Variomatic for the People

Today we recall DAF’s sixteen years as a manufacturer of small passenger cars alongside the heavy trucks for which the Dutch company is famous.

1960 DAF 600 (c) reddit.com

Mention the name DAF to those interested in matters automotive and their mind will immediately turn to the heavy trucks that are a familiar sight as they carry freight across the length and breadth of the European road network. Based in Eindhoven, the Netherlands, DAF Trucks is a subsidiary of the US manufacturer, Paccar Inc, which acquired the Dutch company in 1996. Paccar’s US truck brands include Kenworth and Peterbilt. It also owns UK truck maker, Leyland, which it acquired in 1998. Paccar is one of the world’s leading manufacturers of medium and heavy trucks.

Some readers may be unaware that DAF used also to be a producer of passenger cars back in the 1960’s and 1970’s. The first of these was the 1959 DAF 600, a small rear-wheel-drive two-door saloon with a front-mounted 590cc air-cooled flat-twin engine, which produced 22 bhp (16 kW). The 600 had a conventional steel monocoque body with independent suspension comprising a transverse leaf spring at the front and semi-trailing arms with coil springs at the rear.

In one respect the 600 was decidedly unconventional: its transmission was a unique continuously variable (CVT) design that comprised an arrangement of pulleys connected by flexible drive belts with a V-shaped cross-section. Each pulley was in two halves with cone-shaped opposing faces. Actuators pushed the faces together to increase the effective diameter of the pulley, or allowed them to move apart to reduce the effective diameter. The pulleys at either end of the drive belt were synchronised to move in opposite directions, to maintain the correct tension on the belt and allow road speed to vary while the engine remained within its optimum RPM range. A centrifugal clutch facilitated starting and stopping.

On the 600, there were two pairs of pulleys and two drive belts, one for each rear half-axle and wheel. The pulley actuators were controlled by centrifugal weights and the inlet manifold vacuum pressure, which was in turn determined by pressure on the accelerator pedal. A dashboard mounted switch reversed the direction of the vacuum pressure to allow for engine braking on steep descents.

The ‘gear lever’ was a simple forward / reverse selector and the car was theoretically able to travel as quickly in reverse as it could going forwards. The transmission, called Variomatic, was designed by Hubert van Doorne, who founded DAF with his brother, Wim. It was robust and required no lubrication or other regular maintenance.

DAF Variomatic CVT (c) dafownersclub.co.uk

When the 600 was launched, DAF claimed that the belts had been tested to last at least 80,000 km (50,000 miles). They would, however, eventually stretch a little in use and if this happened, the direction indicator light would illuminate continuously as a warning. An adjuster lug was provided beneath the rear bumper and the owner or mechanic would simply tighten the lug with a spanner until the light was extinguished to restore the correct tension. Surprisingly, the belts and pulleys were exposed to the elements beneath the car, but DAF claimed that stones, mud or other detritus would simply be thrown off the moving parts.

In 1961 the 600 was joined by a new model, the Daffodil, with a mildly updated and more angular bodystyle and a larger 746cc engine producing 30 bhp (22 kW). This reduced the 0 to 60 mph (97 km/h) time to 29 seconds and increased the top speed to 65 mph (105 km/h). A de-contented version of the Daffodil called the 750 was sold on the home market for two years before it and the 600 were discontinued. The Daffodil was sold in some markets as the 30 and renamed 31 and 32 in 1963 and 1965 respectively as it was mildly updated.

1966 saw the introduction of what would become the definitive DAF bodystyle, the 44. Although still a small car, it was usefully larger than the Daffodil, roughly 200mm (8”) longer in wheelbase and overall length than the older model. Giovanni Michelotti had been commissioned to style the new car and produced a neat and contemporary design with slim pillars and a distinctive clamshell bonnet that blended neatly into an indented waistline. In addition to the notchback saloon, there was also a three-door estate model called the Stationcar or Combi.

1970 DAF 44 Combi (c) storm.oldcarmanualproject.com

The 44 was powered by a further enlargement of the flat-twin engine to 844cc, This increased the power output to 34 bhp (25 kW). The Variomatic transmission was carried over unchanged, while the swing-axle rear suspension was replaced with a more compact design. The 44 would remain in production until November 1974. Meanwhile, the Daffodil was renamed 33 in 1967 and remained in production as a cheaper and smaller model alongside the 44 until 1974.

The 44 model’s weak point was its engine, which was noisy and lacked power. In 1967, DAF signed an agreement with Renault to build its 50 bhp (37 kW) 1,108cc Cléon-Fronte engine under licence for an additional model, the 55. This featured a revised front suspension layout, with longitudinal torsion bars replacing the transverse leaf spring to make room for the new engine. The 44’s swing-axle rear suspension was retained, and the extra power of the new engine could make the 55’s handling unpredictable at the limit.

The 55 was produced in the same saloon and estate variants as the 44, plus an additional model, the Coupé, launched in March 1968. The latter was identical to the saloon below the waistline but had a different glasshouse, with frameless door glass(1) behind fixed quarter lights, pop-out rear quarter windows and a more steeply raked rear windscreen. All 55 models had a grille in place of the 44’s flush front panel, to allow airflow to the new water-cooled engine’s radiator.

The 55 was perhaps an unlikely choice as a rally car, but its Variomatic transmission provided similar benefits to a limited slip differential, so the car did enjoy some success, most notably in the 1968 London to Sydney Marathon when the Dutch National Team pairing of Rob Slotemaker and Rob Janssen achieved a credible 17th place overall. DAF produced a Marathon range-topping version of the 55 in celebration.

The 55’s potentially wayward handling was addressed when it was replaced by the 66 model in 1972. This was visually distinguished by a new full-width black plastic front grille incorporating the headlamps, but more significant changes were made to the Variomatic transmission and rear suspension. The former now incorporated a differential to make low-speed manoeuvring smoother(2), while the latter replaced swing-axles with a De Dion tube axle mounted on leaf springs, to the benefit of both ride and handling.

The 66 was again available in saloon, coupé and estate versions, with three trim levels and two power outputs from the 1,108cc engine, a 53 bhp (40kW) version for the De Luxe and Super Luxe models and a 60 bhp (45 kW) version for the Marathon top of the range model.

1973 DAF 66 Marathon Coupé (c) veikl.com

In 1974 the 44 was replaced by the visually identical 46 model, which received a single-belt version of the 66’s Variomatic transmission and differential, the  66’s rear suspension, and some interior upgrades.

Although DAF cars continued to sell steadily and had a loyal following, the business was increasingly peripheral to the company’s main truck making activity, so it was sold to Volvo AB in 1975 when the Swedish automaker increased its minority 33% stake to 75%. Volvo was, of course, a major competitor in the truck business, but it also had a passenger car operation that appeared complementary to DAF as it was focused on larger models.

Volvo’s first move in integrating DAF was to revise the 66 and relaunch it under its own name in saloon and estate versions(3). The Volvo 66 featured side-impact bars in the doors, larger front seats with head restraints and a safety padded steering wheel. Externally it was distinguished by large impact absorbing bumpers, while a ‘Park’ function that locked the transmission was added to the forward / reverse selector lever. The Volvo 66 remained in production for five years and sold 113,431 units.

The total number of DAF branded passenger cars produced between 1959 and 1976 was 815,646, broken down as follows:

Model: Year: Production:
600 1959-63 30,591
750 / Daffodil / 30 1961-63 39,812
31 1963-65 56,200
32 1965-67 54,171
33 1967-74 131,618
44 1967-74 167,902
46 1974-76 32,389
55 1967-72 164,230
66 1972-75 138,733
Total 815,646

In addition to the above, there were around 4,900 light commercial vehicles produced, comprising the Pony pick-up truck, Kalmar delivery van and the 66YA, a Jeep-like (but still RWD) open-top vehicle.

1975 DAF 77 Prototype (c) freethinker.nl

Volvo also inherited the near production-ready DAF 77, a larger three-door hatchback scheduled for release in 1975. Volvo delayed its launch by a year while it re-engineered the design to its own standards and renamed it the Volvo 343. It was initially equipped with the van Doorne CVT, albeit no longer branded ‘Variomatic’.  A manual gearbox option was offered from 1978, using a transaxle version of the 200’s gearbox mounted directly to the rear axle. The manual would go on to comprise the great majority of 300 Series sales and DAF’s Variomatic-only USP was consigned to history.

(1) Persistent problems with water leaks saw the coupé instead adopt conventional framed door windows from 1971.
(2) The previous set up caused a degree of rear tyre-scrub when large amounts of steering lock were used.
(3) The DAF 66 Coupé was never produced as a Volvo.

Author’s note: I am indebted to Richard Butler, editor of the DAF Owners Club magazine and website, www.dafownersclub.co.uk, for his contribution to this piece, including the provision of the DAF production data quoted above.

 

Author: Daniel O'Callaghan

Shut-line obsessive...Hates rudeness, loves biscuits.

34 thoughts on “Variomatic for the People”

  1. Very occasionally I see DAF cars but didn’t realise or perhaps didn’t remember that the Volvo 300 would have been a DAF. It explains why it always felt like an outlier in Volvo’s range. I can’t help thinking that mounting the variomatic business in the back made things rather complicated: duplicating the transmission for left and right sides, needing to synchronise them (What happens if they drop out of sync? Does the car go round and round in circles?), not to mention having prop shaft and differential spinning at engine speed not road speed. In a first generation unitary bodied car I assume that would have given intrusive NVH characteristics.

    Presumably having it in the front would have added weight and maybe required an off centre prop shaft (Or gear arrangement to recentre it). Maybe engine heat damaged the belts.

    By the way isn’t the 600 smart looking, a lot like the Tranbant 601 but with just enough decadent-capitalist brightwork.

    1. Putting the CVT in the back was a logical approach. The DAF system is very voluminous and wouldn’have fitted transversely and having it longitudinally up front would have meant two bevel drives to change the direction of rotation. In the rear there’s only one and you need a propshaft anyway. The propshaft rotates with engine speed instead of the speed of the car but that’s not a big problem in a slow car like the early DAFs. The differential is no problem because up to the 55 there was none. Instead there were two belt drives working at different speed around moderately tight corners. Different wear rates of the belts were kind of automatically compensated for by increased slip and wear on the other belt – remember those were made from rubber like fan belts and had a limited life.

  2. I think the Variomatic transmission was a clever but simple invention and definitely “outside the box” as we’d say today. One of my aunties had a succession of Dafs in the 60’s and 70’s. I’ve never owned a Daf, although driven a few but did own a Volvo 340 GL with the variomatic, CVT, transmission. Worked fine but needs getting used to. The transmission in modern day CVT gearboxes is a further development of the original design, the rubber belts being replaced with a titanium belt.

    1. Today you get two different lines of CVT gearboxes. The unit designed by JATCO and used in many cars has two flat steel belts with stamped steel triangles between them. Torque is transferred by laterally clamping the triangles and by pushing them against each other.

      The other system is developed by LUK and used by Audi (Multitronic) and uses a chain and torque is transferred by pulling on the chain – the contact patches transferring all the torque are the pins in the hinges!

  3. Daf:s mistake was competing with cars in a field they would never be competetive with, at the same time they had a technical advantage that was totally unique and actually sought after by the industry. Why they continued making cars boggles my mind, when they could have concentrated its resources into further development of the CVT that could be sold and licensed to the rest of the industry.

    In Sweden nobody took the cars seriously, they were never considered “real” Volvos, not even the 300-series until Volvo put their own engine into it. The Daf Cars were a constant butt of jokes, and instantly and easily recognisable with its lethargic acceleration and actually quite loud astmathic whining noise from the driveline.

    1. Don’t tell me you dont’t take a car like this very serious when it has everything you need: go-faster stripes, quad headlights and a colourful name “Daf 66 Marathon Super Coupé”

      I only remember one DAF driven by someone younger than sixty and that guy had inherited in from his grandma. The advanced age of the customers was also reflected in the colours: mud-grey or pastel beige for the twin cylinders, pastel green and pastel mustard for the Renault-engined cars.

    2. Yeah, it always had some sort of grandma-appeal? Growing up in the 80’s, I remember a friends parents had one, inherited from the grandmother. It was the time of “his and hers” cars, and while the father of the family had “his” brand new Audi 80 and later VW Santana, the ten year old pastel green Daf 66 was given to the wife as “her” car for doing shopping because the daddy wouldn’t be caught dead in it. Even as a kid I had a problem with his sadistic joy over the car situation, like he saw it as a fitting punishment for the wife.

    3. That’s what they did: Van Doorne’s Transmissie is still extant as a supplier to third parties, now part of Bosch as Bosch Transmission Technology and still making CVT drive belts. The car factory is still active as well, producing cars for BMW, mainly Minis (although that’s ending soon, I gather). It has produced Volvos, Mitsubishis and even the original Smart FourFour (tarted up Mitsubishi Colt, I just saw one today). Of course, Born (the factory’s location) is closer to Belgium than to most of the Netherlands. I don’t mean to knock it: it’s just that Belgium has an infinitely bigger presence in car manufacturing than the Netherlands, a nation more suited to trade than manufacture. The travails of that factory are a history of their own: Daf, Volvo, Volvo-Mitsubishi, Mitsubishi, Mitsubishi-Smart, BMW/Mini, in many ways lurching from crisis to crisis where the factory seems doomed to closure.

      Incidentally, Dafs and their Volvo descendants weren’t taken entirely seriously at home, either until the 400 series (covered at DTW, I think). Both 300 and 400 series did always sell well at home, though, with the 400 even engendering a measure of national pride – in that curious Dutch way where pride is never acknowledged.

  4. The DAF coupé looks like a front-engined competitor for a Skoda 1100r coupé

    1. Hi Pat, you’re right. Here’s a photo of the early DAF 55 Coupé with the frameless door glasses, a feature it shared with the Skoda S110R coupé:

  5. Here’s a film about the 66 and its transmission (brief narration in French). It looks as though the car has a switch to aid with towing and hills, perhaps locking the transmission in some way.

    And one about the 46, which is worth watching for the dancing, alone. I like the way the front seats fold asymmetrically, out of the way, to make getting in to the back easier. I find both films enjoyable for their lack of self-consciousness and straightforward sense of fun.

    1. Tee hee, those crazy Dutch! Brilliant archive stuff, thanks Charles.

      Did I notice the girls removing from the underside of the red car up on the ramp a panel that was shielding the transmission from road debris, at around 2:50 in the second video? Maybe DAF thought better of leaving the belts and pulleys exposed on later cars?

      Those asymmetric folding seats featured on other two-door cars in the 1970’s (though I cannot recall which ones). It was achieved simply by using an L-shaped plate on the outboard side of the seat, to move the pivot point down and forwards, compared with the inboard pivot.

    2. Hello Daniel – re the cover, yes, that crossed my mind, too. It would make sense.

      Some family friends had some small DAFs – they thought they were fantastic. The family particularly wanted a small automatic – one forgets how rare these were on the market, 40 or more years ago, so DAF had something valuable. I think they were often bought by people who would otherwise have given up driving, or not been able to drive.

      That family had some interesting cars and I think the DAF joined or replaced a Triumph 1300 in the household – I hadn’t made the Michelotti connection, before. Incidentally, I saw on Curbside Classic that Michelotti’s son is organizing a tribute to his father, soon.

      One thing – and I don’t mean this as a criticism, as I think they’re charming cars, but the estate reminds me a lot of a Trabant, side-on.

  6. My grandma had an orange red Daf 44 that was traded in for a yellow 66 Marathon coupe. These were once a regular sight on the Dutch roads, but these cars fell out of fashion in the eighties. Since you could drive them backwards fast, they were used for racing backwards. Lots of these cars were destroyed because of that.

    1. Speaking of crazy Dutch…good afternoon Freerk! Thanks for sharing the video.

  7. Here’s a picture of the 66 rear suspension with a single trailing link

    That effectively makes the 66 a poor man’s Alfetta

    1. Hi Dave. Im going out on a limb here, given my somewhat flaky technical knowledge, but is that not the single-belt version from the 46?

    2. You’re right, it’s the 46. Ant I didn’t consume Heineken nor Grolsch before posting.

    3. Was there really a single trailing link, or was the other one “omitted for clarity” from the drawing?

    4. Hi Robertas. To spare my blushes, I’ll assume that question is directed at Dave rather than me! 🤔

    5. There really was only one trailing link as can be seen in the photograph. There was no test of the car where this wasn’t mentioned. The single link was enough to prevent axle tramp caused by the axle tube from rotating on the leaf springs. As these cars were designed for their optimum speed of 80 kph that was plenty enough.

    6. I can see that the single sided link would be sufficient to stabilise the DeDion tube, but wonder if another link would have gone in had that pesky exhaust not been in the way. As Dave says, power outputs were so low it wouldn’t have been noticed.

      It’s interesting to note the active rust protection, also much favoured by BMC

    7. “Active rust protection”? I always thought it was a budget plan for oil changes, allowing you to replace it continuously in small amounts, rather than all at once. 😁

  8. Don’t forget that in the early 60s there was a Formula 3 single-seater raced with twin-pulley variomatic transmission. The experiment was terminated for cost reasons more than anything else. T.he main drawback was the bulk of the transmission.

    1. Hello Mervyn, it could be this one. It looks like it had understeer problems, too.

  9. ….and then there were the DeRooy brothers. Best known for exploits in the Paris Dakar, in earlier times Gerard deRooy raced a….. Daf! But it was not just any old Daf. His one featured a Cosworth BDA transverse mounted beside the driver, powering all four wheels via a central CVT and a pair of differtial units. This was configured at allow whatever torque splits were thought necessary. At various times there was also a rear CVT fitted and also a front one fitted instead of the differential units. The car was unbeatable more often than not. The it got banned. Then came the truck racing….

    1. Correction.

      I think it must have been Jan deRooy. Gerard is his son. Like father, like son, Gerard also races the trucks.

  10. “One retrograde step was the replacement of the Daffodil’s semi-trailing arm rear suspension with swing-axles.”

    Nope. That original DAF 600 had swing axle rear suspension as well, and not a universal joint in sight. The belts were allowed to twist just a little to allow each rear assembly to follow the arcs of the diagonally mounted giant trailing arms. The pivot plane of the arms goes through the centre of the rear pulley. As swing axle as you can get, and looking remarkably like that other 1960 new car event, the Corvair, which had to use jointed axles because of the differential — but it also had diagonally-mounted swing arms whose pivot points lined up with the UJs (rather than with the rear pulley of the DAF).

    The 44 merely replaced the diagonal swing arm with a rear-mounted parallel swing arm, so its geometry was a bit worse with no toe-in on jounce. Or better, who knows? Still got away with no universal joints, though!

    As for the single upper trailing arm on the right rear of the De-Dion tube on the 46, it’s there for torque reaction as the right wheel would spin first with a differential and might cause axle wind-up and tramp with the puny single leaf springs. Of course, the DAF didn’t have a whole lot of torque to counteract, but I think it’s a nice technical touch.

    1. Hi Bill. Thank you for your comments and apologies for the delay in replying. You are correct about the 750’s swing-axle rear suspension. I checked the source of the ‘semi-trailing arm’ reference and can only assume the writer misinterpreted the drawings of the 750’s rear suspension arms as such. I’ve amended the text accordingly.

  11. It’s taken me this long to remember reading that Peter Ustinov had a 600cc DAF, which he kept in Switzerland. According to himself he took great satisfaction on one occasion on sailing past a neighbour and friend, hopelessly bogged in the snow in his latest big Ford. I suppose he can be forgiven. How often do you get to overtake Jackie Stewart?

Leave a Reply

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

WordPress.com Logo

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

Google photo

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

Twitter picture

You are commenting using your Twitter 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.