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rotorwrench · 04-17-2019, 08:59 AM

The 49 through 51 Mercury cars have a heavy duty version of the Gemmer II gearbox. They have a larger sector shaft than Ford cars ever had up to that point. The bushing can wear and allow more than normal movement of the lower end of the sector shaft. This can cause seal damage over time. I've found these bushings on flea-pay but I think there are still a fair amount of NOS ones out there since they were originally for Ford truck gearboxes. The sector lower seal is available at most of the restoration parts suppliers. When everything is sealed up, about any good grade of gear lube will stay in there pretty well. On a leaker, I would use the HD corn header grease. As a thixotropic grease, it coats gears well when moving and solidifies at rest. Those JD corn cutting head gearboxes have a shaft going in and several going out so there are multiple places for the seals to leak. This is why JD chose the stuff. They may still have a video on their web site showing a cut away gearbox functioning with the stuff.

04-17-2019, 08:59 AM	#14
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,422	Re: What oil to in a steering gear box? The 49 through 51 Mercury cars have a heavy duty version of the Gemmer II gearbox. They have a larger sector shaft than Ford cars ever had up to that point. The bushing can wear and allow more than normal movement of the lower end of the sector shaft. This can cause seal damage over time. I've found these bushings on flea-pay but I think there are still a fair amount of NOS ones out there since they were originally for Ford truck gearboxes. The sector lower seal is available at most of the restoration parts suppliers. When everything is sealed up, about any good grade of gear lube will stay in there pretty well. On a leaker, I would use the HD corn header grease. As a thixotropic grease, it coats gears well when moving and solidifies at rest. Those JD corn cutting head gearboxes have a shaft going in and several going out so there are multiple places for the seals to leak. This is why JD chose the stuff. They may still have a video on their web site showing a cut away gearbox functioning with the stuff.