ZR-1 Net Registry Forums - View Single Post - How to install speedometer correction gears

12-31-2009

John,

Thanks for the kind comments, but I don't really know if this is that worthy. I was just trying to share with pictures.

Xlrn8florida,

Based on the ZF Doc, I think it is just a matter of choice in the last sentence. For me I prefer the gear (manual) method and feel I don't have to worry about accuracy with electronics for the box breaking:

Changing the Speedometer Gears on the Vehicle
NOTES: The C4 Corvette Vehicle Speed Indication System (VSIS) uses a pulse-signal-reference generated from the Vehicle Speed Sensor (VSS). The VSS, when equipped with a 15 tooth (T) drive gear (on output shaft) and 42T driven gear turning the VSS combined with a 3.45:1 differential ration, produces 4000 pulses per mile traveled. The VSIS is calibrated to 4000 pulses equaling one mile. When the differential (final drive) ratio changes, so does the pulses generated over each mile. To correctly recalibrate the VSIS signal pulse rate back to 4K/mile either the drive and/or driven VSS gear(s) must be changed or a black box Electronic Ratio Adapter (ERA) installed. Both cost around $140.

12-31-2009	#4
HAWAIIZR-1 Guest Posts: n/a	Re: How to install speedometer correction gears John, Thanks for the kind comments, but I don't really know if this is that worthy. I was just trying to share with pictures. Xlrn8florida, Based on the ZF Doc, I think it is just a matter of choice in the last sentence. For me I prefer the gear (manual) method and feel I don't have to worry about accuracy with electronics for the box breaking: Changing the Speedometer Gears on the Vehicle NOTES: The C4 Corvette Vehicle Speed Indication System (VSIS) uses a pulse-signal-reference generated from the Vehicle Speed Sensor (VSS). The VSS, when equipped with a 15 tooth (T) drive gear (on output shaft) and 42T driven gear turning the VSS combined with a 3.45:1 differential ration, produces 4000 pulses per mile traveled. The VSIS is calibrated to 4000 pulses equaling one mile. When the differential (final drive) ratio changes, so does the pulses generated over each mile. To correctly recalibrate the VSIS signal pulse rate back to 4K/mile either the drive and/or driven VSS gear(s) must be changed or a black box Electronic Ratio Adapter (ERA) installed. Both cost around $140.