From 1953 to 1978, British automaker Rolls-Royce manufactured its own versions of the General Motors Hydra-Matic transmission for use in Rolls-Royce and Bentley luxury cars. One version was very similar to the Hydra-Matic used in American cars and trucks, but Rolls-Royce later created an improved aluminum-case version with modifications to provide smoother shifting. This version was offered in some versions of the Rolls-Royce Silver Shadow I and Bentley T Series from 1966 to 1969. The older version remained in use in the big Phantom V and Phantom VI limousines until 1978.
PAST ITS PRIME
While less elaborate than the dual-coupling Hydra-Matic transmission (which GM had just recently retired), the revised Rolls-Royce four-speed automatic was noticeably smoother in operation than before. Contemporary British road tests of the early RHD Silver Shadow found shifts barely perceptible most of the time, although downshifts into second gear could still elicit the occasional jerk. As before, it was better to avoid kickdown and use the range selectors to shift down when needed, which the electrical selector made very easy.
The only really glaring problem with the updated transmission was that it was still clearly inferior to the new Turbo Hydra-Matic used in LHD cars. The GM 400 transmission’s torque converter (initially equipped with a variable-pitch stator like the ones used on 1965–1967 Buick, Cadillac, and Oldsmobile units) obviated the need for the older four-speed’s high numerical first and reverse gears — starting ratio at torque converter stall could be up to 5:1 in first and 4:1 in reverse, enough that the first prototype fitted with the new transmission snapped a halfshaft on a full-throttle start. The use of sprag clutches for both of the reaction members of the compound Simpson gearset also allowed most shifts up or down to be effected by engaging and disengaging a single multi-disc clutch, eliminating most of the older transmission’s mechanical folderol.
More importantly, Turbo Hydra-Matic had a new and considerably more advanced control system. Unlike the older Hydra-Matic transmission, which measured load using a throttle valve controlled by a series of rods and levers, Turbo Hydra-Matic used a vacuum modulation system that could vary both shift points and operating pressures based on engine vacuum, providing crisp, decisive shifts under hard throttle and nearly seamless changes in gentler driving. Units tuned for high-performance applications, like the M40 transmissions used in some GM muscle cars, could be as harsh and jerky as an early four-speed Hydra-Matic on its worst days, but Turbo Hydra-Matic was an adroit partner for a torquey, mildly tuned six or V-8, seeming to nearly always make the right moves.
Against such formidable opposition, the older four-speed automatic, however improved, was simply outclassed. Consequently, the aluminum-case four-speed gearbox was short-lived. RHD export cars switched to Turbo Hydra-Matic in 1968, and home-market Silver Shadow and T Series cars had adopted the GM 400 transmission by 1969. (Factory literature marks the change based on chassis numbers rather than model years or delivery dates.)
Why would Rolls-Royce spend the money necessary to update the four-speed automatic, only to quickly phase it out? Our guess is that that wasn’t the original plan. The Silver Shadow had a lengthy gestation; early development began in February 1954 under the codename “Tibet,” with tests of prototype cars commencing in 1958. After a number of false starts, including an abortive Bentley project codenamed “Burma,” Rolls-Royce consolidated its various development efforts into the S2500Y (or SY) program, which became the Silver Shadow and Bentley T Series. It was not until after SY development began in mid-1963 that GM introduced Turbo Hydra-Matic, which was first offered on some 1964 Buick and Cadillac models. Prior to that point, therefore, it seems likely that Rolls-Royce engineers assumed that the new models would retain the four-speed automatic indefinitely, and that the revisions to the older transmission were made on that basis.
However, Turbo Hydra-Matic was plainly superior to the four-speed automatic in every respect. Moreover, the availability of Turbo Hydra-Matic on American luxury cars would further elevate buyer expectations in a crucial export market. Rolls-Royce therefore decided that all LHD export models would have the GM 400, which would eventually become standard line-wide. It’s not clear why the newer transmission wasn’t offered across the board at launch; it’s unlikely that Hydra-Matic Division would have had any difficulty supplying the modest number of additional transmissions. Our best guess is that enough work had already been done on revising the four-speed that Rolls-Royce wanted to recoup some of those costs.
Neither the aluminum-case four-speed nor the GM 400 made its way to the big Rolls-Royce Phantom V, which dated back to September 1959 and was more closely related to the older Silver Cloud II than to the Silver Shadow. Made in very limited numbers by H.J. Mulliner & Co. or Park Ward (which merged in 1961 to become a Rolls-Royce division), the Phantom V was built as a traditional rolling chassis — to facilitate custom bodywork — and still retained a live rear axle, drum brakes, and the older iron-case four-speed automatic through the end of production in 1968.
The same was true of the Phantom VI, which succeeded the Phantom V in April 1968. Surprisingly, the reason for keeping the old transmission appears to have been brakes. Unlike the Silver Shadow, the Phantom still used drum brakes — which Rolls-Royce insisted were quieter than discs — along with the old transmission-driven mechanical brake servo, whose power takeoff shaft was incorporated into the tail extension of the iron-case four-speed gearbox. The aluminum-case four-speed and Rolls-Royce GM 400 gearboxes had no provision for the servo, since they mounted the electrical shift actuator mechanism on the side of the tail extension in roughly the same place. Given the limited production of the large formal cars, we assume it was more expedient to simply continue using the earlier transmission rather than adapt the old tail extension to the newer gearboxes. (The formal cars, which were normally chauffeur-driven, also initially forewent the electrical shift actuator.)
This meant that the 1952-vintage four-speed automatic continued in limited use well into the seventies. How long it actually remained in production is less clear. We assume that Crewe would have needed to continue producing parts and spares for the earlier transmission for some years after the introduction of the Silver Shadow and Bentley T Series, for the service and repair of older cars, so assembling the modest number of complete transmissions needed for the Phantom V and VI would probably not have been a great problem. It’s also conceivable that Rolls-Royce retained a small stockpile of the earlier transmissions to draw upon for the Phantom VI; production of the big formal cars was never more than a few dozen units a year.
In 1976, the British Society of Motor Manufacturers and Traders (SMMT) commissioned production of a special Phantom VI for the Queen, originally intended as a Silver Jubilee gift, but not delivered until March 1978. This car adopted the long-stroke 6,750 cc (412 cu. in.) V-8 that had been standard on other Rolls-Royce and Bentley models since 1970, along with Turbo Hydra-Matic. Adopting the GM 400 transmission and its electrical shift mechanism required the deletion of the old transmission-driven brake servo, which was replaced by a more conventional dual-circuit hydraulic system similar to that of the contemporary Silver Shadow II, albeit with drum brakes; the Phantom VI never adopted discs.
The big engine, GM 400 transmission, and hydraulic brake system became standard on the Phantom VI later in the year, which finally consigned the old four-speed fluid coupling transmission to the history books. Remarkably, the elderly Dual-Range Hydra-Matic design managed to outlive all of its lineal descendants, including not only the aluminum-case Rolls-Royce automatic gearbox, but also the second-generation Controlled Coupling Hydra-Matic and the later three-speed Roto Hydra-Matic, which GM had dropped after the 1964 model year.
This means that the production lifespan of the single-coupling, four-speed Hydra-Matic family, introduced in the fall of 1939 as an option for 1940 Oldsmobiles, was a remarkable 39 years. During that time, these transmissions had found their way into almost every manner of automotive application, from passenger sedans to pickup trucks and armored fighting vehicles.
By the late seventies, the four-speed fluid coupling transmission was an anachronism, but it was also the grande dame of automatic transmissions, so it’s somehow fitting that it ended its long career powering royal limousines. Groundbreaking automotive technology rarely receives such a prestigious send-off.
NOTES ON SOURCES
For a full bibliography of Hydra-Matic sources, see our earlier Hydra-Matic articles.
Additional information on the late Rolls-Royce Hydra-Matic came from “After the Cloud—The Shadow,” Autocar 8 October 1965, reprinted in Rolls-Royce, 2nd ed., Peter Garnier and Warren Allport, compilers (London: The Hamlyn Publishing Group Limited, 1981), pp. 208–216; Warren Allport “Royal Phantom,” Autocar 1 April 1978, reprinted in ibid, pp. 252–254, and “Production change,” Autocar 26 February 1977, reprinted in ibid, p. 251; Warren Allport and Stuart Bladon, “The Ultimate in Luxury? A Unique Rolls-Royce Phantom VI,” Autocar 27 April 1972, reprinted in ibid, pp. 224–226; “Autocar road test 1835: Rolls-Royce Silver Cloud III 6,230 c.c.,” Autocar, 9 August 1963, pp. 234–238; “Autocar Road Test Number 2125: Rolls-Royce Silver Shadow 6,230 c.c.,” Autocar 30 March 1967, reprinted in Rolls-Royce, pp. 217–221; “The Autocar Road Tests No. 1510: Rolls-Royce Silver Dawn Saloon,” The Autocar 16 October 1953, reprinted in ibid, pp. 152–155; the Armstrong Siddeley Car Club, “The Armstrong Siddeley Sapphire 346,” n.d., armstrongsiddeley. org.au/ models/ sapphire-346/, accessed 4 September 2022; Martin Bennett, Bentley Corniche & Azure, 2nd ed. (Dorchester, England: Veloce Publishing, 2009); Bentley Motors Ltd., “Technical Library, 1955-1965,” Bentley Motors Ltd. Heritage website, heritage.bentleymotors. com/ en/ technical-library/ 1955-1965, last accessed 2 August 2022, and “Technical Library, 1965-1980,” Bentley Motors Ltd. Heritage website, heritage.bentleymotors. com/ en/ technical-library/ 1965-1980, last accessed 30 July 2022; BMW Group, “King Size. Rolls-Royce Phantom VI,” BMW Group Classic, n.d., www.bmwgroup-classic. com/ en/ history/ classic-heart/ classic-heart-pool/ classic-heart/ rolls-royce-phantom-6.html, accessed 2 August 2022; Malcolm Bobbitt, Rolls-Royce Silver Shadow, Bentley T-Series, Camargue & Corniche, 4th ed. (Dorchester, England: Veloce Publishing Ltd., 2016); Bill Boddy, “Earls Court Review,” Motor Sport Vol. XXVIII, No. 11 (November 1952), p. 518a; “Long Weekend with a Rolls-Royce Silver Shadow,” Motor Sport Vol. XLIV No. 5 (May 1968), pp. 404–408; and “New for 1966: The Rolls-Royce Silver Shadow and Bentley T-Series,” Motor Sport Vol. XLI, No. 11 (November 1965), pp. 996–999; Bonhams, “Past Auction: 1958 Armstrong Siddeley Star Sapphire,” Classic Driver Marketplace, 5 September 2015, www.classicdriver. com/ en/ car/ armstrong-siddeley/ star-sapphire/ 1958/ 326214, accessed 4 September 2022; Gavin Braithewaite-Smith, “Simply the Best? Profile: Rolls-Royce Silver Shadow,” Drives TODAY, 11 April 2021, drives. today/ articles/ 643/ history/ rolls-royce-silver-shadow/ gavin-braithwaite-smith.html, accessed 30 July 2022; Martin Buckley, “How the other half lived: Bentley MkVI vs Armstrong Siddeley Sapphire 346,” Classic & Sports Car 4 November 2020, www.classicandsportscar. com/ features/ how-other-half-lived-bentley-mkvi-vs-armstrong-siddeley-sapphire-346, accessed 4 September 2022, and “Bentley’s heartbeat: the first and last L-series V8s,” Classic & Sports Car 22 September 2020, www.classicandsportscar. com/ features/ bentleys-heartbeat-first-and-last-l-series-v8s, accessed 3 August 2022; David Burgess-Wise, “A good idea at the time: The Black Prince,” The Telegraph 13 October 2001, www.telegraph. co.uk/ motoring/ 4753430/ A-good-idea-at-the-time-The-Black-Prince.html, accessed 15 October 2015; Cadillac Motor Car Division of General Motors Corporation, 1955 Data Book (Detroit, Mich.: Cadillac Motor Car Division, General Motors Corporation, November 1954); Richard Calver’s Jensen website, www.richardcalver. com, last accessed 4 September 2022; David Chaundy, “Roll-Royce Built ‘Hydramatic’ Automatic Transmission,” KDA132, 15 April 2018, www.kda132. com, accessed 3 August 2022; Mike Covello, ed., Standard Catalog of Imported Cars 1946–2002, Second Edition (Iola, Wis.: Krause Publications, 2001); Detroit Transmission Division of General Motors, Detroit Transmission Division Welcomes You to the Home of Hydra-Matic (Ypsilanti, Mich.: Detroit Transmission Division of General Motors Corporation, ca 1958); Edward Eves, Rolls-Royce: 75 Years of Motoring Excellence (New York: Crescent Books, 1979); the Flying Spares website, www.flyingspares. com, last accessed 2 August 2022; Peter Garnier and Warren Allport, compilers, Rolls-Royce, 2nd ed. (London: The Hamlyn Publishing Group Limited, 1981); Bill Gavin, “The Doughty Dowager Comes of Age,” Car and Driver Vol. 11, No. 9 (March 1966), pp. 45–47; Norman Geeson, “History of Bentley R-Type B87UL,” KDA132, www.kda132. com/ history-of-bentley-r-type-b87ul/, accessed 3 August 2022; T. Grace, Automatic Transmission Service Guide (Union, N.J.: Lincoln Technical Institute, September 1966); “Invicta Black Prince,” A to Z of Cars, Classic & Sports Car, 29 March 2011, www.classicandsportscar. com/ guides/ classic-cars-a-to-z/ invicta-black-prince, accessed 5 August 2022; Invicta Car Development Co., “Invicta” [brochure, 1947]; Karl Ludvigsen, “Inside the Rolls-Bentley Great Eight,” Collier Automedia, 2020, www.collierautomedia. com/ inside-the-rolls-bentley-great-eight, accessed 3 August 2022; Eric Nielssen, “Six Luxury Cars: a view from the Automotive Engineering Side,” Car and Driver Vol. 11, No. 1 (July 1965), pp. 26–31, 75; “Nomenclature,” Motor Sport Vol. XXIX, No. 12 (December 1953), p. 5; Pontiac Motor Division, Owner’s Service Department, Pontiac Owner’s Guide (Pontiac, Mich.: Pontiac Motor Division of General Motors Corporation, April 1955); the Old Car Brochures website (oldcarbrochures.org); the Old Car Manual Project (www.oldcarmanualproject.com); “Review of Earls Court,” Motor Sport Vol. XXIX, No. 11 (November 1953), pp. 577–579, 585–586, 589–591; Marinus Rijkers, “Rolls-Royce Silver Spirit,” n.d., www.rrsilverspirit. com, last accessed 2 August 2022; Ian W. Rimmer, Rolls-Royce and Bentley Experimental Cars (Abingdon, England: R.R.E.C. Publishing, 1986); William Arthur Robotham, Silver Ghosts & Silver Dawn (London: Constable & Company Ltd., 1970); Rolls-Royce Limited, Turbo Hydra-Matic Transmission GM 400 Workshop Manual: Rolls-Royce Silver Shadow & Bentley T Series (T.S.D. Publication 2271) (Crewe, England: Rolls-Royce Limited Technical Publications Department, 1966), Workshop Manual: Automatic Gearbox (T.S.D. Publication 2042) (Crewe, England: Rolls-Royce Limited Technical Publications Department, September 1963), and Workshop Manual: Rolls-Royce Silver Shadow (including Long Wheelbase Saloon), Rolls-Royce Corniche, Bentley T Series and Bentley Corniche (T.S.D. 2476) (Crewe, England: Rolls-Royce Limited Technical Publications Department, July 1971); Rolls-Royce Motors Limited, Chassis Numbers Booklet (T.S.D. Publication 4552) (Crewe, England: Rolls-Royce Motors Limited, 1983); Rolls-Royce Owners Club of Australia, “The Rolls-Royce and Bentley Technical Library,” 4 November 2010, rrtechnical. info/ sy/ 04_sy.html, accessed 29 July 2022; “Rolls-Royce 6¼-Litre Vee-Eight,” Autocar 25 September 1959, reprinted in Rolls-Royce, pp. 175–179; Jeremy Satherly, “The Men Behind the Marque: Ernest Hives,” Rolls Royce & Bentley Driver No. 5 (Summer 2018), pp. 100–106; and “The Men Behind the Marque: W.A. Robotham,” Rolls-Royce & Bentley Driver No. 8 (Jan.–Feb. 2019), pp. 52–58; “Six Luxury Cars: A subjective, seat-of-the-pants evaluation by the editors,” Car and Driver Vol. 11, No. 1 (July 1965), pp. 23–25, 62–65; Jon Stephenson, “Vintage Autocar Road Test: 1966 Rolls-Royce Silver Shadow – Britons’ First Look,” Curbside Classic, 28 July 2022, www.curbsideclassic. com/ uncategorized/ vintage-autocar-road-test-1966-rolls-royce-silver-shadow/, accessed 29 July 2022; R.P. Stevenson, “British Cars – Mechanical Marvels,” Popular Science Vol. 150, No. 6 (June 1947), pp. 158–162; Hans Tore Tangerud’s Autoblog website (www.lov2xlr8.no); Tatra87, “Automotive History: British Deadly Sins (A Touch of Class, Part 1) – A Blue-Blooded Sin Called Invicta Black Prince,” Curbside Classic, 5 March 2019, www.curbsideclassic. com/ automotive-histories/ automotive-history-british-deadly-sins-a-touch-of-class-part-1-a-blue-blooded-sin-called-invicta-black-prince/, last accessed 11 August 2022; Mark Wan, “Rolls-Royce Phantom V & VI (1959),” AutoZine, n.d., www.autozine. org/ Archive/ RR/ classic/ Phantom_V_VI.html, accessed 2 August 2022; Frank J. Winchell, Jerry R. Mrlik, John E. Mahoney, Jack W. Qualman, Thomas R. Zimmer, and August H. Borman, assignors to General Motors Corporation, U.S. Patent 3,321,056, “Transmission and Control System,” applied 12 December 1963, Serial No. 330,105, patented 23 May 1967; and Robert Wort, “Automatic Transmissions,” Crewe’d Jottings [the newsletter of the Rolls-Royce Club of Australia] June 2008, rrtechnical. info/ CrewedJottings/ 19.pdf, accessed 3 August 2022.
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