Shift Shaft Bushing Tool for Mercury MerCruiser MC-I, R-MR, Alpha One and Outboards – Replaces 91-31107T, Sierra 18-9817

Product Details

The Shift Shaft Bushing Tool is a dedicated service tool for removing and installing the shift shaft bushing in the gear case of compatible Mercury MerCruiser MC-I, R-MR, and Alpha One drive units and outboards. It is intended to help technicians apply controlled pressure during bushing service while reducing the risk of damage to the surrounding housing.

This aftermarket tool is associated with Mercury Marine OEM references 91-31107T, 91-31107, 91-24150, 91-23033T, and 91-23033. It is also listed as a replacement for Sierra 18-9817. Verify the reference number and drive-unit application before ordering.

• Designed for shift shaft bushing removal and installation
• Supports service work on compatible MC-I, R-MR, and Alpha One drive units and outboards
• Dedicated tool geometry helps maintain alignment during bushing service
• Aftermarket replacement for the references listed below; not an OEM Mercury component

Part Number Matrix

Use the following verified reference numbers to compare this tool with the tool specified for your application.

Engine & Model Compatibility

Compatibility is determined by the drive-unit or outboard application and the applicable service-manual reference, not by horsepower alone. Confirm that your unit uses one of the reference numbers listed above before purchasing.

Technical Specs

Tool type

Shift shaft bushing removal and installation tool

Application

Gear-case shift shaft bushing service

Compatible drive-unit families

MC-I, R-MR, and Alpha One, where the listed reference applies

Product type

Single aftermarket service tool

Primary OEM reference

91-31107T

What's in the Box

• 1 × Shift Shaft Bushing Tool

Installation and Service Notes

1. Shut down the engine completely, remove the ignition key, and follow all applicable marine-service safety procedures.
2. Remove the lower unit or gear-case components as directed by the service manual for your specific drive unit or outboard.
3. Clean the shift shaft bushing area and inspect the bore, housing, and shift shaft for corrosion, debris, scoring, or other damage.
4. Position the tool squarely against the bushing and use an appropriate press or controlled driving method recommended by the service manual.
5. Remove the old bushing without cocking the tool or applying force that could damage the surrounding gear-case housing.
6. Clean and inspect the bore before installing the replacement bushing. Align the new bushing carefully and press it evenly into position.
7. Confirm that the bushing is correctly seated and that the shift shaft moves as specified before reassembling the lower unit.
8. Torque fasteners and complete the shift-operation check according to the manufacturer’s service instructions.

Troubleshooting & FAQ

Which units is this tool intended for?

Catalog information identifies this tool for shift shaft bushing service on Mercury MerCruiser MC-I, R-MR, and Alpha One drive units and compatible outboards. Always confirm the OEM reference for your exact unit; horsepower or brand alone is not sufficient to establish fitment.

What does this tool do?

It is used to remove and install the shift shaft bushing in the gear case. The tool helps keep the service operation controlled and aligned when used with the correct procedure.

Can I install the bushing without this tool?

A dedicated tool is recommended because improvised methods can apply uneven force or damage the bushing, bore, or gear-case housing. Use the procedure and tooling specified in the service manual for your unit.

What should I inspect before replacing the bushing?

Inspect the shift shaft, bushing bore, and surrounding housing for corrosion, scoring, cracks, distortion, and debris. Replace or repair damaged components as required before installation.

Is this an OEM Mercury tool?

No. This listing is for an aftermarket replacement tool. The Mercury Marine and Sierra numbers shown are reference numbers used to identify the intended application.

Is the tool reusable?

It is supplied as a service tool intended for repeated use when handled correctly. Keep the tool clean, inspect it for damage before use, and store it in a dry location.

Safety & Important Information

• Verify the drive-unit model, service-manual instructions, and OEM reference before ordering or beginning work.
• Do not rely on horsepower alone to determine compatibility.
• Use suitable lifting, pressing, and personal-protection equipment when servicing the lower unit or gear case.
• This is an aftermarket replacement tool, not an OEM Mercury component.
• Professional installation is recommended when the required service procedure or tooling is unfamiliar.

About Sea Sierra

• We provide aftermarket marine service parts and tools for repair and maintenance applications.
• Each listing is organized around the available application and reference information to help customers compare parts before ordering.
• For the best fitment result, compare the reference number and service-manual application for your exact unit.