| Description | Date | Identifier | |
| Test report for Magneto number 105629 detailing its performance as received and after adjustments. | 11th Jan 1929 | Box 57 \ 2 Scan217 | |
| Test report for Magneto No. 105629 from North & Sons, Ltd. | 11th Jan 1929 | Box 57 \ 2 Scan218 | |
| Investigation into the R.O.1 Magneto's timing, leak test, and safety gap settings. | 11th Jan 1929 | Box 57 \ 2 Scan219 | |
| Test results for an experimental tunnel, focusing on cobalt magnets and extended pole shoes. | 17th Jan 1929 | Box 57 \ 2 Scan220 | |
| Letter to North & Sons Ltd. regarding test results and specifications for a magneto for the 20 HP car. | 17th Jan 1929 | Box 57 \ 2 Scan221 | |
| Letter to Messrs. North & Son regarding the unsatisfactory performance of R.O.1 magnetos. | 22th Feb 1929 | Box 57 \ 2 Scan222 | |
| Follow-up letter to Messrs. North & Sons Ltd. regarding a magneto for a 20 HP car. | 22th Feb 1929 | Box 57 \ 2 Scan223 | |
| Proposal to order improved and ventilated magnetos from Messrs. North & Sons for 40/50 HP and 20 HP chassis. | 18th Apr 1929 | Box 57 \ 2 Scan224 | |
| The delivery and development of Watford EW6 magnetos and related parts. | 14th May 1929 | Box 57 \ 2 Scan225 | |
| Receipt and dispatch of various chassis magnetos and low tension contact covers. | 29th May 1929 | Box 57 \ 2 Scan226 | |
| Sending a Watford RO1 Magneto to the makers for an overhaul. | 25th Mar 1930 | Box 57 \ 2 Scan227 | |
| The disposal of two Watford R.O.1 magnetos from the Electrical Experimental laboratory. | 20th May 1930 | Box 57 \ 2 Scan228 | |
| Arranging the transfer of two Watford R.O.1. Magnetos to the Electrical Experimental Laboratory. | 18th Jun 1930 | Box 57 \ 2 Scan229 | |
| Specification of performance for a magneto for the R.R. 20 HP car. | 29th Mar 1928 | Box 57 \ 2 Scan230 | |
| Page 2 of a document outlining a series of magneto testing procedures, including short circuit, open circuit, and utility tests. | 29th Mar 1928 | Box 57 \ 2 Scan231 | |
| List of specifications for magneto timing, operation, and physical forces. | 3rd Apr 1928 | Box 57 \ 2 Scan232 | |
| Technical enquiry to B.T.H. Co. Ltd. about a distributorless magneto for the 20 HP car. | 3rd Apr 1928 | Box 57 \ 2 Scan233 | |
| Page 2 of a letter enclosing a magneto performance specification for the 20 HP car. | 5th Apr 1928 | Box 57 \ 2 Scan234 | |
| Letter from The M-L Magneto Synd. Ltd. concerning the requirements for an improved magneto. | 5th Apr 1928 | Box 57 \ 2 Scan235 | |
| Performance issues with Watford magnetos and the subsequent search for a less costly replacement. | 11th Apr 1928 | Box 57 \ 2 Scan236 | |
| Suitability and prolonged testing of Bosch magnetos for 6-cylinder and 20 HP cars. | 12th Feb 1927 | Box 57 \ 2 Scan237 | |
| Prolonged testing and performance considerations of Bosch magnetos for a 20 HP chassis. | 13th Dec 1927 | Box 57 \ 2 Scan238 | |
| Modifying the 20 HP magneto's specified range by using short cobalt magnets. | 13th Dec 1927 | Box 57 \ 2 Scan239 | |
| Requirements for a Bosch magneto for a 20 HP engine. | 13th Dec 1927 | Box 57 \ 2 Scan240 | |
| Unsuccessful enquiry to Bosch for a magneto for the 20 HP chassis. | 11th Jan 1928 | Box 57 \ 2 Scan241 | |
| Letter from J.A. Stevens Ltd. concerning magneto specifications and test performance data. | 20th Jan 1928 | Box 57 \ 2 Scan242 | |
| Correspondence from J. A. Stevens Ltd. regarding the supply of a magneto for a 20 HP car. | 21th Dec 1927 | Box 57 \ 2 Scan243 | |
| Sourcing of a Bosch magneto for a 20 HP engine and rejecting an alternative. | 23th Jan 1928 | Box 57 \ 2 Scan244 | |
| Letter to a supplier declining interest in a Magneto as it is unsuitable for their purpose. | 31th Jan 1928 | Box 57 \ 2 Scan245 | |
| Letter from The British Thomson-Houston Company acknowledging a query about a distributor-less magneto for a 20-HP car. | 13th Apr 1928 | Box 57 \ 2 Scan246 | |
| Letter from The British Thomson-Houston Company with questions regarding the specification for a distributorless magneto for a 20 HP car. | 18th Apr 1928 | Box 57 \ 2 Scan247 | |
| Letter to The B.T.H. Co. Ltd. answering queries about a distributorless magneto for a 20 HP car. | 7th May 1928 | Box 57 \ 2 Scan248 | |
| Letter from British Thomson-Houston Co. Ltd. regarding a distributorless magneto for a 20 HP car. | 11th May 1928 | Box 57 \ 2 Scan249 | |
| Letter from The British Thomson-Houston Company Ltd. regarding a distributorless magneto and alternative ignition system for a 20 HP car. | 17th May 1928 | Box 57 \ 2 Scan250 | |
| Letter from The British Thomson-Houston Company detailing an ignition system with a Type CED-6 magneto and an automatic timing device. | 17th May 1928 | Box 57 \ 2 Scan251 | |
| Letter to The British Thomson-Houston Co. Ltd. rejecting their offered distributorless magneto for a 20 HP car. | 19th May 1928 | Box 57 \ 2 Scan252 | |
| Enquiry sent to The B.T.H. Co. Ltd. regarding a distributorless magneto for a 20 HP car. | 3rd Apr 1928 | Box 57 \ 2 Scan253 | |
| Letter enclosing a performance specification for a magneto suitable for the 20 HP R.R. car. | 5th Apr 1928 | Box 57 \ 2 Scan254 | |
| Letter from Joseph Lucas Limited discussing the supply of a distributor-less magneto for a 20-HP Car. | 5th Apr 1928 | Box 57 \ 2 Scan255 | |
| Letter from Joseph Lucas Ltd. regarding dual ignition systems on current models. | 5th Apr 1928 | Box 57 \ 2 Scan256 | |
| Letter to Messrs. Joseph Lucas Ltd. acknowledging their remarks and advising they will be considered. | 11th Apr 1928 | Box 57 \ 2 Scan257 | |
| Letter to Joseph Lucas Ltd. providing dimensions for a 20 HP magneto and details of the ignition system. | 20th Apr 1928 | Box 57 \ 2 Scan258 | |
| Cross-reference note for further information on 20/25 magneto ignition. | 31th Dec 1930 | Box 57 \ 2 Scan259 | |
| Tyre mileage in France and the necessity of replacing inner tubes. | 24th Aug 1925 | Box 58 \ 1 Scan001 | |
| Questioning the excessive expenditure on tyres and inner tubes for chassis 9-G-3. | 1st Aug 1925 | Box 58 \ 1 Scan002 | |
| Potential arrangement with the Dunlop Co. for supplying tyres for a 10,000-mile test on a 20 HP car in France. | 28th Aug 1925 | Box 58 \ 1 Scan003 | |
| Tyre and tube wear and replacement strategy during a 10,000 miles test in France for chassis 9-G-111. | 26th Aug 1925 | Box 58 \ 1 Scan004 | |
| Tyre performance and durability during a mileage test for chassis 9-G-111. | 26th Aug 1925 | Box 58 \ 1 Scan005 | |
| Tyre mileage, wear, and inner tube stock levels during tests. | 26th Aug 1925 | Box 58 \ 1 Scan006 | |
| Proposing the adoption of over-size medium and semi-balloon low-pressure tyres for comfort and performance. | 24th Mar 1926 | Box 58 \ 1 Scan007 | |
| Advantages and disadvantages of fitting low-pressure tyres to Phantom & Goshawk chassis. | 3rd Sep 1926 | Box 58 \ 1 Scan008 | |
| Customer's refusal to purchase a 20 HP car unless it is fitted with smaller, 6-inch tyres. | 18th Nov 1926 | Box 58 \ 1 Scan009 | |
| Fitment of 6-inch tyres on the 20 HP car, detailing objections and recommendations. | 19th Nov 1926 | Box 58 \ 1 Scan010 | |
| Results of testing 6' tyres on 20 HP cars to prevent wobbles. | 22th Nov 1926 | Box 58 \ 1 Scan011 | |
| Query regarding road tests performed with 6-inch tyres on the 20 HP model, asking where they were conducted and what car body was used. | 22th Nov 1926 | Box 58 \ 1 Scan012 | |
| Requesting the points against adopting 6 inch tyres as standard for the 20 HP model. | 23th Nov 1926 | Box 58 \ 1 Scan013 | |
| Explaining the reasoning for standardizing 5¼' section tyres on the 20 HP model. | 27th Nov 1926 | Box 58 \ 1 Scan014 | |
| Fitting of 6' balloon tyres on 20 HP cars and the resulting effect on steering. | 19th Mar 1928 | Box 58 \ 1 Scan015 | |
| Letter to The Dunlop Rubber Co. Ltd. inquiring about producing smaller 19' rims for 20 HP cars. | 12th Apr 1927 | Box 58 \ 1 Scan016 | |
| Letter from Dunlop discussing the disadvantages of smaller diameter rims and tyres for the 20 HP car. | 13th Apr 1927 | Box 58 \ 1 Scan017 | |
| Safety implications of using smaller wheels and tyres on a 20 HP vehicle. | 21th Apr 1927 | Box 58 \ 1 Scan018 | |
| Letter from Dunlop Rubber Co. Ltd. regarding the trend towards smaller diameter wheels and tyres. | 13th Apr 1927 | Box 58 \ 1 Scan019 | |
| Cover note returning a standardisation sheet with updated costs. | 21th Apr 1927 | Box 58 \ 1 Scan020 | |
| Standardisation of 6' balloon tyres for 20 HP cars and the purchase of a new set from Dunlop. | 27th Apr 1927 | Box 58 \ 1 Scan021 | |
| High-speed wobbles in relation to front axle types and steering geometry. | 27th Apr 1927 | Box 58 \ 1 Scan022 | |
| Letter to Dunlop Rubber Co. enquiring about the effective rolling circumference of a new tyre and rim combination for a 20 HP car. | 28th Apr 1927 | Box 58 \ 1 Scan023 | |
| Adoption of standard Dunlop tyres and tread patterns for the Phantom and 20 HP models. | 2nd May 1927 | Box 58 \ 1 Scan024 | |
| Wobbling speed and steering lightness issues on the 20 HP front axle. | 1st May 1927 | Box 58 \ 1 Scan025 | |
| Letter from Dunlop Rubber Co. Ltd. regarding tyre life, effective radius of different sizes, and supply of tyres and wheels. | 3rd May 1927 | Box 58 \ 1 Scan026 | |
| Page two of a letter from the Dunlop Rubber Co. Ltd. | 17th Jun 1927 | Box 58 \ 1 Scan027 | |
| Query from BJ regarding the effect of new 33 in. x 6 in. tyres on the gear ratio and performance of a 20 HP car. | 17th Jun 1927 | Box 58 \ 1 Scan028 | |
| The effect of standardising 33 x 5' tyres on the gear ratio and performance of the 20 HP car. | 17th Jun 1927 | Box 58 \ 1 Scan029 | |
| Standardisation sheet comparing the circumference and gear ratio effects of different tyres for the 20 HP model. | 21th Jun 1927 | Box 58 \ 1 Scan030 | |
| Standardisation of 33' x 6' tyres for the 20 HP chassis. | 21th Mar 1927 | Box 58 \ 1 Scan031 | |
| Returning a standardisation sheet with updated costs and explaining the reason for the increase. | 21th Apr 1927 | Box 58 \ 1 Scan032 | |
| Letter to Dunlop Rubber Co. regarding the supply of wheels for a 20 HP car. | 29th Jun 1927 | Box 58 \ 1 Scan033 | |
| Letter from Dunlop Rubber Co. Ltd. regarding the despatch of moulds, balloon tyres, and wheels. | 4th Jul 1927 | Box 58 \ 1 Scan034 | |
| Aesthetic benefits of fitting 19 inch wheels to the 20 HP model. | 9th Jul 1927 | Box 58 \ 1 Scan035 | |
| Re-standardization of 6' x 33' tyres for the 20 HP chassis. | 13th Jul 1927 | Box 58 \ 1 Scan036 | |
| Fitting 19' rims to a 20 HP model, noting the need for modified wings and spare wheel carriers. | 19th Jul 1927 | Box 58 \ 1 Scan037 | |
| Challenges of fitting 33 x 6' tyres on the 20 HP chassis due to spare wheel carrier issues. | 21th Jul 1927 | Box 58 \ 1 Scan038 | |
| Fitting non-standard 33 x 6' tyres on a 20 HP chassis and accommodating customer requests. | 22th Jul 1927 | Box 58 \ 1 Scan039 | |
| The use of experimental 6' Dunlop tyres on a 19' rim. | 1st Aug 1927 | Box 58 \ 1 Scan040 | |
| Potential improvements for the 20 HP car, focusing on steering, chassis, tyre sizing, and bodywork aesthetics. | 1st Sep 1927 | Box 58 \ 1 Scan041 | |
| Proposed narrower wire wheels for use on the 20 HP chassis, including alterations to the hubs. | 8th Oct 1927 | Box 58 \ 1 Scan042 | |
| Request for running radius information for high pressure and balloon tyres on two car models. | 23th Nov 1927 | Box 58 \ 1 Scan043 | |
| Implications of fitting low-pressure tyres to the 20 HP chassis. | 15th May 1928 | Box 58 \ 1 Scan044 | |
| 20 HP axle ratios and the effect of different tyre sizes. | 19th May 1928 | Box 58 \ 1 Scan045 | |
| Wheel arch clearance complaints on the 20 HP model, suggesting new clearances and requesting confirmation tests. | 1st Jul 1928 | Box 58 \ 1 Scan046 | |
| Transition to low-pressure tyres and smaller wheel rims for the 20 HP model. | 2nd Jul 1928 | Box 58 \ 1 Scan047 | |
| Tyre pressures and road spring stiffness for the Phantom and 20 HP models to improve riding qualities. | 20th Jul 1928 | Box 58 \ 1 Scan048 | |
| Modifications to the vehicle's spring and shock damper systems for improved ride comfort and high-speed stability. | 23th Jul 1928 | Box 58 \ 1 Scan049 | |
| Requesting a report on improvements to vehicle riding qualities through various means like tyres, springs, and dampers. | 23th Jul 1928 | Box 58 \ 1 Scan050 | |
| Telex message to Derby requesting an urgent supply of wheels and tyres. | 23th Jul 1928 | Box 58 \ 1 Scan051 | |
| Trial of 20 inch wheels for the 20 HP chassis and the related impact on the 10/47 axle production. | 25th Jul 1928 | Box 58 \ 1 Scan052 | |
| The delivery of 20' X 6' wheels and tyres and the resulting cancellation of the rear axle production. | 7th Aug 1928 | Box 58 \ 1 Scan053 | |
| Listing the weights of three different 20 HP wheel and tyre combinations. | 19th Aug 1928 | Box 58 \ 1 Scan054 | |
| The investigation of high-speed wheel wobble and its causes, primarily low tyre pressure. | 21th Aug 1928 | Box 58 \ 1 Scan055 | |
| The impact of rim size on high-speed wobbles and optimal tyre pressures. | 27th Aug 1928 | Box 58 \ 1 Scan056 | |
| Steering tests on car 12-G-4, investigating wobble and shimmy issues with different wheels and tyres. | 27th Aug 1928 | Box 58 \ 1 Scan057 | |
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