Holden HZ Technical Specifications

Holden HZ with Radial Tuned Suspension
"The Test" - Supervised by R.A.C.V and C.A.M.S:
(circa 1977)

You're about to see a compelling demonstration of a genuine automotive engineering breakthrough. This is new Holden Kingswood SL, equipped like no previous Kingswood - with Radial Tuned Suspension. Watch it through this snaking 'S', smooth, safe, with a minimum of lean, average speed 75.96 kilometres per hour. Now watch some competitive cars, same test, same driver. Chrysler CL Valiant, Toyota Cressida. Here's Kingswood SL again. Now XC Falcon 500, 240K Datsun, TE Cortina Six. Watch new Kingswood SL again, Holden's stabiliser bars and suspension components are matched to the steel belted radial tyres - the Radial Tuned Suspension badge means safety and confident road holding - only Holden has it. Now with push-button radio, electric demister, quartz-halogen headlights. New Kingswood SL, with Radial Tuned Suspension - drive a real change for a change, at your Holden dealers now!

Press Release from Holden on Radial Tuned Suspension:
"All components are carefully engineered to increase Holden's confident handling."

The design of modern automotive suspension systems has reached a high degree of sophistification in Holden vehicles. Through the use of advanced computer simulation and technology, improved manufacturing materials and design, and highly skilled automotive suspension engineers, GMH was able to develop Radial Tuned Suspension.

Each suspension component - even the frame and body it'self - had to be examined in detail and re-engineered as required in order to create RTS as a complete system. Neutral handling behaviour is the most important benefit of RTS, this means, in essence, that Holden will do what you want it to, and nothing unexpected will occur. By relocating the front upper control arm bracket for positive castor, we reduced understeer. In addition we increased static camber and decreased dynamic camber and toe change reducing the tendancy of cars to "plough" toward the outer edge of the corner. The front and rear stabiliser bars reduce body lean and are synchronised to transfer cornering load for neutral handling behaviour.

RTS permits smooth ride without sacrificing good handling. Deeper four-coil suspension contibutes smoothness and improved road-handling, while larger front compression bumpers reduce dynamic suspension travel and improve ground clearance.

The re-tuned, larger diameter shock absorbers have less fade, retaining effectiveness over rough terrain. As a result, tyres maintain contact with rough road surfaces, the ride is smooth and the driver stays in control.

High response steering results from the reduction of compliance, or "flex", throughout the system. Holden's steel belted radial tyres fitted on wide rims hold the tread to the road surface while cornering, rather than rolling under as do conventional cross-ply tyres. Front and rear suspension bushings are less compliant in cornering, while retaining longitudinal softness for smooth ride in normal driving.

High cornering force ultimately results from the degree of tyre adhesion to the road. This is increased by the use of steel-belted radial tyres, and the rest of the RTS system is designed to get the most from them. For one thing, the wheel rims and tyres have a revised offset giving Holden a wide-track. Larger diameter shock absorbers help keep the tyres on the road when it is rough. And again, the re-engineered castor and camber retain the proper wheel geometery to get the most from the steel belted radial tyres.

"Anti-dive" controls the amount of front end diving while braking for a greater feeling of control. Reduced body roll (or "lean" in corners) is accomplished by front and rear stabiliser bars working togther with re-engineered 4-coil suspension.

Maximum straight-ahead stability is the result of several RTS suspension components. Steel belted radial tyres, for example, are best in this characteristic. Where conventional cross-ply tyres will tend to pull the car to the right or left in tram tracks or pavement edges, the radial steel plies in Holden's tyres tend to retain straight-ahead direction. Positive castor and negative camber also help keep the wheels straight ahead without driver effort. And all of these characteristics help retain straight-ahead stability in a sudden gust of wind, or the buffering from a passing truck.

A few more benefits of RTS are worth noting. Our tests indicate that Holden's steel belted radial ply tyres increase the kilometer per dollar investment ratio in each tyre by 47%, and the fuel economy by 5% over the biased ply tyre. The durability of the suspension system has been increased. Road noise and vibration has been further reduced. And optional power steering has been redesigned for improved on-centre feel and more predictable driving control.

But it is all the components working togther as one system, which have made today's Holden the best handling cars and wagons we have ever built.