SSM #4 & SSM #6 Gearcase Mounting Hardware Kit
 
The Mercury Racing Speedmaster Fastener Kit is an inexpensive upgrade that helps protect one of the most valuable components on your race boat—the gearcase. Designed specifically for Mercury Racing Super Speedmaster (SSM) #4 and SSM #6 lower units with studs-down mounting systems, this kit replaces the aging hardware that secures the gearcase to the midsection.
 
Many original Speedmaster fasteners have been in service for decades. Over time, Nyloc inserts lose their holding ability, stainless hardware becomes fatigued, washers become distorted, and critical clamping force can be reduced. Unfortunately, reused hardware is one of the most overlooked maintenance items on vintage and modern Mercury Racing tunnel boats.
 
Why Fastener Condition Matters
 
The connection between the gearcase and midsection is subjected to constant vibration, propeller thrust, engine harmonics, rough-water impacts, and repeated heat cycles. As hardware ages, the risk of loosening increases.
 
Buckshot Racing #77 has seen numerous cases where worn Nyloc nuts, incorrect washers, missing washers, or improperly sized hardware allowed the gearcase to loosen over time. What begins as a minor loss of clamping force can eventually lead to vibration, damaged mounting surfaces, cracked cavitation plates, gearcase damage, or in extreme cases, complete gearcase loss.
 
For racers and performance boaters, replacing aging hardware is inexpensive insurance compared to the cost of repairing or replacing a Speedmaster.
 
OEM-Spec Hardware for Proper Clamping Force
 
This kit includes all-new stainless-steel Nyloc nuts and OEM-spec thick stainless washers designed specifically for Speedmaster mounting applications. Proper washer thickness is critical because it helps distribute clamping loads evenly while maintaining the correct engagement of the Nyloc locking feature.
 
Using incorrect hardware-store washers or reusing damaged originals can compromise clamping force and increase the likelihood of fastener movement under load.
 
Designed for Mercury Racing SSM Applications
 
The kit fits Mercury Racing Super Speedmaster SSM #4 and SSM #6 lower units utilizing the traditional studs-down mounting configuration found on many Formula 1, tunnel boat, Mod-U, SST-120, SST-140, offshore, and vintage Mercury Racing applications.
 
Whether maintaining an active race boat or restoring a classic Mercury Racing package, fresh mounting hardware helps ensure the gearcase remains securely attached and properly aligned.
 
Cross Reference Information
 
This kit replaces Mercury Racing hardware associated with part numbers 11-859116 and 12-35935 and provides a complete hardware refresh for the gearcase mounting system.
 
What's Included
 
Each Speedmaster Fastener Kit includes a complete set of sixteen (16) pieces, consisting of new stainless Nyloc nuts and OEM-spec thick stainless washers required for SSM #4 and SSM #6 gearcase installations.
 
Final Thoughts from Buckshot Racing #77
 
The Mercury Racing Speedmaster Fastener Kit is one of the simplest preventative maintenance upgrades you can make to an SSM #4 or SSM #6 gearcase. Fresh Nyloc nuts and proper-thickness stainless washers help maintain clamping force, reduce the risk of loosening hardware, and protect valuable Speedmaster components from unnecessary damage.
When it comes to securing a gearcase worth thousands of dollars, replacing decades-old hardware is cheap insurance.
 
Contact Mike Hill at STVracer@yahoo.com