The Riley RM Series is an executive car which was produced by Riley from 1945 until 1955. It was the last model developed independently by Riley prior to the 1952 merger of Riley's still new owner Nuffield, with Austin to form BMC. The RM series was originally produced in Coventry, but in 1949 production moved to the MG works at Abingdon. The RM models were marketed as the Riley 1½ Litre and the Riley 2½ Litre.[1]

Riley RM Series
Riley RMA BW 1.jpg
Riley RMA, Baujahr 1951, 54 PS
Body and chassis
ClassExecutive car (E)
Body style
LayoutFR layout
Wheelbase1.5 L cars – 112 in (2,845 mm)
2.5 L cars – 119 in (3,023 mm)
Length1.5 L cars – 179 in (4,547 mm)
2.5 L cars – 186 in (4,724 mm)
Width63 in (1,600 mm)
Height59 in (1,499 mm)
SuccessorRiley Pathfinder

There were three types of RM vehicles produced. All used Riley engines with four cylinders in-line, hemispherical combustion chambers and twin camshafts mounted high at the sides of the cylinder block.

The RMA was a large saloon, and was replaced by the RME. Both used a 1.5 L (1496 cc) 12 hp (RAC Rating), developed before WWII.

The RMB was a longer car: it was replaced by the RMF. Both cars used a larger engine, new in 1937, a 2.5 L 16 hp (RAC Rating) "Big Four".

The RMC and RMD were limited-production cars, an open 2 or 3-seater Roadster and a 4-seater Drophead.


Riley's 1937-1939 Kestrel body

The RM was inspired by Riley Motors' successful and stylish pre-war 1.5 and 2.5 Litre Kestrel Saloons but the new cars featured a new chassis. The new chassis with its Riley "torsionic" independent front-wheel suspension incorporated the experience of the wartime years.[2]

The RM series was new because the patterns of dies for the old models were destroyed in the air raids on Coventry.[3]

Riley RMAEdit

Riley RMA
manufactured 1952
10,504 produced.
Body and chassis
Body style4-door saloon
Engine1.5 L Straight-4 as for 2.5-litre Big Four but bore 69mm by stroke 100mm and bhp 60 @5,300 rpm[4]
PredecessorRiley 12/4 and Riley 12
SuccessorRiley RME

The RMA was the first post-war Riley. It was announced in August 1945 with the news it would become available in the autumn.[5] It used the 1.5 L engine and was equipped with hydro-mechanical brakes and an independent suspension using torsion bars in front. The body frame (not to be confused with the chassis) was made of wood in the English tradition, and the car featured traditional styling. The car was capable of reaching 75 mph (121 km/h). The RMA was produced from 1945 until 1952 when it was replaced by the RME.

Riley RMBEdit

Riley RMB
6900 produced
Body and chassis
Body style4-door saloon
Engine2.5 L Straight-4
Wheelbase119 in (3,023 mm)[6]
Length186 in (4,724 mm)[6]
Width63.5 in (1,613 mm)[6]
Height59 in (1,499 mm)[6]
SuccessorRiley RMF

The 2.5 L (2443 cc) RMB was a lengthened RMA launched a year later in 1946.

It used the 2.5 L (2443 cc) "Big Four" engine with twin SU carburettors, starting with 90 hp (67 kW) but increasing to 100 hp (75 kW) for 1948 with a 95 mph (153 km/h) top speed.

The wheelbase was 6.5 in (165 mm) longer and the overall length was a full 7 in (178 mm) longer. The RMB was replaced by the RMF for 1952.

A car tested by The Motor magazine in 1949 had a top speed of 90 mph (140 km/h) and could accelerate from 0–60 mph (97 km/h) in 16.8 seconds. A fuel consumption of 19.6 miles per imperial gallon (14.4 L/100 km; 16.3 mpg‑US) was recorded. The test car cost £1224 including taxes.[6][7]

Riley RMCEdit

Riley RMC
manufactured 1949
507 produced
Body and chassis
Body style2-door open 2/3-seater
Engine2.5 L Straight-4

The RMC (Roadster) was an open 2-door, single bench seat, 2/3-seater version of the RMB, with a large rear deck area and fold-flat windscreen. Announced in March 1948, it was delivered to Geneva just too late to be exhibited at the Geneva Motor Show. Primarily designed for the North American export market, it was normally built with left-hand drive, with the gear change lever on the steering column. The bonnet and radiator were lowered and the bonnet catches were arranged to be operated internally. Extra over-riders were fitted to the bumpers and the fuel tank was enlarged to 20 imperial gallons (91 l; 24 US gal).[8]

Eighteen months later, in September 1949, Riley announced future production would include a small quota of cars with right-hand drive. Riley attributed that to a slight increase in the supply of steel.[9]

Instead of side windows it was supplied with flexible celluloid-glazed side curtains with a hole for hand signals and, when deployed, flimsy synthetic roofing over a light metal frame. It shared that car's 2.5 L 100 hp (75 kW) engine, and could reach 100 mph (160 km/h).[citation needed]

Just over 500 were built from 1948 until 1951.[citation needed]

Both the back and front of the car bore a remarkable likeness to a 1934 Ford V8.

Riley RMDEdit

Riley RMD
manufactured 1950
502 produced
Body and chassis
Body style2-door cabriolet
Engine2.5 L Straight-4

The RMD (drophead) was a traditional 2-door cabriolet, the last cabriolet to wear the Riley name. It used the same 2.5 L 100 hp (75 kW) engine as the RMB, on which it was based. Just over 500 were produced between 1949 and 1951.[citation needed]

This new body was first displayed in October 1948 at London's Earls Court Motor Show.[10]

drop head cabriolet

A motor car that is a cabriolet has fixed sides to its roof known as cant rails and a folding top that remains part of the vehicle. In a cabriolet like this Riley RMD the tops of the fixed sides, the cant rails, the beams over the side-windows, may be folded along with the top. While the hood is being opened or closed the heavy cant rail beams are supported by exterior hood irons. The hood irons, an elongated S-shape when the roof is up, may be seen at each of the roof's rear quarters.

A more English name for a folding cover or canopy of a (horse drawn) vehicle enabling the occupants to be seen clearly is a "head" or for motor vehicles in the mid-20th century drop head.[11]

Riley RMEEdit

Riley RME
first registered July 1953
3446 produced
Body and chassis
Body style4-door saloon
Engine1.5 L Straight-4
PredecessorRiley RMA
SuccessorRiley One-Point-Five (1957)

Released in 1952, the RME was an improved RMA.[12] It still used the 1.5 L four and featured a fully hydraulic braking system. The body had an enlarged rear window with curved glass. To improve acceleration the rear axle ratio was changed from 4.89:1 to 5.125:1.[13]

When the 2.5 L (2443 cc) car ended production in October 1953 a switch to no running boards was amongst many updates to the RME including wholly new shaped front mudguards.

Produced from 1952, it was discontinued in 1955 and ultimately its place in the range went in 1957 to the much shorter and unrelated, intended but unused, replacement for the Morris Minor — Riley One-Point-Five also sold as Wolseley 1500, Morris Major and the Austin Lancer.

An RME tested by The Motor magazine in 1952 had a top speed of 75 mph (121 km/h) and could accelerate from 0–60 mph (97 km/h) in 29.5 seconds. A fuel consumption of 24.2 miles per imperial gallon (11.7 L/100 km; 20.2 mpg‑US) was recorded. The test car cost £1,339 including taxes.[13]

reshaped mudguards all round and no running boards, a 1954 car

Riley RMFEdit

Riley RMF
first registered March 1953
1050 produced
Body and chassis
Body style4-door saloon
Engine2.5 L Straight-4
PredecessorRiley RMB
SuccessorRiley Pathfinder

The RMF replaced the RMB in 1952. It shared that car's 2.5 L "Big Four" engine as well as the mechanical updates from the RME. The RMH Riley Pathfinder, the last automobile to use the Riley "Big Four" engine, and thus considered to be the last "real" Riley by purists, took its place after 1953 and continued in production until 1957.

Riley 2½-litre Big Four engineEdit

The Big Four engine is a four cylinder 2.5 litre engine rated at 16.07 h.p. under the British RAC formula. It was designed in a matter of months, under difficult financial conditions, and announced in the summer of 1937. It followed existing Riley practice, similar to their 1.5 litre engine, but with each cylinder completely surrounded by a water jacket. The fully counter-weighted and balanced crankshaft ran in three main bearings. Pre-war power output was initially 80 bhp (60 kW), then raised to 85 bhp (63 kW).[14] In its final Riley Pathfinder form, it developed 110 bhp (82 kW) and was produced until the end of Riley Pathfinder production in February 1957.[15]

Riley 2½-litre Big Four engine
ManufacturerRiley Motors Limited
Also calledRiley 16 h.p.,[16] Riley 16/4[14]
Production1937 to 1957[17]
Configurationstraight four
Displacement2.443 L (149.1 cu in)[17]
Cylinder bore80.5 mm (3.17 in)[17]
Piston stroke120 mm (4.7 in)[17]
Block materialcast iron, aluminium sump, alloy pistons
Head materialcast iron, hemispherical combustion chambers, spark plugs in centre between valve covers[16]
Valvetrain90-degree angled overhead valves[17] operated by twin high-lift camshafts moving rockers with short light stiff push-rods powered from the crankshaft by duplex roller chains[16]
Compression ratio6.9 : 1[17]
Fuel systemTwin H4 SU carburettors[17] mechanical petrol pump[16]
Fuel typepetrol
Oil systempressure fed from sump by submerged gear-type pump driven by skew gear from camshaft
Cooling systemwater, thermostatically controlled flow, belt-driven water pump and radiator fan[16]
Power output106 bhp @ 4,500 rpm
Tax rating 16hp[17]
Predecessornone before 1937
SuccessorRiley RMH then BMC C-Series engine


  • A-Z of Cars 1945–1970. Michael Sedgwick and Mark Gillies. Bayview Books. 1989. ISBN 1-870979-39-7
  • Book by James Taylor - RILEY RM-SERIES - ISBN 9780947981365
  • Book by John Price Williams - The Legendary RMs - ISBN 9781861267610
  • Ramsey, John. The Swapmeet and Toyfair Catalogue of British Diecast Model Toys. Swapmeet Toys and Models Ltd. p. 29. ISBN 095093190X


  1. ^ Riley advertisements 1931 – 1955, Retrieved on 7 February 2013
  2. ^ The New Riley. The Manchester Guardian (1901-1959); Manchester, 28 Nov 1945: 6.
  3. ^ 200,000 Cars in 12 months: Motor Trade's Plans Fifty percent for export. The Manchester Guardian (1901-1959); Manchester,11 June 1945: 5
  4. ^ Cars of To-Day. The Times, Tuesday, 24 November 1936; pg. 12; Issue 47540
  5. ^ City Notes. The Times, Friday, Aug 24, 1945; pg. 7; Issue 50229
  6. ^ a b c d e "The Riley 2.5-litre Road Test". The Motor. 1949.
  7. ^
  8. ^ News in Brief. The Times, Wednesday, Mar 31, 1948; pg. 2; Issue 51033
  9. ^ Nuffield Cars For Motor Show. The Times, Friday, Sep 09, 1949; pg. 2; Issue 51482
  10. ^ New Nuffield Cars. The Times, Tuesday, Oct 26, 1948; pg. 2; Issue 51212
  11. ^ OED Online. Oxford University Press, December 2015. Web. 13 January 2016.
    • HEAD
    A (folding) cover or canopy for a carriage or (in later use) motor vehicle, usually one which forms a permanent part of the vehicle rather than being detachable. Cf. drop-head
    A motor car with fixed sides and a folding top.
  12. ^ Michael Sedgwick & Mark Gillies, A-Z of Cars 1945-1970, Bay View Books, 1994, page 163
  13. ^ a b "The Riley 1.5 Litre Road Test". The Motor. 10 December 1952.
  14. ^ a b Dr. A. T. Birmingham (1965). Riley : The Production and Competition History of the Pre-1939 Riley Motor Cars. London: G. T. Foulis and Co. Ltd.
  15. ^ Jeffrey Bridges with Bernie Peal (2017). Wolseley Six-Ninety: A Super Profile. Birmingham, UK: Wolseley Register.
  16. ^ a b c d e Cars of To-Day. '’’The Times'’, Tuesday, 16 March 1937; pg. 22; Issue 47634.
  17. ^ a b c d e f g h Rileyrob. "Healey Silverstone (1949–51)". Retrieved 31 January 2014.