ZR-1 Net Registry Forums - View Single Post

XfireZ51 · 09-18-2011

WV,

The tire/diameter delta would be a constant %, but the actual mph delta would vary depending on gearing. The rear gear ratio was verified by Pete when we had car at his place for motor swap. So we are certain about that. I suspected that the speedo was reading low even before the 19's went on. As I posted earlier, using my in dash GPS, speedo reads 41 while GPS shows 47.5mph.
So I would probably install the 3.45 trans gear for the speedo, then
install the 3.73 rear gear to bring things into closer alignment both from readout and performance standpoint.

09-18-2011	#9
XfireZ51 Join Date: May 2007 Location: Chicagoland, IL Posts: 9,662	Re: Contemplating Rear Gear change WV, The tire/diameter delta would be a constant %, but the actual mph delta would vary depending on gearing. The rear gear ratio was verified by Pete when we had car at his place for motor swap. So we are certain about that. I suspected that the speedo was reading low even before the 19's went on. As I posted earlier, using my in dash GPS, speedo reads 41 while GPS shows 47.5mph. So I would probably install the 3.45 trans gear for the speedo, then install the 3.73 rear gear to bring things into closer alignment both from readout and performance standpoint.