Speedometer Correction Gears

 

Speedometer correction gears are available for the popular rear axle gear ratios that are used in the ZR-1. These gears will also work in any ZF S6-40 six speed manual transmission that was used in '89 - '96 Corvettes.

Available Corrections:

Axle Ratio    Tooth Count        Accuracy Relative to the Factory Speedometer Gears        Price for the Set

4.30                13/45                                        Within 1%                                             $125.

4.10                13/43                                        Within 1%                                             $130.

3.90                13/42                             Speedometer reads 2% low                                 $125.          

3.73                15/45                                        Within 1%                                              $10. (one gear)

        For the 3.73 axle ratio, the ZR-1 OE 3.45 gear ratio provides the 15 tooth (light grey) transmission shaft gear.

 

The gears are easy to install. The tail extension housing does not need to be removed from the transmission.

1. Remove the driveshaft.

2. Remove the speedometer sensor. Be ready for about 3 ounces of lubricant to emerge.

3. Remove the spring clip for the transmission shaft gear from the transmission output shaft.

4. Slide the original gear down the transmission shaft and out of the back of the transmission.

5. Oil the new gears and install them. Don't let the spring clip fly!

6. Add 3 ounces of make up lubricant. The factory used GM PN 1052931. In 2007 PN 1052931 was replaced by PN 12345349.