Fork Spring Change - quick question

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canyncarvr
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Post by canyncarvr »

Race sag is generally a third of the total travel. Ex: A common starting point for race sag on the back with (close to in most bikes) 12" of travel is 100mm, or 4".

Your numbers are correct..given those numbers. I'm still stuck on the springs being 545mm long. You wouldn't have that 2mm of space if they were.

You did get the OEM spacer off the BOTTOM of the old springs and put it on the new springs? That part is not shown on the diagram. It clips onto the spring.

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Post by saddletramp »

Yes, I did put those on.
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Post by canyncarvr »

Good deal! They're easy to miss...sometimes come off the spring and sit in the bottom. During a spring change you could not even know they were there!

But..put the 'new' springs in WITHOUT them clipped on..and they will NOT seat themselves. You will end up with a mangled goober of what amounts to a shim 1/2 fast sitting under your spring.

Actually, I didn't even find that out myself! No, really!

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Post by saddletramp »

Yes, I bent the tang on the spacer so it snapped on tight.
545mm? at 21" long that would be more like 525mm or so. I re-checked the fluid level so that is now set correctly. I did some searching and found that other guys doing the same conversion also had the same 1 or 2 mm gap so that should be about right. 1 guy even had a 1.5" spacer in :lol: Front sag is about 55mm, will less pre-load increase sag?
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Post by canyncarvr »

I don't know where I got 21 1/2"..but I did. In any case, you left off a digit..cuz it's not 525mm.

The actual number for length of anything doesn't really matter. It will be what it will be. When the space is measured (or lack of it), THAT is what will determine the preload configuration.

Do each spring separately for exactly the reason you mentioned..don't expect a pair of springs to be exactly the same height. DO use the same preload figuring process..IGNORE the spring difference. Yeah, you end up with differently sized spacers but the same preload.

'Will less pre-load increase sag?'

In a correctly assembled fork, pretty much. There are a number of instances where that will NOT be true.

You're on the right track, and your thinking/method seems to be right on the money. Good job!
Last edited by canyncarvr on 04:31 pm Dec 14 2006, edited 1 time in total.

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Post by saddletramp »

Cool, thanks for the help. :supz: :grin:
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Post by Jeb »

OK . . . Wibby's 0.40s have gone "down the tubes" !! Finished just a little while ago. I cut PVC pipe sections for 10mm of preload and they indeed are significantly shorter than the stock spacers: the 0.40s are longer + I have much less preload. Put enough ATF in them for a level of 105mm below tube top - it wasn't the Mobil 1 to which everyone seems to refer, though, FWIW.

It does indeed pay to make the measurements for each tube to determine what spacer length will provide the appropriate and equal preload - there was nearly 2mm of difference between the two spacers i made.

Cleaned up the front wheel bearings and odometer "gearbox". I thought the front wheel bearings were a tad "stiff" but they both had about the same tightness so I believe I'm OK.

I can already tell the difference by just sitting on it. It sags quicker but doesn't sink as much overall - the front end feels like it's riding a tad higher than before (more balanced?). When I push the bike forward and hit the front brakes it doesn't feel like it's gonna fold in half.

Anyway, I'm feeling pretty good about it and all I've really done is mess with it in the garage. I'll get a good feeling for it tomorrow when the kiddo and I go a ridin'
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Post by Jeb »

Yeah, the changes made to my forks played a big role in the "fun factor" during today's ride . . .

Stability and cornering have definately improved - I ran a bit faster today!!

What's sortof strange is that, despite installing stiffer springs, the front end seemed a little "cushier" - not "mushier", just more . . . plush. A rather pleasant surprise. The result of cutting down the excessive preload perhaps?

I should spend some time on the rear suspension as well.

A sincere thanks to Wibby for the springs - that was a heck of deal!!

And to the rather tireless effort of several of you KDX vets at setting a newbie like myself straight on how this stuff gets done right!
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Post by Colorado Mike »

Good to hear. Back when I had stock forks, they were downright scary. after upping the spring rate they were tolerable. Much improved on downhill braking situations, survivable on medium jumps.

If you want to amaze yourself on how stupid Ma Kawasaki can be in not updating a decent bike, go ahead an take the plunge and get some late model KX forks. My '03's with blown seals and soft springs out perform the stockers in every way. slow stuff , MX jumps, whoops, everywhere.
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Post by Jeb »

>|<>QBB<
Colorado Mike wrote:Good to hear. Back when I had stock forks, they were downright scary. after upping the spring rate they were tolerable. Much improved on downhill braking situations, survivable on medium jumps.

If you want to amaze yourself on how stupid Ma Kawasaki can be in not updating a decent bike, go ahead an take the plunge and get some late model KX forks. My '03's with blown seals and soft springs out perform the stockers in every way. slow stuff , MX jumps, whoops, everywhere.
:supz:
I'll get there . . . :supz:
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Post by canyncarvr »

That's an ages old suspension-tuning story:

BoyRacer says:
'These forks are TOO stiff!! I need SOFTER springs!'

TuneMan says:
'You need STRONGER springs!'


Good to hear you like 'em!

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Post by Jeb »

One thing to add. With the bike NOT running, I can hear something banging in one of the forks - sometimes. I heard this when I first had them put together, took it back apart and found nothing wrong that I could tell.

Anyone else hear sort of a rattle in their forks?
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Post by Mr. Wibbens »

Glad to hear they are working out! :wink:
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Post by canyncarvr »

Everyone what puts their forks together wrong hears that........ :shock:




Try this...take the cap off, put it back on. But THIS time, HOLD the cap and TWIST the tube.

Don't wrench the cap itself.

Don't know if that will fix your noise, but similar noises have been fixed that way lotsa times.

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