The cars : Rover Metro/100 suspension details

The transformation from Austin to Rover Metro/100 was an engineering triumph. As well as the new K-Series engine, it received a thorough suspension upgrade.

This was a remarkable change – a few very clever and considered updates turned the car into a dynamic class-leader… Here’s the original press release and some background.

Rover Metro GTi

I didn’t do the Rover Metro (R6) press kit, but here it is as we released it in May 1990. I think there was a deliberate policy from Rover of not going into huge detail on the suspension changes, because that might have highlighted the compromises forced upon the original Austin Metro (LC8) by using carryover Mini (ADO15) front suspension bits.

I suspect that any cost-saving achieved by doing that was seriously negated by the need for an expensive H-I split dual line brakes with four-pot front calipers…

Chassis design

The design of the chassis systems on the new Metro is fundamentally similar to the existing models. However, significant changes have taken place in the Hydragas suspension system, and the new front suspension design features anti-dive geometry.

The braking system and steering have also seen many detailed design changes to improve efficiency and overall ‘feel’ in line with the suspension change. ‘Torque Axis’ engine mounts are a major feature change allied to the new front end structure and K Series installation.

Origins of the Hydragas System

Hydragas is an interconnected suspension system designed by Dr Alex Moulton. The challenge in the 1960s was to create a ‘big car ride’ whilst maintaining the legendary handling of the then recently introduced Mini. The international rally winning Mini Coopers were fitted with ‘Hydrolastic’, the first of the interconnected suspension systems.

Ongoing development through the 1100, 1800 and later Minis resulted in the birth of Hydragas.

The current concept takes Metro a stage further with front to rear interconnection through plastic pipes with a water-based fluid hermetically sealed in diaphragm displacers – one at each wheel. The displacement of the fluid provides the damping and the sealed nitrogen, the springing.

R6 front suspension

Hydragas has been proven over many years on millions of cars and is an extremely efficient and compact system. Lack of intrusion into boot and under-bonnet space is a major plus for Metro. Changes to Hydragas for the new Metro Hydragas uses hydraulic displacers at each wheel. In the new Metro application these units have been interconnected front to rear.

The interconnection gives a controlled ‘bogie action to the suspension which reacts to and absorbs road irregularities much more in the manner of a large car than the previous Metro. The flatter ride platform is in marked contrast to the existing car and handling also benefits – particularly in respect of wheel control on high speed bumpy cornering. Interconnection is by plastic pipes mounted under the floor.

A sports suspension version is fitted to the GTi 16v Metro (top). Sharper response is provided by front and rear anti-roll bars and additional external shock absorbers at the front.

Other features of all new Metros include

  • Anti-dive, anti-lift wishbone geometry at the front.
  • Optimised camber control in roll for good bump steer characteristics.
  • Front and rear subframes with rubber mountings for good road noise isolation.


The new Metro uses a rack and pinion steering system across the model range.

Ratios have been carefully chosen to reflect Metro’s small car market positioning giving the best compromise between steering effort and sensitivity to steering inputs. With its high percentage of female buyers, the small car sector places particular importance on steering effort for in-town manoeuvring and parking.

All models except GTa and GTi have 3.7 turns lock to lock with a revised ‘quicker’ ratio of 3.3 on the sporting GTa and GTi.

Turning circles are 9.87m (32.4 ft) on all models except GTa and GTi which have a turning circle of 10.71m (35.1 ft).

Steering Column

As a fundamental part of the changes to Metro’s driving position, the steering column angle has been lowered.

Engineering design changes have resulted in a totally new column incorporating collapse and energy absorption sections for added safety.

Steering Wheel

Left-hand drive Rover 100 dashboard

The new Metro incorporates the Rover Safety Steering Wheel concept first used on the new Rover 200 Series.

A joint development between Rover, the Transport and Road Research Laboratory (TRRL) and Sheller Clifford – Rover’s steering wheel supplier – this safety wheel has a layer of energy absorbing foam within the centre boss which reduces the acceleration level of a driver’s head under impact conditions. The securing nut, holding wheel to column, is located deep into the wheel boss behind the foam padding.

This design dramatically reduces the severity of facial injuries caused by contact with the wheel in an accident.

The steering column cowl and bracketry have been carefully designed to eliminate rattles and improve the NVH performance of those steering components mounted inside the vehicle.


The existing Metro brake system has received much acclaim for its good pedal feel, stopping power and optimised servo action.

The new Metro carries forward the same basic layout with an evolution into a larger diameter solid front disc and single piston caliper. This state-of-the-art system is easier and more cost effective to maintain.

The brake pipe layout is simplified by the use of a diagonal split for secondary braking rather than the H-I split used on the existing Metro.

New Pedal Positions

The major revisions to the Metro driving position are carried through to the foot pedal layout. All three pedals are moved further outboard, thereby reducing the offset caused by the intrusion of the existing front wheelarch.

The clutch pedal ratio has been modified along with the throttle pedal to suit the characteristics of the new K-Series engine.

Ian Elliott


  1. I have a question about Hydragas Suspension,
    The bumper height regulations in the United States in the 1970s made it impossible for Citroen to sell in the United States, because hydropneumatic would change the height
    while driving. Is this also applicable to hydragas?

    In addition, can anyone tell me how the 450sel 6.9 and Rolls Royce, which also use hydropneumatic, passed the compliance requirements

  2. Hot on the heels of the SD1 suspension article, another brilliant insight from Ian Elliot. I agree that Rover performed a mini miracle with the updates to the Metro, the ride and handling were exemplary. The trouble is the car should by then have been replaced not updated. What was and is clear as Mr Elliot points out, is yet again BL used rehashed suspension components from old designs -in this case the original Mini. (Marina torsion bars anyone?).The fact the management allowed this from a car that never ever turned a profit shows the fuzzy management thinking at the time. A quick look at rivals – a Fiat 128 for instance, already a decade old, but a revelation nonetheless, a rotbox yes but they drove brilliantly. I have just checked Wikipedia on said vehicle, and I’m not surprised to learn that VW stripped one down and used it as a benchmark for the Golf…One wonders weather BL ever used the same tactic but I wouldn’t be surprised if they were too aloof to do it.

    This is the company then that applied sophisticated and expensive components to its supermini yet put a live axle under the “flagship” SD1.

    One thing that I find astonishing is Rovers bragging about the padded steering wheel and recessed securing nut. What they will have known of course (or at least should have known); is that in a collision the car was not safe. Yes, the 1997 euro encap crash test sorted the men from the boys and highlighted the elephant in the room. This ancient near 18 year old design had no high strength steels in its construction – its A post to roof concoction harked back to the Ford Anglia 105e. A group test we all had a good look at, and I remember at the time the story featured in the national press. The car was revealed as a death trap, and was a significant nail in Rovers coffin. So let’s look what happens to the (airbag equipped 111)’s steering wheel and column in this footage of – believe it or not- the 20th aniversary Rover 111 crashtest at an encap facicility, footage of which can be seen here.

    One thing I remember and unfortunately for him at the time, a (now retired) panel beater colleague of mine had just taken delivery of a brand new Rover 111 Kensington. To say he got some ribbing about it is an understatement. I think the discounting persuaded him.

    Another thing that I found interesting in Ian’s article was the mention of steering wheel manufacturer Sheller Clifford . A feature on this Birmingham factory would be really interesting. There must be many retired workers out there with tales to tell. A quick search brought up a Facebook page in the name of Clifford Covering Ltd and plenty of pictures of manufacturing and a cool pic of the old art deco factory frontage. The only information I can see is that no wheels are manufactured in the UK anymore. How sad.

  3. Rehashed suspension? Double wishbone suspension on the Metro and Rover 100, a cut above the McPherson struts of the competition, how many Supercars use McPherson struts? Now many Supercars use double wishbone suspension?

    • How exactly was anti-squat rear suspension achieved on the R6? From
      memory, it was the addition of anti-dive front suspension geometry, and anti-squat rear suspension that accounted for the R6’s celebrated ride and handling. No more Hydrolastic/Hydragas front end dive under heavy braking, and no more tail sag under acceleration. It begs the question why anti-dive/anti-squat weren’t applied to earlier models. Or could an enterprising owner apply the refinements to an ADO14,15,16, Hydrolastic Mini etc.?Finally, I seem to recall Dr Moulton hated the set up on the Metro GTi (anti-roll bars and auxiliary telescopic dampers – the horror!) but does anyone recall his preferred solution for a “sportier” drive? Thinner diameter interconnecting pipes was one suggestion but there was something else. Got a feeling it was mentioned in Car magazine when the Metro GTi was tested, but my Car collection was jettisoned many years
      ago thanks to a house move.

  4. By trailing arm suspension, apply the brakes and the torque at the brake shoe and hub *pull” or lever down the rear of the car via the radius arm, The leverage ratio, drum to length of the radius arm about 5 to 1. The 2Cv had a similar setup, my RG500 Suzuki motorbike too, the Suzuki needed it, 4-piston calipers per disc and twin disk front wheel setup, 8 pistons for the front, it could outbrake anything.
    Alex Moulton was scathing over the trend for suspension to favour aggressive driving over comfort, he believed his interconnected Hydragas system delivered the best of both worlds, by separating pitch control from roll, he achieved a soft ride in a straight ahead driving, with modest roll when cornering and therefore pleasing fast response to direction changes when demanded by the driver

    • In addition to the force couple at the brake drum, there is the braking force at the tyre to road contact point, the tyre is also a couple around the pivot point of the trailing arm creating squat under braking .

  5. A friend tried to concoct a home made mid engines Metro, and could not understand why it’s handling was so evil. He was using a Metro front subframe at the rear, so of course the normal anti dive provision was reversed, which had some very strange effects.

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