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Lotus Service Notes
Section FJ The clutch housing bolts to the back of the engine block and provides a dry chamber for the clutch mecha- nism, and roller bearings for the gearbox input and output shafts. The taper roller bearing for the differential RH output shaft is also accommodated. The gearbox main case provides ball bearings for the two shafts, and houses gears 1 to 4 including the reverse gear pinion on its idler shaft. The end cover or casing houses 5th and 6th gears. On the 5-speed transmission, the 5th speed gears are overhung on the ends of the input and output shafts, but on the 6-speed, the alloy end cover contains ball bearings to support the ends of the two extended shafts, both of which are thus supported by a total of three bearings. The housing for the final drive and differential is shared between the clutch housing and main case, with taper roller bearings supporting the differential case. 6-Speed Gear Clusters The input shaft includes integral drive pinions for 1st, 2nd and reverse gears, and carries the clutch driven plate, the 3rd/4th synchroniser and the 5th/6th synchroniser, with the latter housed in the end cover. The output shaft features an integral final drive gear, spline fixed 3rd/4th/5th/6th driven pinions, and carries the 1st/2nd gear synchroniser. All forward gears are constant mesh with inertia lock type synchromesh, with reverse gear attained by sliding a spur idler pinion into engagement with both a gear on the periphery of the 1st/2nd syn- chroniser and a drive gear integral with the input shaft. All gears, with the exception of reverse, use a helical tooth form for quiet running. Sychromesh: For each gear ratio, one of the shafts has a fixed gear, and meshes with a freely revolving gear on the other shaft. To engage a particular gear, the freely revolving gear must be connected to its shaft via the sychro hub. As an example, third gear operates as follows: Under normal road driving, when the clutch is depressed as a precurser to a gear change, the input shaft with the third gear synchroniser are de-coupled from the engine, but will be turning under decaying inertia, clutch windage and oil drag, from the drive pinions (which in this condition are being driven by the output shaft). Third gear pinion on the input shaft is driven by the fixed gear on the output shaft, which itself is driven by the roadwheels. Before the outer sleeve of the synchroniser may be slid on its axial splines to engage with the spline ring integral with third speed input shaft gear, the speeds of the two parts must be commonised. To aid this process, a sychroniser/baulk ring is fitted between the two parts, being rotationally driven by the synchroniser, and equipped with a female conical surface to mate with a 6th gear 5th gear 4th gear 3rd gear
2nd gear 1st gear Reverse Input shaft
f130 Output shaft Double cone 2nd Final drive gear gear synchromesh |