Preload adjustments? Curvy. - SV650.org

23-06-13, 11:38 AM

Anybody got a later curvy that's got the adjusters at the top of the forks?
I now have a pair of these later curvy forks fitted to my SY model.
What way do I turn to stiffen the forks?

23-06-13, 11:48 AM

clockwise. as to tighten, pushes the spacer down and thus more compression on the spring giving a stiffer feeling.

New fork oil also makes it heaps better.

timwilky · 23-06-13, 12:58 PM

Nobody loves a pedant so here I shoot myself in the foot.

what do you mean by "stiffen the forks"?

Stiffness of a spring as I remember from mechanical engineering lectures 35+ years ago. (**** doesn't time fly!) is a constant. where K=F/x. F being the applied force and x the resulting displacement. So in short it is impossible to stiffen the spring assuming they are linear.

Applying preload simply increases the amount of initial force that is required to start to compress the forks. Changing the oil or on better forks adjusting the damping, changes the rate at which the compression/rebound takes place. It does not make them any "stiffer"

So if you wish to make the forks stiffer, change the spring.

23-06-13, 08:21 PM

Cheers badge.

yorkie_chris · 24-06-13, 07:47 AM

Quote:

Originally Posted by timwilky

Nobody loves a pedant so here I shoot myself in the foot.

what do you mean by "stiffen the forks"?

Stiffness of a spring as I remember from mechanical engineering lectures 35+ years ago. (**** doesn't time fly!) is a constant. where K=F/x. F being the applied force and x the resulting displacement. So in short it is impossible to stiffen the spring assuming they are linear.

Applying preload simply increases the amount of initial force that is required to start to compress the forks. Changing the oil or on better forks adjusting the damping, changes the rate at which the compression/rebound takes place. It does not make them any "stiffer"

So if you wish to make the forks stiffer, change the spring.

ees right yew know

timwilky · 24-06-13, 08:17 AM

In what respect am I right!

Nobody loves a pedant?
here I shoot myself in the foot?
Time flys and it is a long time since I had Idris Yeo in ONC mech eng scream give me monkeys? (He had a 98% pass rate so his monkeys obviously stop thinking for themselves and did as told)
or the facts about a spring?

yorkie_chris · 24-06-13, 08:20 AM

Well both really.

There is pedantry and what is true. What is also true is the stock springs are useless and the preload adjusters do 3/5ths of f*ck all to patch over the problem

24-06-13, 03:44 PM

Thanks for the replies but the first reply did the trick.

Sid Squid · 24-06-13, 08:26 PM

Really? Badger's right in that turning clockwise increases the preload, but not that it gives a 'stiffer feeling'.

It's the same spring under the same load - it's not stiffer.

25-06-13, 11:43 AM

i understand and can explain it properly....but for the sake of this thread i wasnt using stiffer in its litteral sense.

The rate of the spring isn't changed therefore no effect on stiffness but if you had to quickly explain it those are the words i would use.
new springs and oil is the only way to sort the front end effectively at the end of the day.

and squid you should know im more of an ideal gas flow, head pressures and flow dynamics kinda guy.

23-06-13, 11:38 AM	#1
Knobby Guest Posts: n/a	Preload adjustments? Curvy. Anybody got a later curvy that's got the adjusters at the top of the forks? I now have a pair of these later curvy forks fitted to my SY model. What way do I turn to stiffen the forks?

23-06-13, 11:48 AM	#2
BBadger Guest Posts: n/a	Re: Fork Adjustments clockwise. as to tighten, pushes the spacer down and thus more compression on the spring giving a stiffer feeling. New fork oil also makes it heaps better.

23-06-13, 12:58 PM	#3
timwilky Member Mega Poster Join Date: Mar 2004 Location: Not in Yorkshire. (Thank God) Posts: 4,116	Re: Fork Adjustments Nobody loves a pedant so here I shoot myself in the foot. what do you mean by "stiffen the forks"? Stiffness of a spring as I remember from mechanical engineering lectures 35+ years ago. (**** doesn't time fly!) is a constant. where K=F/x. F being the applied force and x the resulting displacement. So in short it is impossible to stiffen the spring assuming they are linear. Applying preload simply increases the amount of initial force that is required to start to compress the forks. Changing the oil or on better forks adjusting the damping, changes the rate at which the compression/rebound takes place. It does not make them any "stiffer" So if you wish to make the forks stiffer, change the spring. __________________ Not Grumpy, opinionated. Last edited by timwilky; 23-06-13 at 12:59 PM.

23-06-13, 08:21 PM	#4
Knobby Guest Posts: n/a	Re: Fork Adjustments Cheers badge.

24-06-13, 08:17 AM	#6
timwilky Member Mega Poster Join Date: Mar 2004 Location: Not in Yorkshire. (Thank God) Posts: 4,116	Re: Fork Adjustments In what respect am I right! Nobody loves a pedant? here I shoot myself in the foot? Time flys and it is a long time since I had Idris Yeo in ONC mech eng scream give me monkeys? (He had a 98% pass rate so his monkeys obviously stop thinking for themselves and did as told) or the facts about a spring? __________________ Not Grumpy, opinionated.

24-06-13, 08:20 AM	#7
yorkie_chris Noisy Git Mega Poster Join Date: Apr 2007 Location: Halifax/Leeds Posts: 26,645	Re: Fork Adjustments Well both really. There is pedantry and what is true. What is also true is the stock springs are useless and the preload adjusters do 3/5ths of fck all to patch over the problem __________________ Currently Ex Biker Now rebuilding a 63' fishing trawler as a dive boat Last edited by yorkie_chris; 24-06-13 at 08:21 AM.*

24-06-13, 03:44 PM	#8
Knobby Guest Posts: n/a	Re: Preload adjustments? Curvy. Thanks for the replies but the first reply did the trick.

24-06-13, 08:26 PM	#9
Sid Squid No, I don't lend tools. Mega Poster Join Date: Jul 2003 Location: Skunk Works, Nth London Posts: 8,680	Preload adjustments? Curvy. Really? Badger's right in that turning clockwise increases the preload, but not that it gives a 'stiffer feeling'. It's the same spring under the same load - it's not stiffer. __________________ If an SV650 has a flat tyre in the forest and no-one is there to blow it up, how long will it be 'til someone posts that the reg/rec is duff and the world will end unless a CBR unit is fitted? A little bit of knowledge = a dangerous thing. "a deathless anthem of nuclear-strength romantic angst"

25-06-13, 11:43 AM	#10
BBadger Guest Posts: n/a	Re: Preload adjustments? Curvy. i understand and can explain it properly....but for the sake of this thread i wasnt using stiffer in its litteral sense. The rate of the spring isn't changed therefore no effect on stiffness but if you had to quickly explain it those are the words i would use. new springs and oil is the only way to sort the front end effectively at the end of the day. and squid you should know im more of an ideal gas flow, head pressures and flow dynamics kinda guy. Last edited by BBadger; 25-06-13 at 11:45 AM.

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