willeywilson

Hi All,

I am looking for some help on ( BBK ) brake setup, I have searched extensively and have come up against some analysis paralysis and need input from strangers on the internet.

I have a 300+ HP NB that sees more track than it does road. I am not a heavy braker, (my local track is the nurburgring where you always need to leave a margin of error on tourist days) but in my search for more safety and to not be out-braked by the car in front, my SVT / Sport brakes need upgrading.

I have kindly been sent a BBK consisting of stoptech 11.75" x 1.25" (298x32mm) curved vein rotors and C43 (ST43?) Calipers (379.G31.34C4 32+38mm pistons). The kit looks great! Unfortunately it will not fit under my JB 500 15x9 wheels. The outer bolt and caliper hit the inside of the rim with about 5mm left to go before the wheel is seated on the top hat. I cannot grind enough of the bolt/caliper away without it posing safety concerns.
I can't / will not run a 5mm spacer due to fouling the body work.

My options that I need help with are as below:-
1 - My supplier can provide an 11.1" x 1" (282x25mm) rotor and associated bracket that should allow the caliper to clear the wheel. This sounds fine, but I have major FoMo of going to a narrower disc which is also pillar vein instead of the curved vein. It's smaller, thinner, and less efficient at cooling.
2 - I can reverse engineer the kit and make it work with the PFC 11.2" x 1.25" (284x32mm) rotor and make my own brackets and top hat. The problem with that is those rotors are much more expensive, time and effort to design & make my own brackets, and the big question - is the 1.25" really worth it over the 1" rotor?
3 - I send the lot back and purchase the Goodwin Racing v5 BBK with PFC 11.75" x 1.25" with the Wilwood calipers (which was my original direction before being sent these). I have checked the template and it appears to fit in my wheels but the Wilwood Dynapro with a 12mm pad and no bridge bolt appears to be significantly inferior to the Stoptech C43 with 20mm pad and bridge bolt. (plus the stoptechs are more aesthetically pleasing).

Whilst I am sure any of the options will be a significant upgrade to the sport brake package I currently have, I don't want to spend a lot of money on something that isn't extracting the most efficiency out of the package.

Intended pads are PFC11 although Hawk DTC-60 is what was supplied with the current kit.

Any (constructive) input greatly appreciated.
FYI I am based in Europe and cannot get full access to the kits you have stateside.

Thanks

rdb138

iTrader: (1)

I just upgraded my StopTech STR 42 kit (11.75"x0.81") rotors to the AFCO caliper and (11.75" x 1.25") rotor & use PFC11 pads. I would stick with the setup you just bought, vs the other options. A lot more options on rotors, but if you duct air to the brakes, any of those options should work for you. (My STR42 kit was pretty close to working without ducts & I'm at 300hp)

I bought some 15x9.5 FreeForms to clear the brakes, but wanted to continue to use my 15x9 Storms so had the same issue you do. To use the 15x9 Storms, I purchased 10mm spacers to make them clear. That was the "Cheap" & "Quick" answer for me. I plan on purchasing some 15x10 wheels over the winter, but for now, this was the easy button. I know some people get excited about spacers, but a lot of people use them successfully as long as you keep them reasonable.

Hope this helps & Good Luck!

willeywilson

Thanks for that. To be honest with Sport calipers and DTC-60 (or-30 can't remember) I don't get any noticeable brake fade, but I also can't stop as quick as the 'Porsche' in front thats suddenly seen yellows for example. And I want an extra level of margin given the visibility ahead is severely reduced in an MX-5 / Miata when behind something modern. Plus if I venture out to an actual track day I will be stamping on the brakes, unlike the nurburgring nordschleife and probably cook them quite quickly.

Interesting your setup was almost working on the 0.81" rotor. I have ducts (bumper and dust shield) but not actually connected the two together yet. Whether that means an 11.1" x 1" rotor is comparable to a 11.75" x 0.81" rotor however is still a question.

I have seen the AFCO calipers in the BBK threads, they kind of look like they may just about fit my wheels (no outer bolts, more refined shape) whats your take on outer diameter clearance of the AFCO v the ST42 (which looks the same as a C43) to your wheel?

Whilst your solution is a good one, its not really feasible for me at the minute. I have 6 x brand new Joengblood 15x9's which fit absolutely perfectly, I have barely any room left to the spring and maybe 1-2mm left before the already rolled, pulled and chopped fenders need more - and I've just repainted the entire car - so not really an option to add spacers or wider wheels.

I am hoping one of the gurus ( @OGRacing @emilio700 @Bronson M ) will see this and tell me that the Wilwoods in the GWR V5 BBK are **** and go with 11.1"x1" & Stoptechs - which at this point is the easiest option.

Cheers

rdb138

iTrader: (1)

About 3 years ago when I bought my kit, 11.75" X 0.81" rotors were the biggest anyone offered. It does fit behind a 15X9 wheel & with ducts it would be able to handle 30 minute HPDE track sessions in 90+ degree heat outside on a 300hp car. I would GUESS that the 11.1" X 1" would have a little less stopping torque, but would probably have the same mass to shed heat with compared to the 11.75" X .81". It might be able to cool a bit better since there is more space between the vanes, but again, I'm guessing. The 11.1" X 1" is probably going to be a tight fit with your Joengblood 15x9. Those aren't very "roomy" wheels being concaved for brakes (although the do look really nice!) That quarter inch difference in width only gives you 3mm more on each side to work with unless you can also change the width of the C43 caliper too.

The AFCO calipers are made by StopTech. They are pretty big and my guess is they are the basically the same size as the C43. (Here is a picture of mine next to the STR42 caliper to give you an idea of size difference...The AFCO mounts differently thus why it doesn't sit flat making it look even bigger, but its definitely a bigger caliper either way.



That extra half an inch difference in the rotor makes a huge difference with your wheel fitting or not too. (and the C43 holds a 20mm pad vs the 16mm the STR42 fits) I believe Trackspeed made a kit using a Willwood Superlite caliper that is the Willwood version of the C43 (or more accurately, the C43 is StopTech's version of the Superlite Willwood.) with a 11.75" X 0.81" and it fit under most 15X9" wheels.

Guessing you have an NA. My car is an NB, so I have a little more room under the wheel wells. Another option (although it sounds like you really like your Joengbloods, so maybe not) is the Konig FreeFrom wheels. They are 15X9.5 and they fit under an NA with just the roll and pull like you already have done. Here is pictures of mine with no spacers. Huge amount of room with this wheel.

FreeForm & BBK


LOTS of clearance between the caliper and the spokes with the FreeForm:


Sorry I don't have any great ideas. Unfortunately the Joengblood 15x9's aren't a very roomy wheel. I was going to suggest the SuperMiata BBK with the 1.1" rotor, but they require a 5mm spacer for your wheels. 3" ducts and smaller rotor & caliper is probably your best answer at this point...unless you change out the wheels. I know that isn't the answer you wanted.

Holler if you need a different picture or some measurement.

emilio700

iTrader: (3)

Keep the brakes. Get new wheels. At 300whp, you should be on 10's anyway.

willeywilson

I'm surprised about the wheel comments to be honest. I have an NB, mild pull, rolled and cut fenders and I don't see how I could get wider wheels in there without changing suspension.
I have Meister Rs, I cannot remember the spring diameter, but the inside of the tyre basically rubs on the sock / spring and the outside of the tyre is a couple millimetres clear of the fender, so going to 10's at this point is unfortunately out of the question. I should note that this is not a competitive track car. It's a 'clubsport' boosted gold NB that forces its way past M3s and Porsches on what is technically a "toll road", its not all out track focussed. But when I upgrade things I don't want to be wasting my money on something less efficient.

The 11.1 x 1" looks like it would clear. The only actual issue with the 11.75 x 1.25 is the inner diameter of the wheel. If I mock this up on the bench and offset the centre of the disc & caliper I can get it to clear the spokes. i.e. an 11.1 or 11.25 x 1.25" should work. The problem I see is the smaller 1.25" are significantly more expensive than the 11.75" x 1.25" rings. And then its a toss up of if the extra $600 on smaller rings is even worth it over a 1" ring. If that makes sense? I guess I've been given the answer... I just don't like it

You might be able to see in the photos below. with approx a 5mm gap before the wheel was fully seated, the caliper was clashing with the inner diameter of the rim & weights.


To get decent clearance I would have to grind a significant amount of the bolt head away, resulting in a bolt that would probably break if I ever needed to unscrew it.






circa 5mm gap before wheel was fully seated








And please don't give me **** about having a 245 on a 9" I know I should have gone 225, I'll fix that when these wear out.

Thanks

willeywilson

I've been looking through the offerings from Wilwood, 949, Goodwin, AP etc trying to piece a kit together that uses an 11.75"x1.25" rotor and a 20mm pad.
What I can see is that the C43 caliper is ginormous really, I didn't realise it was bigger than the ST-43R which appears to be about the same size as the Afco F88 & Superlight as alluded to above.

Using the templates from 949 the Afco F88 has about 1mm of clearance to the wheel, I can see why they recommend a 5mm spacer, but maybe I could get away with 1-3mm spacer and make this option work without destroying my fenders. Although the Afco is now hard to find.
APs caliper range is vastly reduced and nothing appears to work
Out of Wilwoods full list of calipers, the lug mount Superlight as used in the SuperMiata 1.1" kit is the smallest caliper (OD) that works with a 20mm pad, but it clashes with the ID of the wheel by 2-3mm and requires a 5mm spacer.
The Dynalight v5 option from Goodwin works by a country mile, but thats because the Dynapro is thinner and only takes a 12mm pad...
My supplier is suggesting to drop to the ST-43R with a 11.1" x 1". This caliper also appears to use the same 7420 pad. But I cannot find CAD or an outline of an ST-43R caliper to check if it is marginally smaller / the same size as the Afco F88 and would work with an 11.75".
I was wondering if @jpreston had the CAD to the ST-43R caliper which he might consider sharing so I can check this out before having yet another kit shipped to me?

It appears I can make any sized kit work, its just a trade off of:-

• greater pad volume (20mm v 12mm pad)
• great rotor volume (11.75x1.25" v 11.1x1")
• perceived caliper quality (Stoptechs w/ bridge bolt v Dynapros w/ W Clip)

My head is saying to go with the smaller disc and bigger pad volume and duct the **** out of it.

OptionXIII

The only current source for an Afco F88 1.25" rotor caliper with the right piston sizes for a Miata is Supermiata in their complete kit. They bought the remaining stock that the F88 1.25" kits were based on. Their page for the kit indicates the F88 is basically a private label version of the lug mount ST43 caliper.

You can still get F88s with the same size pistons for 0.81" rotor, but that may be thinner than you want to go. Sounds like you have the capability to make your own brackets and hats, but Bronson at Brofab has a setup ready to go. I'm working on my own version of this setup, it should clear the FM Kogeki 15x9 wheels with lots of room to spare based on templates available online.

willeywilson

Thanks for the info. I was hoping you would have some input actually, as I have seen a lot of your posts with the pressure ratios etc.
Given I am in europe, getting hold of anything stateside is a bit complicated / expensive so it might be that the Afco's are a no go, but they are the only thing at the minute that seems feasible, unless I try the ST-43R calliper.
I may bite the bullet and get the 11.1" ST-43R based kit shipped to me and then see if I could step it up to an 11.75" kit at some point in the future. At the minute I am on stock sized SVT brakes and calipers and desperate for replacement pads...
I have seen Bronson's work and am a fan, I would like his front hubs when mine eventually die. I have only just stepped up to the 9" wheel so not had any issues with hubs up until this point.
My inexperience with brake systems means I am trying to have all 3 options when I can only realistically choose 2.

emilio700

iTrader: (3)

FWIW, our 1.1" rotor in the Superlite kit is the same mass as the 1.25 we offer in our F88 kit. Superlite kit is more compact than the F88, better wheel clearance. Both readily available from Coleman for about the same price. Both accept the same duct kit.

so..
1.1 Superlite more compact but limited to our custom rotor unless you have you own made.
1.25 F88 has many OTS rotors but is less compact.

willeywilson

I hear what you're saying Emilio and thanks for the info on the kits. 'Compact' isn't as much my problem rather than the 'shape' of the caliper. Assuming the top hats of both of your kits are the same thickness, it looks like the following - grey being Afco, Orange being superlight. The red arrow indicates where the template contacts the knecking down of the wheel barrel on my 9's.


As per the instructions and others' recommendations, this could easily be fixed with spacers (if I had the room left in my fenders, or a liberal bit of grinding to the caliper). That 1mm difference on the corner between the Superlight and the Afco results in contact or a 1mm gap (which I know needs to be more but its a start).
I have no clearance issues to the spokes or centre of the wheel so the Afco whilst technically 'bigger' is actually more packageable in my setup.

Out of interest, in your experience, what should be preferred - the greater pad volume or the greater disc diameter / thickness? If ultimately the 11.1" kit I can source locally without import is going to be within a few percent of the 11.75" kit I'm struggling to fit, I may aswell prioritise pad volume hadn't I?

Thanks for tolerating the questions

emilio700

iTrader: (3)

Rotor mass more important than dimensions
Diameter = torque
Bigger pad volume runs cooler than lower volume
Cooler pads last longer and spend more of their life in the flatter part of their torque curve

For short term brake fade mitigation, I think rotor mass wins over pad volume but its nearly a toss up imo.