1980 VC Commodore SL Suspension: Our Shed

By: Dave Morley, Photography by: Dave Morley

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Dave Morley's VC Commodore is out of action for now, propped up on stands, sans suspension

 

VC Commodore SL

The plan was always for Project Duckshit to have more handling than it had power. Given the standard 202 that we’ll be using first up, it probably should be able to achieve that with three wheels. But even once we get further down the road and fit a built engine, I still want the car to be about going around corners rather than simply rushing up to them.

So the suspension needs a big re-think. Not that there’s anything fundamentally wrong with the basic early-girl Commodore. In fact, the VB Commodore was considered a bit of a handling revolution when it was launched in 1978, what with that newfangled rack-and-pinion steering and all. But 40 years of engine oil, road grime and being thumped over Australian roads meant that the stuff under my VC was a bit tired. Not completely stuffed, but not in the first flush of youth, either.

And even if the suspension was in perfect nick, it’d still be too squishy for what I have in mind. So I started by ripping it all out. That included removing the lower front control arms, front MacPherson struts, Z-bars (castor-bars to an engineer) and the upper and lower rear control arms on the live rear axle. The reason for doing that is not to clean them and paint them all shiny (’cos I didn’t), but to replace all the bushes and ball-joints and anything else that can wear out or become floppy with time and kilometres.

Vc -commodore -suspension -3Red Nolathane bushes - they're stiff, but effective for track use

When it comes to road cars, I’m pretty partial to fitting those purple SuperPro bushes that are made somewhere in Queensland. Stiffer than the original rubber bushes, they firm things up nicely but still have enough compliance that the ride quality isn’t destroyed. And not being made of rubber, they won’t deteriorate if oil somehow gets splattered all over them (heaven forbid). For a race-car, of course, ride quality is of no importance, so instead of the purple bushes, I went for the red Nolathane ones that are much harder and really firm things up, allowing the suspension, and not the bushing, to do the work.

Replacing the bushes isn’t too difficult provided you have access to a hydraulic press, although the rear-lower bushes are pressed into the rear axle housing, not the suspension arm, so (short of putting the whole car in a press) you need to make up a puller and wind the old ones out and the new ones in. A rattle-gun is your friend. But be careful and use your scone; you’ll be putting these under bulk tension, so if you’re not sure about it, get a grown-up to help.

The other bushes need to be pressed out of the suspension arm and the new bushes pressed in. But there’s a trick to this on these Holdens (and many other cars). The secret is to use a little spacer (I use a section of old exhaust tube cut to the right length) to stop the two halves of the arm collapsing in on themselves when you get serious with the press. If you don’t, you’ll often find you distort the eyes (or bosses or whatever they’re really called) and stretch them. When that occurs, what happened to me will happen to you: I pressed the new bush into the left-hand-side lower-front control-arm and all was well. But when I did the same to the right-hand one and tried to wiggle it back into place on the car, the bush promptly fell out. The eyes were distorted and wouldn’t grip the bush, which is an interference fit. The solution? Hit the wrecking yards and find a replacement arm with nice, straight bosses, rather than horrible, bent ones. Twenty-five bucks to you, Sir.

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Now, while the suspension was apart, I got to be a bit creative. Looking at the lower-rear arm, it’s a big, tin pressing. The other arms are smaller, but these rear-lowers are monsters and look like they could flex in the heat of battle. And, just like stiffer bushes, having suspension members that don’t flex and flop about allows the actual suspension to do its job better. You’d never notice this in a road car at road-car speeds, I’m sure. But Project Duckshit? I need all the help I can get. So I dragged out some 2mm plate steel and cut a pair of gussets that fit just inside the lower arm. By welding these plates in, I’ve effectively boxed the arms. It’s an old trick favoured by hot-rodders who used to box in the original C-section chassis rails in their Model As and radically increase the torsional strength (handy when you’re cramming those rails full of big-block V8).

The front ball-joints were next; not that they were shot, but they’re cheap to buy and give you a little peace of mind. Mind you, my 20-tonne press was straining pretty hard to remove the old ones and press the new ones in. Again, if you don’t know what you’re doing with equipment like this, find somebody who does.

Next up, it’ll be time to reinstall everything including new springs, dampers, adjustable strut tops (it’s a race-car after all) and a dirty big pair of sway bars. This thing won’t be plush to ride in, but it should really go round corners. Hopefully not backwards and/or on fire.

 

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