have the same braking proportion as the stock rears.

[Dave-ROR]

Originally Posted by Matt Andrews

I don't think this reasoning holds water. If you are changing the front brakes with a kit designed to keep the same stock braking proportion, then changing the rear would in theory need to have the same braking proportion as the stock rears.

100% Agree. You beat me to replying to that, but this kit was definitely designed to keep the stock balance already.

[RYU]

Does Essex recommend rear brake bias adjustments via pad compounds if one was to keep the stock rears? Or do they recommend, for example 1 for 1, meaning if you use Hawk HP+ compound fronts they would recommend the same for the rears?

[JRitt]

Speaking from my limited personal experience having fixed calipers on all 4 corners improves pedal feel and modulation. Better heat dissipation is also a given. Performance improvement? Maybe only marginal in this car.

Would like to hear thoughts from Essex on this.

Okay...lots going on here about rear brakes. IMO, a complete rear brake kit on the FT86 would certainly tend more towards an aesthetic upgrade, rather than a performance improvement.

1. Adding a complete rear brake kit would indeed improve pedal feel and modulation. There is certainly a lot less compliance in a fixed racing caliper and SS lines vs. an OEM slider and stock lines. How that translates to 'feel' is difficult to quantify however.
2. From a strict performance perspective...the biggest difference on a rear setup would likely be weight as Matt said. As Dave pointed out, the OEM rear brakes on these cars are not exactly working overtime. If you look at certain platforms (the base 350Z comes to mind), the rear brakes are woefully undersized. The disc is rather small, and the pads are the size of a postage stamp. On that platform, it's common for people to have heat-related problems with stock brakes on the track. Thus far, that has not been an issue at all on the FT86. The OEM rear pad and disc on these cars seem to have enough thermal mass to not really break a sweat under heavy track use. What we could do, is see how small we could actually go on the rear, and pull as much weight out of it as possible using a 2 piston caliper and a smaller disc. The disc would be sized at the minimum size possible, while still having enough thermal mass to get the job done. To optimize it however, would mean getting rid of the parking brake. That is an issue for some people, while others don't view the parking brake as a requirement. Keeping the parking brake would mean you'd need a hat/disc large enough to clear it, which isn't optimal. Keeping the parking brake would leave a lot of weight savings on the table.
   • The OEM rear caliper and bracket weigh 5.8 lbs. The OEM rear disc weighs 13.2 lbs. (total=19 lbs. per side)
   • We have potential two piston rear caliper candidates that weigh in the neighborhood of 3-4lbs., and discs that weigh 8-9lbs. (13 lbs. total per side)
   • I can therefore conceivably see shaving 5-6 lbs. per rear corner.
3. Our front systems were designed to mate up to the OEM rear brake output. To do a proper rear setup, you just need to mimic the OEM rear torque output. That means any combination of caliper and disc that matches the OEM rear torque output. The disc diameter and piston bore sizes are what we play with to dial it in properly (the friction coefficient of the pads is the other factor that affects brake torque, but we'll assume that you'd be running the same pads front and rear like a stock setup).
   • For example, if we went with smaller diameter disc than stock in the rear, you'd need greater piston area in the rear vs. stock to precisely offset the decrease in disc diameter. Likewise, if you kept the disc diameter the same as stock, you'd have to use caliper piston sizes that match those of the OEM calipers. If you went with a larger diameter disc than stock, you'd use a smaller overall piston area than stock. As you move the caliper further out on larger diameter discs, you're increasing the effective radius/lever arm and resulting torque output. You counteract that by taking the piston sizes down to compensate. Hopefully that makes sense.
4. Cost- Because the rear components we have at disposal are not used as broadly or ordered as frequently, our cost is much higher. Therefore, any rear solution we would come up with would almost definitely cost more than our front Sprint system ($2,099). The cost of a four wheel system would be pushing $5,000.
5. Aesthetics- Yes, four matching brake corners look better than just the fronts.

Summary
A complete rear brake system on these cars for performance purposes starts to get into the realm of diminishing returns. The OEM rear equipment represents itself fairly well under track conditions as it stands. If optimized, you'd save weight, but at a substantial cost, and you'd lose the parking brake. The return on investment in the rear would not be nearly as great as it is with our front systems, which IMO are bordering on a no-brainer if you track your car. You lose nothing, and gain a broad and deep array of benefits.

As a complement to our front system, I'd recommend adding the matching Spiegler rear SS lines and quality pads (to match the front). You will gain greater feel with the lines and pads (and heat capacity/torque output with the pads), and it will only cost a few hundred $.

If you are more focused on Aesthetics and street driving, will be offering at least one complete four wheel brake system from AP Racing. The main one will have a newly designed six piston front caliper (that looks killer from what I've seen of it), and a four piston rear with a one-piece disc. That system will look gorgeous, and still offer performance increases over stock. They will fill an 18" wheel up beautifully, have dust seals, and a painted finish which is better for winter environments, etc.

[Dave-ROR]

Originally Posted by RYU

Does Essex recommend rear brake bias adjustments via pad compounds if one was to keep the stock rears? Or do they recommend, for example 1 for 1, meaning if you use Hawk HP+ compound fronts they would recommend the same for the rears?

I'm beating Jeff to the reply!

They suggest the same pads front and rear. I'll be running AP C300 F&R for the track and AP S100 F&R for the street.

[JRitt]

I believe the car set FTD at the autocross and ran 2:00 laps on the Roval this weekend during the speedventures / FRS86 meet in Fontana. Great modulation, great heat dissipation.

[JRitt]

Does Essex recommend rear brake bias adjustments via pad compounds if one was to keep the stock rears? Or do they recommend, for example 1 for 1, meaning if you use Hawk HP+ compound fronts they would recommend the same for the rears?

To begin with, we recommend using the same front and rear pad compounds. Some people like a little less mu in the rear, but same front and rear is a good starting point, and you can tweak from there to taste.

The Ferodo and AP Racing rear pads will not be immediately available when the first production kits are delivered, but they will be within a couple weeks of our systems' launch. The car will be drivable with OEM rear pads and our front kit with race pads, and it won't present any problems. It just won't be optimized.

If you want a matching front and rear immediately, we can get Endless pads in any of their compounds. From talking with Endless, MX72, ME22, or ME20 would all be good options depending on what you want.

[gmookher]

so I have the ferrodo 2500s up front. is there a ferrodo option for the rear? is there a 3rd party you all recommend for the back end?

[JRitt]

We cant wait to get these on our BRZ this week !

JEFFFFFFFF !

Same wheels but in black are on the way ! Just need the BRAKES ! lol

Patience...patience!

Production parts update:
I got an email roughly 2 mins. ago from engineering...the finished Endurance System hats have passed QC inspection and they are good to go. Sprint hats are being bolted up to discs as I write this.

Sprint System brackets are being anodized this week. Endurance system brackets are still on the mills.

If all goes as planned, we should start shipping production Sprint Systems out late next week. I'd guess 2-3 weeks before the Endurance Systems start going out. Thanks for your patience to all of our pre-order customers.

[JRitt]

so I have the ferrodo 2500s up front. is there a ferrodo option for the rear? is there a 3rd party you all recommend for the back end?

Ferodo DS2500 in the OEM rear shapes are supposed to be here within the next few weeks. We recommend those if you're running DS2500 front. The rear pads were a new design. All of the pad manufacturers are scrambling to get them built and delivered. The smaller pad manufacturers are a bit more agile, thus we're seeing their pads enter the market first. The huge and foreign manufacturers (like Ferodo, which is part of Federal Mogul), are a little slower to respond. Also keep in mind that the European companies didn't have access to these cars as early as Japan and USA did.

[Dave-ROR]

Originally Posted by JRitt

Ferodo DS2500 in the OEM rear shapes are supposed to be here within the next few weeks. We recommend those if you're running DS2500 front. The rear pads were a new design. All of the pad manufacturers are scrambling to get them built and delivered. The smaller pad manufacturers are a bit more agile, thus we're seeing their pads enter the market first. The huge and foreign manufacturers (like Ferodo, which is part of Federal Mogul), are a little slower to respond. Also keep in mind that the European companies didn't have access to these cars as early as Japan and USA did.

I'm somewhat surprised they never made pads for the 2010+ Legacy GTs, but I guess maybe not that many people track their Legacys...

[uncivilised]

Hey JRitt,

Would you think there can be a difference in brake balance if this kit is used on the 86 with the smaller rear brake setup, like the base spec GT model? (australian model)

GT model has solid 286mm x 10mm rear brakes.

[JRitt]

Originally Posted by uncivilised

Hey JRitt,

Would you think there can be a difference in brake balance if this kit is used on the 86 with the smaller rear brake setup, like the base spec GT model? (australian model)

GT model has solid 286mm x 10mm rear brakes.

Will there be a difference? Maybe. There are a number of question marks here since the front and rear discs on the GT model are both different vs. the USDM spec cars.

1. We need to verify the precise diameters on the GT Model discs. My data shows GT Model as front= 277mm (vs. 294mm on the USDM cars). I have GT model rears as 286mm (vs. 290mm rear on USDM cars).
2. Front pads are the same shape, which leads me to believe that the front calipers are likely the same. We don't know that though. We really need to verify front piston diameters on the GT model.
3. Rear pad shape is different on GT and US spec cars. We need to know what size pistons the GT model has in the rear calipers.
4. We need to know if the master cylinder in the GT model is the same as US Spec cars.

Here's my guess on the situation based on the above:

1. The master cylinder is the same on all models
2. The front calipers are identical on all models
3. The rear caliper pistons are a different size on the GT model vs. the USDM cars


If you can get me all of that info I'd be happy to run the calculations and see what brake bias looks like for our front brake kit on a GT model.


The other option (assuming the master cylinder is the same), would be to just put a US spec OEM rear brake setup on the car and call it a day. You'd benefit from the larger vented discs and pads on the track anyway. These will be a dime a dozen soon, as more cars are crashed and parted. Also, I believe the Legacy 2.5 GT 2010+ has the same rear brake setup as the US spec BRZ.



Thanks.