HOW AN AUTOMOTIVE ARTIST PIECED TOGETHER THIS STUNNING MCLAREN M6GT
“All real race cars have to be right-hand drive,” Randy Grubb says, beaming, as he opens the right-side door of the low-slung, V-8–powered missile he only recently completed. “They have to be, not because they’re built in England, not because they drive on the right side of the road, but because of the shifter linkage.” Grubb’s standing inside the garage at the Smith River, California, home he shares with his wife, Jeannet. Before him is an orange, yellow, and purple McLaren M6GT, his longtime dream car, which he pieced together over the past several years.
Grubb has been a hot-rodder since he was a teenager, although he’s best known for crafting gorgeous, completely custom vehicles, including Jay Leno’s “Blastolene Special” tank car, the GMC-motorhome-based Decoliner, and the scratch-built, bare-aluminum Dodeci Roadster whose flowing lines resemble a prewar French Delahaye. Grubb designed each of those and then fabricated their aluminum skins using an English wheel and planishing hammer. Each project he’s tackled also had unique engineering issues to overcome. The Decoliner, for example, could be driven from its cab or atop its roof. The Dodeci roadster, like the Decoliner, featured a polished aluminum skin. It also rode on a custom chassis of Grubb’s design, cut from flat sheets of steel and welded together to form a complex, flowing shape. All that to say he knows his way around aluminum and can handle a welder. His McLaren project stretched his abilities far beyond any previous vehicle.
History
Can-Am racing represented motorsport in its purest form. “This was not a time of homologation and sameness, like we have today,” says Grubb. “It was the opposite. It was a time of innovation. It was a time of creativity, and we had these automotive geniuses conceiving, building, and most amazingly, driving. We’re talking duking it out, wheel-to-wheel.” With 67 gallons of fuel surrounding the drivers, and nothing but thin aluminum between fierce competition and a conflagration, drivers were disciplined. “This is not modern NASCAR, which can be a demolition derby in the last three laps. That would never happen in a Can-Am car because everybody would die. So the racing was vicious, but clean. The cars were brilliant and different and innovative and thus my favorite cars of all time.”
McLaren’s M6GT was planned as a limited run of 250 street-going models based on the M6, the company’s open-cockpit Can-Am race car. The M6GT would use a similar chassis and top it with a sleek, enclosed body. With customer copies available for sale, the car could be homologated for Group 4 competition and take on the 24 Hours of Le Mans, a race that McLaren founder Bruce McLaren had won in 1966 while driving a GT40 with fellow Kiwi Chris Amon. Only a handful of M6GTs were built by the summer of 1970, including one that Bruce chose as his personal car. On June 2, 1970, Bruce was testing the big-block–powered M8D at Goodwood Motor Circuit when the rear bodywork and wing came off at more than 150 mph. Without any downforce keeping the rear of the car planted, it was uncontrollable. McLaren hit an abandoned marshal post and died. He was just 32 years old.
After Bruce McLaren’s death, the M6GT program was shelved. Years went by. In 1976, John Collins, former Shelby American GT40 crew chief, built a new M6GT in a bid to rouse interest in a series of customer cars. The original M6 chassis was built by McLaren’s partner, Trojan, using .050-inch 2024 aluminum alloy. The thin sheet made for a lightweight race car, although the alloy was difficult to work with. “These were race cars,” says Grubb, “so they were designed to last one year, and then next year we’re going to build something stronger, faster, lighter.” Longevity was not a priority. The new chassis that John Collins built used .063-inch 6061 aluminum. It made the chassis a bit heavier than that of the M6, but it was also stronger and better suited for prolonged road use.
Grubb has done plenty of research over the past several years, and to the best of his knowledge, the car was registered and was a roller, not a driver. Worries about the legal liabilities of selling a road-going race car to the general public ended the second M6GT run, before any additional copies were built. The body was sold, as were some of the suspension components. The aluminum tub was hoisted into the rafters of a shop, where it sat collecting dust.
Chassis
It wasn’t a McLaren that began Randy Grubb’s love for mid-engine cars; it was a DeTomaso Pantera. Ever since he sat in one at age 10, he knew he’d have to own one. That lit the fuse. He owned a Pantera, then a Ford GT40 replica, another Pantera which he still owns, and eventually he started working on an open-cockpit McLaren M8E replica, his jump into the world of Can-Am.
Grubb had plenty of fabrication experience from his previous vehicle projects. Learning about some of the failures of homebuilt aluminum tubs quickly disabused him of any notion of building a chassis on his own. “I love aluminum,” he says. “I quickly learned that I’m an artist, not an engineer.”
Grubb sought help from McLaren guru Bill Moir, another connection into the McLaren world who happened to live nearby. “Bill’s nickname back in the day was Overkill Bill,” Grubb says, noting Moir’s fastidious restorations and his adherence to the specifications noted in the car’s blueprints. Moir was helping Grubb put his M8E project together, teaching him the welding and precision machining required to build a vintage race car from scratch. In exchange, Grubb was helping Moir sell parts from his vast collection. Among the parts was the M6GT chassis that had been hanging in Moir’s shop for almost 40 years. Initially, Grubb was only interested in helping Moir sell the aluminum tub. No takers. Grubb assumed that buyers were wary of the project, as there were too many missing pieces. However, as Grubb pored over the shop’s inventory of cardboard boxes, more and more M6GT parts began to appear, including the critical suspension uprights.
New front A-arms were fabricated just as they had been on the original M6. The rear lower A-arms are also new. The one alteration was the addition of toe adjustment at the rear. Grubb used Eibach springs and custom-valved Koni shocks to dial in the handling.
Due to Bill Moir’s meticulous detail and Grubb’s uncanny ability to track down parts and learn the fabrication and machining processes required to build the chassis, Grubb had an M6GT chassis exactly as Bruce McLaren intended. “My car is rivet correct, blueprint correct,” Grubb says, and he would know, as Moir had the original blueprints, complete with Bruce McLaren’s signature.
Transaxle
Grubb was delivering one of his polished-aluminum Decopod two-wheelers to hot rodder and AMBR-winner Dennis Varni and mentioned his next stop was collecting a transaxle for his M8E project. Varni gestured to a Hewland LG 500 Mk II in his shop. He didn’t need it; would it be possible that Randy could use a spare? Well, not quite. Grubb laid out his plans for the M6GT project and the transaxle was offered up for a better-than-fair price. It needed a mild refresh and a new ring and pinion, but was quite complete. Because it had been used in an Indy car, it had a spool that locked both axles together. Grubb replaced it with a cam and pawl limited-slip appropriate for a road car. Parts are pricey but available, and he is grateful that Hewland still makes parts that keep these vintage racing transaxles on the track.
A McLeod metallic triple clutch had worked well in his 427-powered McLaren, so when it came time to pick a clutch for the M6GT, Grubb spoke with a specialist at McLeod to get a recommendation. Based on the engine and the car’s usage, they decided that an organic clutch material would be best, and the double-disc clutch would use extra material to be a bit thicker and more tolerant of slipping and overheating. So far, it seems like the perfect choice.
Body
Perhaps even better than the price he offered for the transaxle, Varni had a serendipitous bit of information: He knew the location of an M6GT body. Jose “Joe” Casanova had one, and it wasn’t even too far away. Grubb got in touch. Knowing that it had languished in the California sun for decades, Casanova offered it up for a low price, especially as far as rare fiberglass sports car bodies go. Grubb had no idea how warped or degraded it might be, but he agreed to a price and made plans to pick it up once the project progressed a bit. Unbeknownst to him, Casanova had been battling cancer and passed away in 2022. When Grubb called back to set up a date to take delivery not long after, he spoke with Joe’s family, who facilitated the sale.
Once he got the fiberglass body home, Grubb began what he assumed would be the delicate and laborious task of mounting it to the aluminum chassis. “It kind of fell right on,” he says. “And more amazing to me, I noticed that there was a hole in the body that lined up with a hole in the tub. Like, you could insert a Cleco through that hole, and it would be perfect. And then I noticed there was another one over here, and then another one over there…” He had Bill Moir come by to check the progress. After he arrived and surveyed the body’s fit, Moir asked if he bought the body from a tubing bender in San Jose. He was referring to Joe Casanova. Moir had forgotten the name, but he recognized the body that had last been on the chassis more than 30 years ago.
Yet another piece of the puzzle fell into place when Grubb tracked down Aircraft Windshield Company in Los Alamitos, California. “They have molds for every car,” Grubb says, “including the molds for the M6GT coupe: headlight covers, rear glass, side glass, front glass; they’ve got molds for everything. However, to be street legal, California does not like Lexan windshields.” Another of Grubb’s fiberglass McLaren race car contacts, Rick Fitzgerald, gave him a tip on where to find a real glass windshield.
Engine
Randy’s M6GT is powered by a small-block Chevy, just as McLaren intended. It was blueprinted and assembled by Rick Harper, a renowned V-8 specialist who just happened to live near the Grubbs in northern California. The engine’s complete history is unknown, though it came from a Lola T70, and several clues suggest it was built in Australia or New Zealand, where the car was raced. It’s clear that the factory Chevrolet block was carefully selected for the Lola, as it is a superb casting, without any core shift.
An offset ground crank and a slight overbore add a few cubes of displacement over the 350 cubic inches that the 4.0-inch-bore block and 3.48-inch-stroke crank would have delivered when both were new. The current total is 365. Harper disassembled the engine, scrutinizing every part in the process, and wound up reusing plenty of it. The rebuilt engine needed a new set of JE pistons, rings, and bearings, of course. A new dry-sump oil pan was fabricated to fit the McLaren chassis.
The only tell that the engine is not a purely ’70s piece is the cylinder heads, which feature angled plugs and center-bolt valve covers from the late-1980s. Because they were in such good condition, and served the Lola’s racing aspirations so well, they were retained. They were reassembled with 15 of the 16 valves it had when it arrived at Harper’s shop.
The focal point of the engine is its quartet of Weber 48 IDA carbs mounted atop a McKay intake. Unlike many Weber manifolds, the McKay mounts them all facing the same way. “Webers are the best carburetor ever designed, in my opinion, because they’re infinitely adjustable,” says Grubb. “And that’s what throws a lot of people. Because of their infinite adjustability, they can be infinitely out of adjustment. But man, there’s nothing like Webers on an isolated runner manifold.”
Randy had a similar quad-carb setup in his GT40 replica, which used shorter intake stacks. If there was a spare moment on the racetrack, a glimpse back through the rearview mirror would show the resonance of the intake charge bouncing back and forth between the intake valve and the atmosphere, creating a jittering cloud of atomized fuel atop the trumpets. A bit unnerving, perhaps. It’s just all the horsepower breathing.
Harper is well-versed in building road racing small-blocks that rev past 9000r pm. Even knowing what Harper was capable of wringing out of the engine, Grubb was willing to sacrifice some top-end zing for drivability. The McLaren uses a solid roller cam that still tickles 8000 rpm, and yet manages to be docile enough to be streetable, at least for Grubb. The fact that the car tips the scales at about 1800 pounds when fully fueled, with a driver behind the wheel, is a big help. There’s just not much mass there to drag the engine down, even at low revs before it really churns out the torque. When the engine is singing, however, it produces about 550 horsepower. Imagine adding 400 hp to a Miata while also stripping more than 700 pounds from its curb weight, and the ridiculous nature of the McLaren starts to come into focus.
Paint
One of the few compromises that Grubb made on his McLaren was the paint. It’s more polished than he’d initially planned. He knew he wanted Tommy Carr to put his skills to work and apply some wild ’70s techniques, yet part of him wanted the car to look like it was a survivor, with some of the roughness of a ’70s paint job. “Tommy and I hit it off right away, because we were both driving ’40 Ford pickup trucks 35 years ago when I met him,” says Grubb, “except his was painted a lot crazier than mine.” Carr has been involved in paint and bodywork since the early 1970s and has been working on custom cars exclusively for about 25 years at his shop in Gold Hill, Oregon. “Randy likes that old-school look, and he wanted orange peel,” says Carr, who suggested the paint should look its absolute best. “Everything that we paint in our shop, I sand and polish and buff and try to get it as perfect as we can.” After some discussion, Carr won the debate, and we think you’ll agree that the graphics deserve to shine.
The paint design was a joint effort. Grubb, who has a hand and eye for art, sketched out the shape of the graphics he had in mind, and Carr mixed some House of Kolor paint that he thought would be appropriate for the eye-catching Can-Am look. The two tried out a few options by laying pinstripe tape on the car, and then Grubb left Carr to do his magic. “When he was gone, we did those blocks on the sides with the shadowing of the yellow,” explained Carr. With the initial color palette of yellow, purple, and orange established, Carr laid them down in varying layers of candy paint over a white base coat. We shudder to imagine how many rolls of tape were used; the fine-line masking probably ate up a few miles’ worth.
“A lot of the colors are done by layering, not just a straight color,” Carr explains. “I put down a base, and then I’ll use some candy colors, which are basically clear, with just a tint that makes that color come around.”
The Experience
While its paint is flawless, the McLaren does have a few idiosyncrasies. The Hewland transaxle can be finicky, and it did have some teething issues on its first track day, which lasted a total of six minutes, after the seven-hour drive to the track. The pinion nut came loose and allowed the Hewland’s gears to start chewing up the differential. “The second time I got to drive it for almost a whole day,” Grubb says, “before one of the pinion shims got eaten, and I found metal in my oil. I don’t run until parts are destroyed. I’ve got to really think about preserving what I’ve got.”
The pure mechanical connection of the Hewland is worth putting up with a hiccup now and then, especially now that Grubb has learned many of its quirks. The four-speed transaxle uses a magnesium case and straight-cut gears. They’re all synchronized, and Grubb describes it like a motorcycle transmission. Once the clutch is out in first gear, the upshifts rely on the transaxle’s dog rings to transmit power from one gear to the next. “Clutchless shifting,” Grubb says with a grin. “Just wicked as hell. But if it bounces off the dog and doesn’t engage, it can kick back violently. The shock that goes through the shifter rod can break your wrist.” It is clear by the way he describes it that Grubb is excited at the prospect of trying to tame such a raw and unforgiving machine. “That sounds like something I want to try. ‘Shake hands with danger,’ right?”
The brakes also had a bit of a learning curve. The four-piston JFZ calipers are loaded with racing compound pads. “Once everything gets up to temperature, they are the best brakes you’ve ever experienced. They’ll throw you through the windshield. But up until that point, while you’re preheating, it’s kind of scary.” One of the benefits about a car like Grubb’s M6GT is that everything is clearly communicated to the driver. His M6GT has fast steering, and every suspension link is a Heim joint. There’s no rubber or polyurethane; every bit of road surface is transmitted through.
“I wanted the real driving experience, not an almost, not a kind of, but the actual,” Grubb says. “I really wondered what Bruce McLaren and Denny Hulme experienced behind the wheel of these cars. What does it feel like to drive something with such low weight and such high horsepower?“
Grubb’s previous on-track experience in his 427-powered M8E gave him a taste, as the mechanically fuel-injected big-block rocketed from idle to more than 7000 rpm when its eight 2.9-inch throttle bores opened up. “It’s a magic moment when you’re in the car, and you’re screaming down the track,” says Grubb. “It’s like nothing else, and those are the moments that motivate me. Those are the moments I live for, and granted, they don’t happen very often.”
The truly rare moments were the times Grubb has been right at the limits of grip in his GT40 replica, usually at Thunderhill Raceway, when the tires are communicating just how close they are to losing their battle with the track surface. “Feeling the whole back end start to get loose, and feeling the front end pushing, and realizing that you’re doing it,” Grubb says with a big grin, “there were guys like Ken Miles, they could do it on every turn, predictably, in a Cobra. I have not come close to four-wheel drifting the McLarens. I don’t think it’s in the cards,” he grudgingly admits. “Your speeds are higher, so the margins are narrower. Driving this car is like you are on the razor’s edge.”
From tracking down missing parts and fabricating new ones, to driving this car near its limit on the track, every aspect of this car has been a challenging experience with new lessons and skills learned along the way, even for a guy comfortable with pushing the envelope in his builds. “I would love to go to Goodwood,” Grubb muses, though he clarifies that he’d never put his M6GT into any kind of wheel-to-wheel racing situation. “There’s always someone faster. There’s always someone richer, and that’s why I don’t put myself in competition. It’s purely a personal journey.” He understands that since his car was the street-going version of the McLaren, it wouldn’t be a candidate for racing at Goodwood anyway, although he certainly wouldn’t turn down an invitation to make some parade laps.
For Randy Grubb, working with some of the same craftsmen who helped so many McLarens stay on track was a dream come true. Bill Moir passed away earlier this year, leaving one less link in the chain of history. This project was the last McLaren he helped get back on the road, and the significance isn’t lost on Grubb. Now his motivation is getting seat time in the car and sharing the experience with the next generation of car lovers, perhaps motivating someone else to pick up a welder and dive headfirst into such an analog and engaging project from a time of unbridled ingenuity.
The post How an Automotive Artist Pieced Together This Stunning McLaren M6GT appeared first on Hagerty Media.
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