Ford 9″ – Getting a ring to clear pilot housing
A very common problem when installing low gear ratios in a Ford 9” is that as the ring gear gets thicker the toe of the gear hits the pilot bearing housing leaving you with only two options, grind the gear, or the housing. We prefer grinding the gear, the problem with grinding on the pilot housing is it tends to make it thin and weak making it prone to cracking. By grinding the gear you have no sacrifice in strength and it takes less time. Some OE Ford gears as well as a small few aftermarket gear manufactures chamfer their gears from the factory to minimize the possibility of additional grinding being necessary during installation.
Below is a picture of the best method we have found to clearance a 9” ring gear to clear the drop out case. CAUTION it is very easy to over heat the gear while grinding it with a bench top grinder, so be patient and only take as much as necessary. Clearing the pilot by 1/16” is more than enough clearance. After you have removed the necessary material, remove any burs with a 3M pad and thoroughly clean the gear before installation.