My Budget Big Brake Kit using Corrado rotors
 

My Budget 11" Big Brake Kit….. Installed on 90 Mazda Miata w/ 15 wheels.

Parts List:

2 1990-1991 Corrado front rotors – Napa part # 4886122
2 Front rotors from Miata (used to make hubcentric rings)
1 Front / Rear set of your favorite brake pads for a 1.8L Miata
1 Wilwood Proportioning valve – 260-8419
4 Grade 8 flanged bolts to mount caliper bracket
4 Grade 8 all steel locking nuts
4 M12 bolts to mount the 1.8L caliper brackets (original bolts are incorrect grip)
1 ¼ chomoly plate steel for caliper mounting plates.

Optional:
2 1.8L Miata Brackets ( for those with 1.6L brakes)

Step 1: Make hubcentric rings and turn down head of 2 Grade 8 bolts.
Take a new rotor and a pair of old rotors to someone with a lathe. Bribe them to cut rings from the original rotors that fit inside the new Corrado rotor. Also, have them cut the head of the bolts down to fit under the caliper brackets (see picts) You may need to clearance the caliper bracket to allow the most material for head bolt.

Step 2: Ream/drill the caliper holes on spindle to fit the new Grade 8 bolts.

Step 3: Cut out mounting plates using downloadable pattern. Drill the holes on a drill press only. I would start by drilling 2 of the holes to size, 2 slightly undersize, then mount on spindle and ream to final size for a secure fit. Alternatively, If anyone wants to put this in AutoCAD step up :)

Step 4: Mount bracket to spindle, bolt rotor to hub, mount caliper bracket. Check fit between both faces of rotor and bracket to rotor OD clearance. They should be even. If not, determine why and correct.

Step 5: When fit is good re-assemble and torque with green locktite.

Step 6: Install Proportioning valve. Bleed brakes, set front to rear bias and enjoy.

Disclaimer – this is provided as educational only. If your brakes fall off this is not my fault. Do not attempt if you are not skilled in this area – get help.

Pictures of hubcentric ring. I would have it cut straight across on the OD of the ring... keep it simple, unlike the pic.

Mounting plate installed...

Caliper bracket mounted to mounting plate.

Bracket pattern file. If anyone with CAD expertise wants to clean this up and verify it would be great.

that would be great, I'd buy a set of them too.

Question: Is there a reason why your 1/4" bracket "rotates" the caliper bracket? Cause that's gonna make it a bit crocked. Curious why you did it that way. Awesome that you wrote this though, many thanks. Not sure I like how much you had to cut off that one bolt head though. Looks pretty weakened.

looks great but try to redo that bottom bolt looks weak u dont want a weak part on brakes

ill try to do that up in cad on my spare time (end of the week).

edit: couldnt open that file, idk what program u were using. I use autodesk inventor. Just try to post up a screenshot of the 2d dimensioned drawing and ill make one in autodesk inventor

I'll see what I can do with that cad file at work tomorrow if i remember.
Instead of trimming that bolt down I could machine some of the caliper bracket away instead. Split the difference between the two.

I'd like to see a picture of how the hubcentric ring sits on the hub and how the corrado rotor interfaces with the ring to be centered.

hey how big is the rotor compaired to stock? any pics of it done?

I wonder if the angle of the caliper is to tip the pad some so that it covers more of the larger surface area of the rotor. So instead of using the 1.75" tall pad surface you use more like 2-2.2" of pad height.

btw... i found in his other post, corrado is 11" stock 94-2000 is 9.9"

Would really like to see someone like M-tuned make a kit for this. Include the hubcentric ring and a bracket bracket design. It's a great idea and I know it's been knocked around. If you could buy a pair of brackets and the rings for under a hunsky plenty of people would do it. Better yet would be a 4 wheel kit to keep the brakes balanced.

here it is done

The pads sit 'square' relative to the rotor. The bracket was rotated along the spindle centerline in order to use this with 15" Konig Helium wheels. Rotor is 11" 1/32. IF I mounted the bracket directly above the original holes it sticks up a little to much. I wanted to avoid cutting down the spindle and bracket.

A side benefit may also be the intersecting lines between each pair of mounting holes. Theory is there is less leverage for this to bend. But it is only a theory.

I agree the bolt head is not ideal, and splitting the difference between some clearancing in the factory bracket is best. But most of the force is in shear and to rip the bolt in tension you would also have to also break all 4 wheel studs and rip off the rotor before the bracket is compromised. Its good the caliper floats.

The the od bevel in the hub centric ring fits the bevel on the backside of the Corrado rotor. But the Corrado rotor also has a flat surface that is sufficient to located on a straight cut hub centric ring. I guess the machinist wanted to kill some time lol

Yes, a kit with brackets, rings and hardware would be awesome. But for me its not worth the risk of getting sued. A business on the other hand has insurance :)

Im sure this isnt even close to scale....

but this is:

awesome. ill make that into an autodesk file later on and do a cool rendering

We have the prototypes made, and are waiting to get them put into a CAD file.

Braineack.... wow! Are those from the dwg file?

If so, please verify the distance between centers. The guy who originally did it was a little off on the holes when pattern was printed and compared to actual plate.

If not - You rock!

Attachment 209952

quick 5 minute rendering

i need the correct diameter of the holes tho

Brain needs some help with his dimension layout. :)

haha yeah it was very hard to follow, but props for him for going thru that .dwg file cause i sure as hell wasnt going to.

i have 2 exams im studying for right now but if i take another study break ill neatly dimension that and put it on a nice layout

factory dia 10 mm bolt dia for the caliper bracket.
7/16 (.4375 ) for mounting bracket to spindle.

M-tuned, any idea when this prototype kit might be ready? Do you have an estimate as to how much it would cost? And what other parts would we need to source?

We plan on making it so you ONLY have to buy Rotors and Pads. I think initial hope was in the $75-100 range for brackets, hardware, and aluminum centering ring.

Dats wut I'm talkin bout. Yeah boyeeee! :bigtu:

+1:bigtu::bigtu::bigtu::bigtu::bigtu:

Awesome, get it done! We'd probably have to get a maximum ID for wheels, so there's no clearance issues.

That $75-$100 is for the front hardware only, correct? I wonder what it would take to put the 1.8 front rotors onto the back...

where do i sign up? :)

If you guys don't get er done I will. I can beat his price, probably in the 50-75 dollar range for the fronts. Maybe front and rear for a 100 U.S.D. Monday I can look into it more. I want this kit for my car and can't justify manufacturing just one.

B.T.W. this design probably needs some refinement. I found critical stress points with my analysis that makes this unsafe for some braking conditions. The last thing you want is an ejected/dangling caliper at 100 M.P.H. that makes your foot sink to the floor.

M-Tuned, too bad it wasnt available 6 months ago...

Travis, great - design them up... do I get a free set for being the OP? ;)

do it travis, compition is always good.

I'll hook you up, can you test these for me though? We're talking tire flat spotting madness :giggle:

Travis

how much shipped to holland?
I'd be in :)

Free shipping group buy on the FM Wilwood proportioning valve kit to correct all the front bias we're gonna have once we do this swap.

https://www.miataturbo.net/forum/t28557/#post334106

I'd think the brackets would cost almost nothing if they were lasered out of mild steel, 100 at a time. You could rough the holes with the laser, put them in a really simple CNC mill and get them perfect in about a minute per part. With the right tool, maybe even put in a slight countersink to allow more bolt head height.

Seems like you could use two brackets per side, sandwiching the ears on the upright. Then use spacers and shims between the brackets where the caliper mounting bolts pass through to match the thickness of the ears. The ears are generally not a precisely controlled thickness, as only the caliper mounting surface needs to be controlled relative to anything else, hence the need for shims. This would significantly increase the strength of the system (especially relative to the bending moments) without changing the z-axis position of the caliper or requiring a lot of fancy machining.

i REALLY want me some.

Why are these not the same?

I've had a set done, but was not ready for mass production. We are ready to go with these but are doing a few things a little different so no grinding of bolts is required etc.

Here is a thread with more details for all of you..

https://www.miataturbo.net/forum/t28696/#post335453

Gee, I wonder if there is a market for a BBK for the Miata that uses larger cheap and easily available rotors, stock calipers and costs less than $100 bucks. Hmmm....


Out with it already! Times a wastin!



he,he

I'm out of the office right now, but I'll post up the pictures of the dangerous resonances and failure modes of the original parts. :giggle: I still can't believe your post about it getting "copied" I do real engineering work here, with 3 different aerospace oriented manufacturers, I don't just COPY work. Just like the oil pump gears, they had both tolerance issues, and features which were not present in the end part.

Anything I touch has my own engineering refinements put into it, and I use the latest software and hardware systems for my analysis. I would never put someones LIFE at risk without doing some serious work on it first. I hope you can guarantee the product for 8-10 years of abuse.

Lets see what I prepared for...

Did you check your material for cold performance? Did you use an SAE or mill-spec certified material? Did you use a coating with a 10 year service life? Did you check for resonances that cause squeal and failure of the assembly and the brake pads? Did you check for fatigue of applying the moment forces present to the part over a 10 year span? How many cycles is that exactly? Did you rigorously check the geometry for flaws?

I did if you didn't maybe you should get a lucky rabbits foot or something:giggle:

As for the sponsor comment in your group buy post, I've sold 6000 dollars in revenue to this forum and made enough to pay for my own set of oil pump gears and about 140 bucks. All my stuff has been as safely close to charitable as possible, that's an asinine thing to say.

If the prices are the same, I'm gonna buy what I think is the better part. Pretty sure that's the mentality of most miata people. This is assuming both parts are available. If one was available first, then that part will likely sell first of course. Some people are impatient. I'm curious as to the "dangerous resonances" comment you made. I worry about the pics posted above where the guy ground the bolts down. That's not for me at all. I want something I can bolt on, torque down, and KNOW it's right. And not so much as second guess whether the parts are overbuilt. The last thing I want to worry about when tripping the lights at the 1/4 miles is if the middle pedal is gonna work.

Travis & Marc,

While everyone loves a good pissing contest between vendors I prefer to mock them when they happen on other boards!

1st to market, best price, best product, availability, etc. all play a factor in who people will buy from.

Again, if someone is going to do a bracket for stock calipers why not also do a bracket that will fit whatever the most popular upgrade caliper might be. Any bracket made to fit with a common and affordable disc is good for me. Corrado or the sport disc won't make much difference.

I agree Cueball, I don't want a pissing contest ...

I posted the original idea on April 15 to use the stock Caliper on the Corrado rotor and have been working on it/testing it ever since. We made one complete set which I have been testing.

As for engineers... We have access to 3-4 and one of them even designs expansion joints for Nuclear Power stations. I come up with the ideas and drawings. They then take it and tell me if it will work, or how they can make it work. John@M-Tuned also designs parts for a large aftermarket automotive company and even has parts on some OE cars. He is not new to this either.

This was not a project we decided to draw on paper or CAD and mass produce. I give the original poster 10 out of 10 for making the brackets. We are doing things a little different and probably have some similar concerns as do you.

Maybe Travis should attack both a bracket for the stock caliper and one for a 4 piston wilwood like goodwin.

I hear ya! John@m-tuned designed a couple of different setups for my old 11.00 Miata, my 9 second Civic and his 10 second CRX. I was running almost 150mph in my civic with a 26" slick and I never worried one bit.

Never mind some different stuff he has done for street cars and some customer stuff.

I'd love to see a kit utilizing a larger vented rear disc. Just for shits and giggles. Go big or go home.

Here it is
 

Here are the problems, with the original part.

Everything sounds cool on the massive side, but...................
That side gets expensive. These guys have to make money, and there are aftermarket kits, they already have available.

I am all about this cheaper way. I can watch a junk yard for rotors and put in wrench time. But I dont want to rig it up. That usually runs into dangerous measures. Yall's plan sounds simple and easy. And something I can afford!

Thanks to both of you guys!!!!!!!!!!!!!!!!!!

I know there are alot of guys on here with 15's, but what do you think about an even larger rotor? Extra stopping power is proportional to the radius of the rotor with no upgrades to hydraulic system. So if you've got 16's, 17's or even 18's we could entertain larger options.

We could go all the way upto something around the Yukon size rotor with 13 inch.

That would give you about 44% more stopping performance over stock, better heat arrest for less fade, and those rotors are generally higher qaulity because they are rated for a larger vehicle. Think about it, 60-0 when stopping a miata at 1000kg you only have to bleed 391Kj of energy to stop. A Yukon loaded to the max combined towing and vehicle weight is rated at 5400 Kg. So it has to stop 1,992Kj. 5 Times the braking energy has to be absorbed by the rotors. So from the factory the rotors must be built for prolonged extreme temperatures for towing in mountains, and very high durability doing it to meet such a rating.

With that size I think the down side is that I would have to make a 4 lug center adapter. Nothing that large is going to magically fit in there. Depending on what I could get the rotors for I could maybe get those done for 80 dollars or so a piece. I've found them for 40 online, but I still have to machine the center hub. The upside is that you would already have your centering ring built in, and these would be very lightweight ontop of huge.

I could still work on both kits, but it was something I was thinking about.

Most would rather use 11" rotors w/ stock calipers. Going from 9" to 10" is well known to be a "great" mod. So going 10-11's has got to be pretty good too.

Getting into say, a 13" rotor, defeats the purpose of this in some regards. Simple, cheap, and easy is the goal. I mean, if someone wants the best, there are several BBK available that are actually lighter than the stock brakes by a good margin, have more clamping force, more rigid calipers that will better deal with the added heat, bigger rotors, etc. 11" corado rotors w/ stock calipers is oriented for the daily driven/occasional auto-x/quarter mile people. People that just want a nice upgrade for little cost. We'll use some after market brake pad and call it good. Maybe throw in a proportioning valve. Some people, like myself, don't really "need" bigger rotors as I never push my car to the point of overheating the factory rotors. I'd just like to have bigger brakes for the hell of it basically. Should make the middle pedal a little more sensitive and if I ever need to kill off a lot of speed fast, it will be less likely to fade on me.

I don't think too many would be interested in 13" rotors. Like you said, we could no longer run 20 dollars-and-bolt-right-up rotors. (with centering ring) You'll more than double the cost of this by using 13" rotors. And while they're a lot bigger, they will also be heavier, and have a larger mass moment of inertia. So while there may be a few people that would buy this stuff, your target audience will substantially shrink.

Yeah, if I was going to go with 13" rotors and make 17" wheels work, I'd put something together with StopTech parts. Keep it simple and light.

Let us not forget that ultimately the tires are responsible for stopping the car. If we keep increasing the rotor diameter for stopping power, an increase in tire section width will also be required.

Tony

What will really happen is they'll be trying to stop the car with the front tires alone. The Wilwood valve can only do so much to allow hydraulic pressure to reach the rear brakes. At some point, the front tires will lock early, the system will be hard to feel and modulate, and braking distances will increase. By increasing the share of braking work done with the front rotors, it puts that same increased share of thermal load into them, and undermines some of the benefit of having bigger brakes in the first place.

Balance is key.

WhhhhhOW! Brake KITs! ARE CRAZY EXPENSIVE!

This is definately doing us a favor. Thanks guys.

Only in our distorted perspective from DIY Miata land. If you're building a "real" race car (Koni Challenge, World Challenge, higher-level NASA and SCCA classes, etc.), a brake system from one of the big name manufacturers is among the least expensive systems on the car.

TravisR,

At some point you reach overkill. One thing to remember is the rotor and caliper are the dreaded and despised "unsprung weight". Miata's are very sensitive to added weight. Sure you could put a 13" rotor and 6 pot calipers in but all that extra weight is going to hurt handling and acceleration. The rotating mass of an overlarge rotor can significantly effect hp numbers on a dyno and performance on the street and track.

The reason people have been working with the Corrado rotor is it's the largest 4x100 bolt pattern rotor that is commonly available, about the right offset and cheap. The jump from a 9 or 10" rotor to the 11" is a pretty good gain without adding a ton of weight. It's all a balancing act. Gains vs. costs vs. losses.

A centering ring, Corrado rotor, stock caliper bracket set up could be a good gain for a reasonable price and without adding too much weight.
-

Thank you for reading my mind, cueball1.

Ok just throwing it out there. I couldn't imagine how rediculously cool a 13 inch caliper filling a 17inch wheel to the edge would look on a miata, but looks aren't everything.