| Description | Date | Identifier | |
| Forwarding blueprints for a 'central change' modification and discussing related parts. | 8th Dec 1938 | Box 104 \ 3 scan0239 | |
| Cost and parts required to fit a central change to a Wraith chassis. | 21th Nov 1938 | Box 104 \ 3 scan0240 | |
| Photographs of a centre change speed gearbox modification for a Bentley. | 25th Oct 1938 | Box 104 \ 3 scan0241 | |
| Complaint of a knock from the change speed lever in top gear on a Bentley, caused by the selector lever fouling the speedometer drive shaft. | 8th Jul 1938 | Box 104 \ 3 scan0242 | |
| Decision to not proceed with cold Fescol depositing for Bentley gearbox shafts due to the high cost. | 15th Nov 1937 | Box 104 \ 3 scan0243 | |
| Tables of box ratios and overall ratios for a 'D' style gearbox, noted as 'Bentley old'. | 16th Oct 1937 | Box 104 \ 3 scan0244 | |
| The examination and repair of Bentley Gearbox 3rd Motion Shafts. | 16th Oct 1937 | Box 104 \ 3 scan0245 | |
| Excessive wear on two Bentley gearbox third motion shafts and a proposal for repair. | 13th Oct 1937 | Box 104 \ 3 scan0246 | |
| Failure of a Bentley gearbox bearing due to an overly tight fit in the casing. | 15th Jun 1937 | Box 104 \ 3 scan0247 | |
| Bentley third gear complaint and the subsequent repair. | 13th Feb 1937 | Box 104 \ 3 scan0248 | |
| Two faults found on a Bentley, an oil leak from the gearbox and a damaged rear axle pinion. | 13th Nov 1936 | Box 104 \ 3 scan0249 | |
| Preliminary drawings and alternative designs for a 'Japan 3' gearbox, focusing on the reverse pinion mechanism. | 23th Jan 1931 | Box 104 \ 4 scan0001 | |
| Hand-drawn schematic of a gearbox mechanism with annotations. | 25th Jan 1931 | Box 104 \ 4 scan0002 | |
| Technical memorandum discussing the design of an eccentrically engaged reverse gear pinion with rounded teeth. | 25th Jan 1931 | Box 104 \ 4 scan0003 | |
| Page discussing alternative gearbox designs with a corresponding gear layout sketch. | 25th Jan 1931 | Box 104 \ 4 scan0004 | |
| Sketch of a swinging reverse mechanism with a reverse slider. | 25th Jan 1931 | Box 104 \ 4 scan0005 | |
| Final recommendation sketch for a shaft and pinion assembly within a box or housing. | 31th Jan 1931 | Box 104 \ 4 scan0006 | |
| Revisions to the Japan 3 gearbox, specifically the inclusion of Maybach jaws. | 31th Jan 1931 | Box 104 \ 4 scan0007 | |
| Providing suggestions for the improvement of the Japan 3. Gearbox design. | 3rd Feb 1931 | Box 104 \ 4 scan0008 | |
| Unfinished proposal for a Japan 3 gearbox actuating mechanism, comparing it to other designs. | 4th Feb 1931 | Box 104 \ 4 scan0009 | |
| Secret memo regarding gearbox arrangement schemes for the 'Japan 3' project. | 2nd Jul 1931 | Box 104 \ 4 scan0010 | |
| Secret memorandum discussing two alternative proposals for modifying the Japan 3 gearbox, specifically concerning the mounting of the reverse wheel. | 2nd Dec 1931 | Box 104 \ 4 scan0011 | |
| Secret memo providing a technical review and feedback on the 'Japan Gearbox' design, including its gears, serrations, and sliders. | 25th Feb 1931 | Box 104 \ 4 scan0012 | |
| Sending schemes and particulars for the Japan 3 gearbox casing. | 2nd Mar 1931 | Box 104 \ 4 scan0013 | |
| Required alterations to easy-change silent gearboxes, specifically concerning the neutral position. | 2nd Mar 1931 | Box 104 \ 4 scan0014 | |
| Gearbox design improvements, comparing various models like Maybach and epicyclic, and future plans. | 9th Mar 1931 | Box 104 \ 4 scan0015 | |
| Design choices for the Japan 3 gearbox, comparing new N. schemes with existing 25HP and P.2 models for cost-effectiveness. | 10th Mar 1931 | Box 104 \ 4 scan0016 | |
| Scheme to incorporate a Warner Synchronising mechanism into the Japan III gearbox. | 14th Mar 1931 | Box 104 \ 4 scan0017 | |
| Issue of rattling side shaft gears and proposing a programme of tests to find a solution. | 16th Mar 1931 | Box 104 \ 4 scan0018 | |
| The investigation and resolution of gearbox oscillation on the 25 HP model. | 11th May 1931 | Box 104 \ 4 scan0019 | |
| Design of a future 25HP synchro-mesh gearbox, comparing it with Buick's design. | 28th May 1931 | Box 104 \ 4 scan0020 | |
| Technical memo investigating the cause and potential solutions for a gear rattle issue on the 25 HP model. | 29th May 1931 | Box 104 \ 4 scan0021 | |
| Experimenting with a flexible drive between the flywheel and gearbox, noting gear rattle issues. | 29th May 1931 | Box 104 \ 4 scan0022 | |
| Investigating the cause of gear rattles on a 25 HP engine, linking it to heavier cast iron pistons. | 9th Jun 1931 | Box 104 \ 4 scan0023 | |
| Questioning the efficacy of the oiling scheme for the 20/25HP Gear Box. | 10th Jun 1931 | Box 104 \ 4 scan0024 | |
| Technical update on gearbox designs for the 25HP and 45HP car models, detailing the synchro-mesh and a new friction-operated unit. | 12th Jun 1931 | Box 104 \ 4 scan0025 | |
| New gearbox with synchro-mesh actuation, its mechanism, and modifications required to fit it to an existing 20/25 model. | 15th Jun 1931 | Box 104 \ 4 scan0026 | |
| Slight alteration to the synchro-mesh gearbox and existing servo gear. | 20th Jun 1931 | Box 104 \ 4 scan0027 | |
| Accompanying schematics for the J.A. Gearbox, specifically for the servo shaft, speedometer drive, and a modification to the change gear pendulum lever. | 23th Jun 1931 | Box 104 \ 4 scan0028 | |
| The J.4 Synchro Mesh Gearbox, requesting figures on the gear lever load and movement of a Buick for comparison. | 1st Jun 1931 | Box 104 \ 4 scan0029 | |
| Modification to a gearbox, incorporating a delay action cam surface on the synchromesh mechanism inspired by a Buick design. | 2nd Jul 1931 | Box 104 \ 4 scan0030 | |
| Sending additional schemes (3290, 3301, 3302) and information for the J.4. Gearbox. | 1st Jul 1931 | Box 104 \ 4 scan0031 | |
| Flywheel vibration and gear rattle for a 25 HP engine, testing a stiffened flywheel and fabric joint. | 8th Jul 1931 | Box 104 \ 4 scan0032 | |
| Design drawing for a Hardy Coupling for a clutch. | 10th Jul 1931 | Box 104 \ 4 scan0033 | |
| Modifications to the Japan 4 model's gearbox clutch pit and pedal. | 10th Jul 1931 | Box 104 \ 4 scan0034 | |
| Assembly method and design discrepancies of the J. 4. Gearbox. | 13th Jul 1931 | Box 104 \ 4 scan0035 | |
| The filling plug, level stick, and cover for the J.4. gearbox. | 4th Jul 1931 | Box 104 \ 4 scan0036 | |
| Standardising adjustable pedals and modifying the clutch pedal for the 25 HP synchro-mesh gearbox. | 15th Jul 1931 | Box 104 \ 4 scan0037 | |
| Modifications to the gearbox, clutch operating shaft, and brake compensator shaft. | 16th Jul 1931 | Box 104 \ 4 scan0038 | |
| Despatched schematic and modifications to the J.4. gearbox, universal joint, and pendulum lever. | 20th Jul 1931 | Box 104 \ 4 scan0039 | |
| Modifications to the J.4 gearbox servo for the 20/25 model. | 21th Jul 1931 | Box 104 \ 4 scan0040 | |
| Modifications to the universal joint flange piece and a sheet metal baffle for the gearbox. | 23th Jul 1931 | Box 104 \ 4 scan0041 | |
| Modifications to the J.4. gearbox, change gear lever, and brake pedal mechanism. | 24th Jul 1931 | Box 104 \ 4 scan0042 | |
| Modifications to a 20/25 gearbox with synchronous mesh. | 26th Aug 1931 | Box 104 \ 4 scan0043 | |
| Issue of sticking cones in a synchromesh gearbox, with references to Buick's instructions and cone angles. | 19th Sep 1931 | Box 104 \ 4 scan0044 | |
| Gearbox component alignment and friction reduction, suggesting a trial of a bronze stirrup. | 22th Sep 1931 | Box 104 \ 4 scan0045 | |
| Performance of a 25 HP synchromesh gearbox after road testing and comparison. | 22th Sep 1931 | Box 104 \ 4 scan0046 | |
| On the successful development of a new synchro-mesh gearbox with a silent 3rd gear. | 26th Sep 1931 | Box 104 \ 4 scan0047 | |
| Dynamometer test report on a 25 HP synchro-mesh gearbox. | 3rd Oct 1931 | Box 104 \ 4 scan0048 | |
| Modifications requested by the Experimental Department for the J. 3 and 4 gearbox. | 6th Oct 1931 | Box 104 \ 4 scan0049 | |
| Testing the reverse gear and the number of keys required for the J. 3 & 4 gearbox. | 1st Oct 1931 | Box 104 \ 4 scan0050 | |
| Adoption of a synchro mesh gearbox versus a new design based on two epicyclic gear units. | 28th Oct 1931 | Box 104 \ 4 scan0051 | |
| Different ideas for a gearbox scheme, including epicyclic units and synchronised brakes. | 20th Oct 1931 | Box 104 \ 4 scan0052 | |
| Development and implementation of easy change and synchro-mesh gearboxes for various car models. | 20th Oct 1931 | Box 104 \ 4 scan0053 | |
| Note expressing concern over gearbox development and the immediate needs of the Phantom II model. | 20th Oct 1931 | Box 104 \ 4 scan0054 | |
| Development and urgency of an easy-change gearbox with synchro-mesh and silent third gear. | 21th Oct 1931 | Box 104 \ 4 scan0055 | |
| Ongoing difficulties with noisy gears in 25 HP synchro-mesh gearboxes, recommending the immediate purchase of gear grinding equipment. | 23th Oct 1931 | Box 104 \ 4 scan0056 | |
| Fitting and testing two different synchro mesh gearboxes. | 22th Oct 1931 | Box 104 \ 4 scan0057 | |
| Test report on the reverse gear of a 25 HP synchromesh gearbox. | 24th Oct 1931 | Box 104 \ 4 scan0058 | |
| Correcting a fault where two gears were meshing simultaneously in the 25 HP synchromesh gearbox. | 26th Oct 1931 | Box 104 \ 4 scan0059 | |
| Design detail for the 25HP Synchro Mesh Gearbox. | 26th Oct 1931 | Box 104 \ 4 scan0060 | |
| Technical memo on the 'China' easy change gearbox, discussing reverse gear engagement, seizing bushes, and gear creep. | 27th Oct 1931 | Box 104 \ 4 scan0061 | |
| Two proposals to improve lubrication of the reverse shaft for the 25 HP Synchro Mesh Gearbox. | 3rd Nov 1931 | Box 104 \ 4 scan0062 | |
| Bearing tests and shaft hardening for a Synchro Mesh Gearbox. | 1st Nov 1931 | Box 104 \ 4 scan0063 | |
| Modifications to a cast iron gearbox. | 10th Nov 1931 | Box 104 \ 4 scan0064 | |
| Technical memorandum on overcoming reverse gear issues in the 25 HP synchromesh gearbox. | 11th Nov 1931 | Box 104 \ 4 scan0065 | |
| Drawing showing modifications to a synchromesh gearbox reverse shaft to increase stiffness. | 11th Nov 1931 | Box 104 \ 4 scan0066 | |
| Requesting confirmation to modify the 25 HP reverse gear on the easy change gearbox before production. | 13th Nov 1931 | Box 104 \ 4 scan0067 | |
| Requesting modifications to reverse shafts for synchro-mesh gearboxes. | 17th Nov 1931 | Box 104 \ 4 scan0068 | |
| Stiffening of the reverse shaft for the 25 HP synchro mesh gearbox. | 17th Nov 1931 | Box 104 \ 4 scan0069 | |
| Criticisms and potential solutions for the Synchro Mesh Gearbox bearings. | 18th Nov 1931 | Box 104 \ 4 scan0070 | |
| Load calculations and adequacy of the spigot bearing in the 25HP Synchro Mesh Gearbox. | 1st Nov 1931 | Box 104 \ 4 scan0071 | |
| Experiment to adapt a reverse gear for the 20/25 HP synchro mesh gearbox. | 24th Nov 1931 | Box 104 \ 4 scan0072 | |
| Sending a striking mechanism scheme for the 25HP Synchro Mesh Gearbox. | 26th Nov 1931 | Box 104 \ 4 scan0073 | |
| Cross-sectional diagram of a mechanical assembly featuring a rubber block. | 1st Dec 1931 | Box 104 \ 4 scan0074 | |
| Permanent lubrication scheme for the 25 HP gearbox. | 1st Dec 1931 | Box 104 \ 4 scan0075 | |
| Updated method for lubricating the reverse shaft on all synchro mesh gearboxes. | 1st Dec 1931 | Box 104 \ 4 scan0076 | |
| Modifications to the side levers for the 25HP Synchromesh Gearbox. | 5th Dec 1931 | Box 104 \ 4 scan0077 | |
| Analysis of gearbox noise and other issues in a 25 HP Synchromesh system. | 15th Dec 1931 | Box 104 \ 4 scan0078 | |
| Gearbox performance, detailing issues with gear noise, engagement, and different gear specifications. | 15th Dec 1931 | Box 104 \ 4 scan0079 | |
| The road test of the 20-G-4 Special Touring Saloon, noting issues with its gearbox and comparing performance to a Trials car. | 17th Dec 1931 | Box 104 \ 4 scan0080 | |
| Experiments to improve the silence of the 25 HP Synchro Mesh Gearbox helical trains. | 19th Dec 1931 | Box 104 \ 4 scan0081 | |
| Issue of top gear working out on a 25HP Synchro Mesh Gearbox. | 19th Dec 1931 | Box 104 \ 4 scan0082 | |
| Experiments to prevent the top gear disengaging on a 25HP synchromesh gearbox. | 21th Dec 1931 | Box 104 \ 4 scan0083 | |
| Experiments to improve idling noise and test the reverse gear on a 25 HP synchromesh gearbox. | 23th Dec 1931 | Box 104 \ 4 scan0084 | |
| Experiment on drawing N.sch. 3396 and a required modification to the 25 HP S.M. gearbox. | 31th Dec 1931 | Box 104 \ 4 scan0085 | |
| The successful testing of a 25 HP synchromesh reverse gear. | 2nd Jan 1932 | Box 104 \ 4 scan0086 | |
| Technical memorandum discussing methods to achieve quieter gearboxes, including the use of single helical sideshafts and different bearing types. | 4th Jan 1932 | Box 104 \ 4 scan0087 | |
| Design, noise, and potential improvements for a 25HP synchromesh helical gearbox. | 9th Jan 1932 | Box 104 \ 4 scan0088 | |
| Progress report on the 25 HP Synchro-Mesh gearbox, detailing improvements in noise reduction and plans for standardization. | 8th Jan 1932 | Box 104 \ 4 scan0089 | |
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