Essay : Not their finest hour – Daimler Roadliner, the Lyons-made blunder bus

As originally intended, the Roadliner was meant to feature a horizontal Daimler CD6 engine. A re-think proved to be the start of a disaster.

Daimler tries things new:

The Daimler motor company had a rich and respected past of which many people, including bus operators, had an enviable loyalty. William Lyons was almost held in regard as being another Donald Stokes, that was until Leyland Motors with Stokes at the helm bought into Jaguar Daimler in the early 1960`s. Many people even today have little or no idea that Daimler also were a big player on the bus market right up until 1981, and up to the point of the Leyland take over, Daimler were the chosen operator for most of the municipal bus companies in the UK.

As with the Leyland Atlantean and Bristol VR, Daimler had also developed their own rear engined double deck chassis with the Daimler Fleetline in 1960 which was selling in steady numbers. Liking what he saw and being a true businessman with vision, Lyons sanctioned a replacement vehicle for the Daimler Freeline single deck chassis. Many components of the Roadliner were shared with the Fleetline but where the Fleetline featured a transverse engine, the Roadliner prototype featured an in line rear mounted horizontal Daimler CD type diesel with turbo charger.

Lyons paid attention to operators views when the prototype chassis was shown at the 1962 Commercial Motor Show and was convinced there would be enough interest to justify putting this into full scale production at Coventry. The Daimler board decided that they were to finish mass production of their CD diesel engine and opt for the ever popular and ultra economical Gardner engine, but this lead to a huge problem. Following a meeting between Daimler and both John & Hugh Gardner, Daimler were told there was no extra capacity available for them.

Gardner back in those days exerted some serious influence over chassis builders, so popular were their engines that they would often add a premium to their costs. Gardner engines were hand made and had a solid reputation for longevity, fuel economy and reliability, many operators both bus & truck had made their fortunes by using the Manchester company`s engines – and Gardners knew it. Hugh Gardner was a first class engineer but a poor business man and suggested that any further capacity would come with a hefty premium.

6LW & 6LX engines were in high demand and short supply. Spurned on by Gardner`s reluctance to supply more engines without a hefty premium, Daimler searched elsewhere for a suitable power unit.

Uncle Sam to the rescue:

Daimler were having none of this, and spurned on by Hugh Gardners demands William Lyons searched around for a suitable power unit. Chrysler-Cummins were an American diesel engine builder that were desperately looking to gain some kind of foothold in the UK and European market. Famed for their heavy automotive & marine diesels, they had introduced a range of V6 & V8 high speed diesels for smaller vehicle types boasting incredible power to weight. Daimler entered a supply agreement with Cummins at a very favourable cost, but the price was payed in other ways.

The V6 diesel would not fit into the Roadliner engine bay, so a hasty redesign of the tail end of the chassis took place. Rather than feature a horizontal engine, the chassis now featured a Y shaped kink beyond the rear axle to take the engine both vertical & in line. There had been plans to enter a building agreement with Cummins, but eventually the V6 VI-M series engine was built in Shotts in Lanarkshire and Darlington, in a brand new plant which to this day, still exists. Owing to Cummins superb PT (pressure timed) fueling system, this compact high revving V6 produced a colossal amount of power.

Standard output was rated at 195bhp which was staggering considering an equivalent Gardner 6HLX which was larger in capacity, developed 150bhp at the highest rating. Rather unwittingly, Daimler had developed not only a bus chassis but a high powered coach chassis too and operators initially beat a path to the Coventry doors of Daimler to place orders for this brand new incredible chassis. At first, order books were heaving as Jaguar Daimler struggled to cope with not only bus chassis, but the E-Type car also.

Engineers from Columbus and Darlington as seen here, worked tirelessly trying to cure the inherent problems of the 9.6 litre V6.

But very soon, it became obvious that something was wrong with the Roadliner as operators started to suffer serious shortcomings with vehicles, and it was all driveline related. The Daimatic semi auto gearbox could simply not cope with the level of power going through it and matters relating to burnt out brake bands and even gearbox fires became common. Cummins engineers de-rated the engines in service buses down to 150bhp in order to prolong the life of the transmission, but other serious design problems became apparent of a magnitude that Daimler were never to recover from.

The engine was never really suited to intense stop start working in service buses, whereby coach applications performed reasonably well, bus versions were dogged with a whole manner of serious issues that included overheating, fouling of the delicate bullet type fuel injectors, piston failure and cracked cylinder liners. The thermo viscous fan systems were replaced with fixed blade metal fans to combat cooling problems but this made an already noisy engine almost unbearable. Cummins powered Roadliners had a soundtrack similar to an air raid siren.

Another serious matter involved flexing of the bodywork which affected the bus chassis more than the coach. Because of the redesign of the rearmost part of the frame in order to accept an in line engine, stress in the fulcrum of the chassis over the rear axle was more than normally expected for a rear engined bus. If the body was of dual door construction, this stress was exaggerated by the lack of body rigidity hence why many bus Roadliner`s were withdrawn from service at a fairly low age with fractures in the rear chassis which were virtually impossible to repair with success.

Coastal Catastrophe? Bournemouth Corporation suffered 17 engines failures inside the warranty period. Just like P.M.T in Stoke, Cummins engineers worked alongside their own fleet engineers trying to put things right.

Getting to grips with the problems:

Coaxed into buying these vehicles with the promise of good performance and fuel returns, operators found them a problematic vehicle and drivers new to this type often blew engines up through intense overspeeding thanks to the gearbox having no lock up clutch to offer any degree of engine braking when descending a hill. Potteries Motor Traction based in Stoke built up a huge fleet of Roadliner chassis as did Bournemouth Corporation, failures were so commonplace that engineers from Columbus in the USA and Darlington worked alongside the depot engineers in a bid to cure faults.

Staying on the Darlington theme, they along with Bournemouth & Eastbourne took a draught of Roadliners in 1967 all fitted with  C.H Roe bodies of a dual door layout. These versions were true British Leyland vehicles to the core with Roe coachworks being a wholly owned subsidiary of BL. The Darlington fleet seemed to fare better than others, the Corporation transport department only ran services inside the Borough and the lay of the land is fairly flat terrain. One major factor with the Darlington buses was the fact that Cummins main UK engine plant was located less than a mile from the depot.

As mentioned before, Cummins did everything they could to rid the power unit of these gremlins with Indiana based engineers jetting to and fro across the Atlantic and a dedicated team of engineers and metallurgists frequently burning the midnight oil at the Yarm Road Darlington plant. Eventually Cummins admitted deafeat by admitting that the V6 I-M series engine could simply not cope with frequent stop start cycles of operation – being originally a marine engine design & not really ideal for local bus operators. By the late 1960`s the Roadliner`s reputation was in tatters, but British Leyland`s solution was far from satisfactory.

Darlington Corporation fared much better with the Roadliner than others. Though a second batch was cancelled in favour of Gardner powered Fleetline`s.

Reputations in tatters:

BL & Daimler dropped the Cummins option and plans were put into place to find alternative suitable power units but the design of the rear of the chassis somewhat limited the options available. The Gardner 6LX which was the industry standard oil burner would not fit nor would the Leyland equivalent – the 0.680 series. Perkins ended up supplying their V8 510 series engine which essentially was a de-rated truck unit, reliable it may have been but fitted into a bus chassis, ferociously thirsty. Down at Southall, AEC had developed their own V8 engine – the 800 series which was a superb design yet woefully underdeveloped became another Roadliner option.

The V8 800 series was rushed into production at the order of BL long before it was a proven engine, tales of main bearings failing at less than 60.000 miles became commonplace. Daimler eventually called time on the bus Roadliner after the launch of the single deck version of the Fleetline came on stream, the coach version was soon the only Roadliner available and stumbled along with dying orders until 1972. Daimler, a once respected company, never really had the same credibility after these events and less so after 1973, when all plant and equipment for bus production was moved to Leyland to free up production space for Jaguar cars.

To draw a conclusion, its interesting that after 40 have passed since the death of the Roadliner, the Daimler brand is now just a fading memory of old buses and posh cars. Today, Cummins engines power more buses the world over than any other diesel engine quite simply because they worked hard in getting to that position. The UK Darlington plant is also the world type approval centre for emission criteria and lab testing, making sure that they do all the development work rather than the customers – which was sadly so much the case in the British Leyland days.




Mike Humble


  1. I’m sure South Shields Corporation (as Tyne PTE) bought a few of these single deck Roadliners. I liked the design of them. I dont think they were in service very long though.

    I preferred the earlier double deck Daimler Fleetline’s that the Corporation owned since the mid 60s – also the traditional Daimler CCG6 with Gardner engines. One of which is still preserved since withdrawal from service in 1977.

    • Yes, Sunderland had 3 Daimler Roadliners. They were identicle to the Leyland Panthers but you could tell the difference by the engine ventilation grills at the rear, they were longer, and didn’t sport the same wheels as the Panthers. They were very unreliable! One being scrapped at only 5 years old. I remember on 3 seperate ocasions having to change buses at Kayle Road/Chester Road junction due to over heating problems with those vehicles. They were so bad they were legends!!!

  2. Mike… cant remember exactly but I am pretty sure the ones in So. Shields looked like the Darlington ones shown here and had the Daimler silver oval badge. They were painted in the Tyneside PTE yellow livery. NCU registrations sound familiar though (CU were the South Shields district letters).

    I know Sunderland had Strachan bodied Leyland Leopards and as you say, Marshall Fleetlines.

  3. Sorry… I meant Leyland Panther’s with Strachan body. Sunderland also had Atkinson Alpha bodied buses that look similar to the Roadliner & Fleetline’s. A couple of these are still preserved with Sunderland “BR” reg plates.

  4. West Riding loved a Lemon in the 1960s….They almost, but not quite had the full house..They had some Roadliners, quite a few Panthers, and the Guy Wulfrunian, no wonder they went just about broke, and had to be rescued, and a large batch of 2nd hand Lodekkas had to be drafted in!

    We must be due a ‘Wulfrunian’ story soon!

  5. Mike – can you keep me right? Am I correct in thinking that Daimler Fleetline’s were available as single and double deckers?

    If so, then I am fairly sure the buses in South Shields (Tyne PTE) were all Fleetline’s, rather than single deck Roadliners as I previously thought.

  6. @8 Mike – Thanks,in that case it looks like the 4 ex TWPTE models that Darlington acquired would be the former So Shields ones. So the NCU Reg plates would tally.

  7. Mike I can send you some scans of shots taken of the Wulfrunian a few years ago when we took it out to play. I could also put you in contact with Paul Salmon from the Dewsbury Bus Museum (owners of the 2 survivors) if you like

  8. I think the Wythall lot have a Cummins Roadliner, but it isn’t on the road. They also have an inline engined Daimler decker which is also Cummins powered, and in Walsall livery

  9. As a keen British biker as well as a bus nut, I wonder if Edward Turner featured in the Roadliner story.

    Turner had joined Daimler in the late fifties when Jack Sangster was appointed Chairman on the ousting of Bernard Docker. Turner was a brilliant engine designer and Daimler were soon building V8 petrol engines in quantity for both themselves and Jaguar.

    Is it not possible that Bill Lyons, the Chairman who backed the Fleetline when all around him wanted Daimler to abandon bus production altogether, may have refused to back Turner to develop a V diesel engine to replace the outdated Daimler CD6 unit? It could be that Turner and his team were working on such an engine for the Roadliner then had to find an alternative engine which would fit.

  10. Does anyone have infomation on the Rolls Royce Silver Shadow derived all-alloy 6.7 V8 turbodiesel engine that was apparently intended for the Roadliner as well as whether there was other intended uses for the engine?

  11. Had the dubious honour of a Roadliner catching fire whist driving for Bournemouth Corporation Transport in 1969
    outside Charminster libary. There was very little damage the fire stopped as soon as I swiched off. They were a lovely bus to drive. Exhaust could sound like a mini-cooper, great fun for a 21 year old. Regards, Eric

  12. A Dennis rep told us that fitting Cummins engines was the death knell for their truck division. Claims from bad engines just made the whole thing not worth while. They couldn’t obtain Gardners in any number so there were few alternatives that customers wanted. I also saw pinned on the office wall of a truck company, a version of the Lords Prayer, but about their Cummins engined ERF’s. It went something like “My engine is a Cummins, I shall not want, it maketh me to lie down in pools of water………… A brilliant and long lament on the reliability of Cummins when they set up shop in the UK. Not just the Roadliner, but everyone who bought the early models had major regrets. I have since read the Mr Cummins was removed from the board of the US company and accountants took over, making awful mistakes which was reflected in serious injury to UK manufacturers.

  13. @17 John

    Well Cummins engines haven’t done Dennis buses any harm, when you consider the vast numbers of Darts, Tridents, Javelins and the current ADL range..

    Plus the DAF 45s, LFs etc

    Maybe it was only their early UK engines?

  14. I suppose it’s somewhat ironic that Cummins now pretty much has the market for engines sown up – indeed I understand that Scania will be moving to Cummins for Euro 6 meaning that with the exception of Volvo and Mercedes-Benz all of the major players in the UK market (Alexander-Dennis, Scania, VDL Bus, and Wrightbus) all use Cummins – I’ve excluded MAN as it’s not really a major player any more…..

    Was the engine the problem or was it the bus itself? I think it would be fair to say that all first generation rear-engined single-decker’s – with the notable exception of the Bristol RE – all had their flaws. The problem was that no-one had designed a low-entry front entrance chassis with the engine suspended at the rear before. The chassis suffered from flexing and structural issues. Factor in an unsuitable engine – not just with the Roadliner but with the Leyland Panther, Panther Cub, AEC Swift and Albion Viking too – and you have one seriously troubled vehicle. Just that the Roadliner’s problems are the stuff of legends. The next generation of single-decker’s – the Leyland National – resolved the body issues but the engine was still a trifle troublesome to bus operators, only really resolved with the National 2.

    However, Cummins worked hard at restoring its reputation but it’s breakthrough came with the B & C-Series engine and the L10 in the Olympian. The L10 saw off Leyland engine production in buses and that of Gardner – indeed it remains the only non-Volvo engine offered in a Volvo bus as it was offered as an option in the first Volvo Olympians. Indeed it was only dropped when Cummins moved to the M11 engine for Euro 2 and Volvo said it couldn’t fit in the Olympain – however Lothian Buses proved that it could by fitting it itself and its example ran very happily. So it could be the case that Volvo just wished to remove it as an option.

    The B-series was associated with the Dennis Dart and Optare/MCW MetroRider. If you look at those early Darts they are virtually bomb-proof in terms of reliability. So as Mike says in the article, it looks as though Cummins had the last laugh.

  15. I can tell Nate that the RR 6.7 litre V8 turbodiesel is mentioned in a Business history of Rolls-Royce, Peter Pugh’s The Magic of a Name, the Rolls-Royce Story: The Power Behind the Jets 1945-1987 ISBN 1840462841 published by Icon Books in 2001 and available at between £20-30.

    I have read the copy available for short-term loan from the Mitchell Library Glasgow. R-R were approached by Jaguar and Ford around 1966 asking for a lightweight V8 engine so the design was developed.

    A little later Ford said they would only take the engine if it was branded as a Ford and all reference to R-R was removed. So R-R pulled out of the deal to supply Ford. By then Jaguar were part of BMH and BMC’s George Harriman was looking at ways to take the Bathgate BMC commercials up the weight range.

    So R-R continued with the engine by now destined for the Roadliner, the smaller versions of the Guy Big J (then using rival Leyland and AEC in-line engines) and the proposed full-size development of the FJ which would use the same tilt-cab, but a Guy-designed chassis and axles.

    An example was under bench test at Wolverhampton by the time BLMC happened. I quote directly from Peter Pugh in the Roadmaster Wikipedia article, when describing Donald Stokes’ (hubristic) reaction.

    The beneficiary of this cancellation was of course not Leyland, but Perkins, the V8-510 went into most Late Roadliners and into the full size BMC, which became the Leyland Redline Mastiff.

    The Perkins (with suitable Ford rocker covers) was also used in the D-Series.

    The Perkins V8 was also available in Seddon Lorries and Coaches and replaced the Chrysler-Cummins VAL and VALE engines in the Dodge K-series.

    Some corrections for Mike.

    Jaguar was an independent company when it bought Daimler Company Ltd (cars) and Transport Vehicles Daimler (buses and military vehicles) from BSA. They bought Guy from its receivers in 1962 and Coventry Climax in 1965. A year later the Jaguar group merged with BMC and Pressed Steel Corporation to form BMH. It was the Merger of BMH and Leyland Motor Corporation that formed BLMC in 1968.

    The V6-200 VIM and V8-250 VINE were always imported into the UK. The plant in Darlington was a joint venture between Chrysler Corporation Inc (Owner of Dodge) and Cummins Engines Inc. Other Cummins Factories in the UK were at Shotts, Lanrkshire (large Plant engines) and Daventry Northants (stationary engines).

    Sir William Lyons had pulled out of a similar joint venture to build the VIM and VINE in Wolverhampton. This was to have been called Jaguar-Cummins Ltd. It seems from his biography (also available fromth Mitchell, that Sir Williams felt as proprietorial about the commercial vehicles made by Jaguar as the private cars and was distressed about the poor performance of the V6-200, both in an experimental Fleetline with Sunderland and in PMT’s pre-production Roadliner 6000EH.

    The production Atlantean was launched in 1958, the Fleetline in 1960, by 1964 the Fleetline was outselling the Atlantean.

    The VRT was not announced until 1968.

    Whilst Charles H Roe was part of Leyland Motor Corporation in 1967 when Darlington took its Roadliners Daimler was not.

    Whilst it’s true the L10 had a better reputation then the VIM it has to be remembered that it did suffer from some valve-hitting-piston events on the over-run as in the earlier engine and it was always regarded like the VIM as an engine that was either off or on. It was the last cummins engine to feature the intermediate pressure fuel-system and cam operated injectors.

    The B and C Series were designed by Case and used a more conventional high-pressure system. It is a development of the B-series that is the current mainstay of Cummins engine production in inter alia the Dennis Enviro 200-400.

  16. Sorry to be so late to the party – by several years – but I recall loathing having to drive anything but the Leyland Atlanteans back in Bournemouth in the early 1970s. I forget which engines the Roadliners had (if I remember it right, at least one had a – I think – Perkins engine, but even that was a miserable beast) but there were routes where they used to insist on using them (low trees, railway bridges, etc) and they were prone to breakdowns. One such route also meant a steep climb, which Roadliners were less than stellar at handling. They were noisy, the exhaust was environmentally most unfriendly and they were loathed by the mechanics for their unreliability.
    Nearly every driver preferred to make the ride smoother by setting off from stops in 2nd gear as 1st was usually rather abrupt. Atlanteans with their air-box shifts (as we called them) were smoother and superior in every way.
    BTW, I passed my test in a “Spaceship” – rear-loading with manual box – so I was often called upon to drive the older buses because fewer drivers had full licences and were thus restricted to the semi-auto boxed vehicles. The working day was made far easier because all I needed to do was drive and listen for the bell.

  17. I think some of this is cobbled together from the detailed article I wrote in the 1980’s. My information came first hand from those involved at PMT who incidentally had 58 buses and 6 coaches of the Roadliner marque. Bournemouth only had eleven! The V6-200 was never built at Yarm Road – this plant only built the later V8 range. Some of this is factual – some of it is speculative. Nice read though! Incidentally I spent three years researching my article and had interviews and letters from engineers involved. The story may never be told in full – some of it I couldn’t put in print.

  18. In my opinion, the Daimler Roadliner behaved erratically and I imagine that one of the guys working at the bus servicing depots in Sunderland back in 1971 that the Roadliner which had been out of action for some considerable time wasn’t fit to be in operation.

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