Replace 600 STI with Sora?
 

I've got an old right (rear der) 8sp Shimano 600 STI that has the inner tab broken off. It doesn't rachet all that well either. I like my rear derailer and am happy with an 8 speed setup. Can I replace the 600 STI with a new 8 speed Sora STI without any weird adjustments or workarounds? Thanks.

Yeah.....

You can also use 9 speed campy to index 8 speed shimano...

I also hear Modolo Morphus shifters are a good choice for 8 speed...

Note that the Sora shifter operates a little differently than your 600 STI shifter. The Sora shifter has a thumb-actuated release lever that's mounted on the top front portion of the hood and is difficult if not impossible to reach from the drops. I find it impossible to upshift from the drops with Sora. If you're okay with that then go ahead. Another option as someone has mentioned is to use Campy 9-speed shifters or hop on eBay and seem if someone is selling NOS 8-speed STI shifters.

You better have a campy RD to go with that, and even then there is .25mm difference in cog spacing.

Most 600's (like mine) will function as a 9spd derailleur no problem. I have Tiagra levers (9spd) and a 9spd Ultegra cassette and good shifting.

What?? I'm assuming you mean you switched to 9 speed,with shifters,casette and chain,and just kept the 600 RD,which is no issue.

Thanks for the help guys. I ordered a new set of Sora STI's from nashbar yesterday. They only ended up being $90 - %10 = ~$81. Pretty good price in my book considering used 600 STI's sell for $80 - $110 on ebay. I realize Sora might not be the quality of 600, but my 600's were very used, so they were no longer very crisp. Thanks again for the help.