H: Hubs, Wheels and Tyres Hydraulic Steering Damper

oexing

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At that price customs are not interested, at least not in my country. You´d pay VAT if ever at all.
I am a bit astonished that you get that quoted stroke with your set up but then I only judge from the pictures and was wrong obviously. I´d have to see it in real life. Still I think the damper should be set more towards the crash bar for better kinematics and the alu lever modified accordingly. But still only my thinking, not knowing . . . .

Vic
 

timetraveller

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I think that you might find it harder than you think Vic. I made five plastic or wooden prototypes before I got it as I wanted it and I had the advantage of having a UFM off the bike and on a work stand so that I could play with the parts and have a good view of what was going to hit what. I still got it wrong because as soon as I mounted the UFM plus damper on to an engine I found that the long ally arm was hitting the front exhaust valve spring cap. Fortunately only by about one millimetre so that I could relieve the ally arm by that amount. The next batch of arms, which will be milled out rather than laser cut out, will have that mod incorporated. If you can produce a better design then you would be doing us all a favour. If you want to use the same damper then you are limited to that 75 mm total travel and in reality one cannot use all of that. I settled for about 65 mm and Vincent for about 70 mm. I know that a longer lever arm would produce more movement but both Vincent and I are using most of what is possible with these damper. I look forwards to seeing if you can produce a better design.
 

oexing

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Norman,
I was thinking in getting the lever roughly 90 degrees to the damper rod - like for brake arms to Bowden cables. I see the levers in the pictures almost parallel to the damper rod which seems a bit contra-productive. So I´d place the damper very close to the Sidecar lug to get some distance between it and the steering bearing. The lever would point to the rear of the bike and about 90 degrees to the damper rod. Don´t know yet if space was enough to achieve that. Anyway no extra long lever planned, but a near 90 degree action with the damper should do and not a lot of swivelling action of the damper cylinder to be expected as in your design - my guess only . . . .

Vic
 

timetraveller

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Hi Vic. Let us know how it goes when you try it. I could not get a layout like that to work but I'm always happy to see someone find a solution to a problem that I could not solve.:)
 

oexing

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Yes, certainly , but not this year, still busy with the engine for a while. You may be right in warning of any snags I do not see yet before trying to get this working. I am always happy to share any ideas and details I come upon when tinkering with motorbikes hoping someone finds them useful - or simply for interesting discussions that may lead to some other new ideas and inspirations.

Vic
 

macvette

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Thanks a lot for the pictures, yes, that is roughly what I was thinking of. BUT, I´d place the damper a few inches more to the rear of the bike when having it across and parallel to the crash bar. Judging from the pictures I guess the dampers do only a fraction of their stroke. The rod universal joint on the alu lever should better be placed more to the back of the bike to get more motion . It is too close to the centre line of the steering bearing to be real effective. The dampers would be OK when directed to some cylinder head nuts, so a lot more of stroke is achieved.
I am not in a stage to decide yet but will no way mount that silly crash bar so I guess to go for a bracket bolted into that side car lug to place an across damper close to the lug and fabricate an alu lever much shorter and pointing about 45 - 60 degrees to the left and rear when sitting on the bike. The lever could be clamped by the old steering damper knob assy just as it does with the friction discs, maybe a locating pin added, no screws required.
When a crash bar is fitted one could fabricate a bracket clamped onto that and get the across damper positioned the critical inches further back for more stroke. The alu lever will point a bit more to the back and be shorter to more effect - I think . . .

The bracket on that damper below has a better positioned universal joint - and it is a very good price, so I got one recently , great. Link:

Steering damper

Vic
Hi Vic,
The damper here is the same as the one I used and later supplied by Norman ( Chinese damper). Vincent's damper looks dimensionally the same but is more sophisticated, acting proportionally, the Chinese one is linear. Nevertheless, their mounted geometries are identical or at least very close. The damper pivot in your link is moveable so can be move from where it is to the centre of the damper body provided that the clamp is fitted so that it doesn't interfere with the damper valve body. The stroke on these dampers is 70mm.
The fore and aft mounting position needs to be such that the steering stops limit the travel before the damper reaches its limits and that the damper stroke is equally divided each side Of the damper body. The further the damper pivot is behind the centre of the steering stem, the longer the stroke used on the damper so the stroke and damper body pivot point are what determine the fore and aft position. Conversely, mounting the damper pivot closer to the centre of the steering stem reduces the stroke on the damper but increases the damper body rotation.
I started with an NHK damper whose body mounting ( like the one in your link) is fixed at the end of the damper but gave up trying to find a way of mounting it across the axis of the bike because of various interference issues on my twin even without a crash bar.
I asked Vincent for some advice and he posted some dimensions for me in the modified steering stem thread. Having got a Chinese damper, I prototyped a few actuating arms using the damper pivot in your link and as used by Norman and the boss for the original damper on the UFM as the hydraulic damper body mounting point. On my first attempt at making a real link ( as opposed to a mock up) to the damper rod and the damper body mounted behind the supplied pivot, I was not happy with the clearance of the damper rod and spring box on full left lock or the clearance of the damper body from the from the front cylinder exhaust cap full left lock.There was clearance but I thought that if I was unlucky enough to have a proper tank slapper I would prefer more so I went with a pivot mounted on the damper body centre line using the boss for original friction damper. Norman and I had quite a bit of correspondence on these issues and I would say that using the original friction damper stop as the mounting point is the way to go with this type of damper.
Vincent and I posted info and pictures in the modified steering stem thread on this subject.
Regards Mac
Forgot to say that my version uses 60mm out of an available 70 mm of stroke 5mm each side
 

timetraveller

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I recently measured the actual stroke of my damper and it is 75 mm. One could not use all of that but it gives you some idea of what you might be able to get away with concerning lever arms. I use about 65 mm of the total potential movement.. To give people some idea of prices. The dampers which I and Macvette use cost about £30. The Hyperpro, depending upon which model is used, costs about £320. One could be changed for the other if one wished and had the money.
 

oexing

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Now here is my idea of damper concept - worked on the bench, temporary setup without head lug bearings in there. So don´t be too eagle eyed in the Youtube video clip that I uploaded to give an idea of the motions. I did run into space problems with my first thinkings but finally changed places with damper rod and cylinder and liked the features as shown. No big problem to have even more clearances to girder parts or head lug casting but it should do like that. I´ll do more photos in daytime later. When a crash bar is fitted that could be used to clamp a bracket to it to provide the anchor bolt for the damper rod in the same relative position like in my alu bar that is fixed in the sidecar lug.
I think this configuration should provide more stroke around the neutral fork position and that is most important I believe. Judging from your pictures with the long alu lever more or less parallel to the damper cylinder I suspect the damper does not do much around the middle position but a lot more with more deflection on the handlebar - not sooo great if my thinking is correct ??
The mounting plate for the cylinder is a 4mm alu simply clamped tightly with the original steering damper knob, even friction discs may stay there. An alu dowel could be handy for keeping the position of the alu lever fixed on the Brampton bottom disc, but having no big torque to deal with. Distance between centres on the alu lever is 57mm presently, still safety space left on the damper rod both ends. Try to get the cylinder and rod roughly parallel to the girder fork bolts when full left lock is set, so in right lock this does not change much and middle position looks allright too, not so much swivelling of damper as in known designs above.
Hope you like it and prepared for discussing this.

Vic

Youtube link:
damper concept Brampton


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timetraveller

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Nicely done Vic. However, are you sure that the system will clear the fork legs/tubes or whatever they are called on the Bramptons? It looks like there might be a clash. I will write later, hopefully with a diagram, why the long aluminium bracket on the other designs does not reduce damper travel like you think. Remember that we are getting about 65 mm of movement on the damper, which is all that is possible.
 
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