Adapting the 4-Speed Shifters to Other Gearboxes

We are often asked whether the Ford Toploader, GM Muncie and G-Force T-101 sequential shifters can be fitted to other four-speed gearboxes. They will not bolt directly to any gearbox other than the one each kit is designed for. However, the mechanism is a simple rod-and-arm linkage, and a builder who is prepared to fabricate a mounting plate, shift arms and rods can adapt a kit to most gearboxes with a similar side-shift layout.

S1 Sequential does not provide design or technical support for custom adaptations. The notes below are published to assist anyone with the mechanical skills to undertake such a project, and any modification is carried out at the builder’s own risk.

Points to consider

Mounting bracket

This is usually the easiest part. Make a bracket that holds the shifter in a position where the rods run as straight as possible and nothing fouls through the full range of movement.

Shift rods

Any rod that spans the distance without binding will work, but flex must be kept to a minimum. Keep the rods as straight as possible and use steel rod of a similar diameter to the rods supplied in the kit.

Shift arms

This is the most involved part. The arms supplied in the kit can sometimes be reused with modification; otherwise new arms will need to be made. Shortening an arm increases the effective throw at the gearbox. Although the shifter has the same throw in every gear, a gearbox with different throws between gears can be accommodated by changing the angle of the arm on the gearbox. This can be calculated from a drawing, or found practically: with the gearbox and shifter each placed in the same gear, mark an arc from the rod end with a marker; where the arcs intersect is the hole position.

Shift arm angle and hole position for an adapted 4-speed shifter

Reverse selection

Check how reverse will be selected before committing to the layout. The current (V2) shifters have a reverse lockout; on the Toploader kit the lever is pulled back to engage reverse, while on the T-101 kit it is pushed forward. Choose the arrangement that suits your gearbox and rod layout. Earlier V1 shifters have no lockout or reverse switch, and fitting one to a gearbox without its own reverse lockout may be a safety issue.

The standard kits are available here: Ford Toploader, GM Muncie and G-Force T-101. Mounting dimensions are on the Shifter and Gearbox Dimensions page.