Posting this in Race Prep because this is exactly where it's most relevant. New release from V8Roadsters that we're very excited about.

The back-story...
By now everyone's seen the Stoptech 11" brake kit for the NA/NB. Some very cool elements in that kit, great calipers. But, someone over there missed the memo that the collective Miata performance community figured out how to fit 11.75" rotors under the car about a decade ago. For many of us running 11.75" kits now, downgrading on rotor size for less braking torque and thermal capacity as a trade-off to get a more rigid caliper isn't a great recipe.

We weren't the only ones wishing ST had done their kit in 11.75". V8R designed a new bracket to fit the ST42 and STR42 calipers over the super popular 11.75" rotor, then they worked with ST to refine the outer shape of those calipers to improve wheel clearance.


** STR42 caliper pictured**

The ST42 caliper is a forged/machined caliper with bridge bolt that is super rigid. The STR42 is a badass true motorsport-grade billet version of the ST42. Both take ST's DR-22 pad shape which is the same as Wilwood's 7816 pad so there are lots of pad options.

You can get these direct from V8R and they're already in stock. We will be offering these kits complete with AP Racing rotor option and will have Porterfield and PFC pad options shortly. I have some PFC pads on the way to verify fitment.
All of the 11.75"" kits use the 36/38mm piston size (3.34 in³ piston area) which balances very well with a Sport package rear brake setup or similar.

Perhaps the best part... The price on these kits is competitive with the standard ST 11" kits.


Pictured above: 15x8 Black RPF1 +28mm

Wheel fitment

If you're considering running this glorious kit, you're on 15x10" wheels right? Riiiight? That said, we'll be getting lots of inquiries about which wheels fit so here's what we've tested so far:

15x10 6UL and 15x10 Jongbloed have tons of clearance

15x9 6UL (gen 1): tight but OK
15x9 6UL (gen 2 & 3): Spins but clearance is too tight. Needs 5mm spacer to get minimum acceptable clearance
15x9 6UL (gen 4): Contacts the barrel. Needs 10mm spacer to get minimum acceptable clearance
15x9 Storm S1: OK

15x8 RPF1 +28mm: tight but OK (surprisingly)


Pictured above: 15x10 Tungsten 6UL

 

Update - fits 15x8 Storm S1 and S2 without spacers.

 

That does look amazing. Can't wait for some track testimonials!

 

Both the ST42 and STR42 are available with either 38/36mm or 36/30mm pistons. The larger ones work best with sport rears and the smaller one better with stock 1.8 rears.

I really look forward to this upgrade!

 

Welp... now I'm never going to sell my v8r wilwood bbk... I guess I'll just install them

 

Do you have a picture with pads installed? Curious what the rotor / pad coverage is.

 

While the ST42 and STR42 come in both piston variants, AFAIK V8R is only ordering the 36/38's from Stoptech. Unlike the standard ST kits which can be ordered with either piston size, the 11.75" kits are 36/38 by default. Might be possible to special request for the smaller piston sizes, I'm not sure.

One not-so-small reason for this is the 36/38's are the right match for the existing rear Powerlite/10.9" kit, and it just may also be the right match for some new rear stuff that is brewing

 

Pads are on the way, can shoot a pic when they arrive. But, not sure what you're trying to see. Swept height?

 

Any chance of testing these with +0 wheels ? I bought the 11.75" radial wilwood kit last black friday that didn't fit. :(

 

I just re crunched the bias numbers. The larger ST calipers look borderline with a sport rear rotor and 1.8 calipers. Not really great though. MC to caliper volume takes a hit too and will have a longer pedal with stock 1.8 master. With Aero you're gonna want more bite from larger sport calipers or V8R rears to balance it out. 15/16" or 1" master is a must have IMHO.

If I had stock 1.8 rears with smaller rotors and stock 7/8" master I would go for the smaller piston ST calipers. That would be a better pedal and balance front to rear. Even with the larger 10.90 rotors I like that combo better than the bigger calipers.

One of the things that got me the most excited is the larger V8R ST Front/Sport rear combo looks to be the perfect foundation for a manual brake conversion. The extra piston area helps increase wheel torque. Move the MC mounting point down and play with MC sizes and I think you'll get there. Not gonna be something I try right out of the gate though. I got a 1" master all plumbed in place with Sport booster. I suspect that with the V8R ST Front/Sport rear combo will keep me happy for a while.

 

Pads are thinner than the superlite calipers but they have a bigger area so they should grab better but last slightly less. The calipers are pretty spiffy looking, I like the appearance. Need a beta tester? :P

How's the pad change on these? Looks like a couple of allen bolts to pull the caliper apart?

 

I see talk of the 1.8 MC, what bout the 1.6 MC? Are they different, and if so by how much?

I currently have a 1.6 car with sport brakes and feel like pedal travel is a bit long.

 

That's the word for it, basically how much of the rotor is in contact with the pad. We had to have custom pads made for the original 11.75" Wilwood setup to get proper coverage or swept height

 

Get a wilwood 1" master kit.

 

The Superlight/11.75" kit by TSE is the top choice for an endurance car looking to maximize pad life. Larger pads (thus larger caliper) comes with a trade-off... The STR42 caliper is ~2lbs lighter than a Superlight.

Pad change: no disassembling of the caliper, you just pull the single bridge bolt on the top and the pads pull out/drop in from the top. The ST calipers have a shelf that the bottom of the pad rests on, unlike the wilwoods that require cotter pins to keep the pads from dropping through the bottom of the caliper.

 

Fun fact (I was digging through wilwood info this morning), on the dynapro wilwood claims the removal of the shelf was an improvement. This info is of no real use. Just funny.

Wilwood High Performance Disc Brakes - Caliper Product Number: 120-9703-SI

 

Perhaps it did help them slim the caliper down in some case where they had limited swept height available and needed to shave the base of the caliper down. IDK. I'm not saying one is better than the other, shelf vs. cotter pin, just pointing out the difference in the features.

 

Shelf = Abutment plate

The ST42 can use different abutment plates to carry different pad shapes; both the DR22 and the DR20 will fit in the ST/STR42 depending on the caliper config (part number). The abutment plate can be lower than the bottom of the caliper so that the edge of the pad can be placed as close to the center of the friction ring as possible, or higher if needed.

Abutment plates don't impact caliper width since the width is custom based on the rotor. The STR42 Miata application comes in 20.6mm wide with an existing option for 22mm wide.

The StopTech differential piston bores and stiffer caliper both combat pad taper so pads tend to last longer in these calipers.

 

Any idea what the cost of replacement rings is?
ST is generally very expensive in that area.

 

For the 11" Stoptech rotor, roughly $66 for a bare rotor ring or $90 with fresh hardware. Looks like the 11.75 AP is $134 per ring from Good-win, hardware not included.