Main Shaft, Disassemble and Reassemble (F 18 / F 18+) Main Shaft, Dismantle If the gears are damaged, always also replace the gear cluster.
 Disassemble Press ball bearing, retaining ring with long legs, spacing washer, thrust needle bearing and 1st gear from main shaft with suitable drift - supporting 1st gear on recesses of press support plates. Remove needle bearing for 1st gear from main shaft.
 Remove, Disconnect Remove retaining ring and thrust washer in front of 1st/2nd gear synchromesh body from main shaft. Press synchromesh body with 2nd gear from main shaft - supporting 2nd gear on recesses of press support plates. Remove needle bearing for 2nd gear from main shaft. | 
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Remove, Disconnect Remove retaining ring for thrust washer halves. Remove thrust washer halves from main shaft. 3rd gear from needle bearing. Bend open needle bearing and remove. Remove retaining ring and thrust washer in front of 3rd/4th gear synchromesh body from main shaft. Press off synchromesh body and 4th gear from main shaft - supporting 4th gear on recesses of press support plates. Bend up needle bearing (2) and roller bearing (1) for 4th gear and remove. | 
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 Important! Main shaft and drive gear (driving) are a single part and cannot be dismantled. Always replace drive gears in pairs. Note continuous identification groove at tooth tip - see "survey" in "Technical Data".
 Clean Clean all parts.
 Inspect Check removed parts for damage and wear. | 
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Main Shaft, Assemble Immerse all parts in transmission fluid before installation. Lubricate all bearing bore holes and seating surfaces with transmission fluid before installation. All transmissions have 3-cone synchronisation for 1st and 2nd gears:
2 Inner synchroniser rings
4 Outer synchroniser rings
8 Synchroniser hub (carrier)
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 Assemble Always replace drive gears in pairs (driving and driven). Note continuous identification groove at tooth tip - see "Survey" in "Technical Data". Assemble 1st/2nd gear and 3rd/4th gear synchromesh bodies. Insert synchroniser springs in sliders with hooks facing different directions. Do not interlace springs. Insert slider in flat middle tooth of synchroniser sleeve.
 Install, Connect Slide slotted roller bearing onto main shaft, must engage audibly when closing. Slide double-row, slotted needle bearing onto main shaft. Place synchroniser ring on cone of the 4th speed gear. | 
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Important! Wear asbestos gloves.
Install, Connect Heat synchromesh body assembly for 3rd /4th gear to approx. 100 ° C. Assemble 3rd/ 4th gear synchromesh body assembly and 4th gear with synchroniser ring - ensure that lugs on synchroniser ring align with grooves in synchromesh body. Press assembly onto main shaft with KM-514 (1) and KM-577 - 2nd mechanic. Slide thrust washer onto main shaft. New retaining ring onto main shaft. Slotted needle bearing onto main shaft. Place synchroniser ring on synchromesh body. Slide 3rd gear onto needle bearing. Join both thrust washer halves with retaining ring. Needle bearing on main shaft. Slide 2nd gear onto needle bearing. Place inner synchroniser ring on gear cone. Place intermediate ring on inner race with lugs in grooves of gear. Place outer synchroniser ring on intermediate ring with grooves on lugs of inner synchroniser rings. | 
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Important! Wear asbestos gloves.
Install, Connect Heat 1st/2nd gear synchromesh body to approx. 100 ° C/212 ° F and with KM-514 (1) press onto the main shaft so that the lugs of the outer synchroniser ring align with the grooves of the synchromesh body - 2nd mechanic. Shift fork groove faces ball bearing seat. Slide thrust washer onto main shaft. Install new retaining ring onto main shaft. Place outer synchroniser ring with lugs into grooves of synchromesh body. Place intermediate ring onto outer synchroniser ring. Place inner synchroniser ring onto the intermediate ring so that lugs are seated in grooves of outer synchroniser ring. 1st gear needle bearing onto main shaft. Slide 1st gear onto needle bearing so that the grooves are seated on the lugs of the intermediate ring. Place axial needle bearing (3) onto 1st gear. Heat spacer washer (2) to approx. 100 ° C and position on main shaft (4) so that large diameter faces axial needle bearing. | 
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Install, Connect Place new retaining ring with long legs for main shaft to end shield on 1st gear. Open ball bearing: press on ball bearing with KM-302 (1) so that the cage side of the ball bearing faces end shield side. Closed ball bearing: press on ball bearing so that the groove milled on the outside faces the gear block - use KM-302 (1).
Inspect All gears must be easy to turn. | 
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