6-speed Transmissions & Lock-Out Controller Kit


1991-1996 manual transmission NSXes were equipped by the factory with a 5-spd transmission using a twin disc clutch.1997-2005 manual transmission NSXes were equipped by the factory with a 6-spd transmission using a single disc clutch.

Owners of early model 5-speed transmission owners may upgrade to the later model 6-speed transmissions. The conversion process is simple. In order two install the transmission, you will need:
1. 6-spd transmission (complete assembly)
2. single disc clutch or convert using a twin spline input shaft
3. reverse lock out solenoid electronics

reverse lock out solenoid electronics:
1997-2005 NSX use a circuit that is a part of the engine control unit (ECU) to fire a solenoid pin when the car exceeds 25 mph. By doing this, a driver can not accidentally engage reverse when the car has forward speed. Since 1991-96 NSX lack this circuit, it must be added. There are three solutions:

  • plug and play solenoid controller - controller uses circuit that plugs into factory speed sensor and solenoid. Just like factory, activates solenoid when the car reaches 25 mph. Plug and play using factory connectors, no wire cutting required.
  • simple relay using brake lights as a trigger - this is the standard method used by ScienceofSpeed. To engage reverse gear, the driver must first step on the brake pedal. Included by default with the transmissions. Requires cutting factory wires and installing relay.
  • aftermarket ECU - if your NSX has an aftermarket ECU (such as the AEM EMS) with output triggers - you can configure the computer to activate a relay to control the solenoid.

single disc clutch or twin spline input shaft modification:
The factory 6-spd transmission uses a single spline input shaft that is compatible with single disc clutches only. If you have a 1991-96 NSX, you may use this transmission with a single disc clutch (like the ScienceofSpeed Sport Clutches). If you prefer to use a twin disc clutch (either factory or aftermarket), we can exchange the input shaft in the transmission using the twin spline 6-spd input shaft from the NA2 NSX-R. The shaft is sold separately below. We also offer the service to exchange the input shaft.

Honda 6-speed A61 Transmission Assembly


ScienceofSpeed 6-spd Lock Out Controller