(This article first appeared in the August 2008 issue of SportsCar magazine)

By Philip Royle

There are flaws with every racecar, and ours is certainly no exception. Thus far, our project Improved Touring A 1996 Mazda Miata has run like a champ, yielding a growing collection of second and third place trophies. The problem? The car isn’t fast. While we were legitimately beating other ITA competitors, our little project car was hardly hanging with the frontrunner. We were, in fact, getting our butt handed to us. Luckily, the car is far from finished.

To this point, we had yet to expand the motor’s power output, even in the most basic sense. There were also a handful of very non-desirable parts living underneath the car – namely an open differential and a tall rear end gear ratio. Beyond that, we’d also simply bolted items like the Koni race coilovers and Eibach springs on the car, neglecting to take advantage of the adjustability by corner weighting the vehicle.

Tying up loose ends

Our 1.8L Miata was the epitome of the “Whispering Death” (as some had lovingly dubbed Showroom Stock back in the day) – namely, our Miata was sporting a stock exhaust system. Beside the stock components bottling up potential power, they were also keeping the car way too quiet. Racing door-to-door with an RX-7 often left us wondering if RX-7 pilot was even aware of our presence.

Like with much of this buildup, our solution was probably not the obvious one. Racing Beat has long been known for producing quality Mazda products – and its header and exhaust system are no exception. Our order included the Racing Beat header ($425), Sport Connecting Pipe, which doesn’t include a silencer ($130), and Power Pulse Muffler ($276). While not an inexpensive option, this setup would guarantee we would always pass sound requirements at any SCCA venue, including some of the more restrictive Solo events we also compete in. A Mazdaspeed cat-delete pipe ($40) rounded out the exhaust system.

When we ordered the exhaust from Racing Beat, we also ordered the exhaust manifold gasket (the only gasket not included) and we supplemented some of the included bolts with our own.

This setup isn’t necessarily the lightest available. The Racing Beat components with the Mazdaspeed pipe weighed in at a hair over 44 pounds, roughly 6.5 pounds lighter than the stock setup. If you’re in the market for lighter equipment, there are a number of Spec Miata exhaust systems that could potentially knock another eight pounds off – but in our case, weight was not a concern. An Improved Touring A Miata has a minimum weight of 2380 pounds. Based on the track scales at our first race, we’d bolted 100 pounds of ballast onto the passenger floor. Consequently, a lightweight exhaust could take a backseat to ease of install and not killing our eardrums.

We also opted not to dyno the car. We did so for multiple reasons, the most obvious being that while this system is all but guaranteed to pick up power, it’s equally as guaranteed not to generate as much power as a deafening Spec Miata setup. We also have plans to capitalize on a 2008 General Competition Rules and Specifications Improved Touring rules changes regarding the ECU in a later project installment, at which point we’ll spend time tuning the car on a dyno.

The next glaring problem with our Miata was the open differential and tall gearing. While it’s debatable as to how much the open differential was actually slowing us down, a factory Torsen limited slip differential couldn’t hurt – and there’s little doubt the 4.10 rear end was not the best to be using. While installing a Torsen was a given, the question was what gearing should we choose.

Flatout Motorpsorts is a company with notable success racing Mazdas, including Miatas in both Spec Miata and ITA. A call to Flatout revealed that our realistic choices for final drive ratios involved the traditional 4.30 rear end or shorter 4.80 gears. However, after testing both setups, the Flatout crew settled on the 4.30 as ideal – not to mention the easiest to install since it’s a direct bolt-in for 1.8L Miatas. Consequently, we ordered and installed a complete differential from a 1999 Miata, which housed the 4.30 gearing and Torsen.

As a side note, we’ve been running different tire sizes to find out if the 205/50-15 tires on most Miata racecars is truly the best size. In addition to the 205mm size, we’ve also been competing on 225/50-15 Kumho Ecsta V710s. With the tall 4.10 gearing, our data showed that coming off several turns the Miata simply did not have the power to rotate the larger diameter tires. Hopefully the gearing change will allow more flexibility when it comes to running varying tire sizes.

We also discovered the wide 225mm tires, while offering more lateral grip than the 205mm tires, rubbed on the fender lip. To solve this problem, we ordered a fender lip rolling tool from The Tire Rack. This tool isn’t inexpensive ($259), but if you’re going to roll fenders on multiple cars, this tool will quickly pay for itself. The process was quick and, best of all, successful.

Professional help

With the car in – what we considered – good shape, we thought it time to get a professional opinion before fine-tuning the setup. Consequently, we headed to Tri-Point Engineering and ProParts USA.

Tri-Point Engineering is no stranger to the SCCA. The company not only campaigns the reigning SPEED World Challenge Touring Car Mazda6 racecars, but it has also setup a variety of Club Racing cars. Along with selling performance parts, the company also offers racecar setup as a service at its Canoga Park, Calif., headquarters.

The Tri-Point team checked the car’s alignment and cross weights and inspected the suspension setup. With a half tank of gas and the cold tires filled to 32psi, the Miata had a cross weight of 47.5 percent. While the cross weight wasn’t horrible the camber and toe were way off. We had set the camber to -2.5 degrees front and rear and set zero toe over a year ago. Now, the car now sported -2.3 degrees of camber in the front, -2.2 degrees in the left rear and -1.7 degrees in the right rear. There was also slight toe-out in the front and toe-in in the rear.

Tri-Point made a number of recommendations about the setup, including adding forward rake to increase aerodynamics, balancing the car on the scales closer to 50 percent, setting the camber to larger negative numbers and correcting the wonky toe. Tri-Point also noted that, in order to take the car’s handling to the next level, we should remove any binding in the suspension. A key component for this would be to allow the dampers to freely pivot at the upper mounting points.

Setting up the car

Beyond Tri-Point’s notes, there was also the issue of the rear suspension travel – or lack thereof. The Koni race shocks we are using are shorter than stock. With the ride height set to just over 5 inches to the lowest point on the rocker panel, the rear shocks were sitting on the bump stops. While raising the ride height and drastically cutting the bump stops would solve the problem, that particular solution would not offer the amount of shock travel we’d like.

A common solution for first generation Miatas is to install damper hats from a 1999-’05 Miata. These factory hats can be purchased through Mazda Motorsports and reportedly offer between 0.5 and 0.75 inches of additional travel for about $25 a corner.

With the back of the our Miata resting on the bump stops, we decided to go a little more extreme, so we ordered four upper shock mounts from ISC Racing Services. ISC is very experienced in the world of ITA Miatas, having built several winning ones – the company has also built Miata damper hats to solve the exact problem we were having.

The ISC shock mounts are direct replacements for the factory units and add roughly 2 inches of shock travel, although the company will build custom height hats to fit your needs. The cost is about $39 per corner, or $45 for custom hats. While the ISC units do utilize a bushing at the top of the hat permitting shock pivoting, this movement probably matches the amount built into the factory hats. While we would have liked to go with a pivoting damper setup like Tri-Point described, we were more interested in greater suspension travel at this point in time.

With the shocks disassembled, we also took the time to trim about a third off the Koni bump stops. Also, if your shock shaft is larger than the hole in the ISC mount then drill out the hole to slightly larger than the shaft. This was the case with our Koni shocks.

With the suspension installed, we adjusted the ride height to 5.5 inches in the front and a touch higher in the rear (the car was sporting the larger diameter 225mm tires, so we wanted to leave room for when we swapped to shorter 205mm tires). This was when we discovered increased shock compression with extremely short shock bodies results in almost no rear droop. Should the lack of droop have too negative of an affect, we could either have ISC custom make rear hats or order a set of rear 1999-’05 Miata hats, depending on how much droop we think we’ll need.

Not to second guess the setup without going to the track, we broke out the corner weighting and alignment equipment.

The scales we used are the Longacre Computerscales DX with PC download corner weighting scales. These scales are one of Longacre’s top-of-the-line scales, costing $2,049, but the company’s $1,098 scales would do just as good of a job. The more expensive scales boast 10 memory settings, auto leveling and shows you the wheel weights and partial percentages at the same time – the less expensive unit does not. However, for the average Club racer, the less expensive Longacre scales would be perfectly acceptable, although the extra features did speed up the corner weighting process.

To make loading the car onto the scales easy, we used a set of Race Ramps scale ramps. Race Ramps is known for its lightweight ramps, and is continuing the tradition with these ramps, which weigh in at less than 4 pounds each. These ramps match the height of the average corner weighting scale and offer a flat area allowing you to push the car off and on the scales with ease.

After looking at the initial weight distribution numbers, it’s obvious why the Miata is such a popular vehicle. By simply setting a ride height with a slight forward rake and a half tank of fuel, our Miata already had a 51 percent weight distribution – and following two shock collar adjustments we had the car sitting where we wanted.

LF: 625lbs.            RF: 628lbs.
LR: 567lbs.            RR: 560lbs.
Total weight: 2380lbs.
Cross weight: 50.2%

The trick to corner weighting any car is to remember to disconnect the swaybars beforehand, have the driver sitting in the car and to remember that any change you make to one corner will affect the diagonal wheel in the same fashion. Raise the shock collar on the right rear and you’ll increase the weight on that wheel and the left front.

Next, we broke out the SmartRacing alignment tools. SmartRacing produces a number of handy and affordable components for setting toe and camber. We started by stringing the Miata with the SmartRacing SmartStrings to measure the toe settings and then calibrated the SmartCamber tool with hands free adapter. The SmartStrings cost about $408, and the SmartCamber tool runs about $260.

While the process of doing your own alignment isn’t quick, it is very precise and allows you the ability to try a variety of settings with the freedom of changing it at the track. Consequently, we got a little adventurous.

As before, we set the car to zero toe, allowing for the least rolling resistance. At the same time, we set the rear camber to -2.4 degrees. Up front, however, we set the camber to -3.8. Many spec Miatas seem to run -2.5 in the rear and about -3 in the front. Owning the SmartCamber and SmartStrings means that should we find the car too much of a handful, we can adjust the alignment settings at the track to correct any problems.

Up next for the Miata is to work out any handling issues and then hunt for more power and speed, capitalizing on a couple recent Improved Touring rules changes – hopefully winning a couple races along the way.

The right rear end

When it came to swapping the differential, we had several choices. Having never built an ITA Miata before, we contacted Flatout Motorsports for some advise. Flatout was founded in 1994 by three autocrossers, Nick Leverone, Andy Bettencourt and Steve Ulfelder. The company had limited success at the time, but the crew breathed new life into it in 2003. By then, the Flatout founders were road racing.

“The company really took off in 2005,” explains Leverone. “In 2004-’05 we started renting out some Spec Miatas, and that started the company on a path to do more with road racers. In 2006, we took on our first arrive and drive client.”

The Bellingham, Mass., company’s arrive and drive program involves Flatout maintaining and transporting owners’ cars. Presently, this constitutes the majority of Flatout’s business. In addition to their own racing, this allows Flatout to see what works and what doesn’t, as the customers all share their setup.

“Everyone shares data with each other [on the arrive and drive program],” says Leverone, “and it helps everyone on the team do better.”

When it came to our gearing question, Leverone had some firsthand experience. “We found the 4.88 gears, even at a track like Lime Rock [where shorter gears can come in useful] the gears were putting Andy into a bad position [in his ITA Miata] when it came to shifting and running out of gear.”

Following that, Flatout installed the 4.30 gears with a Torsen and the result has been Bettencourt running right at the track record at several tracks in the northeast.

“Some tracks may lend themselves to the 4.88,” says Leverone. “You may talk to someone that says a 4.60 or 4.44 is a more suitable gear ratio for all the tracks, but…I think the 4.30 has proven to be the best gear ratio for the [ITA Miata].”

SOURCES:
Flatout Motorsports, http://www.flatout-motorsports.com
ISC Racing Services, Inc., http://www.iscracing.net
Kumho Tires, http://www.kumhousa.com
Longacre, http://www.longacreracing.com
Mazdaspeed Motorpsorts Development, http://www.mazdamotorsports.com
Race Ramps, http://www.raceramps.com
Racing Beat, http://www.racingbeat.com
SmartRacing Products, http://www.smartracingproducts.com
Tri-Point Motorsports and PowerParts USA, http://www.tri-pointengineering.com, http://www.propartsusa.net
The Tire Rack, http://www.tirerack.com

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