Big Brake fun
 

We're exploring some different brake options for production kits we will offer as well as one-off kits for our S1 Supermiata build, "Vegas". This thread may ramble a bit but I wanted to show what we're doing as we go along.
We just received a pre-production Stoptech ST42 based BBK for the 89-05 Miata. Centric own Stoptech so they can offer a start to finish upgrade kit allowing and NA6, NA8 or NB1 owner to switch to NA8/NB1 rear brakes or NB2 Sport rear brakes with appropriately sized master cylinders and ST42 piston sizes. It's an ala carte system. A bit confusing thus far with all the options. I'll work on a table that makes them a bit easier to understand and post soon. Meanwhile, lets look at the calipers.

The big Superlite 5.98" radial mount on the left is what I'm trying to fit onto Vegas. 15x10 6UL's with common 11.75x .810 rotors so we're hoping they'll clear. If we can make them fit, we also want to experiment with fat 11.75 x 1.0" rings.
Our two objectives with the Superlite are greatly increased pad volume and the potential to fit a 1" wide rotor.
The ST42 based Stoptech kit will go onto Taxi, our 180whp N/A HPDE build with the Quaife Sequential.
Love bridgebolts!

https://cimg4.ibsrv.net/gimg/www.mia...ce87d011a6.jpg
https://cimg5.ibsrv.net/gimg/www.mia...95bc2c5110.jpg

Overall, the ST42 looks to be a higher quality caliper than the Wilwood but that's just subjective external observation. I did notice the pad thrust plates are really beefy, one piece and bolted in. The same item on the much larger Superlite is a thin gauge, spring that clips onto the caliper much like the teeny little plate on the Dynalite. We have had issue with plate wear and retention on the Dynalite in racing environments before so they get timed out and replaced. Several small details on the ST42 impressed in the same manner.
https://cimg6.ibsrv.net/gimg/www.mia...aaff2c6778.jpg

Do you have a 4 piston Dynapro caliper to show as well?

Did not have one handy. It's a tad larger than the Dynalite, smaller than the ST42.

Huh, even if the Afcos are private label manufactured by Stoptech, they're definitely different in a lot of details.

I guess you called Andrew at TSE for some help ? He must know many things on this subject.

My TSE 11.75'' V1 and 6UL 15X9 +36 + 10 mm spacer and I can't have those glue weight inside the wheel as they're no eough room. Anyway, reace car only so it doesn't matter.

joyrider, the caliper isn't necessarily any larger from the hub center than the dynalite is.

dynalite from willwood spec is 6.76inch radius on 11.75 rotor and superlite is 6.81" radius on the same rotor.

that's 0.05inches different. pretty sure the wheel barrel wont be a problem with 1mm of growth.. or since its radial mount, you could probably space it towards the hub a hair tighter than spec but you would need to watch for rotor growth.


How tight are the rotors to the balljoints now? you should be able to spec a slightly higher offset on the brake hat to get a bit more spoke clearance, but I haven't seen how little space you have to work with on 11.75 rotors to other things like the balljoints

The DR22 pad is the same dimensions interchangeable with what is used in the Dynapro Radial 7816. The mount holes for the calipers are different though wont bolt to the same brackets.

The Radial clearance for a Dynapro Radial on a 11.75" rotor is 6.57" major advantage for tight wheel fitment. Also note the Dynapro Radial mounts on the same bracket as the Superlite with .020" difference in spacer height radially and 5mm offset difference offset can be adjuste with washer spacers.

Subscribed.

I'm very happy with my V8R 11.75" Dynapro setup, but I'm interested to see what you come up with for a potentially higher-quality caliper.

Installing kit today on Taxi. Sport rear with Sport m/c and prop valve. Testing this weekend.

https://cimg6.ibsrv.net/gimg/www.mia...7a9b9c9d91.jpg

What is the reason for the sport rear over the 1.8+mtuned?

In the past I've seen you recommend the 1.8 caliper on a sport rotor for cars without extreme aero.

Very cool. Are AP Racing calipers out of fashion these days?

Hmm. Jet nuts on the back of those rotors?

And I don't think AP has anything really suitable in a Dynalite-ish size.

What size rotor is that?

Afaik its only available in 11"

I have a full assembly on my desk here with dynapro 4 radial, V8R radial bracket, 11.75" rotor - based on Wilwood's drawings the Superlight 4 for 0.81" rotor would bolt up to this same assembly with just a 5mm change on the bracket offset (inboard).

Pad volume is a no-brainer, that's a commodity among the current landscape of BBK options. On rotor thickness I'm split. Certainly there's a list of reasons the thicker rotor is better on paper, but all reports/requests I get from endurance racers is focused on pad life. Wilwood economy 11.75" rotors don't apply, but assuming good quality rotor I believe even the 24hr guys are good on one set of rotors. Conceivably, a car with enough power and a long enough race could make a case for more rotor mass than currently available though.

For the life of me I can't figure out why the Miata aftermarket tuner supplier crowd didn't jump on the Dynapro Radial bandwagon years ago. I've had them on my car for over 10 years now. It was well over a 50% increase in pad and rotor life when I first bolted them on my car swapping from Dynalite 11" to Dynapro Radial 11.75" due to a combination of 50% more pad volume to wear through plus the better thermal capacity of the larger rotor and they still fit all the different 15" wheels I was using. It's the tightest caliper shape package of all the suitable calipers.

What rotors are you running?

I had a 4 wheel stoptech brakes on my Audi B5 S4. They were better than the big reds on my 993 turbo! Can't go wrong with that caliper IMHO. I remember reading about them at SEMA.

We have always preferred the NA8 9.4" rear when using an 11" front. Stoptech asked us to provide feedback on their 11.0/10.9" combination with hydraulic ratios and pad .mu bias tweaked to compensate for the mechanical leverage bias. We'll see how it works.
Looks bitchin anyway.

https://cimg1.ibsrv.net/gimg/www.mia...31db1eec8d.jpg

Thanks!

I've run a multitude of different rotors. For autocross the lightweight and dirt cheap wildwood ultralight 32 work fine and are light by few pounds worth, They work so so on the track if you don't abuse them too hard where they crack they would also be fine on a lower HP car. I like the more expensive directional vane ones for track use. I've used Coleman racing or the wildwood HD36 with good success some other brands from summit as well do ok.

The kit started as an off the shelf Mini Cooper kit very minor mods required to fit it to a Miata.

Sorry. A better question to ask would be what rotor hats are you running?

The off the shelf ones that cam with the Mini Cooper 11.75" willwood kit + home made center rings.

Side note when I bought this Mini's came with 12mm wheel bolts. looks like wildwood changed the drawing for larger 14mm when Mini changed sizes a several years later.

Id be curious if TrackSpeed or V8R hats would be interchangeable. If not I still Bet they would still work even if they weren't the exact same offset there is a few mm of adjustment range with shims. The trackspeed hats look a bit nicer The Mini Caliper bracket fits and works with the Miata knuckle, bolt holes need to be very slightly enlarged for bigger SAE size bolts.

Yeah. I run the 14mm bolt hole rotors. Just the stock JCW 11.7" though. The centering rings are crucial because the rotors aren't aligned with the studs anymore.

I don't think the current 36/30 piston size is the best match for the sport rears brakes. Not a really great match for the 1.8 rears either.

Stoptech lists optional piston sizes for the STR-42 from 28-40. Assuming that range applies to the ST-42 as well you can fine tune the piston sizes. A 36/34 gets you back near the magic 3.00 piston area. Not sure what splits should be to solve pad taper though.

When I looked at the Piston areas and rotor diameters I suggested to stoptech at least a .2 Delta in friction material mu. That is roughly what we got with the pads they sent us. One concern I had was the shape of the torque curve. I asked them to send me plots for the pads and the shapes of the curve were very similar, obviously just lower magnitude with the rear pads. They had also asked me which other Computing pads they should test in comparative evaluation. I'm not at liberty to share the results of the tests but I can tell you that if you are running on the Hawk DTC line of pads, I feel sorry for you. Anyway, I think the kit will be balanced at a wide variety of temperatures with the pads provided.

One advantage of going at the low end of front piston area is a better pedal. We will have it on track next week at Buttonwillow. We'll see how it fares. The hardware I have is all sort of first article but not what will actually shipped to dealers. Hopefully I can have some influence on the set up and make any tweaks so that if anybody orders a kit is completely track-ready and does not need to be changed in any way. As you might have figured out, we are not yet committed to offering it on our site. But this is what we do with all the stuff we offer. Beat the crap out of it see if it works first.

< Hawk DTC pad user that doesn't understand what you just said

After looking at the torque curves for the DTC60 and another DTC pad compared to several other brands/compounds of race pads, I'm baffled why anyone would want to run them. Looking at the plots, they would be so-so street pads.
I just mentioned that in stark comparison to the Stoptech pads which compared favorably to G-Loc compounds. Still prefer the G-Loc but I'd put the SR33 and SR34 Stoptechs in the same category as PFC01, XR2, et.al.
Time will tell how they wear and feel in race like conditions but so far, they feel pretty good while bedding in on public roads.

Would you say that the test torque graph didn't match this one published by hawk?

https://cimg8.ibsrv.net/gimg/www.mia...34ac4e8e51.jpg

Yes.

Disclaimer: I did not personally conduct either test. Thus my opinion on this is worth exactly what you paid for it.

Cool thanks for the info. Hope the actual test data gets released.

Did my first leek test of the DynaproR today. I hate threaded ALU,
I don't have any confident for my ability to feel the thin line between tight and leek free and stripped threads.

10 years after Bob showed the path, 4years after I decided to take the plunge and one year since I bought the kit. Procrastinator...

Testing in the weekend, and I can take some pictures of an AP option as well (295mm disk). But IIRC that have large pistons, unless the local AP-distributor have made some special arrangement.

http://www.gasoila.com/gasoilar-100-...d-sealant.html

That stuff is win for NPT -- it's their 10k PSI variant that resists most solvents and never cracks. They also make an E85-specific variant for fuel systems.

Did you happen to use TRMotorsport C1 15x7 inch wheels with those rotors?

No I didn't. they did work with Kosi K1, Volk Te37, Sprint Heart CPF, Team Dynamics, 949 6UL 8, 9,10,11" maybe just the first gen on the 8" without a spacer I ran them with 8" first gen 6Uls and no spacer before the 9" existed. some other wheels as well. There is also a template for wheel fit that can be printed out from the wilwood site. its the same as the 11.75" race kit for 15" wheels sold for ~2005 mini cooper.

OZ Superleggera 15x7 fits as well after weight removal. Nice to be able to keep the trusted wet setup wheels :)

Emilio, any updates on the Stoptech kit?

So far so good. We will post something more comprehensive in the next few days.

Not to highjack this thread, but are you guys changing to a different master cylinder when doing big brakes. I have Goodwin version 3 11" brakes up front and M tuned adapted 10.9" sport brakes in the rear with 1.8 calipers. Im running this with a 1.6l Master that came in the car.

Any benefit to upgrading my master?

A larger diameter master will give a firmer pedal that takes more effort to push, which is good if you have changed the piston sizes on the calipers enough that the pedal is getting squishy. Stock Miata masters are 7/8 or 15/16, there is a 1" master available that bolts on (requires custom brake lines) out of a mid-90s 929, or 949 Racing sells a kit to use a Wilwood 1" master. See the big post on miata.net for a lot more info on the various master/etc sizes over the years, but I would guess your 1.6 car probably has a 7/8" master.

IME, using Dynalites/Dynapros up front and the FM rear kit (Wilwood Powerlites) with a 15/16" master makes for a very unsatisfying pedal feel, and the 1" master is a really good idea with that.

--Ian

We always swap in a 1" Wilwood master cylinder. Much firmer pedal. It also allows us to use higher MOT pads which tend to have higher .mu. Too small a master on a high .mu pads can get difficult to modulate. Lots of brake torque is a good thing right up until you can't modulate it. OTOH, modulation is everything. I'll take a low torque pad that modulates and releases well over a high torque on/off switch any day.

Even on stock 1.8 calipers, a 15/16" master and matching booster were a nice upgrade in pedal firmness on my car. If it weren't for the fact that I got the master together with the booster, and the fact that I was hesitant to mess with getting the lines to fit on a non-Miata master, I would've gone 1". Together with the stronger MSM booster, pedal effort is nearly identical (if you do the math, it should be like 10% lower, which is not something I can feel), just with a fair bit less pedal travel.

I look forward to hearing more about the Stoptech kit as it evolves. Last I heard they added a 38/36mm caliper to better match the sport rears. Now if they can only add a 11.75 disk option we got a clear winner.

Cobalt makes pads for the ST40 so that makes this option even more appealing.

Double post

If the Wilwood 4 piston Dynopro calipers with 11 inch rotors fit inside a 15 inch wheel will the 6 piston Dynopro on 11 inch rotors fit?

Hi Emilio!
I noticed that you are going to be running a Tilton pedal set on one of your builds?

My son is 6-8" and I am looking at the 600 series underfoot assembly to create a little more leg room for him. Not sure but I believe the set may be gold plated or diamond encrusted?...Jeez!!!!!
We bought your your stage one brake deal (2000 NB) and though they seem more than capable to me, but given our 350hp + goals I am told more brake is in order....The horsepower is probably a year out while we build and sort the rest of the car (Xida coilovers and big grip kit is next).
ATM I feel no pressure to move toward a BB setup and I am happy to wait and watch what you work out here (happy to pay more for spectacular brakes!).

That said....I would like to sort out that peddle arrangement in the next 6 months or so.
From your comment above I assume I should be looking at double 1 inch cylinders along with Tilton's brake bias system?
If so how will that setup work until the big brakes are installed?

Thanks in advance!

Jamie

There is no space to be gained inside the car with any pedal assembly. The space we gained is under the hood by deleting the booster. I would recommend sticking with the OEM pedals. Don't overthink it.

6-8", you will need to cut a seat sized hole in the floor, fab a box 1-2" lower than the stock pan and mount your seat in it. Make sure that new pan is thick enough to not flex and also provide puncture protection if the car is struck underneath.

Damn, 6'8". I would recommend a different car....

Good luck.

He is 6-5" that was a miss type.
Still...with the Kirkey seat bolted to the floor he still misses the broomstick test by about 1/4 inch. I have been looking at a floor drop kit that Advanced Autosports makes.....It is 16 gauge, but even still adding a bit more protection underneath is a good idea.

Thanks for setting me straight on the pedals! Time to pull apart the dash and see if I can raise the steering wheel a bit....Maybe a bit smaller of a steering wheel as well.

Looking forward to seeing what you come up with on these brakes Emilio!



Miss typed there he is 6-5"
Still a tight space though!

There's also https://www.advanced-autosports.com/...ata-floor-drop which saves the fabbing of the box.

Reading comprehension.

Whoops, what I get for looking at email notifications more than the thread itself.

My comment of adding more reinforcement probably threw you off.

The Advance autosport kit does meet spec miata guidlines...If you have seen those guys drive (the new ones)...thoughts of 16 gauge of protection will make you scratch your head!
1/4 inch plate might be more appropriate! :)

Either way.....16 gauge between butt cheeks and disaster, does not meet with my approval ...So I will add more.

Well, arguably it's relatively infrequent that things penetrating the underside of the car is an issue, even with Spec Miata, but you never know...

I don't know. Around here they're called "wreck" Miata for a reason and I have seen some really bad wrecks :(

What about fitting ST42 calipers on stock 10 inch rotors? Possible or not?

If you make your own brackets, sure.

Thanks a lot Emilio on your reply. I searched a bit and it seems that for the 10" rotors a slight difference in measurement in the Stoptech kit brackets is needed. If my calculations are correct, 1/2 inch movement of the mounting holes will do the trick.
Do you have a schematic or a big close up picture of the brackets?

1. The ST42 in the miata BBK is made for a 0.81” (20.6mm) thick rotor. The stock rotors are 22mm thick. Small difference, but the tolerances are tight enough that stoptech doesn’t recommend using the 20.6 caliper on a 22mm rotor. They do make an STR-42 caliper specifically for a 22mm thick rotor, however.
2. Wheel clearance is really bad when you move the ST42 caliper far enough inward radially to work with a 10” rotor. You run into clearance issues with the mounting pad of the wheel, not with the spokes or the outer barrel. I’m sure there are some wheels that would clear, but 6ULs will not work without a spacer.

The good news is that the ND miata uses an 11” x 22mm rotor that’s a perfect fit for the NA/NB. I’m currently running the 22mm STR-42 caliper on my car with the 11” ND rotor and a custom bracket setup. I’ve been trying to decide whether I want to sell a few sets of brackets or just give the info back to mt.net for free. I don’t want to shit up Emilio’s thread any more so PM me for any further discussion.