091 synchro questions

[Casting Timmy]

Trying to learn about 091 Synchros and thought I would share what I know and see how correct it is.

Physically the 091’s interchange as they are all for the same diameter synchro cone on the gears. This has some builders using the 1st gear synchros (110degrees) on 2-4 as it saves them and the customer money.

The factory put moly synchros on 2 and 3, but a brass one on 4 to save money, but all three are 120 degree synchros. Putting a brass synchro on a gear that used a moly synchro before can lead to it grinding when trying to shift.

Moly synchros should be test fit on the gear’s synchro cone to see if they get grippy or not as the cone may need to be touched up with sand paper so the synchro can have a good surface to grab.

Seen some debate on the outside ring and how many teeth should be present for the best shifting, some prefer 3 sets of 6 teeth and some leave them alone. This is an interesting topic I would like to hear more on people’s experiences.

Last comment would be on identification between 1st (110) and 2nd-4th (120) is the typical 3 notches on the outside on the 120 degree versions. The moly rings really do remind me of motorcycle clutch discs for some reason.

[Pablo2]

I don't know how using a 1st gear synchro in place of a 2nd gear synchro will save money. I just purchase the proper synchros and install them.

The number of teeth on the brass synchro itself shouldn't affect how it shifts. Perhaps there is confusion here with the rebuild practice of knocking off the fatter, worn steel engagement teeth, in order to put the slightly narrower remaining engagement teeth into service? This works quite well, and does allow slightly easier shifting.

Only the originally installed 2nd gear synchros (with teeth all the way around) are missing the notch which identifies 120*. All replacement 120* synchros have the notches.
http://www.thesamba.com/vw/forum/album_ ... id=1395273

[Casting Timmy]

Thanks again, just got able to log in again.