Holden VC Commodore track car - suspension part 2

By: Dave Morley, Unique Cars magazine

Presented by

IMG 2412 VC Commodore suspension upgrade IMG 2412
IMG 2416 VC Commodore suspension upgrade IMG 2416
IMG 2418 VC Commodore suspension upgrade IMG 2418
IMG 2423 VC Commodore suspension upgrade IMG 2423

Unkindly known as Project Duckshit (thanks to the colour), Morley's VC track car is coming along nicely. Here's part 2 of his suspension upgrade

Holden VC Commodore track car - suspension part 2
It's swallowed a bit of cash but will still be cost-effective.

OKAY, SO the suspension arms are now boxed and the old rubber bushes have been replaced by a full set of red Nolathane jobs. So we now have a good base on which to build a hillclimb car that won’t trip over its own mirrors mid-corner.

That said, my workshop still looks like a bomb has hit an early Commodore with struts and sway-bars and what-not scattered around like a mad woman’s breakfast.

I hit the phones to talk with people who’ve done this before and see what was available for the Brown Bomber. Because I wanted to use as much locally-made stuff as possible, talking to King Springs was a no-brainer.  And lucky I did talk to them before placing an order, because what I thought I wanted did not turn out to be what I actually needed. I’d figured that going lower on the ride height would be better. Makes sense, right? Lower C of G and all that…

Turns out, the early Commodore is not overly blessed with wheel articulation to start with, so you’re better off sticking with a 25mm drop (rather than 50mm). Also, the really low springs actually have a softer rate than the only-slightly lower ones, so handling would have suffered. Crisis averted and a set of stiffer, slightly lower coils were soon on my doorstep.

The new fronts are a tapered-wire design with a variable rate that rises from 300 to 500 pounds (180 to 230 pounds for the stock springs) and the rears are also variable rate, starting at 270 pounds and maxing out at 400 pounds (220 to 315 pounds – stock).

Dampers? I was determined to stay Aussie-made. And it turns out, you don’t have to compromise on performance to do that. At the top of the Monroe performance ladder is a damper called the GT Sport. As well as  being shorter to suit my new, shorter springs, they use some pretty advanced internal valving and plenty of new-tech to arrive at an affordable unit that performs like a high-end damper. And you can walk into any shop that sells Monroe stuff and order the whole kit as a package rather than mess about trying to mix and match.

I could have used a set of new, standard strut tops, but the stock Commo item is a big cost-versus-performance trade-off. Nope, what I needed was something a bit more hard-core. Enter K-Mac which makes a replacement strut top that uses a spherical bearing to improve steering response over the stock unit but is also designed to allow you to change camber and caster settings at the race-track… just like a real race-car.

You don’t even have to jack the car up; just loosen the three mounting nuts and angle the strut to achieve the geometry you’re after. Brilliant. And safer too, because the whole plot is stronger. In fact, in V8 Ute racing, the only aftermarket strut top allowed is the K-Mac unit, purely on safety grounds. And now my car has a set.

The anodised material is actually aircraft-grade 7075 aluminium and it’s just gorgeous. The centre plate is notched to allow the adjustment and give you a baseline setting and the whole thing smells of Quality Street. The bearing is even replaceable, making them a buy-once, use-forever deal. Fair dinkum, it’s a crying shame to have to hide them up under the VC’s strut towers.

K-Mac also provided a set of front and rear sway-bars which, at 27mm for the front and 20mm for the rear, trump the stockers by 3mm and 6mm respectively. The big jump at the rear makes sense, too, because my brother nearly choked on his cheeseburger when he spotted the piddly bar Holden saw fit to slap on a VC Commodore. The bars also go back together with Nolathane bushes.

Probably the trickiest bit was rebuilding the struts because in an early Commodore, the strut body is integral with the steering knuckle and hub. So rather than just bolt the new insert in place, you have to actually disassemble the whole strut and bolt the new damper into the strut body. There’s also the small matter of taking the strut apart in the first place. By which I mean, getting the old springs off.

Plenty of people have been hit upside the melon doing this, because they’ve undone the top strut nut without compressing the coil spring first. What you need to do is use spring compressors (lethal weapons themselves if used incorrectly) to take the tension off the top plate and THEN undo the top nut. This is important, you can get dead if you get this stuff wrong.

Which I suppose is another way of saying get a grown-up to help if you’re unsure about this. Even if you don’t lose an eye putting the new suspension in, you can certainly wind up in emergency if you’ve somehow got it wrong and the car develops a mind of its own at the first corner.

Bolt it all back together, stand back and take a look. Yep, it looks great with that fraction out of the ride height and, crucially, a much stiffer, more controlled chassis that provides a bunch more roll stiffness. Don’t actually know whether it handles any better yet, but physics is on my side. Which is lucky, because sanity is clearly not. 

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