So, I now have a 85 Z28 with the 85MPH Speedometer Gage cluster. I found a 145MPH Cluster for a good price. Do I have to change out the Speedometer Gear in the transmission for it to be accurate?

 

No. Your speedo should be cable-driven. Make sure the new head is also. The later years were electronic.

It's now time to update your car in your profile. 2002 Dodge Ram 1500 Quad Cab

 

Camaro was all cable driven through 1989 (Firebird I think changed to electric in 1986,except base cluster through '88)

 

Yeah, I knew that they were cable driven from 82-89. I had a 90 RS and found out they changed it in 90. As well as how the dash shell mounts differently to the firewall.

I'll leave the Quad Cab where it's at until I fully give it to my son after he graduates HS this May. I'll just list my 3rd Gen in my Sig.

 

Use your original cluster and install the 145 Speedo head into it.

The Camaro Speedo cluster ( more accurately; it's printed circuit ) was compatible from 82-85,... then 86-89. If you install an 86 + Cluster in your 85 it will cause a minor conflict with the E-Brake light and a back-light bulb or 2.

** No need to swap Speedo gears when swapping clusters.

 

That's easy too