| Description | Date | Identifier | |
| Standardisation of Firths road springs to replace Woodheads for the 40/50 and 20 HP models. | 13th Apr 1923 | Box 52 \ 2 Scan083 | |
| Standardisation of chassis parts, specifically road springs made by Firths to replace Woodheads. | 26th Apr 1923 | Box 52 \ 2 Scan084 | |
| The cost figures for road springs made by Firths instead of Woodheads. | 8th Jan 1923 | Box 52 \ 2 Scan085 | |
| Supply of road springs for the 40/50 chassis, comparing suppliers Firths and Woodheads. | 27th Apr 1923 | Box 52 \ 2 Scan086 | |
| The signing of a standardisation sheet for road springs made by Firth's. | 27th Apr 1923 | Box 52 \ 2 Scan087 | |
| Standardisation of road springs made by Firths in place of Woodheads for 40/50 and Goshawk chassis. | 29th Dec 1922 | Box 52 \ 2 Scan088 | |
| Standardisation sheet X.4419, concerning the cost of replacing Woodheads' road springs with Firths'. | 6th Jan 1923 | Box 52 \ 2 Scan089 | |
| Letter from Thos. Firth & Sons, Ltd. discussing the performance and friction testing of experimental 40/50 HP springs. | 25th Aug 1923 | Box 52 \ 2 Scan090 | |
| Letter from a supplier discussing the friction of front and rear springs and requesting guidance for modifications. | 25th Aug 1923 | Box 52 \ 2 Scan091 | |
| Supply and comparative testing of road springs from suppliers Firths and Woodheads for the 40/50 chassis. | 5th Sep 1923 | Box 52 \ 2 Scan092 | |
| The 'high nip' characteristic of laminated road springs supplied by Thos. Firth & Sons Ltd for a 40/50 HP Chassis. | 7th Dec 1923 | Box 52 \ 2 Scan093 | |
| Standardising the supplier for 40/50 chassis springs to Messrs. Firths. | 7th Apr 1924 | Box 52 \ 2 Scan094 | |
| Load diagram for a Firth's front spring for 40/50 HP models, complete with clips. | 9th Apr 1924 | Box 52 \ 2 Scan095 | |
| Standardisation report on chassis parts, specifically Firths springs. | 9th Apr 1924 | Box 52 \ 2 Scan096 | |
| Bump test results and standardisation for Firths road springs. | 9th Apr 1924 | Box 52 \ 2 Scan097 | |
| Standardisation of front springs, brackets and shackles to suit front wheel brakes. | 12th May 1924 | Box 52 \ 2 Scan098 | |
| Internal friction and damping characteristics of road springs from Firths versus Woodheads. | 18th Jul 1924 | Box 52 \ 2 Scan099 | |
| Failed spring on an experimental car and arrangements for future testing. | 19th Sep 1924 | Box 52 \ 2 Scan100 | |
| Secret memorandum detailing failures of springs made by Firths and specifying new designs for experimental testing. | 11th Sep 1924 | Box 52 \ 2 Scan101 | |
| Standardisation sheet cancelling a previous version regarding 25% stiffer front springs, brackets, and shackles. | 16th Sep 1924 | Box 52 \ 2 Scan102 | |
| Road tests in France for Firths 12% springs and brakes, with a summary on induction pipe breakages. | 26th Sep 1924 | Box 52 \ 2 Scan103 | |
| Summary report of a 10,000-mile test on vehicle model 9-PK, detailing performance and component wear. | 26th Sep 1924 | Box 52 \ 2 Scan104 | |
| Issues and performance of exhaust, silencers, steering, and engine components. | 26th Aug 1924 | Box 52 \ 2 Scan105 | |
| Multiple component failures and issues during vehicle testing. | 20th Sep 1924 | Box 52 \ 2 Scan106 | |
| Six required modifications to a vehicle. | 26th Sep 1924 | Box 52 \ 2 Scan107 | |
| Arranging a meeting with Firths to discuss tests on front springs for the 40/50 HP Chassis. | 28th Oct 1924 | Box 52 \ 2 Scan108 | |
| Bumping tests for Firths road springs, comparing their performance and design against Woodheads springs. | 29th Oct 1924 | Box 52 \ 2 Scan109 | |
| Bump test report on Firth front leaf springs, detailing fracture analysis. | 29th Oct 1924 | Box 52 \ 2 Scan110 | |
| Continued bump test report for the latest pattern Firth springs, showing fracture details. | 29th Oct 1924 | Box 52 \ 2 Scan111 | |
| Bumping tests for Firths 12.5% thin leaf front springs. | 21th Nov 1924 | Box 52 \ 2 Scan112 | |
| Letter discussing arrangements for a car trial in France with Firths' front springs. | 21th Nov 1924 | Box 52 \ 2 Scan113 | |
| Logistics of testing a car fitted with Firths springs in France, including shift patterns for long-distance runs. | 22th Nov 1924 | Box 52 \ 2 Scan114 | |
| Completion of a 10,000-mile test in Chateauroux and arranging a visit for CWB. | 26th Nov 1924 | Box 52 \ 2 Scan115 | |
| The successful completion of a 10,000-mile test of Firths front springs in France. | 11th Dec 1924 | Box 52 \ 2 Scan116 | |
| Comparison of initial camber and leaf thickness for satisfactory and unsatisfactory 1150 lbs. Firths springs. | 13th Dec 1924 | Box 52 \ 2 Scan117 | |
| Standardisation of firmer front springs for 4-wheel brake cars. | 10th Dec 1924 | Box 52 \ 2 Scan118 | |
| Price negotiations and a standardisation sheet for Firths front springs on 4-wheel brake cars. | 16th Dec 1924 | Box 52 \ 2 Scan119 | |
| Standardisation sheet No. 9410 regarding Firth's Front Springs for 4-wheel Brake Cars. | 9th Jan 1925 | Box 52 \ 2 Scan120 | |
| Standardisation of firm front springs for 4-wheel brake cars. | 15th Dec 1924 | Box 52 \ 2 Scan121 | |
| Standardization and pricing of Firths Front Springs for 4-Wheel Brake Cars. | 16th Dec 1924 | Box 52 \ 2 Scan122 | |
| Ordering and testing 45-inch front springs from Firths for the 40/50 HP chassis. | 17th Feb 1925 | Box 52 \ 2 Scan123 | |
| Confirming an order for a pair of front springs with specified modifications regarding camber and deflection. | 4th Apr 1926 | Box 52 \ 2 Scan124 | |
| Letter from a supplier proposing modifications to an order for front springs for an experimental chassis. | 13th Apr 1926 | Box 52 \ 2 Scan125 | |
| Springing setup for the Phantom model, including shock dampers and spring ratings. | 4th Apr 1926 | Box 52 \ 2 Scan126 | |
| Page two of a memorandum discussing axle control, road clearance, and comparing front axle designs. | 18th Apr 1926 | Box 52 \ 2 Scan127 | |
| Necessary improvements for the Phantom's springing and shock damping systems. | 18th Apr 1926 | Box 52 \ 2 Scan128 | |
| Continued note identifying three potential causes for an issue: tyres, shock dampers, and springs. | 1st May 1926 | Box 52 \ 2 Scan129 | |
| Suspension tests on a Phantom car with weaker front springs. | 1st May 1926 | Box 52 \ 2 Scan130 | |
| Tests conducted on hydraulic shock dampers to assess their durability. | 26th May 1926 | Box 52 \ 2 Scan131 | |
| Continued experimental report on shock absorber performance and the effects of oil viscosity. | 26th May 1926 | Box 52 \ 2 Scan132 | |
| Shock damper oil performance, fluid damping, and low-speed riding comfort tests. | 26th May 1926 | Box 52 \ 2 Scan133 | |
| Shock damper arrangement with a steel sleeve for the rear of a vehicle. | 26th May 1926 | Box 52 \ 2 Scan134 | |
| Graph comparing the viscosity of Prices Motorine C and Lovejoy Oil against temperature. | 20th May 1928 | Box 52 \ 2 Scan135 | |
| Blueprint illustrating the relative positions of the rear spring, safety bolt, and roller on a 40/50 HP chassis under various load conditions. | 21th Sep 1922 | Box 52 \ 2 Scan136 | |
| Diagrams showing the relative positions of the rear spring, safety bolt, and roller on a 40/50 HP Chassis. | 21th May 1914 | Box 52 \ 2 Scan137 | |
| Request to obtain two modified springs from Messrs. Firths with a reduced unloaded camber. | 19th Jun 1926 | Box 52 \ 2 Scan138 | |
| Torsion tests conducted on front springs. | 10th Aug 1926 | Box 52 \ 2 Scan139 | |
| Blueprint diagram showing the shape of a spring contour under torsion. | 10th Aug 1926 | Box 52 \ 2 Scan140 | |
| Graph plotting the angle of rotation against torque from torsion tests on various front springs. | 31th Mar 1927 | Box 52 \ 2 Scan141 | |
| Use of Firths spring clips, comparing solid vs. rivetted types and recommending the latter. | 31th Mar 1927 | Box 52 \ 2 Scan142 | |
| Letter concerning a fracture in a 20 HP spring plate caused by deep stamping, requesting changes to marking procedures for suppliers. | 4th May 1927 | Box 52 \ 2 Scan143 | |
| Examination report on a broken spring (F.5358), identifying a deeply sunk maker's mark 'J' as the primary cause of the fracture. | 1st May 1927 | Box 52 \ 2 Scan144 | |
| Hand-drawn diagram of a top leaf with dimensions. | 7th Apr 1927 | Box 52 \ 2 Scan145 | |
| Drilling jig for Firths, inquiring about parts made under a specific order number. | 7th Apr 1927 | Box 52 \ 2 Scan146 | |
| Fractured 20 HP road spring and new stamping requirements for the supplier, Messrs Firths. | 6th May 1927 | Box 52 \ 2 Scan147 | |
| Letter to Thos. Firth & Sons, Ltd. correcting spring specifications and discussing rear spring materials. | 3rd Jun 1927 | Box 52 \ 2 Scan148 | |
| Comparison and bumper test of American front road springs versus standard Firths springs for Phantom cars. | 13th Sep 1927 | Box 52 \ 2 Scan149 | |
| Test report on the failure and performance of Firths Silco Manganese and American leaf springs. | 30th Sep 1927 | Box 52 \ 2 Scan150 | |
| Request for the return of notes on spring manufacture and for comments before proposing a manufacturing plan to Firths. | 30th Sep 1927 | Box 52 \ 2 Scan151 | |
| Design and manufacture of road springs, referencing Mr. Olley's notes and the company Firth's. | 3rd Oct 1927 | Box 52 \ 2 Scan152 | |
| Test report on the lifespan of different front road springs and the adoption of a new clip. | 10th Oct 1927 | Box 52 \ 2 Scan153 | |
| Letter discussing modifications to road springs and providing test results comparing different spring materials. | 5th Oct 1927 | Box 52 \ 2 Scan154 | |
| Letter to a supplier regarding the decision to adopt Silico-Manganese and a new spring design based on American findings. | 5th Oct 1927 | Box 52 \ 2 Scan155 | |
| Internal request for two 900 lbs. 25% stiffer springs to drawing F.53048 for experimental purposes. | 10th Oct 1927 | Box 52 \ 2 Scan156 | |
| Request to produce brackets for fitting hydraulics and Hartford shock dampers to vehicle 44-PK. | 10th Oct 1927 | Box 52 \ 2 Scan157 | |
| Clarifying the specifications for the rear springs on a 20-HP chassis. | 12th Oct 1927 | Box 52 \ 2 Scan158 | |
| Required alteration to the Free Camber of springs for specific Phantom chassis. | 12th Oct 1927 | Box 52 \ 2 Scan159 | |
| Spring specifications for sports cars, model EAC.14. | 19th Oct 1927 | Box 52 \ 2 Scan160 | |
| Letter to a supplier regarding an order for front springs, discussing blueprints and design specifications. | 25th Oct 1927 | Box 52 \ 2 Scan161 | |
| Letter discussing spring production methods, specifications, and performance testing. | 16th Nov 1927 | Box 52 \ 2 Scan162 | |
| Providing instructions for fitting new road springs to the 10-EX experimental car. | 16th Nov 1927 | Box 52 \ 2 Scan163 | |
| Challenges in replicating American spring designs with supplier Messrs. Firths. | 14th Dec 1927 | Box 52 \ 2 Scan164 | |
| Ordering new, lighter, stiffer road springs for the 40/50 HP chassis from Messrs. Firths & Sons. | 8th Feb 1928 | Box 52 \ 2 Scan165 | |
| Bumper test of various front road springs, detailing test results and failures. | 21th Apr 1928 | Box 52 \ 2 Scan166 | |
| The comparative testing of road springs, noting the poor performance of Firths springs compared to American ones. | 2nd May 1928 | Box 52 \ 2 Scan167 | |
| Effectiveness and testing of lighter and stiffer rear springs on experimental cars. | 11th May 1928 | Box 52 \ 2 Scan168 | |
| Broken front spring plates, comparing special springs with American manufactured springs to determine differences in heat treatment and forging. | 11th May 1928 | Box 52 \ 2 Scan169 | |
| Visit to Messrs. Firths to discuss the manufacturing processes and superiority of American-style road springs. | 12th Jun 1928 | Box 52 \ 2 Scan170 | |
| Specifications and order details for leaf springs, referencing a new American type. | 6th May 1927 | Box 52 \ 2 Scan171 | |
| Design and testing of a new riveted spring clip. | 6th May 1927 | Box 52 \ 2 Scan172 | |
| Letter from a supplier confirming the manufacturing specifications and processes for experimental springs. | 7th Jun 1928 | Box 52 \ 2 Scan173 | |
| Commenting on various aspects of road spring design and manufacturing. | 1st Aug 1928 | Box 52 \ 2 Scan174 | |
| Continued memorandum comparing the quality and cost of Firth springs against American and Lemoine springs. | 29th Sep 1928 | Box 52 \ 2 Scan175 | |
| Further tests into road spring friction, detailing the issue of 'digging-in' on serviced springs compared to new ones. | 29th Sep 1928 | Box 52 \ 2 Scan176 | |
| Improving spring design by comparing Firths and Woodheads springs to address issues like 'digging-in' and internal friction. | 22th Sep 1928 | Box 52 \ 2 Scan177 | |
| Technical memo discussing issues of friction, seizure, and poor bedding in rear leaf springs, comparing manufacturer quality. | 22th Sep 1928 | Box 52 \ 2 Scan178 | |
| Tests comparing the internal friction of front and rear road springs, including the effects of service, cleaning, and cadmium plating. | 29th Sep 1928 | Box 52 \ 2 Scan179 | |
| Series of three graphs showing test results for a Rear Road Spring's deflection versus applied load and hysteresis. | 10th Sep 1928 | Box 52 \ 2 Scan180 | |
| Series of three load vs. deflection tests on a lubricated rear road spring after a 5000-mile run. | 10th Sep 1928 | Box 52 \ 2 Scan181 | |
| Series of three test graphs showing deflection versus applied load for a lubricated standard front road spring. | 13th Sep 1928 | Box 52 \ 2 Scan182 | |
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