FF: Forks Cadwell Landsdowne video + Suspension Setup

vibrac

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Well we were down on power we still got a 1st in our class on Saturdays race but the silencers need to be revised, this is Sundays race the camera is positioned to examine the forks performance (Norman will no doubt be interested) I guess it needs harder springs but looks deceive it handles very well. There were two missed gear changes the first one was a tour of the grass infield (you need engine breaking coming down the mountain!) the other was a lot over 6K and the result was silence. as I said in my bit in MPH that tee shirt said it all "Race Break Mend Repeat!"

 

Bill Thomas

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Too much movement , Frightened me !,
But took me back a few years !,

Can't find any info in any books other than Paul Richardson.
" The racing gearbox has Double backlash on third and top gear dogs "
 
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timetraveller

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Thanks for posting that Tim and Ben. I know you have had 36, 33 and 30 lbs/inch springs from me but am not sure which you are currently using in the twin. Normally I would recomend 36s for a road equipped twin with a medium weight rider so although I don't know Ben's weight I would have thought that the 33s were as light as one would want to go, I know that Greg favours 45 lbs/inch springs for road bikes, even for Comets if I have that correct, but road users over here have found that too stiff unless they are over, say18 stones/252 lbs/114kg. Let us know what failed.
Just noticed that for Greg's information the damper is an AVO and it looks to me as though a touch more damping might help. They are easily adjustable.
 

vibrac

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What springs and front shocker are you running...........?
too soft springs and AVO damper on low setting but of course its very stiff on rebound (forks going down) any harder setting seems very stiff. However to repeat it does handle very well we could wish for more ground clearance at certain times hence a stronger spring to jack it up a lttle
 

Bill Thomas

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I agree with what I think Vic said,
We should try and get the movement less ,
Bit like the Bramptons ?.
 

Chris Launders

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Mine moves as freely as that, just not under power, probably because I don't have as much and the bike/rider is much heavier.
I would have said slightly harder springs were needed, try fitting one 45 then you could play with the 30/33/36 ones to go with it, they don't have to be changed as a pair.
 

greg brillus

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The reason you all feel the 45 lb springs are too stiff is because you are installing them at their full length.........This makes the front end "Top out"........Every one that I do I cut around 15 to 20 odd mm off each spring.........From my findings almost every shock absorber made to suit a Vincent is way too stiff.........the best is either an original Vincent shock or a Thornton front spec shock..........If you study any motorcycle suspension literature it generally states that you should not use stiff shock absorbers to "Mask" soft springs. I have come up with my own modern adjustable shock absorber which is the same as the ones I used on the twin racer i had years ago.......... I have even had to bleed off some of the nitrogen pressure within the unit to remove some of the stiff compression damping........This gives a great ride and has adjustable rebound damping........On Tim's/Ben's racer above you can see the front end diving quite a lot under braking......... I would go to the 45 pound springs both sides and cut them down enough so the front end is not topped out..........This will help a lot........The shock absorber might be ok, but it is good to try others if you have something........The original Koni's are ok, just........They too are too stiff as well........I recently bought some new Ikon shocks to install on 2 road bikes........after a test ride i removed them and sent them back along with an original Thornton front shock and asked them to re-valve them to similar specs. The front end on these bikes felt ridiculously stiff.......horrible....... I question why they make them so stiff, we will see what happens.........Nice to see a Vincent on the track........I raced my Norvin single last weekend, it is my belief that you can easliy make a Vincent handle better than a featherbed frame bike.........I've been really tempted to pull the engine from the frame and go to an all Vincent racer again.
 

Chris Launders

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I think enquiries were made about making the AVO damper softer but it couldn't be done without a fundamental re-design and it's associated cost.
 
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