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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Comprehensive Steering stem, with new lay out
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<blockquote data-quote="oexing" data-source="post: 176623" data-attributes="member: 1493"><p>No matter how nicely you set your steering bearings, below and top, the fit of the stem vs. top casting has to be nil play. So in cruel reality you set the top forging on the mill or lathe - somehow - and bore it oversize round and parallel finally. Only then you can get the stem with its lower yoke and fabricate an adapter to go with the oversized upper yoke. The adapter can be loctited on the stem and then in place turned to slip fit the top yoke. The pinch bolt cannot possibly prevent any excessive play in the fork against playing up on the road. So this way you can restore and old stem for good fit, no oversize stem needed. </p><p> One fact I like about taper roller types is the larger bearing fit on the stem. I have had mangled stems from minimum play of inner race with angular ball bearings working into excessive play. So in case of my two fu***d up Bramptons I decided on the BMW replacement taper types, 34 - 51 - 12 mm, great for fitting them into the headlug, which got standard ca. 50.5 ot 2 " I think. The inner race 34mm gets you some range for dealing with banana shaped stems and you can pressadjusting the lot for perpendicular lower bushes true to the stem, checking them on the lathe between centers. I needed a few loctited bushes on top of each other in the lower place for having a wider adapter to go with the taper bearings. All final o.d.s of adapters were done on the lathe after the loctiting job certainly. So all bearing seats will align perfectly. Even the new adapter for bored top yoke casting can be loctited on and turned to slip fit size. </p><p> Next question, how to get the head lug from 2" to 51 mm : Long time ago with luck I found a truck engine size Hunger manual boring head with horizontal plus vertical automatic feed that is meant to bore recesses for valve seat rings in cyl. heads. These types go on top of collet-clamped pilots in valve guides, so in our case you need to have a mandrel in the head lug fixed in the rough cast middle part of the head lug, so you can machine the bearing seats at both ends with same mandrel in place. So no need to awkwardly setting up the headlug on a mill and somehow making sure both ends of bearing seats will align in the end - very tricky to do unless you got your Hunger device. </p><p> "Wedging up" with taper roller bearings - never come across this effect, wonder what the real roots of this might be. </p><p></p><p> Vic</p><p><a href="https://www.ebay.de/itm/362209326333?fits=DEM_Make%3ABMW&hash=item54555bb4fd:g:qroAAOSwZLtaVez9&amdata=enc%3AAQAIAAAAwLQxhKTyrVg7IMPOKBv6yi9%2FBpOY1btusuqnlje%2FfkZjLZNkmkBtSShsPiz43nYIKrjlT3lmHaozs6K%2FHDm7a2QnOv3xrZ9JoxExDauesJi02FMF5rivTVzey06j8zmjpAGbkRuotvDz%2BNzNJmilJ5wBbAx0oW0BSDfCV17gkkx9hY%2FxUat5vLRf%2B0dXeAe%2Frt1Apr9diEfPOycLkxMhw0lB2wnHqSI%2F%2BsISh%2F377eoerW7MdoH3gSPIsfq2XKughw%3D%3D%7Ctkp%3ABk9SR6akwonyYg" target="_blank">BMW taper roller</a></p><p></p><p>[ATTACH=full]61050[/ATTACH]</p><p></p><p>[ATTACH=full]61051[/ATTACH]</p><p></p><p>[ATTACH=full]61052[/ATTACH]</p><p></p><p>[ATTACH=full]61053[/ATTACH]</p></blockquote><p></p>
[QUOTE="oexing, post: 176623, member: 1493"] No matter how nicely you set your steering bearings, below and top, the fit of the stem vs. top casting has to be nil play. So in cruel reality you set the top forging on the mill or lathe - somehow - and bore it oversize round and parallel finally. Only then you can get the stem with its lower yoke and fabricate an adapter to go with the oversized upper yoke. The adapter can be loctited on the stem and then in place turned to slip fit the top yoke. The pinch bolt cannot possibly prevent any excessive play in the fork against playing up on the road. So this way you can restore and old stem for good fit, no oversize stem needed. One fact I like about taper roller types is the larger bearing fit on the stem. I have had mangled stems from minimum play of inner race with angular ball bearings working into excessive play. So in case of my two fu***d up Bramptons I decided on the BMW replacement taper types, 34 - 51 - 12 mm, great for fitting them into the headlug, which got standard ca. 50.5 ot 2 " I think. The inner race 34mm gets you some range for dealing with banana shaped stems and you can pressadjusting the lot for perpendicular lower bushes true to the stem, checking them on the lathe between centers. I needed a few loctited bushes on top of each other in the lower place for having a wider adapter to go with the taper bearings. All final o.d.s of adapters were done on the lathe after the loctiting job certainly. So all bearing seats will align perfectly. Even the new adapter for bored top yoke casting can be loctited on and turned to slip fit size. Next question, how to get the head lug from 2" to 51 mm : Long time ago with luck I found a truck engine size Hunger manual boring head with horizontal plus vertical automatic feed that is meant to bore recesses for valve seat rings in cyl. heads. These types go on top of collet-clamped pilots in valve guides, so in our case you need to have a mandrel in the head lug fixed in the rough cast middle part of the head lug, so you can machine the bearing seats at both ends with same mandrel in place. So no need to awkwardly setting up the headlug on a mill and somehow making sure both ends of bearing seats will align in the end - very tricky to do unless you got your Hunger device. "Wedging up" with taper roller bearings - never come across this effect, wonder what the real roots of this might be. Vic [URL='https://www.ebay.de/itm/362209326333?fits=DEM_Make%3ABMW&hash=item54555bb4fd:g:qroAAOSwZLtaVez9&amdata=enc%3AAQAIAAAAwLQxhKTyrVg7IMPOKBv6yi9%2FBpOY1btusuqnlje%2FfkZjLZNkmkBtSShsPiz43nYIKrjlT3lmHaozs6K%2FHDm7a2QnOv3xrZ9JoxExDauesJi02FMF5rivTVzey06j8zmjpAGbkRuotvDz%2BNzNJmilJ5wBbAx0oW0BSDfCV17gkkx9hY%2FxUat5vLRf%2B0dXeAe%2Frt1Apr9diEfPOycLkxMhw0lB2wnHqSI%2F%2BsISh%2F377eoerW7MdoH3gSPIsfq2XKughw%3D%3D%7Ctkp%3ABk9SR6akwonyYg']BMW taper roller[/URL] [ATTACH type="full"]61050[/ATTACH] [ATTACH type="full"]61051[/ATTACH] [ATTACH type="full"]61052[/ATTACH] [ATTACH type="full"]61053[/ATTACH] [/QUOTE]
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Tech. Advice: Series 'B' / 'C' 500cc/1000cc Bikes
Comprehensive Steering stem, with new lay out
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