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Old 02-16-2007, 07:36 PM   #16
Luke
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Thanks for the reply, Zerodog!
I bought everything from MX-tech, but they don't have so many of the thicker shims. At least they are cheaper than race tech. I don't mind spending extra to experiment, but I'm a bit pissed at myself for screwing up something that basic.

I'm sure about the float number- my first hint that something was up came when I made a 1.25mm thick washer to fit on the basevalve and it used up all the float. I measured the float at about 1.2mm, but didn't think to pull the spring out to measure it properly. Thanks for the tip.

According to the fiche I read, the '02s and '03s have different rebound taps. According to this page, there was a change in the rebound tap between '02 and '03. These are on Husabergs, but it is the same fork.

The '02 is on the left, '03 on the right:
(edit: there is no '02 in the picture. Someone's modified '03 on the left, stock '03 on the right)


Neither of these look like my rebound tap- on mine, there is no second shoulder- the shims can push back all the way to the lip that surrounds the spring. It's diameter is about 15mm- that's why I figured I could get away with using a washer of a similar OD.

When I talk about adjusting the float with shims, I was thinking of putting 6mm id/8mm od/.2mm thick washers between the rebound tap and the cartridge piston. I can get away with about 1mm before the end nut is hanging off the rebound tap.

In any case, it sounds like I should watch the valve float closely. I guess I'll have to try something different on the stack due to the rebound tap shape- or just replace the taps with the '03 version.

Luke screwed with this post 02-16-2007 at 08:36 PM
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Old 02-17-2007, 07:14 PM   #17
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So I put a few miles on around town, and I'd say the forks are better. I'll reserve judgement until getting it offroad, but there is less brake dive and a distinct fondness for curbs.

For those wondering WTF we are talking about, here's some reading material:

WP4860 Manual This covers complete assembly and disassembly. To change valving there is no need to separate the fork upper and lower or remove the axel clamp from the lower tube. I even left the forks on the bike, and drained them from the base valve instead of tipping the fluid out.

Look at the Husaberg Fork tutorial for an explanantion of what the shims are doing and which shim stack are which in the forks. This is all based on 4860 forks. Lots of pictures of disassembled fork parts.
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Old 02-17-2007, 08:53 PM   #18
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This thread is getting real interestin' for folks out there wanting to tune their forks. Thanks for posting your links and discussing your work fellas.

Hiya Luke!
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Old 02-17-2007, 09:36 PM   #19
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Glad to help!

Hiya Meat
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Old 02-18-2007, 06:50 PM   #20
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Luke the one on the left is the ZP3 modified one. I forget what the benefit was but the guy that did it raved about the effect. I remember reading about it. I think it was to go with even less float and a smaller 6mm shaft to allow more flex over an 8mm OD shim. The 03+ one has a 10mm boss that the 8mm shims come up against. You most likely can build up what you have with some 10mm shims to acheive a similar midvalve to what I have shown. If not you could get new rebound taps. I think they are only around $30 each. It would be a good upgrade for the price.
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Old 02-18-2007, 10:06 PM   #21
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Hmm... so less float and more flex. I'll keep that in mind. I'm going to flog it this week in Death Valley, and then make changes based on how it does there. On the street it already feels like the front works better than the back.
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Old 02-19-2007, 07:45 AM   #22
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Yes less float = more shim flex because the stack can't open as far. So on big fork movements, like braking the stack opens as far as it can on the spring until the shims start to flex. This is what keeps the bike higher in the stroke. I rode a nasty desert OHV area this weekend with ass deep sand whoops and very steep rocky hills. The front performed perfectly. I had enough adjustment in the compression to make the front resit bottoming on that stuff. The rear shock is close. I really pounded the crap out of it. For big whoops and trying to get it skimming I would need to add more shims to the compression side of the shock. But then you give up some small bump stuff on the road. On the mountain trails the shock was great. No kicking or bottoming. I think I will leave it alone for now. It seems to be a good compromise for what I am using the bike for. There are not many times when I am pounding whoops like I am on my real dirt bike. One option to make it better for this would be to add a thicker bottom out bumper.
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Old 02-26-2007, 10:45 PM   #23
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So rule #1 of suspension modification is 'Change one thing at a time'. I broke that big time, but here are my impressions.
Boney and I were riding in Death Valley last week. He was on a stock '02 640A, I had new front springs (+15mm length, .50kg/mm rate) with the new shim stacks listed earlier. My rear shock was stock.
We traded bikes on a relatively clear dirt road. We rode high-speed roads, rock gardens, deep gravel roads, sand dunes and silty washes.

The verdict: By far the biggest difference was from the change in steering geometry. I figure that there was a 1 degree difference in rake due to the change in ride height. My bike was much more stable (and slower steering). In the deep silt, Boney's bike was unstable to the point of being unrideable. Mine plowed a lot, but was stable.

The suspension action was just as expected. Small rocks are now unnoticeable, and larger rocks don't upset the bike nearly as much. Brake dive is reduced significantly. On small jumps the bike feels very balanced on both takeoff and landing. No large jumps for me. I only bottomed out hard once, and it seemed reasonable given the terrain.

I'm very happy with this suspension now. I think I'll leave the shims alone for now and work on the ride height- between the two bikes we have a boundry for very stable and unstable. Finding a good compromise should be pretty straightforward.
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Old 03-13-2007, 01:46 AM   #24
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'02 midvalve substitution for short tap

Z-dog,
Hope the Baja was good.
I got a couple of suspension questions.
My '02 Adventure has the old style tap.
I'd like to make them work.
I measured the midvalve space carefully with the spring and shims out.
It was 1.96mm.

That makes me a little short on your complete midvalve. I don't want to space the nut out much more because it was peaned over as a safety measure to lock it in place. That seems like a good idea to me. The nut is right at the end of the threads with this measurements and tight.

I was thinking I could substitute 1-24x.15 for 3-24x.1. Are they equivalent?
That would leave me a float of 1.06 with the rest of your stack.
My '02 midvalve would be:
1-24x1.5
1-22-.1
1-18x.1
1-14x.1
1-10x.1
1-12x.1
1-14x.1
1-20x.15

So mv space is 1.96mm.
Stack is .9mm
Float is 1.05mm.
What do you think?
Should I order the updated spring for the '03 tap? It's cheap.

BTW I unscrewed the taps to clean them. That was a bad job and needed heat to release the red threadlocker. After a good cleaning they work much more smoothly. The needles were hanging up in the bores.
I am going to order new o-rings just in case the guy that was in there before me used a solvent that expanded them.

Somewhere in my notes I have a shim substitution guide.
Do you have it handy

This is so fun,
Bill.
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bmwktmbill screwed with this post 03-15-2007 at 12:03 AM
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Old 03-13-2007, 03:50 AM   #25
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Quote:
Originally Posted by bmwktmbill
Somewhere in my notes I have a shim substitution guide.
Do you have it handy
Try here, the shim substitution guide is the third from the bottom of the list.

According to this, 1 .15mm shim is equivilent to 3.4 .1mm shims.
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Old 03-14-2007, 04:04 AM   #26
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bump

Hey Luke,
Thanks for the link.
Now where to find a 24x.15 shim. Maybe MXtech
Bill
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Old 03-14-2007, 05:38 PM   #27
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I think that would work Ok. That is a lower float than what I am running now. My float is 1.13. The 03< midvalve spring might be a good thing or a bad thing with that midvalve. If it is lighter that could be good. Then it blows open easier on the small bumps. So it looks like you didn't need the 10mm shims on the back of the stack to get the float down. The 02 must have a longer shoulder than the 03. MX-Tech is a good bet for the shim you need. I will look tonight and see if I have some.
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Old 03-14-2007, 07:19 PM   #28
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does anyone have the shock stack for the stock shock on an 03 Adv?
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Old 03-15-2007, 12:19 AM   #29
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Thanks For looking/commenting on the stack Z dog.
The 24x.15 is just a little heavier than three 24x.1. If I combine it with a little lower float and the soft mv spring it might be OK for the gravel especially because my bike is lowered and I don't have as much fork travel as the stock machines, the stiffer mid valve might be the right diagnosis especially if my fork springs are a little soft.

I keep thinking PLUSH, whatever that means. Suspension tuners throw that word around.
I want plush....
Bill
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Old 03-15-2007, 07:51 AM   #30
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Quote:
Originally Posted by alpiv
does anyone have the shock stack for the stock shock on an 03 Adv?
I have them on my computer at home. I can post them for you when I get a chance.

Bill, Keep in mind soft springs don't always mean plush. Soft springs will give a harsh ride if there is too much weight to support and the suspension blows through its stroke.
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