Tractor & Construction Plant Wiki
Riley RM Series
Manufacturer Riley
Production 1945–55
  • Riley Kestrel body
  • and
  • 12/4 1½-litre engine
  • or
  • 16/4 2½-litre Big Four engine
Successor Riley Pathfinder
Class Executive car (E)
Body style(s)
Layout FR layout
Wheelbase 1.5 L cars – 112 in (2,845 mm)
2.5 L cars – 119 in (3,023 mm)
Length 1.5 L cars – 179 in (4,547 mm)
2.5 L cars – 186 in (4,724 mm)
Width 63 in (1,600 mm)
Height 59 in (1,499 mm)

The Riley RM Series is an executive car which was produced by Riley from 1945 to 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]

There were three types of RM vehicles produced. The RMA was a large saloon, and was replaced by the RME. The RMB was a longer car to carry the larger engine and was replaced by the RMF. The RMC and RMD were limited-production cars, an open 2 or 3-seater Roadster and a 4-seater Drophead. All of the RM vehicles featured the pre-war Riley race developed 1.5 L (1496 cc) 12 hp (RAC Rating) or the successful 1937 new 16 hp (RAC Rating) 2.5 L "Big Four" straight-4 engines with hemispherical combustion chambers and twin camshafts mounted high at the sides of the cylinder block.


Riley's 1937-1939 Kestrel body

The RM was a face-lift of their pre-war 1½ or 2½ Litre Kestrel.

Riley RMA

Riley RMA

manufactured 1952
Production 1945–52
10,504 produced.
Predecessor Riley 12/4 and Riley 12
Successor Riley RME
Body style(s) 4-door saloon
Engine(s) 1.5 L Straight-4 as for 2½-litre Big Four but bore 69mm by stroke 100mm and bhp 60 @5,300 rpm[2]

The RMA was the first post-war Riley. It was announced in August 1945 with the news it would become available in the autumn.[3] 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 RMB

Riley RMB
Production 1946–52
6900 produced
Successor Riley RMF
Body style(s) 4-door saloon
Engine(s) 2.5 L Straight-4
Wheelbase 119 in (3,023 mm)[4]
Length 186 in (4,724 mm)[4]
Width 63.5 in (1,613 mm)[4]
Height 59 in (1,499 mm)[4]

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.[4]

Riley RMC

Riley RMC

manufactured 1949
Production 1948–51
507 produced
Body style(s) 2-door open 2/3-seater
Engine(s) 2.5 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.

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).

The car was primarily designed for the North American export market, and just over 500 were built from 1948 until 1951. The gear change lever was moved to the steering column on left-hand-drive models.

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

Riley RMD

Riley RMD

manufactured 1950
Production 1949–51
502 produced
Body style(s) 2-door cabriolet
Engine(s) 2.5 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.

dropped cabriolet head

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.[5]

Riley RME

Riley RME

first registered July 1953
Production 1952–55
3446 produced
Predecessor Riley RMA
Successor Riley One-Point-Five (1957)
Body style(s) 4-door saloon
Engine(s) 1.5 L Straight-4

The RME was an updated RMA. 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.[6]

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 and Morris Major.

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.[6]

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

Riley RMF

Riley RMF

first registered March 1953
Production 1952–53
1050 produced
Predecessor Riley RMB
Successor Riley Pathfinder
Body style(s) 4-door saloon
Engine(s) 2.5 L Straight-4

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

Riley 2½-litre Big Four
Manufacturer Riley Motors Limited
Also called Riley 16 h.p.[7]
Production 1937 to 1957[8]
Predecessor none before 1937
Successor Riley RMH then BMC C-Series engine
Configuration straight four
Displacement 2.443 L (149.1 cu in)[8]
Cylinder bore 80.5 mm (3.17 in)[8]
Piston stroke 120 mm (4.7 in)[8]
Cylinder block alloy cast iron, aluminium sump, alloy pistons
Cylinder head alloy cast iron, hemispherical combustion chambers, spark plugs in centre between valve covers[7]
Valvetrain 90-degree angled overhead valves[8] operated by twin high-lift camshafts moving rockers with short light stiff push-rods powered from the crankshaft by duplex roller chains[7]
Compression ratio 6.9 : 1[8]
Fuel system Twin H4 SU carburettors[8] mechanical petrol pump[7]
Fuel type petrol
Oil system pressure fed from sump by submerged gear-type pump driven by skew gear from camshaft
Cooling system water, thermostatically controlled flow, belt-driven water pump and radiator fan[7]
Power output 106 bhp @ 4,500 rpm
Tax rating 16hp[8]