Modern Family [Part Two]

In 1962 BMC sprang a surprise with the 1100 – in one area in particular. 

Image: Veikl

Even without its innovative interconnected hydrolastic suspension, the BMC 1100’s status in the automotive pantheon would have been beyond question. However, a good deal of its historical significance remains bound up with its adoption. While interconnected suspension designs were not an entirely unknown quantity by the late Fifties, it was the first production application of a fluid-based system in a compact, affordable (and no small matter this) British car.

The use of rubber (to say nothing of fluid) as a suspension medium was not something that Alec Issigonis seemed to favour at first[1], but he became convinced after sampling a Morris Minor which had been re-engineered with a prototype rubber suspension[2]. Having discerned its potential, Issigonis, in conjunction with Alex Moulton developed an interconnected design employing rubber springs for the the stillborn Alvis TA/350 project, initiated in 1952. After this programme foundered and Alec was lured back to Longbridge, a good deal of this technical carry-over travelled back with him, along with several of his team.

Serious development of what was to become hydrolastic progressed from this point, with a series of Morris Minor mules running versions of the Moulton interconnected rubber/fluid suspension design. And while hydrolastic had been considered for both ADO 15[3] and 16, it was the larger car that was deemed best to pioneer it. Not that it was foremost in Issigonis’ thinking at first; conventional springs were also briefly considered, a matter which lends credence to what some have observed as a longstanding distaste on Alec’s part towards independent rear suspension.

In a 1962 Motor interview which coincided with the 1100’s introduction, Issigonis was asked by the journal’s technical editor why he had chosen an independent rear suspension over a more normative beam axle. Alec’s reply was interesting. “We did consider using a rigid axle, but in the end just didn’t. There were practical considerations, and it did not make such an elegant little unit.” He did however also let slip the following, which was perhaps more telling, stating, “You can only use this interconnected system with all independent springing[4].”

BMC 1100
ADO 16 suspension layout. Image: mginfo

Hydrolastic saw conventional steel springs and telescopic dampers replaced by displacer units at each wheel, interconnected fore and aft. The displacer units were separated into two chambers by a reinforced rubber diaphragm, filled with a mixture of 49% water, 49% methyl-alcohol, with 1% each of a corrosion inhibitor and a mandatory dye. The upper chamber contained a conical rubber spring, while the lower chamber housed a tapered piston, engaged by the action of the upper suspension arm.

As road shocks acted upon the front wheels, upward forces would push against the tapered piston in the lower chamber, displacing fluid through a valve in the diaphragm into the upper chamber where hydraulic pressure would actuate the rubber spring. Fluid would then be displaced through the interconnection tube to the adjacent rear displacer, with hydraulic pressure acting upon the rear piston, forcing the rear wheel downwards, thus allowing the body to remain level, irrespective of road conditions.

A hydrolastic displacer in section, alongside its Hydragas equivalent. Image: mcoopermotorrepairs

In its ADO 16 application, the mechanical and hydraulic layout was carefully designed to allow the rate of displacement to vary according to speed and load, providing an element of progressive rate springing. Furthermore, owing to these progressive effects, in conjunction with the variable flow through the connecting pipes, pitch and bounce were minimised, while cornering forces caused the opposed side displacers to act against downward forces, reducing the tendency to roll. Further aiding road behaviour was the fitment of twin anti-pitch torsion bars anchored to the rear trailing arms and rear subframe. Additionally, a conventional rear anti-roll bar was also fitted, to balance the front-rear roll couple and limit excess understeer[5].

BMC’s new Technical Director outlined the 1100’s hydrolastic principles thus:  “Our suspension is much stiffer [than Citroën’s], and though we don’t make any great claims for it being super comfortable, our compromise has let us put what we think is a very good system into a cheap car. We were not trying to build a DS 19; this car is a compromise“.

Image: adclassix

In their August 1962 test report, Autocar were lavish in their praise for the 1100’s hydrolastic set up. While they found that the car was not entirely free from pitch effects on undulating surfaces, they reported that on really poor roads, like pavé for instance, that not only its ride comfort, but the car’s controllability in such conditions was “extraordinary“. The test team also noted that the “extremely small degree of roll during fast cornering” was “almost uncanny“.

Autocar’s summation of the car’s dynamics deserves quotation in full. “On its behaviour, conclusive opinions have been formed; the unanimous view of the test staff is that for overall rating for ride comfort on smooth or rough roads at all speeds, controllability in these conditions, adhesion in the wet or dry, inherent safety and steering response, there is no better car, irrespective of size“.

There can be little doubt that the 1100 was not only something of a revelation in 1962; there being little to compare it to at the time, but also a car which gave not just rival carmakers, but those in the luxury sector something of a sharp intake of breath. But there was a rather sizeable elephant in the back seat and that was cost. According to Autocar, BMC were charging approximately an extra £137 (in 1962 money), model for model for an 1100 against that of a Mini – itself one of the cheapest cars on the market. The cost of this level of sophistication therefore appears (on face value at least) to have been borne almost entirely by the manufacturer.

Image: Veikl

One therefore might argue that a similar result could have been achieved with conventional springs and dampers; Peugeot illustrated what could be done three years later with the similarly sized 204 model, a car very much in the ADO 16 idiom. Fiat got there even more inexpensively in 1968 with the simply clever 128. It would not be until the early 1970s that anyone returned to a more cerebral approach[6].

Because for all its merits, hydrolastic proved something of a flawed premise, let down by in-service issues, load-related problems a self-levelling addition might have addressed and a lack of quality control in manufacturing and at BMC/BLMC agencies. Hydrolastic could therefore be seen as Issigonis in microcosm. On one hand it illustrated the breadth of his engineering principles, his high-minded conviction in providing the driver with the absolute most in terms of active safety, dynamic capability and living space, but also his disregard towards the economics of the business.

Are we therefore suggesting that hydrolastic may not have been the right choice for ADO 16? That remains a matter of debate. The 1100 would have been a success without it, of that we can be fairly certain. But whether it would have been as significant a motor car is another question entirely.

[1] “Rubber is always too stiff”, Issigonis wrote during the early 1950s.

[2] This experimental Minor was the brainchild of Jack Daniels, then head of R&D at Cowley. Daniels enlisted Alex Moulton to work on this project entirely without Issigonis’ knowledge or input. Given this, it’s a wonder he accepted it at all. Daniels was later to work closely with Alec on the Mini, following the latter’s return to BMC.

[3] Hydrolastic was initially not deemed appropriate for the Mini, Alex Moulton later saying it simply didn’t work on the smaller car. In the August 1962 Motor interview, Issigonis poured cold water on the notion that it would be incorporated, when in fact this did take place in 1964. However it proved to be both ineffectual and costly, and by the decade’s end the Mini (although not immediately the Clubman) reverted to the cheaper and more effective rubber cones.

[4] Alec stated in his notebooks that he only adopted IRS for the Alvis prototype with reluctance, when he realised that the interconnected suspension design could not work with a rigid axle.

[5] Issigonis: “We do not feel we have put the emphasis on comfort; we have erred on the side of making the car safe, making it swervable in an emergency.” (Motor, August 1962)

[6] The 1970 Citroën GS (and to some extent, the 1971 Alfasud) were perhaps ADO16’s spiritual successors.

Sources and quotes. See part one.

Author: Eóin Doyle

Co-Founder. Editor. Content Provider.

21 thoughts on “Modern Family [Part Two]”

  1. Good morning Eóin, and what a wonderful article you have brought the DTW once again, thanks.
    Just wondering about the rear suspension layout of the 1100, and who were first: the Brits or the French, as many French FWD cars have a similar set-up with horizontal dampers?

  2. Issigonis had previously used rubber suspension (in tension?) on his Austin 7 racing car, before the war.

    1. Mervyn: Remiss of me to have forgotten about the Lightweight Special, which is probably the basis of Alec’s initial reluctance to use rubber as a damping medium in a road car application. The Austin 7-powered racing prototype he built in 1936 with George Dowson employed independent suspension all-round (said to have been inspired by the Mercedes W25 Grand Prix car) and used rubber as the springing medium – according to Jack Daniels, somewhat akin to rubber bands. It was a delightful looking thing, and apparently, quite effective in anger.

  3. The DTW Supremo in fine form again – an excellent article. But I’d suggest that the biggest elephant in the room was not cost, it was passive safety. ADO16 was a masterclass in creating an affordable car in which driver and passengers could make rapid and safe progress, the former having at his or her disposal everything necessary to avoid having an accident. But in the event of one happening, the results were catastrophic. At a time when others were developing passenger cells & crumple zones, ADO16 created a passenger zone which crumpled – as anyone who has had to recover the results knows well! The B-post just about supported the weight of the rear doors but under frontal impact, as the A-post sought to join the C-post, it always gave way, allowing the roof and floor to fold up.

    A great car to drive, but not one in which to have a collision.

    1. JTC: From what I can glean, I do not get the sense that Alec placed much store by the concept of passive safety, claiming once that he never wore a seatbelt while driving. He placed a great deal more emphasis on active safety, but as we all now know, that only takes you so far – in some cases straight to the scene of the accident.

      In May 1966, Issigonis managed to get himself tied up in all kind of knots in a rather combative interview on BBC radio on the subject of occupant safety. He didn’t acquit himself very well on that occasion.

    2. BL had to become more interested in safety as time moved on, partly driven by their involvement in the American market where regulations got tighter in the ‘ 70s. ADO 16 was one of the cars used to test a ‘pedestrian catcher’, which I think may have been developed by TRRL. It’s a bit of a crude solution, though.

    3. Wow, I hadn’t realised that the 1100 was so fragile and lacking in passive safety. That said, I was the front seat passenger in an original Mini that was struck on the (driver’s) side by a Renault 16, which was not travelling at great speed. The whole side of the Mini simply caved in and the parcel shelf bent into an upward pointing ‘V’ shape. That was the last thing I remember before being struck on the right temple by the driver’s left elbow. The blow caused a hairline fracture in my skull, from above my ear to the top of my head.

    4. But surely no worse than anything comparable at the same time? Like a Mk1 Escort, or HA Viva, or Triumph Herald, or Peugeot 204, or Citroen Ami, or Opel Kadett.

  4. Good afternoon, Eóin. I think you’ve hit the nail in the head in pointing out that the 1100’s ride probably wasn’t good enough to justify the complication and expense of the Hydrolastic system, especially when a well set up conventional arrangement could be almost as good. Those illustrations of the car remaining perfectly level over a series of bumps were somewhat idealised: in reality, the car still suffered from some front to rear pitching over bumpy roads.

    1. I’m not sure what this advert proves, but it doesn’t look a very comfortable experience. I guess the aim was to show that the car and system were robust.

    2. Daniel: I think it’s fair to point out that Hydrolastic was subject to a good deal of refinement over the intervening years and achieved something approaching its apogee in the Maxi, which incorporated the better aspects of both ADO 17 and ADO 60 designs – as well told by fellow DTW-ite, Robertas in his (as yet incomplete?) exegesis of ADO14 and Fiat 128.

      It’s also worth pointing out that its further refinement as Hydragas moved matters still further forward. However, whether it could ever be said to have equalled or surpassed Hydropenumatics is not so much an ecumenical matter, as one for the entire synod.

  5. The reason the Hydrolastic installation on the Mini was not successful unlike ADO16 was because it needed a longer wheelbase than 80.2-inches, whether Hydrolastic would have been more effective on say an 84.2-inch Minivan wheelbase (if not even longer Innocenti 990 or Austin Metro size wheelbases closer to ADO16) is another question.

    Rubber Cones followed by Hydragas would have been better for the Mini as Hydrolastic was a costly diversion, am curious however to know if the refinement of Hydrolastic applied on the Maxi was originally earmarked for ADO22 and could have sorted most of the deficiencies when employed on a smaller Mini sized car.

    As far as alternative suspension arrangements go for its FWD cars, was it within BMC’s ability to produce a similar layout as achieved by the Peugeot 204, Fiat 128, Alfa Romeo Alfasud and Nissan Cherry E10? Would any of those suspensions have had a negative effect the handling, dynamic qualities and in the case of the Mini motorsport success compared to the Rubber Cone and Hydrolastic layouts?

    Both Alec Issigonis and later Spen King were said to have been advocates for a MacPherson strut front and Twist beam or Trailing Arm suspension layout, had Issigonis thought of adding Torsion Bars to the rear (with a Trailing Arm) on his FWD cars like he originally planned for the RWD Morris Minor with an all-independent Torsion Bar layout (before it was vetoed) and BMC would have preceded the Peugeot 305 Estate and Peugeot 205.

  6. OK, lots of good points here, but, I wonder how many of this commentariat have actual experience of the model(s) in question, plus their direct competitors … as at the ADO16’s 1962 launch date ?

    During their heyday, via a spell in the motor trade, I had experience of all the Issigonis models, both their delights and foibles, also owning ADO 16’s and Minis ( both dry, and Hydrolastic) . Trust me … for 1962, the 1100’s ride / handling combination was a revelation, it drove like a grown up Mini, which was a Good Thing.

    Yes of course, it then suffered from BMC’s usual patchy and tardy approach to development, but comparisons with later competitors are surely missing the point. The 204 didn’t come out until 1965, followed by the Simca 1100 in 1967, the 128 in 1969, the 205 in 1983, all of which I’ve driven, ‘better’ in many ways, but BMC surely deserve a lot of credit for this revolutionary product, and Hydrolastic was integral to its design.

    Also, unreliability or ‘service issues’ around BMC’s Hydrolastic models is largely one of those Internet myths. The huge majority of them went to their (rusty) graves with all the orignal displacers and pipework instact, maybe the odd pump-up to combat settling.

    1. The ADO16 had vastly higher qualities of ride, handling and roadholding than any of it’s opposition. Having driven Triumph Heralds, VW Beetles, Mk1 Ford Escorts, Vauxhall Vivas, Datsun 120Ys, early Corollas, and Renault 8s and 10s, I would rather be in the ADO car.
      As did my parents. Back when I was a wee lad, my parents didn’t own a car, renting one when they needed it. The Austin 1100/1300 was their preferred choice of any of those cars. The bonus was that in New Zealand the NZMC assembled ADO16s were well made compared to their opposition, also locally assembled.

  7. Asking which suspension was “better” is silly. It depends on what is sought. Is it ride you are after? If so what sort of ride quality is it you seek? Pillow soft? Firm? Comfortable but not floaty? “In touch” with the road or some such (and what do you mean when you deploy the term “firm” or “comfortable” or whatever).

    Is it road holding you seek? If so, what type of road surface are you optimising for? Which tyres are you using? Or is it handling you are after? Well, OK then. Better be aware that handling and road holding are different things. How do you like a car to handle? What characteristics ought it to have? And feedback, how ought it to feel to the driver? What tactile qualities are you after?

    Context please.

    The compromise reached was not available to other systems. There are ways in which it behaves which are different. For example, I’ve found it all but impervious to speed bumps taken at speed. That’s such a useful feature. Meanwhile the car corners “flat” and it has little phase delay.


    Did you know that Jaguar developed with a self-leveling version of hydragas for the XJ sedan? They stopped one step short of providing an active anti-roll, although they did realise the potential for that was there.


    Back in the USA in 1955, Packard had an interconnected suspension. William Allison invented and developed it. Forest McFarland got it to production. It was known as “Torsion-Level-Ride”. The most important feature is a very low rate in warp. Most everyone misses the significance of that. This is a system which ought to be under cars today, particularly SUVs and trucks. Here are some links.

  8. I have to concur with all who point out what a revelation ADO16 ride & handling was in comparison with others in the same class. But RichardF is correct in pointing out that the others mentioned were later – and the Herald, of course, was considerably earlier (and with a separate chassis carrying bodywork incidental to the car’s structure).

    J T worries me – why is it useful to be able to drive over speed bumps at speed? Doesn’t that rather defeat the object? It does, though, bring us back to active/passive safety (I’d forgotten about Uncle Alec’s views on the latter – thanks Eóin for the reminder!). In the matter of active safety, ADO16’s suspension system is undoubtedly “better” in mitigating stupid or simply inattentive actions on the part of the driver.

  9. “Did you know that Jaguar developed with a self-leveling version of hydragas for the XJ sedan? ”

    This wouldn’t be referring to another of Dr Moulton’s systems called Telegas by any chance?

    I can find little about it online. It seems to have been another interconnected system but not highly-levered like Hydrolastic and Hydragas. It was tested on a Jaguar S-Type, Rolls-Royce appears to have played with it and that’s about I can dig up.

    It’s described as a successor to Hydragas here:

    However, in the University of Bath research paper – the link to which I posted in the comments to part one of this article – it’s referred to as a predecessor of Hydragas. It’s all very confusing.

  10. Active safety was more important 60 years ago.
    In 1963 mum was a new driver with a used Mini van, Dad had a new VW Beetle. Swapping cars one day mum was rushing home from work to pick us up from school. She tried a sharp bend at Mini speed in the Beetle and ended upside down in a field.
    Whatever their many faults, you wouldn’t spin or roll a fwd BMC car like you could the contemporary swing axle cars made at that time.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: