Product description

Synchromesh rings are used to ensure smooth operation of the gears. Synchromesh rings ensure that the shaft and gear speeds are the same when engaged.

Beginning in August 1960, Volkswagen offered a fully synchronized transmission for most models, with the exception of the reverse gear. You may notice this because the gear sometimes squeaks when engaging reverse. Gears that are not engaged rotate freely around the output shaft. Therefore, engaging a gear means connecting a freely rotating gear to the output shaft.

When a gear is engaged, the speed of the output shaft must match the speed of the gear to be engaged. The gear to be engaged has a different speed than the output shaft, so it also has a different speed than the synchromesh. As the shift fork moves, it drags the synchromesh with it and the tapered portion of the synchromesh ring is pressed against the inner tapered surface of the gear. The tapered portions of the two parts are pressed together, equalizing the friction between the tapered surfaces. When there is no longer a difference in speed between the two gears, the shift sleeve can be pushed so that the teeth slide into each other and the gear is engaged without any squeaking.

The synchromesh device works not only when the gears are engaged, but also when they are shifted and downshifted. It is very bad for the synchromesh rings to change gears very quickly, i.e., to push the lever very hard into a gear. The synchromesh then does not have time to synchronize. It is therefore preferable, when changing gear, to push the lever gently against the resistance and only when it slips almost automatically into the gear.

A synchromesh ring is a wearing part. Friction occurs when shifting gears, so the part will wear over time. When the gearbox is disassembled, it is possible to check the synchromesh rings for wear. Using a feeler gauge, the distance between the synchromesh ring and the gear wheel can be measured. The gearshift must not be engaged. As the synchromesh ring wears out, the distance between the synchromesh ring and the gear wheel reduces. Your workshop manual describes the wear limit of the synchromesh ring. If the measured value is less than the maximum wear value stated in the workshop manual, it must be replaced.