28-07-2021, 09:10 PM
Bearings used to carry bright spots. One was close clearance and 3 greater than normal. An old article in the Companion recommends one spot. As I have recounted before my father was fastidious and with oils of the time and short running used to replace the rear or all bearings every 2 or 3 years, about 10,000 miles. He was sold bearings of all grades and reckoned he could hear the difference.
From the NSK Manual. C3 is a grade more clearance than normal (unmarked). Running clearance is much influenced by the interference fits. Curiously the bearing tolerances are negative on both dias. To 12 and 15 microns, inner, outer.. A micron bit less than 1/2 a ten thousandth of inch. Older bearings were to a slightly more loose spec.
The Seven housings are seldom now still round. If somehow get less then no clearance difficult to assemble.
For normal crank deflections I suspect the light casting easily accomodates.
Has anyone had a main bearing fail by the classic rolling bearing process of spalling? Or all just by clearance increase (largely due to rust)
From the NSK Manual. C3 is a grade more clearance than normal (unmarked). Running clearance is much influenced by the interference fits. Curiously the bearing tolerances are negative on both dias. To 12 and 15 microns, inner, outer.. A micron bit less than 1/2 a ten thousandth of inch. Older bearings were to a slightly more loose spec.
The Seven housings are seldom now still round. If somehow get less then no clearance difficult to assemble.
For normal crank deflections I suspect the light casting easily accomodates.
Has anyone had a main bearing fail by the classic rolling bearing process of spalling? Or all just by clearance increase (largely due to rust)