FF: Forks Girdraulic Springs

druridge

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Many thanks all for your replies - yes I now do feel like I've just kicked over the can of worms!
However.....
Davidd : I've looked at a couple of photos of the bike on the(central) sidestand, and all show the front lower link FF3 tilted down at the leading edge. I now see I should have checked this more carefully before it came to bits (leant against a wall under its own weight, me sat on it etc).
Timetraveller : I clearly need to read and absorb the 'modified steering head' thread, I have seen some of the posts already but hadnt linked my problem to that.
I honestly haven't noticed any chassis lift when the brakes are applied (but would have said it doesnt squat either), it's fitted with two Grimeca calipers and they work well.
I've never had any head shake or nervousness so have never thought of a steering damper.
Macvette :Once I've checked the lower link for horizontal, then I agree any mods should best be done one at a time and checked out on the road. I'm thinking a new pair of D springs might be in order as Step1
Much appreciated!
 

timetraveller

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I think that when you have fitted the 'D' springs you will find that the front end is higher. Then when you brake hard I think you will find the effect that David mentioned, that is the bike will try to rise up over the forks. After that you might want to consider what to do next. Good luck with it.
 

everiman

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My easy way of finding spring rates for anonymous springs, find a round bar or tube that will fit inside the spring, about 6" longer than the spring. Clamp tube in vice, put spring over the tube, measure spring length

Get some barbell weights, if you don't have any, your local thrift store will. Slip at least 25 kg, or 50 pounds whatever will fit, onto the tube so the springs are compressed, measure the length, you might need a large washer for a skinny spring. Lets say that 25 kg compresses the springs 3/8 inch, convert kg to pounds, 25 X 2.2 = 55 pounds (55/3) X 8 = 147 pounds per inch. Not extremely accurate, but accurate enough.
 

Martyn Goodwin

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I think that when you have fitted the 'D' springs you will find that the front end is higher. Then when you brake hard I think you will find the effect that David mentioned, that is the bike will try to rise up over the forks. After that you might want to consider what to do next. Good luck with it.
what to do next? First Panic, second release brake, next panic, repeat sequence
 

Bill Thomas

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Anybody know Paul Norman, He has his own web site, He has just rebuilt a Comet, And did an 1/2 hour road test Video, His forks worked very well for a Comet, I thought, I think it was Standard front end, He did not say.
Warning, It made me ILL, I suffer from Motion sickness. Cheers Bill.
 

Old Bill

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Big Sid used to set up girdraulics using two outer C springs and one inner. Rider sits on bike and observes lower link; aim as david says is to get the link parallel with the pavement. To adjust add spacers such as old coins ( not ideal but once the desired ride height is achieved a spacer of a suitable material can be made) to the one spring case, should produce a good compliant front suspension. Another tip passed on re brakes; when applying brakes apply rear first, then front firmly, front suspension will compress and front brake becomes very effective; ie ploughs the road up, as the man said, try it!! Please note, this is all with standard set up except for the spring spacer. No doubt others will have different views, each to there own.
 

vibrac

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'Ploughing up the road' a good point often overlooked. When PCV got his magic 30ft from 30mph stopping distance it was on a rough road surface. I dont think we shall see that sort of large granite chipping very much in the future,. smoother and smoother asphalt seems to be the order of the day. Rough surfaces upset the precious tin box pilots and spoil the music and in car entertainment.
 

Bill Thomas

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I find with a Twin, As long as the springs are not too strong, Just closing the throttle, A nats before braking sorts the forks out, On the road and on the Track, For me, Not so much a Comet !. Cheers Bill.
 

Old Bill

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Agreed Bill, closing the throttle has a very similar effect especially from high revs, the rear brake trick is really for those oh poo moments ! Helps on a comet if hail mary fails !
 
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