I am changing gears in my 964 turbo to C2 ratio
3-4-5 for trackday car.

Thinking about syncro 2 and 3 gears
heard there was a upgraded on RS with less teeth, is that the best?
can I change only syncro or must change the sleeve to?

anyone have the measurements for original wear syncros G50?

 

The RS uses steel synchronizers, and modified shift sleeves (bevel angle). Brass synchros can expand, and lock you out of gear when hot. I will defer to others far wiser on your installation questions.

 

For 964 the synchro and guide sleeves are both different for the RS and street boxes

You might want to look into the Cup steel versions which are available for all of the transitions, 964 RS versions are only available for 1/2 and 3/4

I have the Cup/RSR versions in mine and they make a very noticeable difference in feel of the shifts

 

Are the cup/rsr synchos the same for the g64 as well. Or would they not be interchangeable.

 

what are the part number for the Cup version?

i was thinking only change the 2 and 3 synchro because they take the most damage.
does Cup has diffrent Sleeves as well?

 

This is from the RSR manual which is a bit tough to break out
928 34 211 30 steel syncroring
950 304 021 80 3/4 guide sleeve

950 304 611 11 syncroring
950 304 061 02 1/2 guide sleeve

The following is for GT2 evo(I think 97 version) which is mostly the same except gearing

 

I have the Box of my Trackday 964 also redone with Shorter 3/4/5th and my box builder is a very reputable Workshop in Germany for old Porsche and beetle Race gearboxes. For normal Trackday use they more or less insisted to Stick with oem brass syncros instead of steel ones. More stable of course with steel, but for trackday sufficient with brass and moneywise a complete different animal… After three seasons, still happy with it…

 

so from what i understand this steel ring would work together with original c2 sleeve?

https://www.fvd.net/us-en/9503043113...-rs-model.html

how about this one any one know if its any good?

https://www.rauchandspiegel.com/prod...el-cf-1st-2nd/


or maybe best to go with the brass one

https://www.fvd.net/us-en/9503043110...-2nd-gear.html

 

I already posted in other topics but I m still looking to find out the cause of some shifting problem on my 964

I fitted a 993 6 speed gearbox and before fitting it was servced and equipped with some 2nd to 6th steel synchros and a 8/32 final ratio and oem 993 rear limited slip differential

The clutch disc is new and the clutch was bled

The car is fitted with rothsport quickshifter and FD golden rod and there are semi rigid motor mounts with polyurethane inserts , and at the moment oem 964 transmission mount but fitted with a powerflex polyurethane insert and the powerflex polyurethane small bushings for the small rod near the transmission mount

The problem is that when accelerating hard from 1st to 2nd or from 2nd to 3rd the disengagement of the gear feels rough ( as if you would shift out of gear under load without using the clutch or as if there would be some of engine and transmission misaglinment under load and then it comes back in place
when shifting out of gear but making you feel the effort trought the shift linkage )

Of course I just describe how it feels but I m not sure if this is caused by some actual engine and transmission movement and the unbalanced stiffness between the engine mounts and transmission mount and if using the golden rod without extra bushings makes it noticeable or if
it s caused by something internal to the gearbox that was not correctly fitted ( someone suggested a selector sleeve that could be installed backwards or not replaced correctly )

I of course went back to the porsche specialist and they bled again the clutch that did not change a lot and of course when I mentioned some eventual internal part not correctly fitted they would tell me that all was ok ( not that they would be unfitting a gearbox without reason of course )
but the shifting is really not as it should be

On taller gears everything is ok as of course there is less torque anyway on the engine on taller gears and also everything is ok is shorter gears if driving slowly

Thanks for any suggestion and details about the gearbox sleeve

 

It’s not uncommon for steel synchros to feel a bit notchy in lower gears. Oil also makes a big difference; you should be using Mobil 1 75w-90.