Shift Shaft Bushing Tool – Fits Mercury/MerCruiser Alpha/R/MR Drives (Replaces 91-31107T)

$14.50 $23.00

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Shift Shaft Bushing Tool – Fits Mercury/MerCruiser Alpha/R/MR Drives (Replaces 91-31107T) is backordered and will ship as soon as it is back in stock.

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You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This Shift Shaft Bushing Tool is designed for removing and installing the shift shaft bushing in the lower gearcase housing on Mercury/MerCruiser drives, including MC-1, R, MR, and Alpha One models.

It serves as a direct replacement for Mercury part numbers 91-31107T, 91-23033T, and 91-24150, as well as Sierra 18-9817 and GLM 90140.

Engineered for manual use to precisely remove and install the lower shift shaft bushing.
Constructed from high-strength forged steel for durability and reliable performance.
Features a corrosion-resistant zinc-nickel plated finish to withstand the marine environment.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket.

Brand	Part Number
Mercury	91-31107T
Mercury	91-23033T
Mercury	91-24150
Sierra	18-9817
GLM	90140

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury outboards, this tool fits a range of 2-stroke models including DFI, EFI, JET, and Pro XS variants. Please check your specific model and year range for a match.

For MerCruiser stern drives, compatibility is listed by drive type. This tool fits all years of MC-1, R, MR, Alpha One, and Alpha One Gen II drives.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.
Mercury	V-115 DFI	115	2-Stroke	Up to 2006	91-31107T
Mercury	V-135/V-150	135-150	2-Stroke	Up to 2006	91-31107T
Mercury	V-135/V-150 DFI	135-150	2-Stroke	Up to 2006	91-31107T
Mercury	V-150/V-175/V-200 EFI	150-200	2-Stroke	Up to 2006	91-31107T
Mercury	MAGNUM III	150	2-Stroke	Up to 2006	91-31107T
Mercury	XR-6	150	2-Stroke	Up to 2006	91-31107T
Mercury	140 JET	140	2-Stroke	Up to 2006	91-31107T
Mercury	110 JET	110	2-Stroke	2006 and Up	91-31107T
Mercury	150 Pro XS	150	2-Stroke	2006 and Up	91-31107T
Mercury	175 Pro XS	175	2-Stroke	2006 and Up	91-31107T
MerCruiser	MC-1	All	N/A	All	91-31107T
MerCruiser	R	All	N/A	All	91-31107T
MerCruiser	MR	All	N/A	All	91-31107T
MerCruiser	Alpha One	All	N/A	All	91-31107T
MerCruiser	Alpha One Gen II	All	N/A	All	91-31107T

Technical Specs

Product Type: Specialty Service Tool
Installation: Manual Drive Tool
Material: High Strength Forged Steel
Color: Black
Surface Finish: Zinc-Nickel Plated
Dimensions: 5.0" × 4.0" × 1.5" (approx. 127mm × 102mm × 38mm)
Weight: 0.4 lb (0.18kg)
Warranty: 1 Year (Aftermarket)
Key Attributes: Corrosion-resistant coating, high-temperature resistant

What’s in the Box

1x Shift Shaft Bushing Tool (Replaces 91-31107T)

Installation Notes

Ensure the engine is off, cool, and disconnected from the battery.
Drain the gearcase lubricant completely into a suitable container.
Access the lower gearcase housing to expose the shift shaft bushing. A service manual for your specific drive is recommended.
Securely position the tool onto the old bushing.
Carefully operate the tool to extract the worn bushing from its seat.
Thoroughly clean the bushing bore to remove any debris or corrosion.
Align the new bushing and use the installation side of the tool to press it evenly into place until fully seated.
Reassemble all components in reverse order of removal.
Refill the gearcase with the manufacturer-specified lubricant to the correct level.
After reassembly, check for smooth shifting operation and inspect for any leaks.

Troubleshooting & FAQ

How do I know if this tool fits my drive?

This tool is designed for MerCruiser MC-1, R, MR, Alpha One, and Alpha One Gen II drives, as well as the Mercury outboard models listed in the compatibility table. Always cross-reference your drive/engine model and year before ordering.

What are the signs of a worn shift shaft bushing?

Common symptoms include difficulty shifting gears, excessive "slop" or play in the shift mechanism, or a persistent water/oil leak from around the shift shaft area in the lower unit.

How does this tool compare to the OEM Mercury 91-31107T?

Our tool is built to perform the exact same function as the OEM equivalent. It is constructed from high-strength forged steel with a protective zinc-nickel finish. A key benefit is that our aftermarket tool includes a 1-year warranty, which is not typically offered for the OEM version.

Is this tool difficult to use for a DIY repair?

The tool is a manual-drive tool that simplifies the removal and installation process. However, accessing the bushing requires some disassembly of the lower unit. We recommend having mechanical experience or following a detailed service manual for your specific engine.

Can this tool be used for any other bushings on my engine?

No, this tool is specifically designed and dimensioned only for the lower shift shaft bushing on the compatible models listed. Using it for other purposes could damage the tool or the engine components.

What is the tool made from?

It is manufactured from high-strength forged steel and features a zinc-nickel plated surface finish to provide excellent corrosion resistance in marine environments.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 facility, batch-inspected for consistency.

Shipping speed & cost

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our policy page or reach out for instructions.

Safety & Important Info

Verify images/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days.
Manufacturer-Direct Value — Fair pricing without compromising on materials or QC.

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