Synchromesh Mechanism

BAULK RINGS
To change the baulk rings, follow the description for "To dismantle the gearbox" which specifies that the differential unit must be removed and the 5th gearwheel must be removed to enable the primarv chaincase to be removed.
No further dismantling is necessary to change the 4th gear baulk ring.
To change the 1st and 2nd gear baulk rings, the output shaft must be removed from the gearbox, so that the gearwheels can be removed from the shaft.
The baulk ring for 5th gear can be changed after the input shaft has been removed. The primary chaincase need not be removed.

TO DISMANTLE





To dismantle the synchromesh unit, remove the circlip retaining the baulk ring on the gearwheel. To remove the 5th baulk ring, remove the circlip at the guide ring. The circlip at the baulk ring need not be removed.

TO ASSEMBLE





First fit the guide rings for the springs and the circlips for the 3rd and 4th gearwheel guide rings. The 1st and 2nd gearwheels have no circlips for the guide rings. Fitthe spring with the long end towards the guide ring and locate it so that there are II teeth between the spring ends. Locate the baulk ring so that the ends of the spring are between the teeth of the baulk ring, and then fit the circlip.
(The spring for 1st gear synchromesh is softer and its free length is smaller than the others.)

NOTE: The guide rings on 3rd and 4th gearwheels fitted in production are peened in position in a special tool after the circlip has been fitted. The guide rings supplied as spares should not be peened.

Guide plate 87 02 730 together with pear-shaped circlip 87 02 722 should be used as spare parts.
As an alternative, use a complete unit 87 11 632 consisting of the gearwheel and factory-fitted synchromesh unit.
Fit the 5th gear baulk ring. Fit the springs so that there are 5 teeth between the spring ends. Then fit the guide ring and circlip.
The 2nd and 3rd synchromesh unit has molybdenum-coated conical surfaces. This type of baulk ring is also suitable for 1st and 4th gears.





1ST AND 2ND GEAR SYNCHROMESH UNIT
1. 2nd gearwheel
2. Guide ring
3. Spring for 2nd gear
4. Baulk ring
5. Circlip
6. Synchromesh hub
7. Synchromesh sleeve
8. Spring for 1st gear
9. 1st gearwheel





3RD GEAR SYNCHROMESH UNIT
1. Circlip
2. Baulk ring
3. Spring for 3rd gear
4. Guide ring
5. Circlip for guide ring
6. 3rd gearwheel





5TH GEAR SYNCHROMESH UNIT
1. Synchromesh sleeve
2. Circlip
3. Baulk ring
4. Synchromesh hub
5. Spring
6. Guide ring
7. Circlip