OME cars are constructed with bolt-on parts plucked from a catalogue, but Chris Willett’s HT Holden is being built in the truest possible sense of the word. We’re talking CADdesigned laser-cut chassis rails and handmade double A-arm front suspension kind of built. The body still closely resembles that of a Kingswood, but beneath the façade lurks a completely bespoke modern muscle car that upon completion will go, stop and steer like no other.
When Chris brought the HT to The Chop Shop in April 2013, it was a bit of a basket case. “I bought the car to do it up, and while that was only supposed to mean a quick freshen-up, it turned out to be so rusty that I either had to go all out or send it straight to the scrapmetal yard,” he says. “The guys at The Chop Shop were keen to take on the job and I’d been to MotorEx and had a look at their work, so I knew what they were capable of.”
The original design brief called for flat floors throughout, a custom firewall, tubular A-arms, a four-link rear and plenty of grunt. Under the guidance of the late, great Laurie Starling, the Chop Shop team set about transforming the HT into a high-end street machine based on the principle of function over form. Chris wanted the car to look exceptional, but it was to be a driver first and foremost.
“An HT Holden is a big, floppy car never designed to take 1000hp, so instead of attempting to make the original car handle, we decided it was best not to muck around trying to Band-Aid it,” fabricator Aaron Gregory says. “We started again with a brand new chassis and underpinnings to make it handle the grunt.”
The move to a full custom chassis opened up a whole realm of possibilities, but it also presented a vast array of challenges that required a great deal of forethought to overcome. “It’s all well and good to go ahead and do flat floors, slam it super-low and do all the custom sheet metal, but you have to think ahead,” Aaron says.
“A 1000hp car needs a twin three-inch exhaust as a minimum, so before you do the crossmembers and chassis rails you have to make sure you have room for it. That’s where Laurie’s mind came to the fore with 10 years’ experience building minitrucks. The seating and steering positions were all considered before the chassis design was determined, so that we wouldn’t get to the end of the build and have nowhere to run a handbrake cable, for example. Every aspect of the design of the car was planned ahead.”
Chris was very specific about his choice of rolling stock, and that too had a pronounced effect on the overall chassis design. He liked cars with big dish on the rear, but couldn’t stand the fact that they never seemed to have dished wheels on the front, too. Large-offset 20-inch fronts meant the pointy end of the chassis had to be far narrower than stock. This in turn meant that a custom engine plate was a better option than traditional-style engine mounts, with the 427ci Harrop-blown LSX slung as low and as rearward as possible for optimal weight distribution and bonnet clearance.
When the time came to build the chassis, the whole process was carried out in-house. “Laurie would design the rails in the workshop, run upstairs, knock them up in CAD, come back downstairs with a USB drive and plug it into the plasma cutter and punch them out, then we’d weld it all together,” Aaron says. “Wheel diameter and width, ride height, position of the back seat, position of the four-link, mounting points for the Shockwaves, the profile of the floor and the position and design of the fuel tank were just some of the considerations involved in determining the design of the rear half of the chassis.”
Likewise, the front and rear suspension systems were designed and hand-fabricated specifically for this car. The double A-arm front end was drawn up in Solidworks, which allowed the team to simulate its operation through a full range of motion and evaluate factors like bump-steer and toe-in. “The Shockwave struts we used allow low ride height but have plenty of lift for bumpy country roads, and the front crossmember features an internal sway-bar. Ryan, Fret and Laurie spent a lot of time developing that,” Aaron says. “The custom billet top block is more of a showy piece, but it saved a lot of labour time fabricating it.”
A number of important factors had to be considered in the design of the rear suspension too, specifically the size of the rolling stock, the amount of power on offer from the blown and stroked LS, and Chris’s
decision to retain a full-size back seat. “That meant no massive IRS set-up or drag-style rear end; we had to go with a smaller four-link, which was designed to be adjustable so the car can be set up when it hits the road,” Aaron says. “We had to go to a Watt’s link to keep the diff central through 280mm of travel, all the while keeping huge wheels centred in the wheelarches.”
Knowing how low the car was going to ride and that the quality of the roads around Chris’s hometown of Corowa left a little to be desired, flat sheet-metal floors were built with all the plumbing and wiring run through the sills, so that nothing under the car was exposed to potential damage. The quality of engineering involved in the chassis and suspension is otherworldly, but one thing you won’t see in the undercarriage is a lot of is intricate swage lines and other decorative work. “The car is built to be a real driver, and if it happens to do well on the show scene when it’s finished, that’s secondary, really,” Chris says.
Once the engine was slotted in without any accessories, the team was taken aback by how impressive it looked in its bare state. “We stood around looking at it and Laurie said: ‘How good would it be not to have to bolt all that ugly shit to the front of the motor?’” Aaron says. “That comment kind of snowballed, and we tried to figure out a way to keep the motor looking nice and clean.” The boys resolved to rid the engine of all bolt-on accessories, resulting in the fitment of a remote electric water pump, electric power-assisted steering from a Holden Barina, and an electric air-conditioning compressor.
The only accessory that proved challenging was the alternator; the team was reluctant to run it off the tailshaft and lose voltage whenever the car was stationary. “That’s when we thought we’d take advantage of Harrop’s rear-belt-driven centre-shaft supercharger and drive the alternator off the rear of the blower,” Aaron says. “It kept it off the front of the motor and meant we could show off how far back and low we could sit the motor in the car.”
Around the time the suspension and chassis work on the HT was being finalised, Chop Shop frontman Laurie Starling lost his life.
Needless to say, this had a profoundly tragic effect on everyone involved with the build. “The Chop Shop team continued on the HT for three months before deciding to close that chapter in our lives, and the car was put into storage,” Aaron says. “Chris stuck by us, and after three months of soul-searching, Chubby at Lowe Fabrications gave me the opportunity and the space to get back into it. Memphis Hell Custom Vehicle Builders was born, and the car was brought back out of storage.”
The engine bay was Aaron’s first foray on his own with the car, and Chris let him get creative with the tinwork. “I’d send drawings to make sure he was happy with what I had planned, and it was a pretty straightforward process because we have similar taste,” Aaron says. With all the stock HT Holden structure gone, Aaron had to find strength in other places. Tubes from the firewall pick up the guard mounting flanges, running forward to the radiator support and wrapping down to the top of the chassis rails, adding rigidity. They are also the tracts through which the front wiring and plumbing will run.
The front wheel tubs might seem large, but they’re actually as small as possible given the size of the wheels and the range of suspension travel and steering lock on offer. The windows in the wheel tubs were painstakingly constructed from a cut and sectioned wheelarch outer, which actually came off the original front guards that were factory
fitted to the car. “They show off the suspension hardware and give us a bunch more clearance around the headers, so it shouldn’t burn the paint when they get hot.”
Plenty of subtle body mods have been carried out too, but Chris was adamant that he wanted to keep it looking like an HT, so there’s nothing that upsets the factory lines. The drip rails were shaved, but peaks were added in their place to retain some character, keep water out of the window rubbers and stop the car whistling down the freeway. Factory oversights such as the hump in the B-pillar were taken care of, and the door frames extended to suit. Chris wanted to stick with factory-style push-button door handles, but with the tubs extending well into the rear doors, that presented something of a challenge. “The door handle had to remain in the factory position, yet the door latch had lifted 100mm,” Aaron says. “It required a triplepivot bellcrank set-up within the door to transfer the motion from the handle to the latch.”
With the fuel filler shaved off the rear quarter panel, it had to be placed somewhere else. Chris liked the idea of it being central in the rear of the car, but didn’t want to have to open the boot to fill the tank. “We had to move the boot shut line from below the tail-lights to the top of them,” Aaron explains. “This required fabbing a new beaver panel from scratch, and cutting and shutting the boot while retaining drip channels and a place for the boot rubber to go, in order to keep the boot sealed and maintain factory aesthetics.”
With the deadline of MotorEx 2016 looming large on the horizon, the car is constantly progressing. “It’s really evolved since it’s been at Aaron’s new shop; especially the engine bay,” Chris says. “He’s finishing off all the finer details and ticking things off the list; he’s absolutely killing it. When I saw the car all set up at MotorEx this year I was blown away by his metal work. It had been a while since I’d seen the car, and the photos just hadn’t done it justice. To see it all together and back on four wheels for the first time was mind-blowing.
Hopefully next year she’ll be ready to roll!”
The car created a real stir at MotorEx, but it was a trying week for Aaron. “It was the toughest, most emotional week I’ve had since Laurie’s passing,” he says. “The last time I’d been put through the wringer pulling all-nighters on a car was the MotorEx prior, and the one person you could count on to keep you awake and be there clowning around was Laurie. The set-up day for MotorEx was the 12-month anniversary of his passing, and that’s when it really hit home that he wasn’t there to see the car. It was such a rollercoaster; it was awesome that I’d managed to get the car there looking so rad, because that’s what it’s all about. When Chris saw the car he was speechless, and that was amazing because at the end of the day I’m building the car for him.
“The feedback from MotorEx was awesome, and there was a constant crowd five deep around it all weekend. It stood out among fully finished cars with three times the money spent on them, and for me that was proof of just how bad-arse this car really is.” s
CHRIS WILLETT 1970 HOLDEN HT KINGSWOOD
Brand: 427ci LSX Throttlebody: Fly-by-wire Supercharger: Harrop 2300 Black Series Inlet manifold: Harrop Heads: Trickflow Gen X 255 Camshaft: Russo Performance Conrods: Callies Pistons: CP Bullet Series Crank: Callies Oil pump: Melling Cooling: VE SS radiator and thermo fans Exhaust: Custom 17/8in headers, twin 3in exhaust, Magnaflow mufflers
Gearbox: Tremec T56 Magnum Clutch: McLeod RXT Diff: Sheet-metal 9in
Springs & Shocks: Ridetech Shockwaves (f & r) Brakes: Baer 14in discs, six-piston calipers (f & r) Master cylinder: Tilton pedal assembly
Rims: Intro Hammer 5; 20x8in (f), 20x11 (r) Rubber: Michelin Super Sport; 245/35/20 (f), 305/35/20 (r)
Aaron at Memphis Hell Custom Vehicle Builders; Laurie, Aaron, Ryan, Muz and Fret from The Chop Shop; Chubby at Lowe Fabrications; Ryan at United Speed Shop; Russo Performance; Julian at Harrop; Troy at Fink Engineering; Scotty at Oxytech; Pete at Mallaby Sheetmetal; Stephen Gregory
1: The underside of the car has no swage lines, dimples or other aesthetic trickery because it’s designed as a driver rather than a trophy-hunter.
Chassis and suspension design was Laurie Starling’s forte, and from the custom double A-arm front to the Watt’s link in the rear and everything in between, he knocked this one out of the park. Notably, Chris made the decision to change his own gears, opting for a T56 Magnum six-speed and McLeod RXT clutch 2: There’s not much to see in here just yet, but the cockpit layout, seating positions and ergonomics were critical considerations during the initial chassis design phase of the project. The rear seat base is in the same position as factory, yet it is now a stressed member that also forms part of the tailshaft loop, fourlink pick-up point and main structural suspension point 3: The HT is so low and the wheels so big that with the suspension aired out the standard bonnet hinges fouled on the front tyres and wouldn’t allow the bonnet to close! “A lot of time was spent with cardboard and sheetmetal templates figuring out how to make the hinge come in and out of a 50x50mm hole in the firewall,” Aaron says. The hinge is gapped 5mm the whole way around right throughout its motion, and the pivot under the dash can be adjusted from front to back and side to side
Replacement sills wrap around underneath to the chassis rails Lower door gap continues through to the front wheelarch Bottom of lower rear door radiused Step in C-pillar flattened out Front corner markers removed Hump in the front valance removed Hump in B-pillar removed and door frames extended Air intake added to grille Snug-fitted bumpers Shaved drip rails, raised peak added to body Fuel filler relocated to beaver panel Boot opening moved to top of tail-lights
Harrop 2300 supercharger Ringbrothers billet rocker covers Custom billet upper shock and A-arm mount Custom A-arms Ridetech Shockwave airbag struts Water-jet-cut alloy engine plate Rear-driven MSD alternator Fabricated, hand-swaged over-the-radiator air intake 800hp 427ci LSX Custom flat firewall with alternator recess Front tubs with outer guard inserts Custom bonnet hinges Fabricated, hand-swaged air dam and radiator shroud Handmade 17/8in headers