Speed wasn't working when I put the Hurst back on the road. Found out it was the little plastic gear had "apple cored". After replacement everything was fine for about 2 weeks. Then the gauge was choppy and loud (very) and poof two days ago speedo stop. I am going to guess the plastic gear is shot again. What is chewing it up?

2004r- shift kit

 

Make sure the drive gear on the output shaft isn't chewed up. If its chewed up it will chew up the driven gear. Make sure the driven gear turns freely in the housing. Lastly, make sure the speedo cable turns freely. It might not be a bad idea to remove it and relube the cable.