Derby Models

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TECHNICAL SPECIFICATION OF DERBY BENTLEYS 1933 - 1940

CHASSIS Ladder frame - channel section side members with tie rods and riveted cross-members
BRAKES Servo-assisted mechanically operated 12" drums
REAR AXLE Semi-floating: hypoid gears with differential
SUSPENSION Semi-eliptic cadmium plated leaf springs - hydraulic dampers (MK V - independent front/coil springs)
GEAR BOX 4 Speed & reverse (overdrive fitted to late 4¼ litre cars), attached to engine
CLUTCH Single dry plate
WHEELS Wire, splined hubs - 18" x 4" (overdrive models - 17" x 4")
STEERING Rolls-Royce worm & nut steering box (overdrive models - Marles cam & roller type)
RADIATOR shutters controlled by thermostat in header tank
ENGINE Six-cylinder cast iron monobloc & detachable head, aluminium crankcase, sump & clutch casing
Two valves per cylinder - overhead inlet & exhaust operated by pushrod
Nickel chromium crankshaft in 7 white metal main bearings, big ends white metal bearings
Camshaft carried in seven plain bearings, driven by helical gears
Aluminium alloy pistons
IGNITION Coil & distributor, single plug per cylinder
CARBURETTOR Twin 1 3/8" S.U. ( 1 5/8" on all 4¼ litre cars)
   
 
Production Figures
3½ litre (1933-36) 1,177
4¼ litre (1936-40) 1,234
MK V (1939-40) 9 delivered
     
 
  3½ litre 4¼ litre and Mk V
 
Bore 3¼" / 82.6mm 3½" / 89mm
Stroke 4½" / 114.3mm 4½" / 114.3mm
Capacity 3,669cc 4,257cc
RAC Rating 25.3hp 29.4hp
Brake Horsepower 114 125
Compression Ratio 6.5:1 6.8:1 / 6.4:1
Maximun Speed 91 mph 92mph (93mph -overdrive models)
Wheelbase 10' 6" 10' 4"
Track 4' 8" 4' 8¼ (front)
4' 10" (rear)
Overall Length 14' 6" 15' 11"
Overall Width 5' 8" 5' 9"
Weight 2510 lbs 4½ - 2558 lbs
Mk V - 2719 lbs