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).
Rear bumper test report detailing daily spring failures and Brinell hardness results of the leaves.
| Identifier | ExFiles\Box 80\2\ scan0307 | |
| Date | 24th July 1920 | |
| X3981 X.1331. REAR BUMPER TEST. X.3981.24.7.20. Springs F.4666 - 2324 lbs. O.S. (N.S. crossed out) Springs F.4665 - 2226 lbs. N.S. (O.S. crossed out) First Table: Date. | Total hrs. run. | Remarks. 19.7.20. | 1 hr. 10 mins. | Front tie clip O.S. spring broken?. 20.7.20. | | O.K. 21.7.20. | 19 " 45 " | Rear tie clip O.S. broken spring. 22.7.20. | 21 " 15 " | K.419 Bolt broken on centre main spring bracket. 22.7.20. | 24 " 15 " | O.S. Spring 5th. leaf broken(centre) 23.7.20. | 61 " 45 " | N.S. spring 2nd., 8th 9th. and 10th. leaves broken centre. 24.7.20. | 26 " 20 " | O.S. Spring 6th. and 7th leaves broken (centre.) 26.7.20. | 29 " 5 " | O.S. spring 8th leaf broken(centre) & Spring F.4665 (2226 lbs.) run 61 hrs. 45 mins. & F.4666 (2324 lbs.) T Second Table: Leaves | Brinell. | Remarks. & 1 | 444 | O.K. 2 | 444 & 415 | broken centre 3 | 401 | O.K. 4 | 444 | O.K. 5 | 415 | O.K. 6 | 415 | O.K. 7 | 415 | O.K. 8 | 429 | broken centre 9 | 429 & 444 | " " 10 | " 363 | " " 11 | 415 | O.K. | ||