Chapter 8 Manual Transmission Construction and Operation 161 Copyright by Goodheart-Willcox Co., Inc. Mainshaft gears Main drive gear U-block Countershaft gear Adapter plate Reverse idler shaft Needle bearings 3rd speed blocking ring Clutch teeth for synchronizer Front bearing Input shaft Main drive gear Front bearing retainer Front bearing retainer gasket Front bearing Clutch shaft Clutch shaft needle bearings (15) Fill plug Reverse lever pivot bolt C-clip Reverse lever Reverse lever fork Transmission case Reverse lever pivot bolt Backup lamp switch Front bearing locating snap ring Front bearing retaining snap ring Front seal Figure 8-5. Exploded view shows the position of the input shaft and its related parts in relation to the transmission case. (Chrysler) Figure 8-4. Study the typical input shaft and its integral drive gear. Most are one-piece, hardened-steel castings. The front bearing is pressed on the input shaft. It can be removed if defective. Needle bearings are placed inside the bore at the end of the input shaft. The output shaft rides on needle bearings. (General Motors) Figure 8-3. Note the typical manual transmission gears. The reverse idler gear is not shown. (General Motors) gear assembly, which includes the gear, countershaft, and related parts, is shown in Figure 8-6. The largest gear on the countershaft gear is always the countershaft driven gear, which is the forward most gear. This gear is always in mesh with the main drive gear, as shown in Figure 8-7. The entire countershaft gear turns whenever the main drive gear turns. In addition to the driven gear, there is usually one gear on the gear cluster for each available reduction and overdrive ratio, plus a gear for reverse. There is no gear for direct drive (1:1 gear ratio) the countershaft gear is not used in direct drive. The cluster gear of a 5-speed transmission with overdrive, for instance, has six gears. In addition to the countershaft driven gear, it has first, second, third, over- drive, and reverse gears.