20/25 hp
(1929-1936)
Years in production : 1929 - 36
No. made : 3,827
Engine : 6-cylinder in-line configuration
Bore & stroke : 3 1/4" x 4 1/2"
c.c. : 3,669
Transmission : Single dry-plate type clutch, 4 speeds and reverse
Chassis : Pressed steel, parallel girder with tubukar crossmembers, semi-elliptic springs front and rear
Dimensions : Wheelbase 129"
Performance : Early models max. speed 68 mph (109 km/h), later models max. speed 76 mph (123 km/h)
1929 saw the debut of the further development in the small Rolls-Royce concept, when the 20/25 was introduced, initially as an alternative but, in reality, as the successor to the 20 hp.
The significant change was to the engine. A bigger bore had increased the capacity to 3,669 c which, in conjunction with a higher compression ratio of 4.6:1, now gave a more satisfactory power output. The 20/25 could exceed without any problem the 60 mph mark (100 km/h) and, when fitted with a body of low wind resistance, in excess of 75 mph (120 km/h) might be expected.
The increase in power had not changed the highly esteemed qualities of the model : the engine still ran inaudibly and the usual technique of changing into top gear soon after moving off and remaining there, suited the 20/25 because of its even greater torque.
The earliest 20/25s were identical in chassis to the final production of the Twenty, the larger capacity engine with new cross-flow cyinder head being the only distinguishing feature, and the two models were produced side by side during 1929. The Twenty had by then received vertical radiator shutters like those of the Phantoms, and the 20/25 followed suit.
The chassis design teams worked conitnuously to make improvements. Already in the first year the new model was modified by being given a longer chassis. Flexible wheel mountings were introduced and the exhaust system and charging system were improved. An increase in the compression to 5.25:1 resulted in more engine power and more efficient use of the higher octane petrol that was becoming available. During 1932 the compression was raised yet again to 5.75:1.
A considerable improvement in roadholding and passenger comfort was promoted by modified shock absorbers, which were fitted from 1932 onwards. They didn't come up to expectastions completely, however, and in 1934 adjustable shock absorbers were fitted. These permitted adjustment via a lever on the steering wheel and ensured appropriate settings for low and high-speed drive conditions.
The series of "small" Rolls Royces which had begun with the the Rolls-Royce 20 hp, found a most successful continuation in the 20/25. With a production figure of 3,827 this model turned out to have the highest sales in the period between the wars.
Since 1922 the "small" Rolls-Royce had been priced at £1,100; although a small increase had occurred on the lauch of the 20/25 this had later been reduced and thus increased production costs which had taken place in the meantime, and costs accrued as a result of the model change, had not been passed to the customer. The critics did not precipitate immediate changes to reduce production overheads or increase chassis prices. Even for the the following model, the 1936 25/30 hp the company asked an unchanged price of £1,100.
The problem of high production costs resulted in Rolls-Royce's first attempts to economise. In the past the purchase of parts from outside suppliers had been limited to electrical components - and even then the company had laid down strict standards of quality. In the last series of the 20/25 model, use was made for the first time of components from independent suppliers for mechanical parts. Thus the clutch was supplied by Borg & Beck and the steering box manufactured by Marles. These were clearly economy measures for Rolls-Royce. Nevertheless, the suppliers charged higher prices to Rolls-Royce than to other car manufacturers because of the short production runs involved - and Rolls-Royce could not be isolated from the effects of asking suppliers for high quality standards.