“What would you say the weakest point is?” We had just asked John Heinricy, basically the godfather of the C5 Corvette, if he had any regrets about the car’s final design. Instead of answering our question, though, he threw it back at us.
“Well, the seats kind of suck,” we admitted.
Heinricy’s grin, sly but regretful, told us we nailed it even before his words did.
Now, we weren’t trying to bust the guy’s hump here. He and the rest of the C5 team built the Corvette into a world-class sports car–especially with the Z06 version. But Heinricy himself agrees that the interior simply doesn’t accommodate the car’s true capabilities.
And we get it: Big automakers need to be profitable to survive. This means watching costs, appealing to broad markets, and sometimes making compromises to keep the bottom line in the black.
But the C5 seats still suck, and their suckiness became all the more apparent once we started augmenting our car’s already stellar performance. We refreshed the stock buckets in our last installment, swapping in fresh foam and adding custom leather covers from Mid America Motorworks, but that didn’t resolve the flaws in their basic architecture. We needed driving accommodations that would allow us to take advantage of our Vette’s expanding performance envelope.
Human Factors
Forget seat and steering wheel adjustments for a minute. Let’s start by placing the most important factor in any driving configuration: the driver’s body.
Plenty of “experts” on the internet can tell you the “correct” driving position for high-performance motorsports, but they tend to provide one-size-fits-all advice for what are definitely not one-size-fits-all situations. Simply put, there’s just no way a 5-foot-9, 170-pound YouTube sensation can prescribe his ideal driving position for a 6-foot-4 volleyball player or a 5-foot-5 human fireplug.
Sure, some position-based guidelines are helpful, like making sure you can fully depress the pedals without extending your legs to their limits. Others are too specific to be truly useful: A 90-degree bend at the elbows isn’t always best, since body types vary and cars have different adjustment limitations. Instead, we’re going to pitch a slightly different paradigm based on muscle usage.
The muscles of the human body each have their own specialties and weaknesses. The big muscle groups–the ones in our core, shoulders, hips, butt and chest–are about power. Moving out from the torso and toward the extremities, muscles generally lose overall strength but gain fine motor control. Our wrists, hands, fingers, calves, feet and toes are less powerful but far more precise and tuned to smaller sensations.
So with this knowledge, we can better define the ideal driving position: We want our large, coarsely attuned muscle groups to keep the body planted and stable, leaving our finer muscles free to pick up on subtle feedback and make quick, detailed adjustments.
In other words, we shouldn’t put ourselves in a position to use our fine muscles for strength or our strong muscles for precision. We want to be able to depress the brake pedal firmly by engaging the muscles in our hips, thighs and butt, yet gingerly trail off those brakes to perfectly balance corner entry using the muscles in our ankles, feet and toes. Aggressive steering inputs should come from the chest, shoulders and back, while precise inputs should come from the wrists, hands and fingers.
Of course, even if we’re thinking in terms of muscle specialties, some cars simply won’t allow certain shapes of driver to achieve an ideal position. The stock seats in our Corvette position the thigh bolsters more than 11 inches above the floor–a very poor setup for someone with short legs.
To properly work the pedals, our short-legged driver has to position the seat so far forward that the steering wheel begins to intrude. So to provide some clearance, a compromise is introduced: the seat is leaned back. But our driver may have to recline so much that it becomes impossible to properly work the wheel with the chest and shoulder muscles.
Add in the fact that the C5’s seats are rather flat, causing the driver to brace against the door panel just to keep upright, and the whole situation is far from ideal.
Let’s Get Comfy
How can we tweak the Corvette interior itself to achieve the best possible driving position? Well, we can’t move the floor or change the location of the steering column, but we can adjust the pieces that are attached to those hard parts–like the seat and steering wheel. We can also make small adjustments to the pedals.
Let’s start with the steering wheel, because it’s another glaring shortcoming of this amazing performance car. A stock C5 steering wheel measures 15-plus inches in diameter and features spokes at about 3:45 and 8:15–and thanks to their design, we can’t quite wrap our fingers around those spokes. The wheel itself is also covered with a durable but slick leather that looks like something a city put on the “nice” subway cars when it tried to convince everyone that tax dollars were being spent wisely.
The wheel also features an integrated airbag, which means we have to pause here for some disclaimers: We would never, ever, encourage you to disable or remove OEM safety features from a street car. Period. Full stop.
1. Yanking off our wheel wasn’t as simple as it sounds. We first tried using a standard pulley-style puller, even going as far as machining the jaws for extra grip.
2. This strategy simply bent the steering wheel’s soft aluminum center. Fearing the aluminum would fail, we changed tacks.
3. The correct tool turned out to be a proper GM-style J-hook.
4. This puller features arms that extend through the hub itself, placing the pulling forces closer to the center of the wheel.
But if you do happen to take a T27 Torx bit with a 3-inch extension and remove the two screws securing the factory airbag to the wheel (first turn the wheel 90 degrees for better access), absolutely disconnect the battery first. In fact, disconnect the battery and wait 10 to 15 minutes before touching anything airbag-related. The bags are actually fired from charged capacitors and not directly from battery voltage, so you need to give those capacitors some time to drain. Of course, all of this information is irrelevant, since disabling OEM safety gear is something that we would never recommend and you would never attempt.
So anyway, once the airbag is free from the wheel, disconnect the power connection. Do not cut the wires: This is not “The Hurt Locker” and you are not Jeremy Renner. Cutting the wires with a pair of metal snips could give electricity a path to ground, which could give that now-loose airbag a path to breaking your nose.
And that’s it. Just understand that once that bag is off, you now have a race car and not a street car. Don’t say we didn’t warn you.
Once the airbag is clear, you can access the nut that secures the wheel to the shaft. Remove that nut with an impact gun or prepare for frustration. (And you don’t want to create any additional frustration for yourself because, believe us, there’s plenty a-comin’.)
After freeing that nut comes the great moment of truth regarding C5 steering wheel swapping. Grab the wheel and try to yank it off. Did it pop off easily? Yes? If so, congratulate yourself on being one of a small number of lucky people in this great universe of ours.
If the wheel doesn’t just pop off, then you’re like so many other C5 owners, including us. Now this process is going to get involved–and likely a little personal.
Our Momo 69 steering wheel (5) required its own hub, so we used a quick-release version from NRG (6). It simply bolts to the steering shaft–no trimming of the plastic column necessary. The hub indexes itself, too, so it always goes on straight. (7. For those who like their wheel a little closer, NRG offers a half-inch spacer.)
You’ll see plenty of C5 steering wheel install videos on YouTube where people get to this point and face this struggle. Some successfully beat the wheel off with a hammer, some yank it free with a multi-jaw puller, and some just kind of jump-cut straight to the hub install.
While those other methods may work, there is one true method, and it involves the J-hook steering wheel puller. The steering wheels found in many late-model GM vehicles feature slots designed to accept a specific type of J-hook. This hook will pull said wheel from said shaft. Get one. We bought a cheap version at a local auto parts store for less than $20, but commercial options are available if you think this is a job you’ll be doing more than once.
Before you set about using said puller, take some time to blueprint it, if necessary. Our cheap-o J-hook sported lots of casting flash as well as pulling faces that weren’t totally perpendicular to the surfaces they’d be mating with. We took a few seconds with a grinding wheel to tune up our tool a bit.
If this attention seems like overkill, understand that the failure mode here involves the wheel’s soft aluminum hub simply ripping apart–yep, it’s a thing–and leaving you with a mangled chunk of what was once a steering wheel still stuck on the shaft and no easy way to remove it.
The beauty of the J-hook puller is that it puts all the pulling force close to the hub. A jaw-style puller applies that force to the rim of the hub, potentially breaking hub itself. Score one for the right tool.
For our replacement wheel, we chose a suede-covered Momo model 69. It retails for $229.95. At 14 inches in diameter, it’s more than an inch smaller than the stock wheel, yet doesn’t block the view of the gauges. It’s also a darn nice piece to wrap your hands around.
Yes, mounting the wheel can be complicated, too. Momo offers an adaptor hub that bolts to the steering shaft, but the grommet for the wiring is in the wrong place, requiring the adaptor to be installed 30 degrees off center, which requires adjusting the alignment to compensate. And after that, the steering column bezel has to be trimmed.
Fortunately, NRG offers another adapter option. This hub not only positioned our wheel within a quarter-inch of the stock location, but provides a slick quick-release feature. Our solution uses the brand’s SRK-170H Short Hub (MSRP $129.99) and SRK-200 quick release (MSRP $134.99). Our wheel still ended up a few degrees off center, but enough that the alignment didn’t require too much adjustment.
NRG offers an optional spacer (SRK-500B) that brings the wheel an additional half-inch closer.
So boom, we had a proper steering wheel. Now let’s find a better seat to operate it from.
Have a Seat
Comfort is a concept that should never be overlooked in a race car. “It’s a race car, so it’s supposed to be uncomfortable” is a bullcrap excuse for lousy lap times. Better options exist.
“The biggest thing with seating position is comfort,” says pro racer Robb Holland. We polled a few friends who spend a lot of time in race cars, and they all echoed this sentiment. Comfort simply lightens the driver’s physical and mental load.
“I do a number of endurance races, and if you’ve got a compromised seating position, it becomes more and more draining on the driver as the stint goes on,” Robb continues. “Even in a sprint race or an autocross it has an effect, because discomfort is an unwanted distraction.”
We agree with Robb–not just because he’s cool, but because he’s right. So we set out to find a seat and a mount that would put us exactly where we wanted to be.
We also wanted a seat comfortable enough for the occasional street transit, one that could accommodate different drivers, and something that would position our stumpy little legs close to the pedals.
8. The AMT Super Low seat mount is practically made of holes, so it accommodates a huge variety of seats and offers plenty of adjustment. Bolting on our Kirkey 47 aluminum race seat was a snap.
9, 10, 11. The stock seat studs are recessed into cavities that sit lower than the floor. These AMT mounts use clever stud extensions that allow them to bolt flush with the floor, meaning the seats can then be mounted at or near floor level as well. The result: more headroom. When mounting seats, remember to use hardware that’s Grade 8 or better and at least 5/16 inch in diameter.
The answer was a Kirkey 47 Series aluminum road racing seat–which, right after we ordered ours, was superseded by the 65 Series. At less than $250, the 47 was a bargain–and it’s also downright comfortable, especially with the optional padded cover. The seat is also easy to mount in a variety of configurations.
We chose the widest option–18 inches across–which more than a few people will say is too wide for a C5. We’re here to say that they’re wrong. It takes some effort, plus the correct mount, but the 18-inch Kirkey slides home like a champ.
In this case, the right mount comes from AMT Motorsport. Mark Petronis of AMT makes some trick, bespoke gear for competition Corvettes–wait until you see his rad spherical suspension bushings in a future issue–and his super-low seat mount is rapidly becoming one of the most popular options for Vette racers of all sizes.
With help from some slick fabricated bolts that go over the stock studs, the AMT mount makes it possible to place a side-mount seat right on the floor of the car if need be. It’s infinitely reconfigurable for nearly any side-mount seat and features numerous adjustment holes plus built-in sub belt-mounting options.
We couldn’t get our 18-inch seat all the way on the floor, but it turned out that we didn’t need to. Remember how the stock seats positioned our thighs more than 11 inches above the floor? Our new arrangement cut that figure to a tidy 7 inches, and we can still lower it a bit if necessary. And where the stock seat cramped our headroom, our new one gives us plenty.
Here’s a friendly reminder to always use Grade 8 or better hardware when mounting a seat. Grade 8 fasteners can withstand 130,000 psi of force before failure, whereas standard Grade 5 stuff can begin to fail at 80,000 psi. Your safety is worth a few extra pennies, and many sanctioning bodies won’t sign off on a seat mounted with Grade 5 hardware anyway.
Sit Your Way to Better Lap Times
With our new seat and wheel setup, the improvement in the driving experience is truly staggering. We always knew that the C5 Z06 was an astonishing performer, but now we can actually use that performance without worrying about how we’re going to hold ourselves up in the process.
12. This 1-inch clutch extension from Mid America Motorworks installs in seconds and fixes an ergonomic issue. 13. Thanks to our new seat, pedals and wheel, we now have a track-ready interior.
In future project installments, we’ll flesh out the safety gear inside the car for time trial use. For now, though, we’re just excited to have a solid, practical place to go about the business of driving.
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