V8Roadsters BBK @ 949Racing
 

The guys at V8 Roadsters have just finished this 11.75" Race Big Brake kit. We will be offering the kits with these changes:

• Carbotech pads
• Quick release pad retaining pins
• 1 liter Motul RBF600 fluid

The kit is designed as an absolute no compromise race system. Spacers are required to clear the calipers on most wheels except 6UL's. The fronts with Dynalite 4's are designed to clear gen II 15x9 6UL's. The rears require a 2~3mm spacer to clear the 15x9 6UL. Gen I 15x9's clear the rear without spacers. As you can see, there is no provision for an emergency brake.

Replacement friction rings (rotors) are the same part for all four corners and are a measly $50 each! Ya gotta love that.

My rough measurements put the total weight savings at about 18.5 lbs over the 100% stock brake system including e-brake hardware.

For the average dual duty or track only car making less than 200~250whp, the 11"Goodwin V4 BBK we have been offering is probably the best choice. More power than that and trailered, the 11.75" V8R BBK starts to be the better choice I think. We're removing the old 11" BBK from the OGK and installing one of these.

The system includes:

4 - 11.75" x .810 Wilwood rotors, straight vane
4 - Ultra light weight alloy hats
2 - Wilwood Dynalite 4 piston calipers, 1.75" piston
2 - Wilwood Dynalite 4 piston calipers, 1.38" piston
2- Carbotech CTW7112 brake pads, your choice of compounds
4 - Aluminum, helicoiled caliper brackets. Hard anodized
1 - Wilwood tandem master cylinder
4 - Stainless brake lines, PnP
2 - Cunifer, hand formable hardlines for master conversion
2 - Motul RBF600 brake fluid .5 L

Options:
Dynapro 6 piston front caliper (huge!)
Red powder coated calipers
Any Carbotech pad compound including the 1521 street pad

Full details and pricing on the website

http://949racing.com/images/products/detail/V8R_BBK.jpg

It's amazing how the cheap the 11.75 friction rings are compared to the 11" ones more common on Miata kits. Another example of The Man sticking it to the little guys.

No, it's all about volume. The 11.75" rotor format is standard for most of the circle track racing in the US, so the volumes are high and the piece price comes way down. There's also tremendous choice on the price/content value spectrum.

i didnt notice... but will this kit allow you to retain your cable handbrake?

no it won't

More importantly, does it come with caliper-cover heatsinks? I hear that's the stuff for fast cars...

Silly me, when I saw it was from V8Roadsters, I thought it was a Big Block Kit... :bang:

What is "cunifer", exactly? Google says it's just a flexible hand-formable brake line, but there's got to be more to it than that? Wouldn't stainless lines be more than adequate for these cars?

Can't precisely bend standard SS lines by hand and they can still rust. The Cunifer stuff is awesome, can't kink it, bends to tiny radii and will never rust.

Hey Emilio, is there any I can get just the FRONT portion of this package with 6-piston calipers? (Only need calipers, rotors, brackets and pads as I already have SS lines and the factory Sport rear brakes).

The front portion would have pistons sized for the 1" bore Wilwood MC. You would have a serious brake bias problem if you did that. We would have to special order the smallest bore DP6 but even then you should be looking at a 626 (7/8") or 929 MC (15/16"). If we used the rear DL4 with 1.38" piston (same as Goodwin front BBK), you would be close. Overall, I have found the the Goodwin BBK works best with a bigger diameter M/C.

Shandelle mentioned at one point that V8R had no plans on offer breakdown kits. I'll clarify it with them and if it changes, we'll add it to our website.

So are these 6 piston calipers different than the ones used for the other BBKs that GWR sells?

FWIW, I'm running a Brembo GT (read-massive 4 piston calipers) front brake kit right now and bias feels good.

Same Dynapro 6

929 master cylinders were 7/8" up intil 1991, 1" there after. 15/16” is from a protégé Or a late model sport brake NB miata.

Oh yeah, Emilio, my car has the sport brakes already...so I have the larger MC. Might that change the brake bias issues you speak of?

I always get those mixed up. That's what I get for replying from home without my shop PC's database. There is also a 1-1/16 or 1-1/8" Mazda MC that can be adapted to the Miata, although that might be too big.

The 15/16 Sport Brake MC will work well. Shandelle tells me they're having trouble getting the DP6 into our Gen II 15x9. Bleed screws hitting rim.

We could do a front DL4 kit with out MC. Contact me directly for pricing and availability.

Thank you Sir. Will do once I hock these Brembos.

Interesting looking into this the DP6 will mount on the same bracket as a Dynalite. And comes with piston sizing pretty darn close to the standard 1.38” 4 pistons that Good-Win uses.

To go to a 6 pistion with my Radial mount Dynapro the billet narrow Superlight would bolt up but doesn’t come with as small of pistons as the DP6 normally. So brake bias will be an issue.

Honestly even turning low lap times in a super high hp Miata and abusing the brakes I have not seen the need for more brakes than I have with 11.75” directional vane .81” thick front rotors and Dyna-Pro 4 piston calipers. And defiantly vented rotors in the rear is overkill extra weight. A .38” thick solid rear rotor is significantly lighter and still doesn’t get as hot as the fronts. The difference in thermal capacity with the 11.75” directional vane over a Good-win kit is huge.

Bob

I’m considering going to a 1" MC myself. Would you think that would work well with Good-win sized caliper pistons like I’m running? I’m thinking I can be a bit more accurate and smooth with my downshifting with a stiffer pedal.

I put a 1” 929 on a 323 GTX that I have but it has the calipers I put on have bigger pistons all around and Still feels mushy compared to my Miata with the stock 7/8”

Bob

A local guy here has a Goodwin V3 kit on a a fast N/A with ABS and a 1" 929 MC. Those are the best feeling Miata brakes I have ever driven buy a fair margin. So yes, +1 for the 929 MC. Tricky part is the hard lines are different on the different year Miatas so there is no one PnP MC. You have to make some hard lines. For those of use that have the right flaring tool that's easy. If not, you either want to DIY Cunifer lines or invest in a $300 flaring tool. The cheap flaring tools are worthless.

You want a bigger MC and smaller caliper pistons for reduced leverage/stiffer pedal. Bigger caliper pistons give you more leverage (power)/softer pedal.

Emilio,
Any clue if the fronts will clear 6UL-1 in 15x8 +40?

Not even close. Probably 10mm spacers.

Interesting. Im pretty sure my Mini Cooper 11.75" Dyna Pro kit would fit.

Thanks for the input.

On one of my GTX’s I have 4 piston 1.75” front calipers and single piston 1.38” Rx7 rear calipers with a 1” diameter 929 Master Cylinder. The brake bias works out good on that car with this combo because it has 67% of the car weight on the front tires statically. Problem is the brakes still feel mushy compared to my Miata with 1.38 4 piston fronts and 1.25” single piston rears and a just a 7/8” MC and the same rotors. I still think I want my Miata less mushy even though I have never felt a Miata with better brakes than mine.

Seems like the V8R kit would need bigger than 1” MC with those big piston calipers all around to feel good.

Also what about ditching the power assist. I hate the feeling of uneven brake assist due to throttle blipping while braking. Seems like the check valves never really hold vacuum right in some situations. A bunch of my Rally friends disconnect the vacuum entirely because they are using brakes and throttle together a whole lot but they are doing it on gravel where you simply cant use full assisted braking power anyway.

Bob

Confused. So yours are the best Miata brakes you ever experienced or unsatisfactory?

The V8R kit components are sized correctly. I'm not much with math but you calculate the leverages with the piston area and MC bore and it adds up to less leverage than the OEM system which is what we are after.

Not unsatisfactory just curious if it could be better yet. I understand the math and I have my own spreadsheet for that. What I have found is the math is still not a perfect substitute for trial and error.

The leverage ratio is a simple thing to calculate. The sponginess feeling which arises from component flex and fluid compressibility because of trying to contain the pressurized fluid is a bit more complicated than a simple math problem. I’m not certain but it seems larger fluid volume systems operating at lower system pressure ranges exhibit more sponginess behavior based on my limited trial and error.

Bob

The additional volume could contribute to increased compressibility. We have also measured quite a bit of flex in the brake booster and particularly the firewall itself. A brace projecting rearward from the shock tower to the nose of the MC or its mounting flange helps a bunch.

Bbundy,

Emilio brings up an interesting point about flex. An MC brace is on my long list of future projects too. If you do it it will likely be long before I get around to it. Let us know what you think!

Yep MC brace is on my list too. I've been wanting to do the 1" MC for a while
Just never got around to it. It will require some brake hard line modification.

I just found it interesting that the V8R kit uses what appears to be a 1” Wilwood MC that requires an adapter and it uses the same size piston calipers that I tried on another car that seemed like it could use a bigger than 1” MC.

FWIW it looks like Wilwood maks a 1-1/16 MC that is a direct boltup to the stock booster without an adapter. 260-4893. The only problem is the size of the otlet flare fittings are huge.

MasterCylinder

Bob

Larger piston bores in caliper bodies mean less-stiff caliper bodies. This is illustrated perfectly here

StopTech Caliper Stiffness Discussion - see chart at bottom of page

where the caliper with 36 & 40mm pistons is stiffer than the otherwise identical caliper with 40 & 44mm pistons.

Yea but the chart says shows it as a function of pressure the larger piston will be aplying more clamp force at the same fluid pressure. The chart is tiny and hard to read but I wonder what the curves look like if you convert the lower axis to clamp force rather than system pressure. I bet they would be pretty darn close to being on top of each other for the same caliper configuration with different piston sizes.

I’m guessing the stiffer feel is more because the brake lines and the fluid compressibility are nonlinear and they behave like stiffer springs at higher pressures. It requires the same amount of clamp force at the caliper to slow the car down at a given rate and using smaller pistons all around to provide that clamp force requires higher system pressure. The lever ratios all work out so the pedal force required is the same but the higher system pressures put the flexy bits into a stiffer portion of there spring rate curve.

The correct amount of stiffness is subjective as well. I don’t think it would feel right if the pedal didn’t move at all ether.

Bob

Drive a GT3 if you get a chance. Some Porsches modulate with pressure, not distance. Personally, I like it.

My God, this system with a proper set of tires would be sick.

Some ideas:
1) add volume to the vacuum reservoir of the brake booster
2) place a vacuum regulator between the manifold and the booster, set it to 12" or 15" vac, whatever. This would also require more force for the pedal.

So, I currently have:
- 94 OEM MC
- 94 OEM Booster
- Front: 4-pot Dynalites fro Goodwin V4
- Rear: 94 OEM (relocated)

Currently pedal travels alot. I have the V8R MC kit here. I will mount this soon.
Travel will decrease, effort will increate.

Is the 94 OEM Booster enough? Or should I go larger? Currently I could do with a bit more effort, but another car with the same setup but 6-pots up front is very heavy IMHO.

Compressible pad = more pedal throw
pad taper = more pedal throw
bad wheel bearings (rear) = more pedal throw

I stopped those three issues and the problem went away with pedal throw. I later added a super-baller 2001 MC and couple with the 11.75" front rotors, this car feels awesome on the brake pedal. I wouldn't say the larger MC is required

Sorry, wrong thread.

Are the 11" ND kits on track to be available next month? The original post mentions a pre-order, is that currently open? I did not see anything on the website.

This thread is 11 years old.

Try this one https://www.miataturbo.net/suspensio...2021-a-104292/