These things are called SPHERICAL ROLLER BEARING , for Crank shaft WHIP . Which can shatter standard ' parralel roller ' roller bearings .
The NORTON ' superblend ' was a single row barrel roller . Dunstall had done deep track heavy duty Ball races , which waylayed the result of CRANK ' BOW ' where the central flywheel
gets around 4 thou. flex per revolution . Cunning old swine ' pre cambered ' cranks , so as they were STRAIGHT under maximum duress - thereby loosing less output losses , thereby
GOING FASTER .
Theyed tried first , radiused edge parrallel barrel rollers , as symptom was ' the ends dug in ' Failure evidence . The DEEP TRACK Ball Races just carried greater load than standard .
P 24 & 26 Here .
http://archives.jampot.dk/general/Dunstall_Catalogue_1969.pdf . ANY ball race would have SOME linear ' side load ' acceptance / capabilty .
Cyclic , oscilating , & more ' skidding 'is a worry . Ducati roller mains & XR H. Dav. benifit from PRE WARMING the OIL , as a countermeasure to oil wedge causing skidding & cosequent failure .
TRIUMPH , at one time , had ' thrust ' ball race - timing side or worse primary ( drive ) side , open ' ball race . where the groove was removed inward on the inner race - caged outer .
so ' free sliding ' to account for case expansion . Perhaps as much as 10 thou. linear , across the crankshaft housing - in the alloy case .Typical for Ball Races to work loose on the shaft.
Otherwise . fret . Like the shiny marks on a crankcase housing if the bearing outer has ' spun ' .
Id think muddle injuns just run anything thats proved acceptable reliability . As In if theyve continually failed , theyve put a bigger one in for better reserve . Like Most things !
or a more expensive , better quality , or greater load capeability one . But Mass Production costings get bigger is better , if the accountant want to keep their expense accounts .
Typically , 7 thou. perhaps ' end float ' is required in a pommy twin , on set up . but not mort than 10 . on a 40 or 45 cu. inch injun . Ours are a bit smaller . 2 thou. might be mentioned .or less .
https://web.archive.org/web/20060923041135/http://home.wxs.nl/~wakke007/fmv/fmv_7.htmhttps://www.real-classic.co.uk/2018/02/15/classic-techniques-superblend-bearings-part-one/