There's no minimum or maximum 'space' for the pin. The center pin is is 1 1/2" long and with the right axles for the housing, you should be able to adjust them for the proper clearance cold. IIRC, it's around .010" but man, I've been adjusting them all my life just by feel and have never had an issue. Also, the thrust pin doesn't have much to do with the proper functioning of the SureGrip and associated parts. It's job is to take up the space between the axles so they have the proper bearing preload....which really isn't much until they warm up but it's enough to make them work.
