I'm trying to figure out how brand new speedometer cables would fail less than 300 miles from installation. I meticulously threaded the new upper cable into place and installed a new bottom 'elbow' section that connects to the transmission. I have replaced the upper and lower sections twice in the past 6 months. It appears that the upper cable overheats, binds up, then the bottom section unwinds and breaks. The center section was not replaced and appears to be fine. Does anyone have a theory on this?