| Description | Date | Identifier | |
| Proposed linkage modifications for mixture control, necessary for fitting shutters to a 20 HP vertical radiator. | 6th Jan 1927 | Box 105 \ 1 scan0007 | |
| Standardisation of a thermometer with an electrical contact to prevent radiator shutters being left closed. | 4th Jan 1927 | Box 105 \ 1 scan0008 | |
| Modifications to the 20 HP vertical radiator shutters and steering column controls. | 28th Jan 1927 | Box 105 \ 1 scan0009 | |
| Modifications to the mixture control, throttle, and ignition levers for a 20 HP vehicle with vertical shutters. | 14th Feb 1927 | Box 105 \ 1 scan0010 | |
| Design schemes for fitting vertical radiator shutters to a 20 HP car. | 16th Feb 1927 | Box 105 \ 1 scan0011 | |
| Modification to the 20 HP control column tubes to prevent friction and binding. | 5th Mar 1927 | Box 105 \ 1 scan0012 | |
| Proposed changes to the 20 HP radiator and cast dash. | 4th Apr 1927 | Box 105 \ 1 scan0013 | |
| The standardization and implementation timeline for 20 HP vertical shutters. | 21th Jun 1927 | Box 105 \ 1 scan0014 | |
| Standardization of vertical shutters for the 20 HP chassis, considering design changes and tooling costs. | 23th Jun 1927 | Box 105 \ 1 scan0015 | |
| Introduction of 20 HP vertical shutters, associated costs, and design issues with the control lever. | 22th Jun 1927 | Box 105 \ 1 scan0016 | |
| Standardisation sheet X.5250 for a 20HP radiator and asking about a car examination. | 30th Aug 1927 | Box 105 \ 1 scan0017 | |
| The trial and inspection of a 20 HP radiator with integral shutters after a 10,000-mile test. | 31th Aug 1927 | Box 105 \ 1 scan0018 | |
| Standardisation document for a radiator with integral vertical shutters. | 23th May 1927 | Box 105 \ 1 scan0019 | |
| Form detailing costs and implementation for fitting a new part to an 'M' series chassis. | 1st Apr 1928 | Box 105 \ 1 scan0020 | |
| Explaining the delay in fitting vertical shutters to 20 HP cars. | 8th May 1928 | Box 105 \ 1 scan0021 | |
| Standardisation of an improved appearance for the 20 HP model's bonnet, radiator, and dashboard. | 19th May 1928 | Box 105 \ 1 scan0022 | |
| Querying which sales official requested a delay in introducing vertical shutters for the 20 HP model. | 21th May 1928 | Box 105 \ 1 scan0023 | |
| Dimensional modifications for the radiator and dash of the 20 HP chassis. | 21th May 1928 | Box 105 \ 1 scan0024 | |
| Cover note for correspondence regarding vertical shutters on the 20 HP model. | 21th May 1928 | Box 105 \ 1 scan0025 | |
| Modifications to the radiator, bonnet, and dash for the 20 HP Improved Bonnet model. | 23th May 1928 | Box 105 \ 1 scan0026 | |
| Postponed introduction of vertical shutters for the 20 HP model from 'M' series to 'N' series. | 23th May 1928 | Box 105 \ 1 scan0027 | |
| The standardisation of the radiator, bonnet, and dash for the 20 HP Chassis 'N' series. | 6th Jun 1923 | Box 105 \ 1 scan0028 | |
| Design and casting quality of radiator mascots and fillers for the Phantom and 20 HP models. | 27th Jul 1928 | Box 105 \ 1 scan0029 | |
| Standardisation proposal for a higher radiator and dashboard to improve appearance. | 7th Jun 1928 | Box 105 \ 1 scan0030 | |
| List of details for fitting a new part to a chassis, including costs and test dates. | 27th Nov 1928 | Box 105 \ 1 scan0031 | |
| Depot sheet on the procedure for cleaning cylinder blocks to remedy car overheating due to oxide deposits. | 9th Apr 1929 | Box 105 \ 1 scan0032 | |
| Proposal for increasing the 20 HP model's capacity and addressing associated overheating issues. | 23th Apr 1929 | Box 105 \ 1 scan0033 | |
| Request to order special radiator tubes with expanded ends for the 20 HP chassis. | 24th Apr 1929 | Box 105 \ 1 scan0034 | |
| Radiator modifications for the India 4 model using smaller diameter tubes. | 13th May 1929 | Box 105 \ 1 scan0035 | |
| Unbearable faults, including radiator jelly and heavy pistons, in a 20 HP Close Coupled Saloon. | 23th May 1929 | Box 105 \ 1 scan0036 | |
| Improvements to a 'Japan' car, including vibration reduction and new piston suggestions. | 21th Jun 1929 | Box 105 \ 1 scan0037 | |
| Request for a 6/7 mm tube radiator for testing purposes on a 20 HP model. | 21th Jun 1929 | Box 105 \ 1 scan0038 | |
| The fitting of an auto-friction damper and spring drive on a 20 HP chassis. | 27th Aug 1929 | Box 105 \ 1 scan0039 | |
| Requesting a new design for thermostatically operated radiator shutters for the 20 HP chassis. | 10th May 1929 | Box 105 \ 1 scan0040 | |
| Use of Staybright and chromium finishes for car parts, particularly the radiator. | 14th Oct 1929 | Box 105 \ 1 scan0041 | |
| On design improvements for the 25 HP model, focusing on the radiator and transmission line. | 26th Oct 1929 | Box 105 \ 1 scan0042 | |
| Testing a frame with great vertical stiffness to improve radiator steadiness and steering on Phantom II and 25 HP models. | 26th Oct 1929 | Box 105 \ 1 scan0043 | |
| Modified bonnet, radiator, and dash design for the 25 HP chassis. | 4th Nov 1929 | Box 105 \ 1 scan0044 | |
| Modification of dropping a 20 HP radiator 2 inches into the frame. | 8th Nov 1929 | Box 105 \ 1 scan0045 | |
| New design for a test radiator with cleanable water passages. | 25th Nov 1929 | Box 105 \ 1 scan0046 | |
| Query about how to overcome noise from 20-HP radiator shutters when fully open at high engine revs. | 28th Feb 1929 | Box 105 \ 1 scan0047 | |
| Tests on anti-freezing mixtures comparing a 33% Glycerine solution with pure water in a 20 HP radiator. | 12th Dec 1929 | Box 105 \ 1 scan0048 | |
| The force required to operate radiator shutters, issues with the current geometry, and proposed design changes. | 24th Dec 1929 | Box 105 \ 1 scan0049 | |
| The successful 90-hour durability test of a Staybright radiator. | 6th Jan 1930 | Box 105 \ 1 scan0050 | |
| Reporting repeated failure of radiator support springs on the 20 HP chassis during bump tests. | 6th Jan 1930 | Box 105 \ 1 scan0051 | |
| Results of tests on water pump cavitation in radiators. | 10th Jan 1930 | Box 105 \ 1 scan0052 | |
| Analysis of radiator water flow, pump cavitation, and hydraulic restriction in a cooling system. | 10th Jan 1930 | Box 105 \ 1 scan0053 | |
| Analysis of radiator and cooling system performance, including comparisons between Phantom I and Phantom II models. | 10th Jan 1930 | Box 105 \ 1 scan0054 | |
| Radiator and cooling system performance, discussing issues with circulation, back pressure, and top tank capacity. | 10th Jan 1930 | Box 105 \ 1 scan0055 | |
| Summary of radiator design and performance results, including comparisons with Chrysler and Phantom II specifications. | 10th Jan 1930 | Box 105 \ 1 scan0056 | |
| Comparison table of various radiator specifications, including dimensions, hydraulic resistance, and weight. | 18th Feb 1930 | Box 105 \ 1 scan0057 | |
| 1½ m.m. gap for 20 HP radiator tubes and requesting two test sets, especially for the 'Japan' engine. | 18th Feb 1930 | Box 105 \ 1 scan0058 | |
| Modifications to the 20 HP dashboard and radiator. | 27th Mar 1930 | Box 105 \ 1 scan0059 | |
| Improved design of the dashboard, bonnet, and radiator for the 20/25 HP chassis. | 27th Feb 1930 | Box 105 \ 1 scan0060 | |
| Frame and radiator 'jellying' issues observed on the 20 HP model. | 20th Mar 1930 | Box 105 \ 1 scan0061 | |
| Confirming the lower radiator cap is on the new 20 HP car being built. | 21th Mar 1930 | Box 105 \ 1 scan0062 | |
| Solutions for radiator vibration ('jellying') and improvements in body mounting. | 5th May 1930 | Box 105 \ 1 scan0063 | |
| Three methods of insulation for the power unit, car body, and passengers. | 5th May 1930 | Box 105 \ 1 scan0064 | |
| Use of a double spring for a single point radiator suspension. | 7th May 1930 | Box 105 \ 1 scan0065 | |
| Reasons for the stagnation of sales of the 20/25 car model, including body size, performance, and price. | 13th May 1930 | Box 105 \ 1 scan0066 | |
| Required improvements for the 20/25 model, including radiator connection, shutters, and lubrication. | 13th May 1930 | Box 105 \ 1 scan0067 | |
| Reverting the activation temperature for the radiator thermometer's red warning light. | 16th Jun 1930 | Box 105 \ 1 scan0068 | |
| Standardisation of the Lower Radiator Cap for the 20 HP model. | 30th Apr 1930 | Box 105 \ 1 scan0069 | |
| Modifications for increased engine cooling on 25 HP and 45 HP models. | 4th Jul 1930 | Box 105 \ 1 scan0070 | |
| Modifications to thermostatically operated shutters on the 25 HP model. | 5th Jul 1930 | Box 105 \ 1 scan0071 | |
| Extract regarding the simplification of the Automatic Radiator Control for interchangeability between 25HP and 45HP models. | 8th Jul 1930 | Box 105 \ 1 scan0072 | |
| Cooling tests for 25 HP and 40/50 HP models, including the Phantom II. | 1st Jul 1930 | Box 105 \ 1 scan0073 | |
| Next test for a square tube radiator and plans for comparison tests against other cars. | 10th Jul 1930 | Box 105 \ 1 scan0074 | |
| Recommended procedure for dealing with complaints of overheating cooling water. | 1st Aug 1930 | Box 105 \ 1 scan0075 | |
| Continued guide on troubleshooting and maintaining the car's cooling system, focusing on the radiator, water pump, and fan. | 1st Mar 1930 | Box 105 \ 1 scan0076 | |
| Continued page discussing factors affecting engine water temperature, including bonnet ventilation, mixture strength, and cut-out usage. | 1st Aug 1930 | Box 105 \ 1 scan0077 | |
| Guidance on engine overheating symptoms, the function of the red warning light, and acceptable operating temperatures. | 1st Aug 1930 | Box 105 \ 1 scan0078 | |
| New radiator for car 18-GIV and discussing a tank unit for a petrol gauge. | 13th Aug 1930 | Box 105 \ 1 scan0079 | |
| Instruction to condemn the taper sided radiator for car 18-GIV due to appearance and issue a replacement. | 1st Aug 1930 | Box 105 \ 1 scan0080 | |
| Revised bonnet and dash modifications for the 20/25 HP model. | 8th Aug 1930 | Box 105 \ 1 scan0081 | |
| Modifications to the 20/25HP radiator shutters and bottom bearings. | 1st Sep 1930 | Box 105 \ 1 scan0082 | |
| Design requirements for thermostatically controlled radiator shutters and radiator construction. | 16th Sep 1930 | Box 105 \ 1 scan0083 | |
| Modifications to a 25 HP car, including radiator, lubrication, clutch, and propeller shaft. | 25th Sep 1930 | Box 105 \ 1 scan0084 | |
| Summary of decisions from a conference regarding urgently required and desirable items for 20/25 HP and 25 HP models. | 25th Sep 1930 | Box 105 \ 1 scan0085 | |
| Progress and improvements for the P.2 & 25HP model's cooling system and radiator. | 29th Sep 1930 | Box 105 \ 1 scan0086 | |
| Halt in production for a new square tube radiator and the testing of horizontal louvres. | 30th Sep 1930 | Box 105 \ 1 scan0087 | |
| Comparing square tube radiators to standard ones and discussing improvements to overflow valves and bonnet vents. | 14th Oct 1930 | Box 105 \ 1 scan0088 | |
| Improving radiator efficiency by indenting tubes to resolve customer overheating complaints. | 15th Oct 1930 | Box 105 \ 1 scan0089 | |
| Table of test results from Brooklands, comparing water temperatures for different radiator and louvre configurations at various speeds. | 18th Oct 1930 | Box 105 \ 1 scan0090 | |
| Radiator modifications and testing to address overheating issues on the Phantom II model. | 18th Oct 1930 | Box 105 \ 1 scan0091 | |
| Results of radiator and bonnet tests. | 20th Oct 1930 | Box 105 \ 1 scan0092 | |
| Use of 7 m.m. square radiator tubes compared to round tubes, including performance and cost. | 20th Oct 1930 | Box 105 \ 1 scan0093 | |
| Comparison table of radiator performance, showing critical overheating temperatures under different conditions. | 21th Oct 1930 | Box 105 \ 1 scan0094 | |
| Early implementation of a modification, indenting a tube, to resolve an overheating issue. | 21th Oct 1930 | Box 105 \ 1 scan0095 | |
| Request to build up a matrix in an 18-G4 radiator with intentionally dented tubes. | 23th Oct 1930 | Box 105 \ 1 scan0096 | |
| Recommending the immediate adoption of indented radiator tubes to address overheating issues. | 25th Oct 1930 | Box 105 \ 1 scan0097 | |
| Design criticisms and potential improvements for car bonnets and radiators. | 25th Oct 1930 | Box 105 \ 1 scan0098 | |
| Design suggestions for a detachable filler cap, horizontal louvres, and bonnet modifications. | 25th Oct 1930 | Box 105 \ 1 scan0099 | |
| Modification to radiator tubes to prevent overheating. | 27th Oct 1930 | Box 105 \ 1 scan0100 | |
| Design and cost of radiators and bonnets, comparing square and round tubes, and the style of louvres. | 27th Oct 1930 | Box 105 \ 1 scan0101 | |
| Design and performance of radiators and bonnets, comparing square and round tubes. | 30th Oct 1930 | Box 105 \ 1 scan0102 | |
| Radiator tests comparing different tube designs at Brooklands. | 6th Nov 1930 | Box 105 \ 1 scan0103 | |
| Use of wind tunnels for obtaining results and continuing investigations into turbulence. | 6th Nov 1930 | Box 105 \ 1 scan0104 | |
| Petrol consumption for a 20 HP car with thermostatically operated shutters. | 16th Dec 1930 | Box 105 \ 1 scan0105 | |
| The proposed modification to a radiator's bottom tank and shutter bearing plate for model 18-G-4. | 17th Dec 1930 | Box 105 \ 1 scan0106 | |
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