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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Interesting big end...
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<blockquote data-quote="oexing" data-source="post: 99282" data-attributes="member: 1493"><p>Now that big end assembly is definitely olde style with them big 1/4" rollers in there. That was bad practise decades ago already when nobody had much of an idea what is going on in a big end with all that heavy weight in a very dynamic space. Do you realize that each of these overweight rollers have to be accelerated and shortly after decelerated in each single revolution of the crank ?? You will know the swivelling motion of the conrod when it goes past TDC and BDC pointing to the front of the bike and shortly after to the back of the bike. Means, the big end bearing accelerates a bit , then has to slow down a bit - each revolution of the crank. So there is a constant pushing and shoving within all components in the bearing and heavy items in there are quite simply "reeal baaad". In consequence there is a lot of slipping and friction between components to keep all parts in their places.</p><p> To add to the drama, the big end bearing does not rotate around its own centre but instead it is placed half of the crank stroke out from the centre of the crank main bearing so it gets the full force of the centrifugal effect at the crank pin radius onto all bearing components on top . So it is crucial to have light weight items in there and big rollers are just not what you´d want. You will not find these types of rollers any more in modern engines. INA have never had needle rollers bigger than 4 mm in their famous big end bearings, no two rollers in one steel cage slot, always full length. And they knew their job. BSAF in Netherlands get the 35-42-20mm needle bearings INA type for the new production Gold Stars, Manxes had the biggest INA type 40-48-20 mm needle bearing in last decades but both types are no longer available from INA for many years. </p><p> Anyway, no question for me to have the 40-48-20 mm bearing for the B-Rapides, pressed up crank with 40 mm pin, case hardened rods of my own design and manufacture. Big rollers make for a weak crank pin too, not great for long pins like in Vincents. </p><p></p><p> Vic</p><p></p><p>[ATTACH=full]23636[/ATTACH]</p><p></p><p></p><p>[ATTACH=full]23637[/ATTACH]</p><p></p><p></p><p>[ATTACH=full]23638[/ATTACH]</p></blockquote><p></p>
[QUOTE="oexing, post: 99282, member: 1493"] Now that big end assembly is definitely olde style with them big 1/4" rollers in there. That was bad practise decades ago already when nobody had much of an idea what is going on in a big end with all that heavy weight in a very dynamic space. Do you realize that each of these overweight rollers have to be accelerated and shortly after decelerated in each single revolution of the crank ?? You will know the swivelling motion of the conrod when it goes past TDC and BDC pointing to the front of the bike and shortly after to the back of the bike. Means, the big end bearing accelerates a bit , then has to slow down a bit - each revolution of the crank. So there is a constant pushing and shoving within all components in the bearing and heavy items in there are quite simply "reeal baaad". In consequence there is a lot of slipping and friction between components to keep all parts in their places. To add to the drama, the big end bearing does not rotate around its own centre but instead it is placed half of the crank stroke out from the centre of the crank main bearing so it gets the full force of the centrifugal effect at the crank pin radius onto all bearing components on top . So it is crucial to have light weight items in there and big rollers are just not what you´d want. You will not find these types of rollers any more in modern engines. INA have never had needle rollers bigger than 4 mm in their famous big end bearings, no two rollers in one steel cage slot, always full length. And they knew their job. BSAF in Netherlands get the 35-42-20mm needle bearings INA type for the new production Gold Stars, Manxes had the biggest INA type 40-48-20 mm needle bearing in last decades but both types are no longer available from INA for many years. Anyway, no question for me to have the 40-48-20 mm bearing for the B-Rapides, pressed up crank with 40 mm pin, case hardened rods of my own design and manufacture. Big rollers make for a weak crank pin too, not great for long pins like in Vincents. Vic [ATTACH=full]23636[/ATTACH] [ATTACH=full]23637[/ATTACH] [ATTACH=full]23638[/ATTACH] [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Interesting big end...
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