From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Specification table for various front and rear suspension spring types and associated valve settings.
| Identifier | ExFiles\Box 105\3\ scan0279 | |
| Date | 18th October 1932 guessed | |
| HEADER: TYPE. | FRONT. REAR. | POUNDAGE. | HOLES IN VALVES. | EQUIV. AREA SQ. INS. | REMARKS. | | UP. DOWN. | NO. DIA. | | TABLE DATA: CF-20 Front. CR{Mr Cra???ster / Mr Chichester}-20 Rear. | 75 | 95 | 1 | .031 | .000755 | 20/25 HP. Standard Springs. Good all round suspension with well lubricated springs. BY-20 Front. | 90 | 115 | 2 | .039 | .00239 | 20/25 HP. Low Rating Springs. Max. freedom suitable for town carriage and old ladies etc. BR-20 Rear. | 90 | 115 | 2 | .039) | .00314 | | | | 1 | .031) | | BF-20A Front | 90 | 115 | 1 | .044 | .00152 | 20/25 HP. Low rating springs. Provides additional damping to improve riding at speed. BS{A J. Barnes - Assistant Manager}-20A Rear | 90 | 115 | 2 | .039 | .00239 | AP. Front, | 120 | 120 | 2 | .031 | .00151 | Phantom I. Best combination for use with plated and grooved springs. AR-2 Rear. | 80 | 100 | 2 | .031 | .00151 | AR-5 Rear | 100 | 130 | - NONE - | | --- | P.II. Provides additional damping to reduce bouncing etc. BY-5 Front | 110 | 110 | 1 | .039 | .00119 | P.II. Low rating springs. Suitable for town carriage, old ladies, and cars for U.S.A. BR-5 Rear | 90 | 115 | 2 | .039 | .00239 | BF-5A Front | 110 | 110 | - NONE - | | --- | P.II Low Rating Springs. Provides maximum damping to improve riding at speed. BR-5A Rear | 110 | 110 | - NONE - | | --- | FOOTER: Hd{Mr Hayward/Mr Huddy}/MS. | ||