128 vs Maxi Part 3 : Spring Song

We return to our two stars of the spring 1969 season with a look at the different approaches to chassis design adopted at Longbridge and Lingotto.  One car defied convention, the other defined the new orthodoxy.

Image: BMC

Raw facts first:  The Fiat 128 uses MacPherson struts at the front, with coil springs and a transverse anti-roll bar, and a fully independent system at the rear, comprising a transverse leaf spring, struts, and a single wishbone per side. The Austin Maxi has Hydrolastic springing and interconnection, with upper and lower links in a parallelogram arrangement at the front, and fully trailing arms at the rear.

That disregards the detail, which is significant in the understanding of the designers’ mindsets.

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There are two important things to understand about Hydrolastic / Hydragas suspension. The first is that interconnection is more fundamental to the system than the springing medium. The second is that it went through a process of constant evolution. The 1100 and Mini were most similar, the 1800 brought a near-complete rethink, eliminating front and rear subframes, and placing the front displacers horizontally, high on the front bulkhead.

The Austin 3 Litre, launched in October 1967, had self-levelling, and introduced a new type of displacer in which the front to rear connecting pipes feed below the damper partition, rather than above it, to allow separate control of pitch damping through sizing of orifices in the front and rear interconnection pipes.

Maxi front suspension exploded. The drawing shows both the original Hydrolastic displacers (upper) and the post-1978 Hydragas units (lower) Source: Haynes

The 3 litre’s displacers were found to be a worthwhile improvement, and were adopted for the Maxi. The Maxi’s front suspension follows the subframeless 1800’s principles, but with a subframe which incorporates a tube enclosing the horizontal ‘back to back’ displacers.

This arrangement facilitated off-line assembly of the complete powertrain and suspension.

Maxi cutaway and suspension arrangement. Note the wide based arms – transverse at the front, fully trailing at the rear. The front subframe is outlined in a red ‘wireframe’ line for clarity. Source: Autocar

To the same end, the Maxi’s rear suspension was a bolt on-unit with wide-based trailing arms shaped like an asymmetric letter T. Unique in the Hydrolastic pantheon, the rear displacers are centrally located, side by side.  At the time of the Maxi’s introduction, it was speculated that the arrangement could facilitate the addition of a self-levelling system, though none ever appeared. There’s evidence of intelligent cost-saving and production simplification – wide based suspension arms to simplify bearing design and use of pressings instead of forgings.

Maxi rear suspension exploded. Source: Haynes

Two other details are worthy of note in the Maxi’s rear suspension. Items 30 and 35 are ‘trim bars’, small torsion bars which are used to control pitch.

Item 60 is an arch spring, effectively a refined bump stop which removed the need for self-levelling. Alex Moulton’s developments in rubber suspension had their origins in the railway buffers produced by his family’s business, so there is a nice piece of historical continuity in these items.

It is a matter of regret that the Maxi was the last Moulton / Issigonis collaboration on suspension. Issigonis’ abortive 9X Mini replacement used steel springing, while Dr. Moulton continued to work with Harry Webster on the Allegro and 18/22 Series, and on into the Metro / MGF era.

Regrettably the Maxi’s steering let it down, being low geared and yet also heavy.

Image: Autocar

Autocar is either being kind here, or simply ignoring the plainly obvious.  The Maxi’s wheel is tilted at least 40 degrees to the vertical – around the same angle as the 1800. There is a good reason for this – the angle facilitates putting more physical effort into the wheel, disguising the ‘weight’ of the system. It is a form of “poor man’s power steering” more usually found on commercial vehicles. The Maxi would have benefited greatly from a power steering option, but never got it, unlike the 1800, on which hydraulic assistance was available from March 1967.

Steering apart, the Maxi’s chassis seems to have been thoroughly competent in ride and handling characteristics. It’s a pity that the “platform” did not find wider use at BLMC. The Moulton / Issigonis spat and the Stokes-era drive to cut costs slowed the momentum of development.  The 1973 Allegro’s Hydragas system was compromised by cheapening to the point where it had no real advantage over a well-designed steel sprung set-up.

Dante Giacosa has been consistently praised for his modesty, decency, and sympathetic character, but wasn’t above making the occasional side-swipe at his rivals in his memoirs.  In 40YODWF he wrote:  “As far as I was concerned, I had played about with various designs for pneumatic and hydro-pneumatic elastic suspension systems but I came to the conclusion that cost and risk of defects were against it. The traditional system of metal springs is simple, reliable, and cheaper, therefore preferable in my opinion, even though it does not keep the level of the vehicle constant as the load varies.”

The final sentence typifies Giacosa’s mindset – simplify, refine, do not accept cost effectiveness and functional effectiveness as being mutually exclusive.

Peugeot and Honda had already shown how MacPherson struts could work with front wheel drive; Giacosa and Cordiano’s task was to do more with less.

Image: Fiat SpA

The 128’s front suspension has no wishbone per se, rather a forged transverse link and an anti-roll bar of substantial section forming the front part of the triangle, insulated from the transverse link by a flexible bush.  Rack and pinion steering is used, with the rack mounted on the front bulkhead.

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Some time in early 1968, Dante Giacoasa and Ettore Cordiano had a mild disagreement over the rear suspension of the Fiat 128. Surprisingly, given his reputation as a chassis wizard, Cordiano favoured a beam axle on longitudinal leaf springs, as used on the Autobianchi Primula. Giacosa insisted on all-round independent suspension, citing the need to match the ride quality of French competitors.

Image: Fiat SpA

Giacosa prevailed, and he and Cordiano developed a deceptively simple design of remarkable effectiveness, with the struts set up to provide some passive rear wheel steering, and the transverse leaf located to be able to ‘float’ to give roll resistance and accommodate adversely cambered surfaces.

Image: Autocar

The biggest design problem was accommodating the difference in weight distribution between driver-only use and fully laden conditions in a light car with its heaviest masses concentrated over or just ahead of the front axle. Judicious choice of spring rates, and the use of progressive bump stops as an active element of the suspension addressed the problem effectively – Dr. Moulton would have approved.

Giacosa was rightly proud of the design and wrote in 1979:

“I consider the rear suspension of the 128 and the ‘138’ (the Ritmo) to be one of the most functional, economical, and simple of all. And when the transverse spring can be made of a single layer of synthetic material reinforced with glass fibre or some equivalent, a further step forward will be taken in reducing its weight.”

Look upon the 128’s suspension and it looks slim to the point of fragility, but it performed effectively, and was not just copied closely by other manufacturers, but was also used as a benchmark for ride and handling for the upcoming generation of front wheel drive cars.

Reference sources: See part one

13 thoughts on “128 vs Maxi Part 3 : Spring Song”

  1. At that time Fiat was a true technical leader.
    The combination of Ettore Cordiano, Sergio Camuffo and Aurelio Lampredi under guidance of Dante Giacosa produced brilliant designs like the 128 or the intelligent rear suspension of Fiat 130/Dino MkII/Spider Abarth/131 Rally, let alone the famous and appropriately named Camuffo rear axle. Had Fiat properly patented the latter they most probably could have earned more money through royalties mainly from Japanese manufacturers than by making cars.

  2. I really miss the kind of suspension system innovation which the likes of Moulton and Mages made their signature. Moulton in particular seemed to be constantly, almost restlessly refining his art. It’s ironic that the winners (thus far) in the car manufacturing stakes are now increasing deploying ‘air’ suspension in their luxury models, although usually as an expensive option. Moulton clearly saw his suspension systems as solutions to basic engineering problems – intelligent engineering for everyman. How refreshing!

    I also miss this kind of intelligent engineering review from Robert, here – too draw and bravo!

    1. Suspension systems without steel springs are getting used in the class of vehicles they’re best suited for. Hydropneumatic suspension à la Citroen is found in heavy load transportation or tanks and air springs find their way into passenger cars. They get used in expensive cars because the system itself is expensive and cost cutting is the most important thing for car manufacturers. A Citroen GS wouldn’t be possible today because nobody would pay for the suspension system.
      It’s crazy that suspension designers have honed steel sprung systems to a point where oleopneumatic systems offer no advantage over a properly tuned steel spring and now they introduce systems like adjustable suspension setups just to have something for the pricelist and an additional button on the centre console.

  3. Knew the Allegro’s version of Hydragas was later updated via an active anti-roll system and fluid filled engine mountings connected to the suspension amongst other things, though never knew it was cheapened to begin with.

    Was also under the impression the 9X’s conventional suspension was similar in some respects to what was adopted at Fiat, Peugeot, Renault, etc?

    It is unfortunate that Fiat endured a period of decline partly due to the 1970s oil crises up to the Stilo, with the reputation of good suspension being passed on to Peugeot (via the 305, 205, 306, 106, etc) and later Ford and Renault.

    It is a shame we missed out on an R6 type Hydragas Mini, not sure about viable the suspension system could have been up to the present day had it merited the funding and proper development it deserved as shown in the 1997 Rover Spiritual / Spiritual concepts, particularly whether it would have still been used on most of the range or reserved for the odd few or more models (as was the case with Citroen until recently). Apparently Rover were working on a similar suspension system for the Rover P8.

  4. As Dave points out, Fiat had incredible engineering talent, harnessed by the rigorous logic, and it would seem, humane qualities of Giacosa. This isn’t to say that BMC lacked talent; notwithstanding Dear Alec himself, a good number of his fellows were excellent in their own right, had they been allowed to shine.

    The primary differences it seems between Giacosa and Issigonis (both of whom believed in excellence for the ‘common man’) is that Fiat’s engineering chief was fully cognisant of the constraints involved in making model programmes pay their way, so engineered simple, yet sophisticated solutions, which would be economical to develop and cheap to build – also paring weight relentlessly. Of course, in Valetta, Giacosa also had a CEO who understood the business, unlike Harriman at BMC. Issigonis on the other hand, appeared to be impervious to the realities of large scale manufacture, presenting his cars as a fait accompli – often refusing to alter a thing.

    Giacosa appeared to have genuinely cared about his staff, and his memoir is notable for the due credit he lavishes upon others. Alec on the other hand appeared to carry on as though he singlehandedly created everything, basking in the limelight he felt was his due. BL designer, Harris Mann apparently used to occupy the office next to Issigonis’ and stated that once Dear Alec learned that he [Mann] lacked an engineering degree, wouldn’t speak to him. This form of behaviour speaks very poorly of him as a human, but in this of course he is not unique.

    On the subject of hydrolastic / hydragas, one wonders in retrospect whether it would have been better to have proven it in an upmarket vehicle application? It never struck me as a very sensible medium for an inexpensive car, given the cost and complexity. Because once it became established, it became inextricably linked to these downmarket vehicles and perhaps tarred with a similar brush. At its best, it is believed to have provided truly excellent ride and handling qualities and would have made a good deal more sense being applied to BLs more upmarket marques. More what ifs…

    Back to Alec for a moment. The party narrative states that with 9X, he finally grasped the importance of cost, developing a car that would have been cheaper to build than existing models and future-proofed for the coming decade, before going on to lament the bitter irony of him becoming the victim of internecine politicking in the early BLMC melee. What this ignores is that alongside the car itself, Issigonis was proposing yet another entirely new four/six cylinder engine/gearbox programme, completely ignoring the enormous cost implications of this and the fact that he had championed the disappointing E-Series at enormous cost only a couple of years previously. Clearly the man had learned nothing.

    1. Was Issigonis affected by some form of military thinking, that he could simply order what he wanted and expect it turn up? The snobbery of the man is unimpressive. Harris Mann wasn´t there as an engineer. For engineering they had engineers, didn´t they? What an oaf. Cars are about engineering and the aesthetic. Forget that and the product is doomed. Issigonis seemed to imagine that his products were bought in the same way a farmer might be a tractor.

    2. Think with Moulton’s hydrolastic / hydragas suspension, Issigonis at the time (along with a few others) was motivated by the idea of creating a British Citroen whose suspension was capable of matching the Hydropneumatic system whilst being cheaper to produce and easy to maintain.

      He seems to have later belatedly realized his mistake by reserving the suspension for the 3-litre, whilst investigating a more conventional suspension system with the 9X and Austin Ant prototypes.

      Issigonis apparently came close to Dante Giacosa’s solution with an experiential FWD Morris Minor prototype that used an end-on gearbox prior to his move to Alvis though nothing became of it, apart from being merely a stepping stone for his later FWD cars nor is it known to what degree the suspension of his experimental FWD Minor was close to the norm as in Giacosa’s Autobianchi Primula.

    3. Despite hydrolastic being hit or miss with ADO16, it is difficult to imagine BMC’s FWD cars without it and also find it difficult to imagine the Mini being as successful in motorsport had it featured conventional suspension.

      It seems an attempt was made in the 1970s to fit Coil-Spring suspension* to the Mini in place of the rubber cones, whilst retaining the same leverage ratio. Along with rubber-mounting the subframes, with two top mounts and four bottom mounts for the front subframe and four slab mounts set vertically at the back.

      *- Motivated in part to get away from Dunlop, on the basis they believed their pricing was probably too high.

  5. “It’s crazy that suspension designers have honed steel sprung systems to a point where oleopneumatic systems offer no advantage over a properly tuned steel spring…”

    They still offer the advantages of self-levelling and an adjustable ride height, but no-one cares about that stuff nowadays, at least not enough to pay for it as you point out.

  6. A great article. The lack of any technical features in what remains of print publications compared to the past is easily shown up by this detailed exposition and the illustrations are first rate. Wonderful.

    I’d be interested in knowing what both Maxi and the 128 used for inner and outer joints for the front driveshafts. Both look a bit primitive from what can be actually seen. Renaults in particular used out-of-date stuff well into the ’80s and their axles didn’t last at all well – became a running joke with Fuegos in these parts. Both Subaru and the Olds Toronado had introduced six row plunger inboard joints and proper constant velocity outers for the 1966 model year, which is why I mention axles.

    Also, the Fiat using a generator instead of an alternator seems well behind the times.

    The 128 front suspension has lower links including anti-roll bar to make a wishbone very similar to the middle ’50s Ford Consul. The forward angle of the lower link presumably offsets drive torque to some degree which the Ford obviously didn’t require. But the piercing of that link to bolt the anti-roll bar to is the same. As for the rear, and it is a personal opinion of course, I am not so convinced. One could do away with the tranverse leaf spring entirely and merely put coil springs around the struts, which is what virtually everyone else did for decades starting with the original Elan and ending with the Impreza even in FWD form. The leaf offers no anti-roll characteristics unless mounted at two points some distance apart and forced into an S Curve on knife pivots which is what later Corvettes have done.

    None of this has anything to do with the article itself, which is first rate. It is merely my brain ticking over on the details of these cars.

    1. The 128’s leaf spring acutally *is* mounted at two points and therefore offers anti roll characteristics.Therefore it cannot simply be replaced by coils.
      That’s why Dante Giacosa used it exactly this way.

  7. I’ve never considered the angle of the steering wheel on the Maxi, 1300 and Mini as being a type of ‘poor mans power steering’, but I can see the point. My assumption was that it increased crash safety (as the column was less likely to be pushed into the driver) and also negated the need for expensive universal joints in the steering column. Perhaps it was a little of everything, but it does seem the main downside was the impact on the driving position.

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