How to Prep a Mazda MX-5 Miata ND for C Street

J.A.
By J.A. Ackley
Jan 9, 2023 | Mazda, Miata, Autocross, MX-5, Mazda Miata, Mazda MX-5, ND, Good-Win Racing, Brian Goodwin | Posted in Buyer's Guides | Never miss an article

Photography Credit: Rupert Berrington

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The Mazda MX-5 Miata ND (2016–present) is one of the most popular cars in autocross competition, especially SCCA C Street (we’ll cover STR in a future story), and with good reason. It’s nimble, responsive and, most importantly, quick, straight off the lot.

However , you can always make something better. We asked Brian Goodwin, of Good-Win Racing, for his recommendations for the Mazda MX-5 Miata ND.

Trim Level Matters

Photography Credit: Courtesy Good-Win Racing

Photography Credit: Courtesy Good-Win Racing

One trim stands head and shoulders above the rest for the MX-5, and that’s the Club trim.

“The Club trim gets the pretty critical upgrades of the limited slip differential and additional rear spring rate–100 lb/in vs just 80 lb/in,” Brian says. “We desperately want that extra rear spring rate since we cannot upgrade springs in CS, and we can do just one sway bar upgrade.”

The Club level adds a few other perks.

“Some prefer the support of the optional Recaro seats, but they add a few pounds over the standard seats,” says Brian. “Some go for the better feel of the Brembo calipers, but that too adds weight.”

If you’re weight-conscious, Brian advises to go with the Club package, with standard brakes and seats, in the color white. Yes, color matters.

“White is less weight than the multi-stage paint choices,” Brian says. “The team building MX-5 Cup cars told us that multi-stage red is 15 pounds more than white. We still went with red, because we love the color. We vowed to drink less beer to make up the difference. That still has not happened, yet.”

Which Years to Buy and Why

Photography Credit: David S. Wallens

Photography Credit: David S. Wallens

“My preference would be to get a ND2, the second generation of the car,” says Brian. “It looks the same as the other generation, but it’s different on the inside.”

Those differences start with the engine. Mazda upped the power, from 155 horsepower to 181 horsepower.

[GRM Exclusive: 2019 Mazda MX-5 Miata ND2 Dyno Test]

“The motor revs a little higher, and the power’s more up at the top end,” Brian says. “It’s not significantly faster, but it’s certainly more joyful to drive.”

Mazda also introduced a dual-mass flywheel.

“It’s essentially a shock-absorber between the engine and transmission,” says Brian of the flywheel. “The gears don’t shatter as much as we were doing on the ND1.”

Wheels and Tires

To start, Brian recommends upgrading to wider, 200tw tires and wheels that support that rubber.

“We stuff a 225/45R17 200tw tire in there,” Brian says. “It’s a stuff job, because the factory wheel is only 17x7, and for C Street you have to run factory wheel width. You can change the offset, so most of our customers are running the 40mm-offset Advanti Racing Storm 17x7 that’s only 14 pounds. It’ll rub the plastic fender liner at full steering lock, but we’ll only use that when we’re trying to make a K-turn in the post office parking lot. We will relax the caster setting to 6, where from the factory it’s often 8, to reduce that rub.”

[200-treadwear tire test | Bridgestone Potenza RE-71RS vs. Falken Azenis RT660]

Shocks

The market offers a bunch of different choices for shocks. Brian prefers one over the others for most autocross enthusiasts.

“The standard for decades has been the adjustable Koni Sport shocks,” says Brian. “There’s certainly high-end stuff for which you could spend thousands, but the standard Koni Sport shocks work. We leave them full soft up front. Because they’re a twin-tube shock, we’ll leave them at lower pressure than the stock monotubes. The car will sit a little bit lower and you’ll pick up a little negative camber, even though the length for the Koni Sport shocks is the same as the stock ones.

“To balance the big front sway bar, we’ll leave the rear shocks full stiff.”

Anti-Roll Bars

Back when the Mazda MX-5 debuted, Brian told us the car’s body lean is “extreme.” That hasn’t changed–nor has the solution. The front anti-roll bar remedies this issue, but now Good-Win Racing offers two setups.

“Since we’re on a budget, we use the Progress Technologies front sway bar, which was good enough for us to win a local Solo tour event,” Brian says. “A better bar has come out, the Karcepts bar. It’s a lot more expensive, a lot more technical bar. It doesn’t have a big squishy, bushing, so the response is more linear and instant. And, it has end links that allow you to change settings quickly between runs, with a single wrench. The only downside to the Karcepts bar is that since they have solid end links, they’ll eventually chatter a little bit, which some might not find desirable on the road.”

Bump Stops

In addition to adjusting the shocks, Brian tweaks the bump stops.

“Per the rules, you can’t go longer, but you can go shorter or trim the bump stops,” says Brian. “Most guys trim an inch off the front stops, so we’re not into that stop as quickly on the course. In the back, we’ll run really stiff stops, with lengths of the stock stop.”

This type of setup particularly helps one type of section in autocross.

“When you get into a long, five-cone slalom, the car will sort of jack down,” Brian says. “We got the Konis in the back at full stiff, and they’re only rebound-adjustable. So, the car will jack itself down and sit on that hard stop. At that point, the balance with the front sway bar will permit the car to change directions pretty quick through a slalom.”

Exhaust

Photography Credit: Andy Hollis

Photography Credit: Andy Hollis

Brian adds that swapping out the stock muffler with their Roadster Sport Race model saves nearly 9 pounds over stock. Our Andy Hollis tested the SuperStreet version of the muffler, which weighs 2 more pounds than the other, on the Triple Threat Miata project car.

[Upgrading the Exhaust and Testing Different Wheel-and-Tire Setups | Project Triple Threat Mazda MX-5 Miata]

“The test said it gained 8 horsepower at the top end, and in autocross, you spend a lot of time in the top end of second gear, so that helps,” says Brian. “He dyno-ed the ND1 motor, so I’d expect the ND2 motor to have more gains.”

Odds and Ends

Overall, the Mazda MX-5 Miata ND doesn’t require many upgrades–and that includes not needing an oil cooler for naturally aspirated ND2 models, according to Brian. It also provides a perfect platform for not only autocross, but other endeavors.

“I have a lot of customers who run their autocross C Street package as their track day package,” Brian says. “That’s because it’s really benign on the track when it’s set up for autocross–it’s not going to suddenly bite you. So, that’s fun for both uses.”

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maschinenbau
maschinenbau GRM+ Memberand UberDork
10/12/22 9:55 a.m.

Because they’re a twin-tube shock, we’ll leave them at lower pressure than the stock monotubes. The car will sit a little bit lower and you’ll pick up a little negative camber, even though the length for the Koni Sport shocks is the same as the stock ones.

To me this goes against the intent of Street class rules. It's an open secret that certain aftermarket shocks lower the car, even though *supposedly* the spring perch locations are dimensionally correct. It is not insignificant either...about an inch, picking up at least a 1/2 degree of camber. The best racecar alignment shop in Atlanta can only get me -1.2 at all 4 corners meanwhile the same car, same year, same color, but on Konis is at -1.8 according to the owner. The difference is really obvious when were parked together in grid. But I guess that's racing. Sincerely - a slow complainer :) 

David S. Wallens
David S. Wallens Editorial Director
10/12/22 10:57 a.m.

I've had that very discussion with someone a bit high up in the Solo community: ride height isn't protestable yet spring perch height is. 

dps214
dps214 Dork
10/12/22 11:46 a.m.
maschinenbau said:

Because they’re a twin-tube shock, we’ll leave them at lower pressure than the stock monotubes. The car will sit a little bit lower and you’ll pick up a little negative camber, even though the length for the Koni Sport shocks is the same as the stock ones.

To me this goes against the intent of Street class rules. It's an open secret that certain aftermarket shocks lower the car, even though *supposedly* the spring perch locations are dimensionally correct. It is not insignificant either...about an inch, picking up at least a 1/2 degree of camber. The best racecar alignment shop in Atlanta can only get me -1.2 at all 4 corners meanwhile the same car, same year, same color, but on Konis is at -1.8 according to the owner. The difference is really obvious when were parked together in grid. But I guess that's racing. Sincerely - a slow complainer :) 

It's specifically written in the rules that shocks are allowed to affect ride height. Considering manufacturing tolerances, option packages, tire size differences, etc, good luck enforcing anything else anyway.

maschinenbau
maschinenbau GRM+ Memberand UberDork
10/12/22 12:39 p.m.

I get why in theory it's allowed. To accommodate true "street" cars, they have to allow for aftermarket options so owners can maintain their cars for years to come without relying only on OEM parts supply (Rockauto, Advance, etc). This allowance accommodates all sorts of practical options, and their differences in tolerances and option packages, but also opens the door of opportunity for performance companies to sell pricey products that have a targeted advantage. So the only 2 options the rulemakers have are 1.) mandate OEM factory shocks only or 2.) allow all aftermarket shocks.

So I totally understand it. It just sucks that you have to drop $1k on shocks in addition to 200tw "street" tires to be competitive in the closest thing to a stock class. I guess that's why it's called "Street" not "Stock".

dps214
dps214 Dork
10/12/22 1:05 p.m.

The funny thing is a very similar conversation has been going on on another forum, except there's another zero in the damper cost figure (okay, realistically it's like $5k). I do sympathize, and I think it's a little ridiculous that there's zero functional restrictions other than being limited to two adjusters. But gas pressure and the resultant ride height effects are always going to have to be open unless you're only allowing OE dampers. And even then, replacement OE dampers are very often not exactly identical to the actual original parts, so they could still end up not being fully compliant.

ConeKiller1
ConeKiller1
10/12/22 11:20 p.m.

Don't forget you need really cool graphics... they really help the car go faster :)

badair
badair New Reader
10/13/22 12:07 a.m.

My setup is the same.

I found that cutting an inch off the front bumpstops wasn't enough for me. I took another 0.25 inch off and now the balance is tolerable (but still pushy).

I notice that with the Karcepts bar where I like it for steady-state balance, and with the front Konis on full soft, the front seems way too floppy during the fastest transitions -- delayed reaction followed by an upsetting bounce. I was happier last event when I went up to 1.25 turns from full soft between runs, although I'm not sure that's in the range of the valve where it really matters so maybe it was placebo and increased caution on course. I'll continue experimenting.

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