H: Hubs, Wheels and Tyres Hydraulic Steering Damper

[Bill Thomas]

When I raced with a standard damper, I found it was safer to have it a bit tight, But on slow bends, ie hairpin
I would go round in jerks, After I stopped racing and fitted an Hydraulic one on the road, It was so much better, I am sure I would have been faster, Too Late !. Cheers Bill.

 

[oexing]

Admittedly there may be no real need for a hydraulic damper on a Brampton, but I feel the ride could be more smoothly with it and less judder/flutter than with the old friction system that you do not want to set too tight to avoid producing hexagonal or octogonal lines around basically smooth round corners - as was just confirmed by Bill while writing this. At € 30.- from China and a couple of rewarding and nice hours in your workshop this is no big deal anyway. There was a word about providing some extra backlash in a friction damper set for better straight line steering - I would better not do this on purpose, believing that some free motion may lead to flutter and even to a fierce wobble . Backlash here is likely not desirable but simply worn out components.
Mac also just confirmed my experiment from a few days ago when I fabricated an alu lever with said 57mm between centres to use most of the available stroke, I started with 53 mm and revised it with no. 2 lever. In past hours I studied some more damper installations on youtube but as I said, at my very first sight ever of an across damper in Norman´s design I really could not figure out how that behaved at the critical position around neutral straight ahead direction. By now I think it does not matter much in real life in his and my setup which one to choose. One has to look at ways to mount the kit on your particular bike to find out what suits best without collisions of components.
While having been unable to figure out how Norman´s concept worked I came to the - for me- more obvious design with a simple alu lever cum cylinder at 90 degrees to the rod at neutral . And still I think , even considering some second lever effect in academic view in there, that effect is more or less to be ignored at these critical +/- 5-10 degrees from neutral. Any trigonometric effect from this second lever influence is of minimal practical consequence on the road - or at least not worthwhile to care for. There is more bonus to have from the offset clamp in the China kit like finding more space in end positions due to that offset.
Mac, could you post some photo of your setup for studies ? Sorry for not supplying numbers of stroke versus steering rotation, I have no bearings yet for the steering lug, resp. lug not yet machined for taper rollers on stock.

Vic

Youtube clip version Vic:
damper concept Brampton

 

[timetraveller]

Thanks for all that Vic. It is interesting how different people come up with different designs to do the same job. I started with the pre-conception that it had to have a lever and played around with bits of plastic and wood until I got the movement I wanted. I assume that both Macvette and Vincent did something similar. You had a different vision to start with and yet all the designs seem to work well enough. I found it amusing to watch some of the videos that you gave links to. I always assume that there is a team of highly trained people behind commercial designs but when I saw them having to insert 'o' rings and rotate fork legs to get clearance, similar problems which I had to overcome, I realise that at some level we are all just chaps messing about in sheds.
I do agree with you that it would be a mistake for Vibrac to put some slop into his system but it is his bike and health so it is up to him. It is just worth emphasising that it should not be necessary and could be counterproductive/dangerous.

 

[Simon Dinsdale]

When you refer to backlash or slop in the original Vincent friction steering damper just be aware that in Paul Richardson Vincent Motorcycles on pg 28 in my copy it states "the anchor pin must be a slack fit in the head-lug to assist self centralising". I've also read somewhere Phil Irving refer to exactly the same.

 

[Bill Thomas]

But not needed with the Hydraulic set up, If the Hyd' type was that stiff, It would weave. Cheers Bill.

 

[timetraveller]

If you can manage to get hold of one of these hydraulic dampers you will see why I am suspicious of the need for any slackness. At low speeds there is very little resistance to movement. They are intended to resist rapid movement. It is a totally different animal to friction dampers which have some resistance to initial movement (sticktion) and then less resistance once they are moving. Note that several people have now used these on Vins (the Tilley's trip to the French rally being the easiest to look up) and non of them have found the need to build slop into the system.

 

[Nulli Secundus]

It is a totally different animal to friction dampers which have some resistance to initial movement (sticktion) and then less resistance once they are moving.

And that explains why the old technology was never likely to work.

 

[macvette]

Hi Vic, pictures of my set up in thread hyperpro damper assembly. if you pivot your damper body on its centreline, it will give very nearly the same stroke as you have now.
On the subject of weave;- when I first rode my bike after originally rebuilding it, there was an annoying click from the front end as I rode off. After checking, I finally chased it down to the friction damper stop. The first few times I rode with the modified stem and hydraulic damper, I wobbled up to about 10 mph. It wasn't the bike, I had got used to subconsciously compensating for the stiction in the original damper. I don't think you should have any slop in the hydraulic damper set up.

 

[vibrac]

If you can manage to get hold of one of these hydraulic dampers you will see why I am suspicious of the need for any slackness. At low speeds there is very little resistance to movement. They are intended to resist rapid movement. It is a totally different animal to friction dampers which have some resistance to initial movement (sticktion) and then less resistance once they are moving. Note that several people have now used these on Vins (the Tilley's trip to the French rally being the easiest to look up) and non of them have found the need to build slop into the system.

that weave as described by Bill is exactly what I was getting from my new steering head steering damper it is I repeat only a slight anoyance I am sure just a slackness of a few degrees would cure it we shall see in the spring

 

[Bill Thomas]

The other thing could be if taper rollers are fitted, Some set ups the inner sticks out the end of the outer,
Inside, And can touch the steering head casting, A lot has to be ground out. Cheers Bill.