SUR­VIV­ING THE PLUNGE

EIGHT YEARS AF­TER HE CHOPPED UP HIS SHOW CAR, WE CHECK IN ON SHAUN JUDD’S EPIC HOME-BUILT GT1-SPEC FC RX-7

NZ Performance Car - - Contents - WORDS: MAR­CUS GIB­SON PHO­TOS: ADAM CROY / MITCHELL BODNER

UN­DER THE SKIN OF A GT1 RX-7

One class within the up­per ech­e­lons of New Zealand mo­tor­sport ex­em­pli­fies the Kiwi can-do at­ti­tude by of­fer­ing such a loose set of rules that mad sci­en­tists– cum–race engi­neers can piece to­gether tin-top ma­chines ca­pa­ble of blis­ter­ingly fast lap times. It’s a class in which only one’s imag­i­na­tion, prac­ti­cal abil­ity, and lust for speed are the hur­dles be­tween you and how fast you can go.

GTRNZ is home to our coun­try’s fastest tin-top cir­cuit rac­ers, and one of them is the wildest-look­ing RX-7 you’re ever likely to lay eyes on. But the best bit about the flame-spit­ting FC is that owner/builder/pi­lot Shaun Judd has man­aged to piece to­gether this weapon right from in­side his hum­ble two-car home garage.

It’s not the first time that we’ve pointed a cam­era at this FC, and, if we’re hon­est, we doubt it’ll be the last, as the 17-year­long project has seen Shaun’s once-show-car-qual­ity street car un­dergo more op­er­a­tions than Mickey Rourke. But in all that cutting, re­work­ing, and re­shap­ing in the quest for speed, sur­pris­ingly, the FC still hasn’t lost its soul — it is still in­stantly rec­og­niz­able as an FC, and a sur­pris­ing amount of fac­tory tin re­mains, in­clud­ing most of the chas­sis rails, floor, fire­wall, and roof, all of which are a nod back to the orig­i­nal in­ten­tion to run un­der the SS2000 regs. That plan quickly de­railed and di­verted onto a new track into what was then known as ‘Su­per GT’ and now as ‘GTRNZ’, a move made due to the re­stric­tions placed on ro­taries in SS.

It was 2010 when we first took a look at Shaun’s hand­i­work on the FC. It was then pow­ered by a nat­u­rally as­pi­rated 13B pe­riph­eral port (PP) and had the same ba­sic sus­pen­sion lay­out that you see to­day, al­though it was all a lot less de­vel­oped than it is now. The cus­tom dou­ble-A-arm con­fig­u­ra­tion front and rear, pushrod Koni coilovers, and cus­tom up­rights were all fab­ri­cated by Shaun, and, for all in­tents and pur­poses, it was an over­sized 224kW go-kart, which is fit­ting when you re­call that Shaun had built the car as his step up from com­pet­i­tive kart­ing.

Af­ter a some­what lack­lus­tre first sea­son, the up­grades be­gan, a close-ra­tio box, ad­justable sway bars, new rub­ber, and an ex­tra 60hp ex­tracted from the 13b by Brent Cur­ran, soon brought the FC up to speed — a little too much speed, as it turned out, as Shaun broke out at both Taupo and Pukekohe: “We ran a 1min 04.4s at Puke; I never thought we’d break out there.” This forced a shift to GT2, al­though they were now at the back of the grid again. “We needed some ex­tra power. It was ei­ther build some slid­ing throt­tle bod­ies and try [to] get some more pace from the PP, or add in some boost,” Shaun ex­plains. A su­per sim­ple set-up soon turned into a pack­age that pro­duced 328kW the first sea­son and 410kW the fol­low­ing one, af­ter switch­ing from av­gas to E85. The car was no longer ham­pered by a lack of straight-line speed or re­ly­ing solely on cor­ner­ing pace to keep up; it now had the boost to bat­tle those big­ger ca­pac­ity V8s on the straights, which placed Shaun squarely at the pointy end of the GT2 class. But, as with any home­brew racer, there are al­ways im­prove­ments to be had, and the team never stopped up­grad­ing, or re-en­gi­neer­ing, parts as bud­get or imag­i­na­tion al­lowed.

The big­gest ‘up­grade’ was forced by the cold, hard slap of a con­crete barrier dur­ing the 2013 ITM 400, when the FCs clutch failed bring­ing it to a hault on track. Hit from be­hind, the re­sult­ing crash dam­age was ex­ten­sive, com­pletely de­stroy­ing the rear end

Both the front and rear blade-type sway bars are ad­justable right from the driver’s seat. Work­ing be­tween a hor­i­zon­tal and ver­ti­cal po­si­tion, the more hor­i­zon­tal the blade is, the softer the bar

and bend­ing the front. It wasn’t a pretty sight, al­though it did give Shaun the ex­cuse to re-engi­neer the sus­pen­sion de­sign, this time ditch­ing the rear chas­sis rails and mod­el­ling ev­ery­thing us­ing CAD.

New body­work was needed, so the op­por­tu­nity was seized to step to broader 280mm wide 18-inch slicks (and wheels). Ki­los were also saved, bring­ing the kerb weight back down to what it once was with the nat­u­rally as­pi­rated (NA) mo­tor. These sav­ings came in the form of new fi­bre­glass doors, bon­net, rear hatch, and Lexan win­dows all round. The rear wing dou­bled in size and was at­tached di­rectly to the chas­sis. A sec­ond wing ap­peared on the boot, and new aero up front in­cluded a large split­ter, bon­net vents, ca­nards, and box-style side skirts. The ride height dra­mat­i­cally de­creased, giv­ing the car an almost body-dropped look, with flares that now tow­ered over the bon­net line.

It was almost two years af­ter the crash that the FC resur­faced, dis­play­ing Shaun’s trade­mark metic­u­lous show car pre­sen­ta­tion. The at­ten­tion to de­tail was sec­ond to none, paired with his fab­ri­ca­tion abil­i­ties — show­cased via myr­iad laser-cut plate and bent tubes. But the two-year re­build nearly went up in smoke dur­ing

the first time out at RE­union, when the trade­mark flame-lick­ing ex­haust got away and took hold in the rear cor­ner: with­out fire mar­shals on track — it wasn’t a race event— the mer­cury was soar­ing and flames spreading fast by the time Shaun made it back into the pits.

De­spite this set-back, it wasn’t long be­fore Shaun was back in the GTRNZ fold, and those up­grades made an in­stant im­pact, as, this time, he was nip­ping at the heels of GT1 class times. So, when a shake-up of the class break­out times was an­nounced ahead of this sea­son, Shaun knew ex­actly what up­grades would get him up to speed for his pro­mo­tion to GT1. The old (and heavy) GForce was swapped for an HGT Pre­ci­sion six-speed se­quen­tial. Aside from chop­ping nearly a sec­ond from his lap times, it also helped Shaun be as pre­cise as pos­si­ble in the driver’s seat. This home-built war­rior now found him­self on the grid among a pack of wolves, and these wolves were show­ing their teeth. These were pro­fes­sional-built race cars, many with all the best pieces in all the right places, and the little 13B now had its work cut out to keep up, so Shaun’s driv­ing had to be on point at each and ev­ery cor­ner. Any mis­takes would cost the torque-less 13B big time, “The big­gest thing is you can be mid cor­ner now and you can just pull an­other gear with­out think­ing about it. Now if it comes on boost

The cur­rent weight sits a few ki­los over a tonne. This means that when the ‘pass­ing’ switch is hit and all 462kW is re­leased, the car is a real rocket ship. Shaun ad­mits, though, that the V8s he races against have a far eas­ier job, as one mis­take in gear se­lec­tion ex­it­ing a cor­ner is hard to come back from, un­like in the V8s No, your lo­cal dump truck isn’t miss­ing its turbo. This is ac­tu­ally a Holset HX55 built by Tur­bocharg­ers New Zealand, and sit­ting on a cus­tom stain­less man­i­fold

and starts to step, I can bog it by short shift­ing,” he says.

How­ever, best-laid plans have not seen a fruit­ful de­but GT1 sea­son, due to the new mo­tor­sport power-steer­ing pump. This prob­lem plagued the car and was even­tu­ally traced to the pump be­ing sup­plied with the in­cor­rect pres­sure-re­lief valve. It’s fair to say that it’s been a sea­son the team would much rather for­get. But this is mo­tor­sport, and they are not about to give up. In fact, the day be­fore our shoot, new AP Rac­ing Pro 5000 brake calipers found their way onto the hand­crafted up­rights via a pair of CNC’d mounts — whipped up, you guessed it, by Shaun. But that should come as no sur­prise, as you’ll strug­gle to find a cus­tom piece on the car that he hasn’t built. It’s a never-end­ing chal­lenge in the quest for speed, and one that shows no signs of slow­ing. In fact, this pho­to­shoot is just like our last, when Shaun was speaking about the turbo mo­tor it has now: there is more talk of a sim­i­lar na­ture, only, this time, it in­volves mak­ing his own crank. We’ll let you join the rest of the dots on that one.

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