I spoke with Yakima about your Yakima Quarter ROC Bike Rack 8002533 and they stated that this bike rack was discontinued in 2001 and the hitch bolt is not a replaceable part. I asked if they have any dimensions of this bolt but they could not advise due to it's age. Therefore the only option I have for you is a full replacement for which I recommend the Thule Camber 2 Bike Rack part # TH9058.
The Thule Camber 2 like your Quarter ROC is gong to last you another 20 years or even longer... view full answer...