was the 145 MPH speedometer in IROCS only? I am selling one I bought a while back and a potential buyer asked me this question- is it a true IROC speedo?

 

IROC's had 145 speedo IF they had Z rated tires, so yes an IROC speedo but only if the IROC had the 16 wheel (QLC) tires.

 

In 1986, according to our site's tech date "the 85mph speedometer in the Z28 and IROC-Z were replaced with a new 145 mph unit."

JamesC

 

z28's also could of had the 145 speedo also .. i had a 1986 z28 with the 145 speedo and it was all original with 15 inch rims ..

 

2nd half production in 86 iroc or z28 as long as it was the tpi engine had 145 speedo. 87 iroc's all had 145 speedo except the base carb motor. 88-90 305 irocs had 115 speedo unless it was a G92 5 speed car. 88-90 350 irocs got 145 speedo only.

 

Sorry 1989 Formula, I have an 88 IROC Convertible 305 Auto and it has the 145 Speedo and I am the third owner. All original numbers matching. The 145 Speedo was part of a 'package' with upgraded rear end 16" wheel package. I believe a car that was ordered with the G80 (limited slip rear) and G92 (performance ratio axle) received the 145 Speedo.