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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
1951 Black Shadow Restoration
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<blockquote data-quote="oexing" data-source="post: 133861" data-attributes="member: 1493"><p>The lipped roller bearings are all metric with PA 66 gf cages, sizes 30-62-20 resp. 16 mm. The positive thing is you can sleeve fu***d up bores for mains from 63.5 to 62 without weakening the case again by oversize boring for a 63.5 mm sleeve for original size. You then could have the mainshaft sleeved from 1 " /25.4mm for new 30 mm inner race, all to restore exact fits - without Loctite or staking marks, so with a hot engine no race walk will happen. Lipped roller bearings are no different to work out for side play and depths in cases than with ball bearings so no reason for unlipped races on the outer - plus safety (certainly <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /> ) staking circumference of bores. Another choice is the 25-62-17 or -24 mm sizes, same sleeve from 63.5mm to 62 bore. The inner race could be opened for 25.4 mm standard mainshaft for half thou shrink fit. I do all engines with roller bearings with rollers contained in outer race, a lot easier to handle and slick to put together. Have never come across types with rollers on inner race fixed, not very common here. Also these PA 66 modern bearings can take a LOT higher loads than the ancient steel cage relics.</p><p> When having the metric lipped outer races with rollers you do assembly a bit different to normal practice as the oil pump worm will not pass the rollers later. So first drop in the smaller outer roller bearing, drop in the worm, then the inner main bearing with its rollers. You have to line up the worm for the key on the mainshaft and look there when lowering the upper engine half so it slips down and through the inner race of the small outer bearing. Seems tricky but I had no problem with it, the inner race of the small bearing a push fit on the main by some polishing done.</p><p> When races fall out of bores when turning over a hot case - reason for staking (??) - this would be another telltale for dodgy machining. You only need extra high heat for fitting follower spindles at 200 degrees but you do this job at the start of rebuilding. So later all fits for bearings should be allright up to 100 degrees without dropping out else you´d get walking races with operating engines from correct shrink fits gone - or never achieved at all. As to Loctites, for tricky fits the type 620 and 640 offer extra slow curing times for dropping races into a hot case or for follower spindles too. Important point, you got to have the engine cases at minimum operating temperatures, so at least 100 degrees I´d say for loctiting bearing races etc . . If you do this at room temps the glued race will be loose with a hot engine as the alu case will grow a gap to the less expanding steel race. The Loctite is not a real glue but will just fill all gaps and cracks and pores and its strength is in shear loads, not glue power.</p><p> Taper roller mains are not my thing, you´d be very sure to get preloads on the bearings at cold engine right, else they will be sloppy at hot conditions - less critical with narrow cranks like Velocettes or HDs but even more questionable with wide cranks on Vincent twins. And not as easy spinning as cylindrical rollers I´d believe. Spacing taper rollers in the engine is a bit lengthy to do compared to ball or roller bearings. For the Vincent engines I made copies of all bearings from POM rounds, easy slip fit in bores and shafts, but exact width of actual bearings for getting all sizes of spacers . That is simple to fabricate with a lathe and saves a lot of head scratching and you can do trial assembly of gearbox contents too. You could sand down old bearing races for same trial assemblies but the POM bits are just great for this job.</p><p></p><p> Vic</p><p><a href="http://dm.henkel-dam.com/is/content/henkel/The-Adhesive-Sourcebook" target="_blank">Loctite retaining compounds</a> from page 127 .</p></blockquote><p></p>
[QUOTE="oexing, post: 133861, member: 1493"] The lipped roller bearings are all metric with PA 66 gf cages, sizes 30-62-20 resp. 16 mm. The positive thing is you can sleeve fu***d up bores for mains from 63.5 to 62 without weakening the case again by oversize boring for a 63.5 mm sleeve for original size. You then could have the mainshaft sleeved from 1 " /25.4mm for new 30 mm inner race, all to restore exact fits - without Loctite or staking marks, so with a hot engine no race walk will happen. Lipped roller bearings are no different to work out for side play and depths in cases than with ball bearings so no reason for unlipped races on the outer - plus safety (certainly :) ) staking circumference of bores. Another choice is the 25-62-17 or -24 mm sizes, same sleeve from 63.5mm to 62 bore. The inner race could be opened for 25.4 mm standard mainshaft for half thou shrink fit. I do all engines with roller bearings with rollers contained in outer race, a lot easier to handle and slick to put together. Have never come across types with rollers on inner race fixed, not very common here. Also these PA 66 modern bearings can take a LOT higher loads than the ancient steel cage relics. When having the metric lipped outer races with rollers you do assembly a bit different to normal practice as the oil pump worm will not pass the rollers later. So first drop in the smaller outer roller bearing, drop in the worm, then the inner main bearing with its rollers. You have to line up the worm for the key on the mainshaft and look there when lowering the upper engine half so it slips down and through the inner race of the small outer bearing. Seems tricky but I had no problem with it, the inner race of the small bearing a push fit on the main by some polishing done. When races fall out of bores when turning over a hot case - reason for staking (??) - this would be another telltale for dodgy machining. You only need extra high heat for fitting follower spindles at 200 degrees but you do this job at the start of rebuilding. So later all fits for bearings should be allright up to 100 degrees without dropping out else you´d get walking races with operating engines from correct shrink fits gone - or never achieved at all. As to Loctites, for tricky fits the type 620 and 640 offer extra slow curing times for dropping races into a hot case or for follower spindles too. Important point, you got to have the engine cases at minimum operating temperatures, so at least 100 degrees I´d say for loctiting bearing races etc . . If you do this at room temps the glued race will be loose with a hot engine as the alu case will grow a gap to the less expanding steel race. The Loctite is not a real glue but will just fill all gaps and cracks and pores and its strength is in shear loads, not glue power. Taper roller mains are not my thing, you´d be very sure to get preloads on the bearings at cold engine right, else they will be sloppy at hot conditions - less critical with narrow cranks like Velocettes or HDs but even more questionable with wide cranks on Vincent twins. And not as easy spinning as cylindrical rollers I´d believe. Spacing taper rollers in the engine is a bit lengthy to do compared to ball or roller bearings. For the Vincent engines I made copies of all bearings from POM rounds, easy slip fit in bores and shafts, but exact width of actual bearings for getting all sizes of spacers . That is simple to fabricate with a lathe and saves a lot of head scratching and you can do trial assembly of gearbox contents too. You could sand down old bearing races for same trial assemblies but the POM bits are just great for this job. Vic [URL='http://dm.henkel-dam.com/is/content/henkel/The-Adhesive-Sourcebook']Loctite retaining compounds[/URL] from page 127 . [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
1951 Black Shadow Restoration
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