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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
main bearings
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<blockquote data-quote="oexing" data-source="post: 103794" data-attributes="member: 1493"><p>Bernd, the question about brass cage or modern plastic is a thing of religion: I did not have particularly positive experiences with these once very expensive and old time brass cages, not worth the money. Brass is veeery heavy , worse than steel and I will never again install these rattly heavy cages in an engine. PA 66 GF have a max 120 degrees C permanent so in a classic all roller bearing type engine you will hardly ever see more than 100 degrees , no reason for expecting trouble with them. </p><p> Basically I´d go for restoring the correct shrink fit in the engine case and my way would be to downsize the o.d. in the case for the metric type with 62mm so you don´t weaken the case by taking out another millimeter or rather two for a substantial bush. As expected there were reports of cracked cases by drilling screw holes or some such. Only extra job towards metric is to fabricate a sleeve on the mainbearing shaft for 30mm from standard 25.4 . </p><p> But in Erik´s case a temporary solution is wanted, possibly by Loctiting loose outer races. A very safe way I came up is to heat case with outer race dropped in up to 120 - 130 degrees, check clearance with fine feeler gauge blades at this temperature , cut 2mm strips from blades for even gap around the race to keep it concentric with four strips of feeler blades - that you can pull out after the Loctite has settled a bit. A very low strength/viscosity type like 221 will fill the gaps around the race in the hot case instantly and at normal engine operating temps at , my guess, 80 to 100 degrees the races will still be gripped with correct shrink fit. In classic times bearing shrink fits were calculated for dropping out at about 120 degrees, 200 degrees seem to me way over top. This kind of heat is required for inserting valve seat rings or valve guides only into alu heads. </p><p>Never cared about C 3 or any other classification. In motorbike application you are lucky to operate an engine with good shrink fits after decades and even then that shrink will be next to zero when hot , so why provide extra play in the bearingm for what reason ? Whenever a crank is out of true a C 3 will not help much. </p><p></p><p> Vic</p><p>brass cage bearings :</p><p><a href="https://www.ebay.de/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=rollenlager+messingk%C3%A4fig&_sacat=0" target="_blank">Roller bearings</a></p></blockquote><p></p>
[QUOTE="oexing, post: 103794, member: 1493"] Bernd, the question about brass cage or modern plastic is a thing of religion: I did not have particularly positive experiences with these once very expensive and old time brass cages, not worth the money. Brass is veeery heavy , worse than steel and I will never again install these rattly heavy cages in an engine. PA 66 GF have a max 120 degrees C permanent so in a classic all roller bearing type engine you will hardly ever see more than 100 degrees , no reason for expecting trouble with them. Basically I´d go for restoring the correct shrink fit in the engine case and my way would be to downsize the o.d. in the case for the metric type with 62mm so you don´t weaken the case by taking out another millimeter or rather two for a substantial bush. As expected there were reports of cracked cases by drilling screw holes or some such. Only extra job towards metric is to fabricate a sleeve on the mainbearing shaft for 30mm from standard 25.4 . But in Erik´s case a temporary solution is wanted, possibly by Loctiting loose outer races. A very safe way I came up is to heat case with outer race dropped in up to 120 - 130 degrees, check clearance with fine feeler gauge blades at this temperature , cut 2mm strips from blades for even gap around the race to keep it concentric with four strips of feeler blades - that you can pull out after the Loctite has settled a bit. A very low strength/viscosity type like 221 will fill the gaps around the race in the hot case instantly and at normal engine operating temps at , my guess, 80 to 100 degrees the races will still be gripped with correct shrink fit. In classic times bearing shrink fits were calculated for dropping out at about 120 degrees, 200 degrees seem to me way over top. This kind of heat is required for inserting valve seat rings or valve guides only into alu heads. Never cared about C 3 or any other classification. In motorbike application you are lucky to operate an engine with good shrink fits after decades and even then that shrink will be next to zero when hot , so why provide extra play in the bearingm for what reason ? Whenever a crank is out of true a C 3 will not help much. Vic brass cage bearings : [URL='https://www.ebay.de/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=rollenlager+messingk%C3%A4fig&_sacat=0']Roller bearings[/URL] [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
main bearings
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