| Description | Date | Identifier | |
| Letter from Hermetic Rubber Co Ltd concerning a Pro-Forma invoice for 8 Hermetic Couplings. | 23th Apr 1931 | Box 5 \ 5 05-page38 | |
| Urgent internal request to order a specific fabric ring from Messrs. Hardy Spicer Ltd. for experiments. | 15th Jun 1931 | Box 5 \ 5 05-page39 | |
| Follow-up letter from Hermetic Rubber Co. Ltd. requesting test results for couplings sent previously. | 26th Aug 1931 | Box 5 \ 5 05-page40 | |
| Letter to The Hermetic Rubber Co. Ltd. explaining a delay in testing four pairs of couplings due to more important work. | 27th Aug 1931 | Box 5 \ 5 05-page41 | |
| Summary of test results for fabric and hermetic couplings. | 30th Sep 1931 | Box 5 \ 5 05-page42 | |
| Letter to The Hermetic Rubber Co. Ltd. regarding the performance testing of eight couplings. | 5th Oct 1931 | Box 5 \ 5 05-page43 | |
| Test results for various Hermetic fabric couplings on a 130% flywheel. | 5th Oct 1931 | Box 5 \ 5 05-page44 | |
| Arranging the dispatch of eight tested couplings to The Hermetic Rubber Co. Ltd. | 6th Oct 1931 | Box 5 \ 5 05-page45 | |
| Letter from the Hermetic Rubber Co Ltd concerning the results of tests on flexible fabric couplings. | 17th Oct 1931 | Box 5 \ 5 05-page46 | |
| Continuation sheet of a letter from Hermetic Rubber Company Ltd. soliciting an order for couplings. | 24th Oct 1931 | Box 5 \ 5 05-page47 | |
| Letter to The Hermetic Rubber Co. Ltd. regarding the performance of tested couplings. | 24th Oct 1931 | Box 5 \ 5 05-page48 | |
| Letter from Hermetic Rubber Co Ltd discussing the production and cost of flexible fabric couplings. | 1st Dec 1931 | Box 5 \ 5 05-page49 | |
| Letter to The Hermetic Rubber Co. Ltd. regarding the submission and testing of new couplings. | 3rd Dec 1931 | Box 5 \ 5 05-page50 | |
| The prevalent failure of the Phantom II Hardy Fabric Coupling and a suggestion for a design modification to ease replacement. | 20th Sep 1932 | Box 5 \ 5 05-page51 | |
| Fabric coupling sent for inspection after 11,000 miles on car 19-2X. | 21th Sep 1932 | Box 5 \ 5 05-page52 | |
| Complaints regarding fabric couplings on the P.2 chassis, proposing a new, larger coupling for replacement. | 8th Feb 1933 | Box 5 \ 5 05-page53 | |
| Standardisation of an engine coupling to resolve complaints of fabric coupling disintegration. | 8th Feb 1933 | Box 5 \ 5 05-page54 | |
| Details for fitting a new part to a 'P' Series chassis, including test date and costs. | 2nd Sep 1933 | Box 5 \ 5 05-page55 | |
| The moment of inertia for the Goshawk flywheel and clutch. | 19th Dec 1924 | Box 5 \ 6 06-page001 | |
| Authorisation sheet for a modification to the clutch coupling rod for model 'India'. | 24th Apr 1925 | Box 5 \ 6 06-page002 | |
| 'India' authorisation sheet to modify the coupling rod and clutch operating lever. | 27th Apr 1925 | Box 5 \ 6 06-page003 | |
| Modifications to the 20 HP slipper flywheel to prevent spring bolt breakage, referencing drawing LeC.2126. | 24th Aug 1925 | Box 5 \ 6 06-page004 | |
| 20 HP slipper flywheel failure in France, detailing the probable cause and proposed solution. | 25th Aug 1925 | Box 5 \ 6 06-page005 | |
| Drawing for a Slipper Flywheel, clarifying that the dowels do not need to be hollow. | 1st Aug 1925 | Box 5 \ 6 06-page006 | |
| Standardisation proposal for slipper wheels fitted with dowel pegs to improve reliability. | 10th Dec 1925 | Box 5 \ 6 06-page007 | |
| Clutch failure issue on the 20-HP chassis where the clutch sticks when hot. | 1st Jan 1926 | Box 5 \ 6 06-page008 | |
| Modification to the 20HP undershield to prevent it fouling the flywheel and brake levers. | 10th Jun 1928 | Box 5 \ 6 06-page009 | |
| Recurring issues with the Slipper Drive on 40/50HP and 20-HP models, particularly after a chassis has stood idle. | 17th Nov 1926 | Box 5 \ 6 06-page010 | |
| Recurring issues with the slipper drive and friction damper on 40/50 and 20 HP models, particularly after standing for a period. | 22th Nov 1926 | Box 5 \ 6 06-page011 | |
| Inconsistent working and known weakness of the slipper wheel drive on the 20 HP and Phantom models. | 29th Nov 1926 | Box 5 \ 6 06-page012 | |
| Request for particulars on lubricating the 20 HP chassis clutch for inclusion in a leaflet for owners. | 4th May 1927 | Box 5 \ 6 06-page013 | |
| Outlining suggestions for reliability modifications to the 20 HP Starter and improved Bijur system. | 12th Jul 1927 | Box 5 \ 6 06-page014 | |
| Proposal to modify the 20 HP slipper flywheel to match the Phantom design and an instruction for testing new friction materials. | 29th Sep 1927 | Box 5 \ 6 06-page015 | |
| Materials for Slipper Flywheel friction discs, comparing fibre with woven cotton and cork for the 20 HP and Phantom models. | 4th Oct 1927 | Box 5 \ 6 06-page016 | |
| Potential materials, specifically plain cotton duck and cork, for use in slipper flywheel friction discs. | 4th Oct 1927 | Box 5 \ 6 06-page017 | |
| Proposing a modification to the 20 HP clutch flywheel to facilitate lubrication. | 11th Oct 1927 | Box 5 \ 6 06-page018 | |
| Short internal memo agreeing to a suggestion regarding 20 HP clutches. | 13th Oct 1927 | Box 5 \ 6 06-page019 | |
| Bench test results for slipper wheels with cotton duck friction rings and placing an order for parts. | 7th Nov 1927 | Box 5 \ 6 06-page020 | |
| Investigation into a multiple clutch design for the LdC. 2442, detailing tests with different materials and spring configurations. | 1st Nov 1927 | Box 5 \ 6 06-page021 | |
| The performance of a lubricating scheme and the results of using a specific brand of oil. | 23th Nov 1927 | Box 5 \ 6 06-page022 | |
| Exhaustive tests of two schemes for a 20 HP starter motor, detailing failures related to cork washers and buffer springs. | 23th Nov 1927 | Box 5 \ 6 06-page023 | |
| Report page detailing findings on a clutch slipping issue, including test rig reproduction and clutch spring specifications. | 23th Nov 1927 | Box 5 \ 6 06-page024 | |
| Recommendation to standardise the 20 HP starter motor to the multiple clutch type. | 23th Nov 1927 | Box 5 \ 6 06-page025 | |
| Achieving satisfactory results for a 20 HP Starter Motor with a multiple clutch. | 23th Nov 1927 | Box 5 \ 6 06-page026 | |
| Clutch material tests, comparing cork and Ferobestos discs under different oily and wear conditions. | 23th Nov 1927 | Box 5 \ 6 06-page027 | |
| Test results and modifications for clutch and starter motor components. | 28th Nov 1927 | Box 5 \ 6 06-page028 | |
| Weight reduction on a 20 HP chassis by modifying the flywheel, clutch, and engine head. | 28th Nov 1927 | Box 5 \ 6 06-page029 | |
| The disappointing ride quality, slipper drive, and engine vibration of a GAK-52 Barkerlite Limousine. | 12th Dec 1927 | Box 5 \ 6 06-page030 | |
| Blueprint for a proposed lightened flywheel. | 23th Dec 1927 | Box 5 \ 6 06-page031 | |
| Recommendation to delete a lubricating scheme for the 20 HP multiple clutch due to oil congealing in cold weather. | 21th Mar 1928 | Box 5 \ 6 06-page032 | |
| Tests carried out on a lightened 20 HP clutch, detailing weight reduction and performance. | 14th Apr 1928 | Box 5 \ 6 06-page033 | |
| Blueprint for a proposed lightened flywheel design. | 10th Dec 1927 | Box 5 \ 6 06-page034 | |
| Over-run vibration issues with a lighter 20 HP flywheel and potential solutions based on a Chrysler model. | 3rd May 1928 | Box 5 \ 6 06-page035 | |
| Modification to the India 3 clutch thrust for improved oil retention. | 1st May 1928 | Box 5 \ 6 06-page036 | |
| Valve oil supply and clutch shudder issues on Phantom and 20 HP cars. | 19th Oct 1928 | Box 5 \ 6 06-page037 | |
| Clutch 'jagger' issue and special valve guide clearances on a 20 HP car. | 22th Oct 1928 | Box 5 \ 6 06-page038 | |
| The limitations of a one-stage relief valve and the proposal for a 3-stage valve for the 20 HP model. | 20th Nov 1928 | Box 5 \ 6 06-page039 | |
| Arranging to test a freewheel with a cancelling clutch on a 20 HP and an epicyclic 3rd gear on EAC.7. | 20th Nov 1928 | Box 5 \ 6 06-page040 | |
| Technical diagram and notes on the 25 HP clutch pedal movement and lever adjustments. | 2nd Dec 1928 | Box 5 \ 6 06-page041 | |
| Blueprint for a Clutch Intermediate Lever. | 27th Apr 1925 | Box 5 \ 6 06-page042 | |
| Engineering drawing for a clutch lever. | 29th May 1930 | Box 5 \ 6 06-page043 | |
| Blueprint for a bush component with drilling and chamfer specifications. | 20th Dec 1928 | Box 5 \ 6 06-page044 | |
| Blueprint of a clutch operating lever. | 22th Sep 1924 | Box 5 \ 6 06-page045 | |
| Blueprint for a Hardy coupling for a clutch. | 28th Nov 1930 | Box 5 \ 6 06-page046 | |
| Damaged flywheels on the 20 HP model and the colour of the oil pressure gauge finger. | 24th May 1929 | Box 5 \ 6 06-page047 | |
| Note on the 20 HP chassis regarding not reducing the weight of the flywheel and clutch. | 15th May 1929 | Box 5 \ 6 06-page048 | |
| Letter discussing the design and placement of a slipper flywheel, comparing wet versus dry friction faces. | 19th Jun 1929 | Box 5 \ 6 06-page049 | |
| Page 2 of a letter regarding the time required for the examination of a slipper component. | 22th Jun 1929 | Box 5 \ 6 06-page050 | |
| Design and experimental trial of a new 20HP auto friction damper flywheel. | 22th Jun 1929 | Box 5 \ 6 06-page051 | |
| Cover note forwarding a letter about a RRAI Slipper Flywheel for comments. | 23th Aug 1929 | Box 5 \ 6 06-page052 | |
| Suggestion to connect the 20 HP car's clutch trunnion to the Bijur pump for lubrication to prevent squeaks and rattles. | 17th Aug 1929 | Box 5 \ 6 06-page053 | |
| Unsuccessful modification to the clutch trunnion lubrication on a 20 HP model. | 20th Aug 1929 | Box 5 \ 6 06-page054 | |
| Future policy for the 20 HP transmission, focusing on the freewheel and a new clutch design. | 24th Aug 1929 | Box 5 \ 6 06-page055 | |
| 'Japan' improvements to the 20 HP clutch, including a new damping plate and washer adjustment. | 1st Oct 1929 | Box 5 \ 6 06-page056 | |
| Modifications to the 20/25 HP clutch, including the use of Ferodo and changes to the damper plate and starter ring attachment. | 3rd Nov 1929 | Box 5 \ 6 06-page057 | |
| Proposed modifications for the 'Japan' clutch, focusing on automatic lubrication for the spigot bearing. | 6th Nov 1929 | Box 5 \ 6 06-page058 | |
| Clutch plate shuddering and potential lubrication issues in 20-HP cars. | 30th Nov 1929 | Box 5 \ 6 06-page059 | |
| Modification to 20 HP clutches to resolve an issue with non-case-hardened pins. | 23th Dec 1929 | Box 5 \ 6 06-page060 | |
| Change in specification for 20 HP clutch friction material due to rapid wear. | 31th Dec 1929 | Box 5 \ 6 06-page061 | |
| Letter to Ferodo Ltd. confirming the fitting of rivetted fabric rings to clutch plates. | 31th Dec 1929 | Box 5 \ 6 06-page062 | |
| Clutch slipping issues on high compression 25 HP cars, attributing the problem to using springs from the 20 HP engine and outlining the torque increase that necessitates stronger springs. | 6th Feb 1930 | Box 5 \ 6 06-page063 | |
| Suggesting an increase in clutch spring load and pedal stroke for the 20 HP 10,000-mile test. | 6th Feb 1930 | Box 5 \ 6 06-page064 | |
| Request to issue a standardisation sheet for the increased load on the friction clutch for the 20/25 HP chassis. | 8th Apr 1930 | Box 5 \ 6 06-page065 | |
| The availability and implementation of increased clutch springs for the 20/25 HP chassis. | 24th Apr 1930 | Box 5 \ 6 06-page066 | |
| Modification to prevent clutch slipping on high compression 20/25 HP cars. | 30th Apr 1930 | Box 5 \ 6 06-page067 | |
| Standardisation of chassis parts by fitting 20% stiffer springs in the clutch to prevent slipping, including modifications to the clutch leverage. | 16th Apr 1930 | Box 5 \ 6 06-page068 | |
| Alterations to friction clutches for 45 HP and 25 HP cars. | 10th Jul 1930 | Box 5 \ 6 06-page069 | |
| Experiments investigating flywheel vibrations on a 25 HP engine. | 2nd Oct 1930 | Box 5 \ 6 06-page070 | |
| Flywheel vibration experiments, detailing measurements of runout parallel and at right angles to the axis. | 2nd Oct 1930 | Box 5 \ 6 06-page071 | |
| Engine experiments investigating crankshaft alignment, flywheel inertia, vibrations, and noise. | 2nd Oct 1930 | Box 5 \ 6 06-page072 | |
| Analysis of engine vibrations related to modifications of the clutch and flywheel assembly. | 11th Oct 1930 | Box 5 \ 6 06-page073 | |
| Cover note regarding an enclosed print for a 25 HP Clutch. | 11th Oct 1930 | Box 5 \ 6 06-page074 | |
| Internal instruction to stop a 25HP flywheel and clutch job and to modify the design of the bonnet louvres. | 11th Oct 1930 | Box 5 \ 6 06-page075 | |
| Cover note regarding sending a document about a 25HP clutch. | 10th Oct 1930 | Box 5 \ 6 06-page076 | |
| The conclusion on the cause and potential reduction of flywheel vibration for the 25HP model. | 20th Oct 1930 | Box 5 \ 6 06-page077 | |
| Experiments conducted to investigate flywheel vibrations on a 25 HP engine. | 2nd Oct 1930 | Box 5 \ 6 06-page078 | |
| Investigation into flywheel and crankshaft vibrations, detailing experiments to isolate their source. | 22th Jan 1941 | Box 5 \ 6 06-page079 | |
| Experiments to diagnose the source of flywheel vibrations. | 31th Mar 1915 | Box 5 \ 6 06-page080 | |
| Instruction to fit a standard flywheel and clutch to part 12-G4, while retaining the plain parallel shaft. | 31th Oct 1930 | Box 5 \ 6 06-page081 | |
| Test to ascertain the amount of deflection in the flywheel and crankshaft for a 25 HP engine. | 31th Oct 1930 | Box 5 \ 6 06-page082 | |
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