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).
Specifications for the brake areas of the Phantom II, WJ. XJ. series.
| Identifier | ExFiles\Box 12\5\ 05-page252 | |
| Date | 1st December 1930 | |
| FOR FILES. PHANTOM II. BRAKE AREAS WJ. XJ. SERIES. REAR FOOT BRAKES. Drum dia. 15.38". Arc of Contact, 1 liner 54.0º. Total area of Ferodo per side of car. (15.38 x pi x 54 x 4 x 1.75) / 360. = 51. Total area of rear brake lining = 102 sq. ins. FRONT BRAKES. Drum dia. 15.00". Arc of Contact, 1 liner 54.5º. But a chamfer of 1.5" is put on the end of each liner, 1.5" = 11.5º. Actual arc of Contact = 43º. Total area of front lining per side of car. (15 x pi x 43 x 4 x 1.750) / 360. = 39.4 Total area of front brake lining = 78.80 sq. ins. Average total car weight. 5,800 lbs. Total foot brake linings front and rear 180.8 sq. ins. ∴ 1 sq. in. of Brake lining is available/32 lbs of car weight. | ||