FF: Forks Comprehensive Steering stem, with new lay out

[davidd]

Loctite there seems like a good idea.

The nut does the bearing adjustment...the pinch bolt is the mechanism that should be tightened second. Although I found that the adjustment would stay put with lock wire, I did not see the pinch bolt as harming anything and it is not much of a weight penalty (which is why John left it out) so I used the pinch bolt on the second racer.

I had plenty of handling problems, but I would have a difficult time saying that the pinch bolt caused any of them. When I sorted all the problems I was overjoyed, but I only had three races where the bike worked like a champ.

David

 

[greg brillus]

The issue we found at Goodwood took me by surprise........So much so that at first I was a little angry at Adam for even advising the problem......how dare he question the ability of the legendary Vincent........Anyway after holding the front wheel with my lower legs and twisting back and forth on the bars, there was clearly some play there.......perhaps with a steel column tube the 2 pad collet devices would have gripped better, the alloy one perhaps not so much as these small collets could "Bite" into the soft alloy and deform it enough to create a problem.......after all the top large nut just adjusts the bearing load, but would not stop the FF1 from being able to rotate on the stem.......I don't see it being a problem for normal riding or even track work......as David suggested, there are few of us who could push a Vincent as hard as a pro rider.

 

[Vincent Brake]

I think to put the grinders through first. Would be better.
And than use a clamping bolt.
Good idea.
Oh i machined the stem bit bigger there, so i can skim out the the FF1 to suit, light interfer fit.
So it ll be really fixed on the stem. After all we do the same with any new type of forks.

 

[oexing]

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
BMW taper roller

 

[Vincent Brake]

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
BMW taper roller

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thats the way to do it VIC !!!!!!!

 

[Vincent Brake]

New outside rings, as they need to be bit bigger. To suit the head stock. When that is cleaned up. With Hunger valve seat tool.
Material 1.2363 at 60-61HrC

 

[Vincent Brake]

And ready. Yes the front grease nippel should be pointed down.
But I always like them up.....