| Description | Date | Identifier | |
| Letter from Mechanics Universal Joint Company regarding drive shaft tube critical speed formulas. | 19th Oct 1931 | Box 105 \ 2 scan0125 | |
| Mathematical comparison and specification for a J.3. propeller shaft. | 5th Nov 1931 | Box 105 \ 2 scan0126 | |
| Propeller shaft and axle clearances for a 25HP chassis. | 6th Nov 1931 | Box 105 \ 2 scan0127 | |
| The decision to use a 3-inch propeller shaft on the J.3. model and the required modifications. | 6th Nov 1931 | Box 105 \ 2 scan0128 | |
| Standardisation of a 3.00' diameter propeller shaft to overcome periods and whirling. | 5th Jan 1932 | Box 105 \ 2 scan0129 | |
| Fitting of a new part to a chassis, including test date and associated costs. | 12th Mar 1932 | Box 105 \ 2 scan0130 | |
| Failing 20/25 Brake Servo, discussing material failures and potential remedies. | 5th Sep 1932 | Box 105 \ 2 scan0131 | |
| Providing preliminary figures on the end force exerted in the sliding splined joint of the propeller shaft. | 8th Sep 1932 | Box 105 \ 2 scan0132 | |
| Test graph plotting sliding effort against torque for a 20/25 HP propeller shaft spline. | 8th Sep 1932 | Box 105 \ 2 scan0133 | |
| Standardisation of parts document for needle bearings in propeller shaft joints. | 2nd Nov 1933 | Box 105 \ 2 scan0134 | |
| Standardisation of parts for needle bearing propeller shaft joints filled with Mobilgrease No. 2. | 8th Jan 1934 | Box 105 \ 2 scan0135 | |
| Request to produce two propeller shaft dampers and investigate modifications for fitting one to chassis 21-G-IV to address over-run gear rattles. | 20th Apr 1934 | Box 105 \ 2 scan0136 | |
| The rectification of gearbox rattles on chassis GEX.68, caused by excessive grease and end float. | 7th May 1934 | Box 105 \ 2 scan0137 | |
| Investigation of gearbox rattles on chassis GEX.68, which were resolved by reducing grease and end float. | 7th May 1934 | Box 105 \ 2 scan0138 | |
| Propeller shaft sliding joints and the effect of removing grease on transmission overrun rattles. | 10th May 1934 | Box 105 \ 2 scan0139 | |
| Recommendation for Vacuum Motor Grease No. 2 for 20/25 & 40/50 HP chassis universal joints with needle type bearings. | 30th May 1934 | Box 105 \ 2 scan0140 | |
| Note on the damping springs for the Propellor Shaft Damper on the 20/25 HP and Bentley chassis. | 8th Sep 1934 | Box 105 \ 2 scan0141 | |
| Standardisation of a propellor shaft damper to delete over-run rattle. | 7th Sep 1934 | Box 105 \ 2 scan0142 | |
| Cost estimate and production notes for a new damping feature on the Bentley 'G' series chassis. | 20th Sep 1934 | Box 105 \ 2 scan0143 | |
| The slip load for the propeller shaft damper on the 20/25 and Bentley chassis. | 16th Jan 1935 | Box 105 \ 2 scan0144 | |
| Requesting a note be added to the arrangement drawing for a 20/25 HP chassis propeller shaft damper. | 17th Jan 1935 | Box 105 \ 2 scan0145 | |
| Propeller shaft modifications for the 20/25 model, comparing performance to the Bentley. | 27th May 1935 | Box 105 \ 2 scan0146 | |
| Comparing propeller shaft specifications and performance for the 25/30 HP car. | 20th Dec 1935 | Box 105 \ 2 scan0147 | |
| The lack of propeller shaft vibration for the 25/30 HP car during a 10,000-mile test. | 24th Dec 1935 | Box 105 \ 2 scan0148 | |
| On the performance of a propeller shaft for the 25/30 HP car during a 10,000-mile test. | 24th Dec 1935 | Box 105 \ 2 scan0149 | |
| Notice regarding the retention of the propellor shaft damper on 20/25 HP models. | 17th Jan 1936 | Box 105 \ 2 scan0150 | |
| Road test report on the 25/30HP chassis detailing the propeller shaft hitting the crossmember on rebound. | 20th Apr 1936 | Box 105 \ 2 scan0151 | |
| Transmission vibration issues on the 25/30HP chassis and the proposed solution of fitting a propeller shaft damper. | 4th Aug 1936 | Box 105 \ 2 scan0152 | |
| Requesting the reintroduction of the propeller shaft damper for the 25/30 HP model. | 8th Apr 1936 | Box 105 \ 2 scan0153 | |
| Requesting to change the material of 20/25 Propeller shaft damper hubs to RR.53 to reduce weight. | 10th Nov 1936 | Box 105 \ 2 scan0154 | |
| Change in the manufacturing process for the 25/30.HP. Damper Flywheel to save costs. | 16th Nov 1936 | Box 105 \ 2 scan0155 | |
| Materials for the propeller shaft damper flywheels on the 25/30 HP chassis. | 20th Nov 1936 | Box 105 \ 2 scan0156 | |
| Specification document for the 25/30 Propeller Shaft, detailing its components and comparisons. | 2nd Apr 1937 | Box 105 \ 2 scan0157 | |
| Secret memo regarding piston stops, recommending they be filed below the surface and that the practice of counterboring the stop pin hole be discontinued to avoid leakage. | 23th Mar 1925 | Box 105 \ 2 scan0158 | |
| Secret memo sending a drawing for an India Piston. | 23th Mar 1925 | Box 105 \ 2 scan0159 | |
| Secret memo regarding a piston modification for the 'India' specification 20 HP engine. | 23th Mar 1925 | Box 105 \ 2 scan0160 | |
| Piston design, specifically scraper rings and pin sizes. | 31th Mar 1925 | Box 105 \ 2 scan0161 | |
| Design and materials for piston pins for various engines, proposing a spring ring device. | 28th Aug 1926 | Box 105 \ 2 scan0162 | |
| Standardisation of a piston with 5 narrow rings to replace the existing 3 narrow and 1 wide ring design. | 6th Apr 1927 | Box 105 \ 2 scan0163 | |
| Standardisation of chassis parts form detailing the first chassis for a new part, test date, and tooling costs. | 8th Oct 1927 | Box 105 \ 2 scan0164 | |
| Instructions for modifying the gudgeon pin fitment on 20 HP engine pistons to prevent distortion. | 30th Aug 1927 | Box 105 \ 2 scan0165 | |
| Design changes and die-casting methods for cross web pistons for the 20 HP engine. | 22th Dec 1927 | Box 105 \ 2 scan0166 | |
| Providing drawings for piston components for the 'India' project and instructions for assembly. | 11th Jan 1928 | Box 105 \ 2 scan0167 | |
| Trialling die-cast car pistons made from Halls alloy for 20 HP and 40/50 models. | 1st Feb 1928 | Box 105 \ 2 scan0168 | |
| Proposal to trial rectangular piston rings on the 20HP engine to address overoiling issues. | 27th Feb 1928 | Box 105 \ 2 scan0169 | |
| Recommending the use of hardened and spring tempered high duty alloy steel over case-hardened steel for piston pins. | 15th Mar 1928 | Box 105 \ 2 scan0170 | |
| The material of piston pins and a request for further fatigue tests. | 4th Jul 1928 | Box 105 \ 2 scan0171 | |
| Strengthening modifications for the 20 HP piston, including a special taller version for 'India 3'. | 14th Jul 1928 | Box 105 \ 2 scan0172 | |
| Confirmation of a wire communication regarding 'Twenty' piston issues, with instructions to scrap and replace with a strengthened design. | 16th Jul 1928 | Box 105 \ 2 scan0173 | |
| Relaying the contents of a telegram from Royce concerning dangerous Phantom pistons. | 17th Jul 1928 | Box 105 \ 2 scan0174 | |
| Piston breakage on a 20 HP chassis and proposing design modifications for rings and piston strengthening. | 7th Jul 1928 | Box 105 \ 2 scan0175 | |
| Failed piston and scraper ring design for the 20 HP car. | 19th Jul 1923 | Box 105 \ 2 scan0176 | |
| A broken 20 HP piston from an experimental car being sent for inspection. | 19th Jul 1928 | Box 105 \ 2 scan0177 | |
| New and experimental piston designs for the 20 HP and Phantom models. | 20th Jul 1928 | Box 105 \ 2 scan0178 | |
| Changing from 'L' shaped to plain rectangular piston rings for the 20 HP chassis. | 20th Jul 1928 | Box 105 \ 2 scan0179 | |
| Confirmation of a telegram discussing piston ring solutions for the Twenty HP and Phantom models. | 23th Jul 1928 | Box 105 \ 2 scan0180 | |
| Pedestal piston design for 'India 3', featuring an Invara steel control ring to prevent piston slap. | 24th Jul 1928 | Box 105 \ 2 scan0181 | |
| Fitting and testing of pistons and rings for 20 HP and Phantom engines. | 1st Jul 1928 | Box 105 \ 2 scan0182 | |
| Performance and design of piston rings, including the phasing out of 'L' shaped rings. | 20th Aug 1928 | Box 105 \ 2 scan0183 | |
| Decision to switch from 'L' shape to plain square section piston rings for 20 HP engines. | 27th Aug 1929 | Box 105 \ 2 scan0184 | |
| The addition of oil holes to the gudgeon pin bosses of 20HP pistons. | 4th Sep 1928 | Box 105 \ 2 scan0185 | |
| Car modifications addressing issues with slipper drive, engine mounts, pistons, and suspension shudder. | 4th Sep 1928 | Box 105 \ 2 scan0186 | |
| Immediate modification instruction for 20 HP pistons concerning oil flow around the gudgeon pin. | 5th Sep 1928 | Box 105 \ 2 scan0187 | |
| Gas-tightness of 4-pinned rings on 20 HP pistons. | 19th Sep 1928 | Box 105 \ 2 scan0188 | |
| Valve lubrication issues on engine 12-G-4 causing unreliability at slow speeds. | 16th Oct 1928 | Box 105 \ 2 scan0189 | |
| Design and specifications of pistons and piston rings. | 18th Oct 1928 | Box 105 \ 2 scan0190 | |
| Desired features and dimensions for Phantom and 20 HP pistons. | 25th Jan 1929 | Box 105 \ 2 scan0191 | |
| Issue of pistons seizing on new 40/50 and 20 HP cars. | 25th Jan 1929 | Box 105 \ 2 scan0192 | |
| Secret internal memorandum discussing potential engine modifications to improve 20 HP car performance. | 15th Apr 1929 | Box 105 \ 2 scan0193 | |
| Calculations comparing engine performance based on increased capacity, weight savings, and a lower axle ratio. | 8th Apr 1929 | Box 105 \ 2 scan0194 | |
| Proposed alterations to cylinder studs for a larger 3.200' bore engine, including stress analysis. | 8th Apr 1929 | Box 105 \ 2 scan0195 | |
| Proposed alterations to cylinder studs for a larger 3.250' bore engine. | 18th Apr 1929 | Box 105 \ 2 scan0196 | |
| Reporting on the improved performance of a 20 HP chassis fitted with 3.200 diameter pistons. | 23th Apr 1929 | Box 105 \ 2 scan0197 | |
| Design of piston pin retaining circlips for 'China' chassis. | 4th May 1929 | Box 105 \ 2 scan0198 | |
| Confirmation of a wire message with instructions on fitting a turbulent head to a sixteen-G-four engine. | 29th May 1929 | Box 105 \ 2 scan0199 | |
| Inquiring about the production and testing status of various car piston models. | 17th Sep 1929 | Box 105 \ 2 scan0200 | |
| Progress update on 'CHINA' pistons and subsequent handwritten annotations. | 30th Sep 1929 | Box 105 \ 2 scan0201 | |
| Summary of car piston designs and their technical features. | 4th Oct 1929 | Box 105 \ 2 scan0202 | |
| Piston and ring specifications for 20 HP engines with 3.000' and 3.250' bores. | 16th Jul 1928 | Box 105 \ 2 scan0203 | |
| Confirming the resolution of an over-oiling issue with Goshawk Pistons. | 12th Oct 1929 | Box 105 \ 2 scan0204 | |
| Trial of 'Perfect Circle' type piston rings on the 'China' engine to address over-oiling issues. | 31th Dec 1929 | Box 105 \ 2 scan0205 | |
| Instructions regarding an experiment to replace a piston and fit a channelled scraper ring to a 20HP Chassis. | 16th Jan 1930 | Box 105 \ 2 scan0206 | |
| Requesting the modification of 20 HP piston drawings to use Perfect Circle type piston rings. | 21th Jan 1930 | Box 105 \ 2 scan0207 | |
| Requesting modifications to a 20 HP engine to achieve variable compression ratios for testing. | 18th Mar 1930 | Box 105 \ 2 scan0208 | |
| The successful testing and production of pistons in R.R.53 material for Phantom II and 20/25 HP models, requesting a standardisation sheet. | 2nd Sep 1930 | Box 105 \ 2 scan0209 | |
| Out-of-date practices on piston ring clearances for the 25 HP engine. | 27th Nov 1931 | Box 105 \ 2 scan0210 | |
| Standardisation of chassis parts, specifically pistons with a 5.75 to 1 compression ratio. | 4th Jan 1932 | Box 105 \ 2 scan0211 | |
| Introduction of a new part to a chassis, including costs and test dates. | 12th Mar 1932 | Box 105 \ 2 scan0212 | |
| Practice of pinning piston rings in aero and car engines. | 24th May 1932 | Box 105 \ 2 scan0213 | |
| Tests carried out on pistons to determine stiffness and sustained load. | 1st May 1933 | Box 105 \ 2 scan0214 | |
| Load tests performed on a 20/25 piston skirt to determine its failure point. | 21th Apr 1933 | Box 105 \ 2 scan0215 | |
| Series of graphs and tables detailing the results of piston skirt pressure tests. | 8th Aug 1932 | Box 105 \ 2 scan0216 | |
| Graph showing the results of deflection and permanent set tests on a 20/25 HP piston skirt under increasing load. | 21th Apr 1933 | Box 105 \ 2 scan0217 | |
| Limitations of spring skirt chassis pistons and proposing new test designs. | 11th May 1933 | Box 105 \ 2 scan0218 | |
| Requesting the manufacture of one set of pistons for Bentley & 20/25 models. | 26th Sep 1934 | Box 105 \ 2 scan0219 | |
| 25-29 HP split skirt piston for a large bore engine. | 10th Oct 1935 | Box 105 \ 2 scan0220 | |
| The discontinuation of semi-split type pistons and their associated grinding tackle. | 12th Oct 1934 | Box 105 \ 2 scan0221 | |
| Recommendation to standardize the longer skirt Bentley piston on the 20/25 HP model. | 13th Nov 1934 | Box 105 \ 2 scan0222 | |
| Use of Bentley long skirt type pistons on the 20/25 HP chassis. | 19th Nov 1934 | Box 105 \ 2 scan0223 | |
| The scrapping of 20/25 pistons and a suggestion to await results from a 10,000-mile test run. | 21th Nov 1934 | Box 105 \ 2 scan0224 | |
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