Originally Posted by BenRNBP

There's a really interesting series on youtube of a full gearbox rebuild https://www.youtube.com/watch?v=At826habFbk , it also explains the carbon coating on some of the syncros in the later facelift/AP2 gearboxes. You're right you can't just buy the rings by themselves mostly 'cos you'll probably have damage to the sleeve too ( watch the video series for further explaination )



3rd 4th part numbers are;
Honda S2000 2001-2004 AP1 F20C1 Engine P/N: 23623-PCY-306
Honda S2000 2004-2010 AP2 F20C2 Engine P/N: 23623-PCY-316

and looks like you might be able to get a deal here GENUINE HONDA SYNCHRO SLEEVE HUB SET 3rd-4th GEAR S2000 AP1 AP2 F20C eBay