I just brought my new '87 iroc home yesterday, but the speedo's messed up. i'm not sure if it's electric or cable-driven though. anyone know how to adjust it? i was driving behind a friend, taking it home, and when i went 60mph, he said we were going 70. (i also gotta swap out the gauges since the damn thing is in km) thanks

 

an 87 IROC will be cable.....I belive IROCs (all camaroos) were cable until 89/90 and firebirds were cable until 86/87(?)

sounds like you may need to change your speedo gears(in the trans), the gears or the rear end may have been replaced