Apr 6, 2020 update to the Mazda Miata project car

Project Endurance Race Miata: Big Brakes, Stronger Hubs and a Full-Race Suspension

Although we’re in the middle of more urgent work (namely, swapping a V6 into this endurance-racing Miata), we couldn’t resist a little detour in the garage. 

We knew we needed to upgrade the rest of the car to properly take advantage of its upcoming power increase, and two areas stuck out like sore thumbs: the brakes and the suspension. 

The former was still stock, while the latter was a dirt-cheap setup severely limited by the ChampCar rule set we’d been racing under. More power won’t help without more chassis to back it up, so we went to work. 


Bigger Brakes for the NA-Chassis Miata

Our Miata has been a race car for years, but it never ran anything fancier than stock 1.8-liter Miata brakes. 

Why? Because it didn’t need more. For years, it’s been raced with nothing more than competition pads and good fluid, but that will have to change with the V6. 

Both the V6 engine and upcoming aerodynamic elements will tax the brakes beyond the limits of the stock equipment. 

We’re also going to continue endurance racing the car, where the stock Miata brakes have a major downside: The caliper has to be removed for brake pad changes. This only takes a minute, but every minute counts during a race, and we didn’t want to be fumbling with caliper removal if we didn’t have to. 

So we called the folks at Wilwood and posed a question they’ve heard a million times: “How do I keep my fast Miata from nuking its brakes in an endurance race?”

After a quick discussion of our goals, they pointed us in the right direction. We chose Wilwood’s Forged Dynalite Big Brake Kit, which features 11-inch front rotors and anodized four-piston calipers that don’t need to be removed for brake pad changes. The kit also includes everything else necessary for installation and retails for $1174.60. 

We wanted to upgrade the rears to match, so our next call was to Flyin’ Miata. The shop offers Miata brake kits ranging from mild to wild, most of which feature Wilwood parts. 

After a quick chat with the company’s experts and a look through its catalog, we ordered the Stage 2 Four Piston Rear Brake Upgrade. This kit pairs four-piston Wilwood calipers with custom brackets to fit an 11-inch rotor from a NB-chassis Miata. 

What’s the benefit? This kit drops 3 pounds per corner compared to stock sport brakes and doesn’t require removing the caliper for pad changes. It’s even available in a version that retains the factory parking brake if so desired, although we skipped that feature since we won’t need it. The kit retails for $569, and we paired it with some parts-store rotors meant for a later Miata. 

 

Beefier Miata Hubs From Wilwood

Brakes ordered, there was another weak point on our car to address: the front hubs. These are well-known consumables in the Miata world and need to be replaced every few races as the wheel bearings wear out. 

We’d been running blueprinted front hubs from Flyin’ Miata but knew we’d need an upgrade for our faster car. After all, we’re planning on 10-inch-wide wheels and aero, meaning far more stress on the front hubs than the factory ever intended. 

So we went back to Wilwood, which recently announced an upgraded front hub kit for these cars. Its bolt-on Front Hub Kit (Race) ​​​features forged hubs and adjustable bearings. Instead of using cartridge bearings like a stock hub, the Wilwood kit uses tapered roller bearings so preload can be adjusted. It spaces the bearings farther apart, too. 

The result is a user-serviceable hub that can handle far more abuse. At $699.99 per pair, these hubs cost just a bit more than the blueprinted hubs from Flyin’ Miata, which retail for $438 per pair. 

What about the rear hubs? We needed to make some changes there, too. 

Miata rear wheel bearings aren’t a weak point, but we needed to replace the factory hubs with the custom ones included with our V8 Roadsters V6 swap kit. The upgraded hubs are stronger and feature a different spline pattern to match the upgraded axles included in the kit. 

While we had the rear hubs out, we pressed in a fresh set of stock wheel bearings just to be safe. We also replaced the last few stock rubber bushings with fresh polyurethane pieces from Energy Suspension.

The Ultimate Miata Suspension?

We knew we’d have the car apart to swap brakes, which presented the perfect opportunity to address its suspension, too. We admit, it was a bit basic: We’d installed a few urethane bushings here and there, yes, but were using Koni’s entry-level STR.T street shocks with a set of cut stock Miata springs.

This setup worked great for its price point, especially after we corner-weighted the car by cutting its springs, but it always faced two major limitations: The springs didn’t have enough rate, and damping was fixed. 

We knew that simply installing stiffer springs on our orange Konis wouldn’t help much, either. They simply weren’t up to the task.

So we called Flyin’ Miata’s experts again and asked for their advice. Fortunately, this wasn’t a hard question for them, and they recommended the Stage 2 Fox Suspension kit

At $2319 including springs, it’s not the least expensive option, but they promised it would work: They’ve tested it on cars ranging from stock Miatas to their 500-horsepower V8 Targa Miata, meaning it shouldn’t have an issue with the car we were building (though we might need to fine-tune spring rates after testing). Larger adjustable anti-roll bars are also included to replace our ChampCar-mandated factory units. 

We did stray from the recipe a bit and source our own springs, since the rates included with the kit lean more toward street and HPDE use than dedicated track work. We ordered Hyperco Springs, choosing 6-inch-long, 750 lb./in. springs for the front and 7-inch-long, 500 lb./in. springs for the rear at Flyin’ Miata’s recommendation.

Flyin’ Miata calls this “the best suspension we’ve ever offered for the NA.” Why? As the shop’s own Keith Tanner explains, it’s custom-made for this application, not merely an existing set of parts that’s been adapted. 

What’s the benefit? Travel. Suspension travel is an issue on almost any lowered Miata, but this kit allows 5 inches of shock shaft travel. That should mean our car spends less time on its bump stops and more time putting down power. 


Rejuvenating Our Miata

Parts in hand, we hit the garage to install everything. We threw the stock brakes and coil-overs in the spares bin, then bolted all of our shiny new parts onto the car, making sure to adequately lube the Wilwood front hubs and set the bearing preload according to the included instructions. We needed to trim the rear brake rotor dust shields a bit, but that wasn't too hard.

Success! We were still a ways away from driving on our new brakes and suspension, but we’d crossed a major to-do item off the list. 

We enjoyed this side quest, but now it was time to get back to the real work: swapping an LFX V6 into the car. We’ll get back to that in the next update.

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Comments
View comments on the GRM forums
Tom Suddard
Tom Suddard Director of Marketing & Digital Assets
4/7/20 10:34 a.m.

Man I'm excited for the tracks to reopen so we can race this car!!!!

Colin Wood
Colin Wood Associate Editor
4/7/20 12:01 p.m.

I never really considered the potential weight savings that can be had by upgrading brakes.

Keith Tanner
Keith Tanner MegaDork
4/7/20 12:20 p.m.

You can knock 18 lbs of unsprung mass off an ND by swapping calipers. It's real.

Looking forward to seeing this thing come to life so we can get it working well! That's the most fun part, the fine-tuning.

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