For the most part the only issue with a noisy tob is the noise. Based on my own experience, when they get real bad - which generally takes a while (mine lasted at least another 5K from the moment I first noticed any noise) you will eventually experience clutch pedal issues or issues engaging/disengaging the clutch. By the time the noise became unbearable and constant, the pedal also had a bit of a "ratchety" feel to it and I had to stick my foot under the pedal as to pull it up once or twice due to the bearing sticking. Once it got to that point I just parked it until I got new parts rounded up.
The only real risk with a bad tob is possible damage to the transmission input shaft. But even as bad as mine got that still didn't happen.
Other parts you should consider replacing at the same time as clutch etc is get an aftermarket aluminum quadrant and firewall mounted cable adjuster, along with a new cable (oem or equivalent is what is most often recommended) and some people also elect to replace the clutch fork as well. The factory plastic quadrant has a built in cable adjustment mechanism, but being made out of plastic it is known to flex a bit under hard use which causes engagement/disengagement issues and additionally if you go with any sort of aftermarket "performance" clutch setup it generally does not offer correct cable adjustment which will lead to a shortened life of your new clutch.
Last edited by Z28KLR; 01-07-2015 at 02:21 PM.