Opinion : Last gasp for Hydragas?

Austin Ambassador managed to look different to the Princess, but like just about all end-of-term facelifts of aging cars, it did not improve on the original. The addition of a hatchback made a vast difference to the practicality of the car and, overall, the Ambassador was a useful improvement over the Princess. But by 1982, did anyone care?

Hydragas… Only the most avid BL enthusiast knows what on earth Hydragas is. Fewer still care for it and only a tiny minority know how it works and can therefore truly appreciate it. I’ve been a huge Hydragas fan for as long as I can remember. I used to hunt down any review or technical insight into the system and spend hours reading it until I’d fully absorbed the paper. If only I had been half as diligent towards my academic studies. I lie – I once took a Physics A-level class on the subject, but I digress.

Hydragas offered the motoring world a way out of cart-springs, which we used for hundreds of years. It was as simple as it was effective in what it did – it offered a ride comfort and handling balance light years away from other systems. Anything that rivalled it was complex, expensive and usually feared in the repair side of things.

Essentially, what Hydragas does is give a level ride for comfort (it doesn’t pitch, that is make the car body sew-saw over bumps) and it gives consistent handling because it offers variable springing (rubber or nitrogen) meaning no unpleasantness with variation in the cars load – not to be underrated that virtue.

A more efficient system

It also reduced the number of components fitted to a car. No wretched anti-roll bars that corrupt handling which are, in effect, an un-damped spring that compromises any form of independent suspension system. They don’t need separate dampers, which lose their effectiveness with each and every compression (they foam under duress and wear beyond tolerance within 40k miles). Hydragas was designed to be within tolerance for 200k miles.

Steel springs are now catching up with what Hydragas offered, but it has taken 30 years. Essentially, every car now features some Hydragas idea; be it a rubber sleeve around the damper to offer a degree of variation in spring or a sturdy subframe to strengthen a car body and increase refinement.

Switchable valving in dampers to suit your mood? Hydragas automatically switched between valves depending on the severity of a bump or if the car was in a state of roll. Indeed, Hydragas used the energy of a front wheel striking a bumper to stiffen the rear suspension! How green and free from electronics is that?

How about we cobble together a medium size
car and retro-fit it with Hydragas, just for fun?

With Hydragas well out of production now (all spares are very scarce) and Dr Alex Moulton no longer with us, maybe we should give the Class of Gas one last grasp at greatness. Certainly, Toyota who latterly employed Moulton is showing no signs of taking up the idea.

Moulton was on record as saying the finest incarnation of the system was on the Rover Metro – for three main reasons. It showed how it could give large car ride comfort to a car with a tiny wheelbase though interconnection. It demonstrated excellent body control regardless of payload (which could vary the cars weight by some 50%) because of the nitrogen springs (the finest springing medium known to man).

It didn’t roll like and Citroën AX, nor did it jar like the Japanese competition. It took-up no space in the boot and lowered the c-of-g at the same time! The side effects to the body engineering were those robust and refined subframes. The final car to feature Hydragas was the MGF, but it used a ‘buggered” version of it, with anti-rolls bars and additional, external dampers. However, it did give some further refinement to the engineering of components. Incidentally, Rover only paid £20 per Hydragas unit, so really, it wasn’t that expensive.

How about we build our own?

I recall having a conversation with Rob Oldaker about switching from Hydragas to coils for the TF and then having to further revise the coil settings some years later. Moulton had been onto him for a round of ‘I told you so’ almost instantly. Having driven many, many Fs and TFs, Moulton, was right and the TF was a more compromised car because of its demise.

Interestingly, The Austin Ambassador showed how good the system could be in a large car, but the Ambassador itself was criminally ignored. So, here’s an idea, how about we cobble together a medium size car and retro fit it with Hydragas, just for fun? Pick-up a Rover 200 say, a written-off MGF or rotten Metro set-to with some steel cutters and a MIG welder?

Maybe then we can show something a bit different at next year’s Longbridge bash, something which demonstrates what a wise man once said: ‘What Is Good For Roadholding, Is Automatically Good For Ride’.

Steven Ward


  1. Excellent idea! I’ve been fascinated by both the Hydragas and earlier Hydralastic system ever since I found this site. I really hope you get the opportunity to try this idea out!

    One thing I’ve been keen to ask; some called the system complicated, expensive and difficult to work with, but from what I can see, it’s fairly straightforward in practice and it reduces the number of parts needed, so shouldn’t it be cheaper and easier instead? Was it just more of BL’s mismanagement and poor build quality letting the side down again?

  2. What is interesting is that Dr. Bose developed his own suspension system using electromagnets and no auto maker has adopted it after testing. So exotic ideas are not something the auto industry is interested in.

    • Bose finally sold it off in 2004, though an offshoot of the technology was used on seat design for long haul HGVs. I have seen the affects of the Bose suspension in Pictures and it does look very affective at producing a flat ride.

  3. Under better circumstances could Hydragas have matched the conventionally suspended dynamic benchmarks of the period by the opposition from the 1970s up to the early/mid-2000s and after, including bettering the conventional arrangement used on the Montego, Maestro and stillborn AR6 prototype? Could it have been an asset on other models beyond mini/supermini and sportscars?

    The Lotus Elise (previously the Elan M100) and Mazda MX5 stand out as the benchmarks for the MGF, while for the Metro it would be the Peugeot 205 and 106. whereas the 309/306 and 405/406 (plus Nissan Primera P10/P11 and Alfa 156) serve as benchmarks for the Maestro, Montego (had the previous two featured Hydragas) and Ambassador respectively.

  4. I wonder who owns the patents/rights now. What happened to the Dunlop tooling? I thought it might make more sense to demo it on a current model which relies on good ride/handling, thinking of the current generation MX5, but then what about the forthcoming MG electric two seater?

  5. Having read latest reviews of the new Citroën C5X, I think we have moved on, with the next innovation! As to Hydragas, my father in law is still trying to get his hydragas fixed on his MG Metro.

  6. Hydrolastic & Hydragas: The most effective suspension in the world.
    I have about 25 cars with this technology, and I’m very happy.
    Over time I had to learn to recover the hydrolastic & hydragas units, and now all my cars drive very well.

  7. I can always say every Princess and Ambassador I was in a passenger in always rode far better than their rivals due to Hydragas. This was always something the cars sternest critics had to concede.

  8. Hydrolastic/hydragas were ‘interesting’ developments, but just like Citroen’s hydropneumatics which went out of production about 30 years back, they were ultimately shown to be expensive evolutionary dead-ends. High-value cars could perhaps justify the additional cost of hydrolastic over conventional springs, but it seemed odd that it only found its way into BMC/BL’s low-rent models.

    I remember at uni someone had a BMC 1300 Estate; the problem with its Hydrolastic setup was that with a couple of hefty Rugby-players in the rear seats and any sort of sensible load in the rear, the back went down, the front went up and the headlights became only useful for spotting aircraft.

    At least the 3-Litre incorporated a load-leveller.

  9. I wonder how easily it would have been to fit variable rate valving to Hydragas units and so get dashboard adjustable sport/normal/comfort settings. Speed sensing to switch out of comfort mode at high speed to promote agility.

    Electric hydraulic pumps to vary the line pressure gets you adjustable ride height, again lowering from normal to low for high speed cruising to get better motorway fuel economy.

    Could even have been hooked up to a Sinclair Spectrum under the seats to give a version of Land Rover ACE (Active Cornering Enhancement) which was absolutely brilliant on the 2002 Discovery I had as a lease back a couple of decades.

    Fit it to a 4*4 version of the Rover 75, with the MFI grade wood trim replaced by engine turned aluminium or carbon fibre, and it would have sold as a high tech fast hauler.

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