Before
Project RX-8
Last month we upgraded the wheels and tires on our Titanium Gray RX-8, and the results around Toronto Motorsports Park were nothing short of spectacular. We're talking a 4-second reduction in lap times and a significant reduction in understeer, not to mention drastically improved appearance thanks to the more aggressive offset and design of the Volk Racing G2 wheels.
To continue the handling and style transformation, we needed to add a proper coilover kit, one that would allow us to independently adjust the ride height and spring preload without reducing shock travel. And that's exactly what we got with BC Racing's affordable BR-series coilover kit, though not without some extra effort to dial-in the spring rates and overall handling balance.
After
We started the suspension upgrade process by spending a few hours bolting up the BC Racing coilovers. We were impressed by the kit's build quality, given its entry-level pricing of just $1,250. But with dampers all the magic happens inside the monotubes, so we were determined to reserve judgment until after some street and track testing. If the spec sheet is any indication, these BR-series coilovers should offer lots of tuning potential because of their 30-way single-adjustable damping, independent ride height and spring preload adjustment, front pillow-ball mounts and patented concave lower locking rings that prevent any unwanted slipping to the ride height settings. It's also worth noting that the dampers are rebuildable and come with a one-year warranty.
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The BC Racing BR-series coilovers allow a wide range of ride heights to be dialed-in witho
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... have less available travel than the fronts.
Having done some homework on what the hot setup for STX (Solo 2) class RX-8s is (as we mentioned in the intro story, we're planning on competing in this class at the Solo Nationals), we opted for 450 lb/in (8 kg/mm) spring rates up front and 280 lb/in (5 kg/mm) spring rates out back. The OEM spring rates are 156 lb/in front and 113 lb/in rear, so we've increased the front rates by 188 percent and the rear rates by 148 percent. We planned to combine these spring rates with adjustable antiroll bars, but we haven't quite narrowed down our choices yet, so we'll report back on this once we install and test whatever bars we go with.
We've shown some restraint when lowering the 8 because going too low would've upset its su
With the BC Racing coilover kit bolted up, we moved on to the tedious but vitally important process of setting the ride height and dialing in the alignment. Having researched what most RX-8 racers consider the lowest possible ride height without overly compromising suspension geometry and shock travel, we set ride height to 13.5 inches all around, measured from the center of the wheel to the top of the fender lip. This drop was a bit on the aggressive side, according to some experienced RX-8 racers on rx8club.com, but we like the way it looks so decided to give it a try. Since the BC coilovers have independent ride height adjustability - meaning we shouldn't lose any shock travel no matter how low we go - we also felt this would be a good way to see just how sensitive the RX-8's suspension geometry is to moderately aggressive lowering (but certainly not super low, as you can see from the pics).
After that, we dialed in -2.75 degrees of camber and 1/16-inch toe-out on each front wheel and -1.85 degrees of rear camber and 1/16-inch toe-in on each rear wheel. These alignment settings were chosen based on tire temp data collected during the wheel and tire track test. To measure the alignment, we used a digital camber gauge and a string box so that we could measure toe settings at each wheel separately. For a more detailed discussion of DIY wheel alignment techniques, check out this month's Tech Talk on page 14.