Seen any HSV Coupes getting around with little wheel-arch flares tacked on? Then chances are you’ve already spotted a Coupe 4 doing some development kliks.
This feature was originally published in MOTOR’s March 2004 issue
Yep, Oz’s first home-grown all-wheel-drive performance car is reality. How do we know? Because we’ve nailed HSV’s white-coats to a chair and grilled them at length, and we’ve seen the cars ourselves getting around the ’burbs. Oh yeah, nearly forgot to mention: we’ve also driven the bugger.
There are three cars on the road right now, busily racking up miles, and after some arm-twisting, eye-gouging and bottom-lip wobbling, HSV finally handed over the keys for a thrash. So wazzit like, then?
Well, aside from anything else, it’s important to remember that the Coupe 4 marks the Australian industry’s move into the big time. A large-capacity, all-wheel-drive performance/luxury four-seater was previously the preserve of brands like Audi, and maybe Jaguar and Subaru if you include the X-Type and Liberty B4 (now GT). And it’s not like you just talk management into the idea and then sketch up such a device.
See, attempting to make an all-wheel-drive performance car from something like the Holden Adventra was never going to be easy. In fact, a lot of engineering houses would have thrown their set squares in the air and hidden in the bogs until the marketing department had moved on to something easy – such as three-wheeled, methane-powered commodes.
But the Australian industry is not known for head-in-the-sand stuff, so the job of turning a soft-roader into a hard-noser was green-lighted and suddenly it was clipboards at 10 paces.
Meanwhile, the fact that the end result – in componentry terms – is more or less equal parts HSV Coupe and Holden Adventra (or Avalanche, if you like) shouldn’t come as a massive surprise. But while that’s a broad-brush picture of the finished product, the detail stuff is far more interesting.
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The front suspension has been treated to plenty of Coupe 4-specific bits and pieces. The front struts, with their specific lower mounts to account for the front driveshaft, are similar to the Adventra’s units, but the low-boy’s items are obviously shorter and run different valving. There are also different lower control arms to drop the ride height, while the front cross-member is a straight lift from the Adventra.
The rear end is still the subject of some fiddling and fettling and the overall specification isn’t yet signed off. But either way, bank on modified rear trailing arms from the Commodore sedan, the mods mainly contributing to a wider track.
According to HSV engineering boss John Clark, the biggest job in making it all work is not, as you might have imagined, packaging all those whirring driveshafts, but getting the bodywork to cover it all.
“The biggest hurdle is getting clearance in the rear fender inner and outer panels,” he says. “Our solution has been to plasma cut the panels and roll them while the shells are still at Elizabeth. Then they’re put back on the line to get the full dip treatment and away we go again.”
That panel work is also why the Coupe got the three-diff trick first; the sedan would have required reworking the wheel arches and rear doors. But come on, Clarky, surely making a high-ride soft-roader into a bitumen-sucking handler can’t have been easy?
“Yeah, obviously there were suspension hurdles. And the bulk of the work in that department has been to get the grip we wanted and the suspension geometry we needed.”
And packaging, er, issues?
“Um, well, it’s pretty tight in the engine bay now. Some more space would be nice, but given the engine bay we have to work with, we’ve had to redesign the headers to clear driveshafts and other componentry. That’s why the power will be 270kW [the same as the Avalanche] and not 285, but we’re still in the development stages there, so nothing’s finalised.”
What is decided for now is that the Coupe 4 will be offered only in four-speed automatic form. Essentially, the six-speed manual doesn’t mate with the Adventra-derived transfer case and the projected volumes probably won’t justify the development costs, given the type of buyer HSV is eyeing up with the Coupe 4.
Speaking of which, about 30 punters have already stumped up the deposit based on a $95,000 (roughly) sticker price, with dealers expecting stocks about June this year.
Given that price tag, it’s no wonder she’ll carry plenty of fruit. Although the final trim specs are still up in the air, speculation is that the Coupe 4 will probably come in somewhere between Senator and ClubSport trim.
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But, says Clark, it will definitely be its own thing. And with all-paw grip in an IRS, low-ride platform, a thumping great V8 mill and an Aussie badge, you really can’t argue with that.
That point is hammered home when you back-to-back the Coupe 4 with, say, a GTS. Yes, the newbie still feels like an HSV product, but it really is different (subtly, anyway) from the 300kW sedan.
For a start, you can feel a bit more damping in the front end of the Coupe 4, a necessity given the extra unsprung mass. And while the rear-wheel-drive GTS needs a reasonably supple rear end so it can paste its power down, the Coupe 4 doesn’t need the same squat factor.
So the rear end is substantially firmer in the Coupe 4 (and is a better match with the more heavily damped front end in the process). And while smaller bumps and ripples don’t have a noticeably huge effect on ride quality, bigger lumps and holes come through the seats more faithfully.
There’s not much to pick between the Coupe 4 and GTS in steering-feel terms, but there’s no doubt that the former has pretty eager turn-in, provided you adopt the ‘slow in, fast out’ style that suits all-pawers so well. There’s a bit less weight in the wheel of the Coupe 4 than in the GTS, too.
Maybe a racetrack will unearth some tendency to understeer, but at road speeds it ain’t gonna be a problem, and the upside of the tauter ride is a flatter cornering style, helped by the wider track.
The big difference at the tiller is a slight (and I mean slight) tendency for the steering to feel woolly when you’re right up it in the lower gears. It’s about the only time you feel that the front hoops are doing some of the driving (there’s a static 32/68 front/rear torque split), though, so it’s not really a problem.
Frankly, if HSV has deliberately tried to make an all-wheel drive that doesn’t instantly feel as though the front wheels are contributing to the power delivery, it’s succeeded admirably.
As for the power fall-off, well, I’m damned if I can really pick it. You do notice a bit more weight at times, but, like any LS1, she feels well fit once you’ve got a few revs on board. Hopefully I’d be able to pick 15kW gone AWOL in something like a Hyundai Accent, but in an HSV, where 15 is only about six per cent of the total output anyway, hairs don’t split easily.
All up, the revised platform has yielded a car with a 60mm wider track front and rear and a turning circle bigger than the original Coupe’s, but the same as a Commodore wagon. So kerb mass has jumped by between 140 and 150kg, and power has fallen – hardly a conventional forward step. But grip is grip, Dorothy.
So, the big question is: will the extra weight and lower peak power output be enough to cancel the extra launch potential afforded by the all-wheel-drive grip? Good question, grasshopper. The Correvit awaits the Coupe 4, so stay tuned.
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So what’s the best way to go: start with a low-ride all-wheel-drive system and adapt it to a high-ride application, or, as HSV has done, the other way around?
According to HSV’s engineering manager John Clark, it’s a moot point anyway, because the Holden-derived system was always designed to build crossover vehicles (specifically the Adventra) first and anything else second.
“So our low-boy – as we’re calling it – is a next-step program, not the original concept for the driveline,” he says. “Either way, I don’t think it would have made any difference to what we ended up with.”
What’s more relevant, says Clark, is that the system was developed into an AWD set-up from a rear-wheel-drive platform, including the north-south engine placement.
That’s why there’s been no borrowing of technology from boardroom buddy Subaru, because Fuji Heavy’s knowledge is of adapting front-drive platforms [east-west engine and relatively simple rear axles] to AWD. Sorry, said Holden at the time – not relevant to what we’re trying to do.
Maybe Audi’s quattro system, with its north-south engine installation, might have been more enlightening, but nobody at Clayton’s fessing up to pulling an S8 down to its jocks and socks for a look-see.
But while HSV will be the first of the locals to market with a low-ride all-paw, the engineering that’s gone into the project has been a 50/50 joint venture with Holden.
“Both companies have had about 10 engineers each working on the platform at each stage of the program,” says Clark. “A joint program was the only way we could have done it.”
Five Landmark all-paw coupes
1 - Audi Quattro – brought AWD to rallying, and wiped the floor
2 - Porsche 959 – a late ’80s technological tour de force
3 - Bugatti EB110 – a flop, but capable of around 335km/h
4 - Jensen FF – gets credit for being the pioneer
5 - Nissan Skyline GT-R – Japan’s greatest GT ever
Spreadin' it Around
Just as we speculated when the Adventra was announced, you don’t go to this sort of trouble and expense for a single model.
Thus far, the Adventra’s all-wheel-drive system has found its way into the Cross8 and HSV’s Avalanche, with an HSV version of the Cross8 already on the drawing boards. But where else can we expect the driveline to crop up?
Well, like we said, the only reason the coupe got the treatment before the sedan is all to do with the bodywork mods needed. But presumably the next model Commodore will be designed with rear wheel arches that can swallow the wider track, and that opens up all sorts of possibilities. How about a Commodore SS sedan with AWD?
And if that were to eventuate, suddenly the volumes might just make financially viable the R&D needed to make the six-speed manual fit between the diffs.
Export-market Commodores are another likely recipient, although whether the set-up is suitably compatible with left-hook is another matter.
And then there’s Ford, which, with its Territory crossover waiting in the wings, is poised to revolutionise its big-car range (should it choose to). The RTV ute, which now gets a locking diff and jacked-up suspension, would be a natch for the Territory’s driveline. And if the idea of an all-wheel-drive XR6 Turbo doesn’t float your boat, get thee to a taxidermist.
2004 HSV Coupe 4
BODY: 2-door coupe
ENGINE: front-mounted 5.7-litre pushrod 16-valve V8
POWER: 270kW @ 5700rpm
TORQUE: 475Nm @ 4000rpm
BORE/STROKE: 99.0mm x 92.0mm
COMPRESSION RATIO: 10.0:1
TRANSMISSION: 4-speed auto
SUSPENSION: MacPherson struts, coil springs, anti-roll bar (f); semi-trailing arms with toe links, coil springs, anti-roll bar (r)
TRACKS: 1610mm (f); 1615mm (r)
BRAKES: 2336mm grooved and ventilated discs, two-piston calipers (f); 315mm grooved and ventilated discs, single-piston calipers (r), ABS, EBD
WHEELS: 19 x 8.0-inch (f & r), alloy
TYRES: Pirelli P Zero, 245/35 ZR19 (f & r)
PRICE: $95,000 (est)