shim stack front suspension

[flop2]

Remenber seeing a post about removing 2 shim stacks from the valve in the front suspension. this is supposed to help with the high speed compression. I would like to give it a try before going Gold valve.
Is it worth it?
and do I have to take apart the forks completly?

 

[kdxiowa]

I did it on mine and noticed a smoother front end imediately. I took out two shims on each side. Have to use and impact wrench though unless you take the fork apart and use the special tool to grab the nut on the inside. The impact will spin it right off.

 

[invernessmike]

replacing springs ?

i am hearing alot of people talking about replacing there springs for a fat guy like me i weigh about 220 lbs should i replace my front or rear springs or both i just bought a 2006 kdx200 don't wanna trash it yet. if so any suggestions for what springs or where to look.

 

[QLD_KDX]

Hey Flop2, I'm the bloke who originally posted that mod.
Kdxiowa, glad you persevered and are happy with it.
Flop2, this is how you do it:
1. remove a fork leg. 2. turn it upside down and compress it. I trap it under the bench while I do the next step. 3. remove the rubber plug that covers the compression clicker. 4. Using an impact driver, loosen and then remove the valve assembly from the fork. Note that you should release the compression of the fork once the valve is loosened enough to remove by hand. The oil remains in the fork. 5. On top of the valve assy there is a nut. Remove it. Note that the thread on the shaft is staked at the top, so the nut is hard to remove. Once it is off, clean up the shaft thread with a file, to make it easier to remove the rest of the components. 6. under the nut is a plate and spring. The plate has 'fingers' that curve down and hold a series of thin washers, the SHIMS. 7. There will be 10 shims - take two of them out. Put the rest back onto the stack (inside the 'fingers') and place the whole assy back onto the shaft. 8. Replace the nut and nip it up (not too tight or you may strip the thread - that assy is only aluminium!). 9. make sure it is cleaned of any metal filings from step 5 before placing it back into the bottom of the fork. Compress the fork once more and use the impact driver to make the valve nice and tight in the fork. 10. Replace the fork back on the bike, remove the other fork and do the same thing.

This mod really is worth doing, it noticably improves the action of the fork on hard, square edged bumps such as rocks and roots. This is because the shims absorb the initial impact (the high speed circuit) by restricting oil flow before the fork springs start to take the shock (the slow speed circuit). The rocks and roots don't make the forks move deeply enough for the springs to take up enough of the impact. By removing two shims you are reducing the resistance to the oil flow and therefore making that initial stroke 20% plusher - just enough to make the front end a lot less jittery over the sharp stuff. If you think it is a little too soft now, simply replace one shim, but I think you'll like it. Admittedly, gold valves have a more advanced shim stack and so can be tuned a lot more precisely than the stocker, but they cost $$$ and this mod is totally free.

glad to help,
Andrew

 

[flop2]

Thanks

thanks again, I'm just waiting for my 14mm allen to get here from McMaster. I'll let you know how it went.

 

[bleedngreen]

QLD_KDX, how does the mod afffect your clicker settings?

 

[QLD_KDX]

Well, I think it gives you more a more useable range of adjustment. You see, before I did this mod i had the clickers out as far as they would go in an atempt to reduce the harshness or 'spike' in the fork. It didn't work, but now that I have got to the root of the problem (the shimstack), I have the clickers set in a more normal position about halfway out - I now have a lot more potential to fine tune with the clickers.

Hope this answers your question!

Cheers,
Andrew

 

[80elkster]

USD Forks Too??

Hey I have a 93 with upside down forks, do you think process would work on my forks??
I have .42 springs that I just about sent back to FRP to trade for .40 springs because I thought they were too harsh, but if this will help, I'd like to give it a try first.

 

[sotchong]

Hey I have a 93 with upside down forks, do you think process would work on my forks??
I have .42 springs that I just about sent back to FRP to trade for .40 springs because I thought they were too harsh, but if this will help, I'd like to give it a try first.

Hey old man your gonna need more than that to ride better!!!! HA HA

( this is my dad so i can make fun of him) :nener:

 

[80elkster]

Hey don't give me a bad time, who looped it out last ride?? :nener:

 

[QLD_KDX]

Re USD forks

mate, I can't really say as I have never looked at an USD fork and don't know if they share the same crappy characteristics of the normal fork. But, if you're unhappy with them, it costs nothing to try. And, if it wasn't quite what you're looking for, you can always put them back in, or go get a set of GV's.

cheers,
Andrew

 

[gurdy]

Hey Flop2, I'm the bloke who originally posted that mod.
Kdxiowa, glad you persevered and are happy with it.
Flop2, this is how you do it:
1. remove a fork leg. 2. turn it upside down and compress it. I trap it under the bench while I do the next step. 3. remove the rubber plug that covers the compression clicker. 4. Using an impact driver, loosen and then remove the valve assembly from the fork. Note that you should release the compression of the fork once the valve is loosened enough to remove by hand. The oil remains in the fork. 5. On top of the valve assy there is a nut. Remove it. Note that the thread on the shaft is staked at the top, so the nut is hard to remove. Once it is off, clean up the shaft thread with a file, to make it easier to remove the rest of the components. 6. under the nut is a plate and spring. The plate has 'fingers' that curve down and hold a series of thin washers, the SHIMS. 7. There will be 10 shims - take two of them out. Put the rest back onto the stack (inside the 'fingers') and place the whole assy back onto the shaft. 8. Replace the nut and nip it up (not too tight or you may strip the thread - that assy is only aluminium!). 9. make sure it is cleaned of any metal filings from step 5 before placing it back into the bottom of the fork. Compress the fork once more and use the impact driver to make the valve nice and tight in the fork. 10. Replace the fork back on the bike, remove the other fork and do the same thing.

This mod really is worth doing, it noticably improves the action of the fork on hard, square edged bumps such as rocks and roots. This is because the shims absorb the initial impact (the high speed circuit) by restricting oil flow before the fork springs start to take the shock (the slow speed circuit). The rocks and roots don't make the forks move deeply enough for the springs to take up enough of the impact. By removing two shims you are reducing the resistance to the oil flow and therefore making that initial stroke 20% plusher - just enough to make the front end a lot less jittery over the sharp stuff. If you think it is a little too soft now, simply replace one shim, but I think you'll like it. Admittedly, gold valves have a more advanced shim stack and so can be tuned a lot more precisely than the stocker, but they cost $$$ and this mod is totally free.

glad to help,
Andrew

 

[gurdy]

Can this be done on a 1990 model or just the current models

 

[QLD_KDX]

This is for the cartridge fork - not sure if 1990 had a cartridge fork or not.

Andrew

 

[80elkster]

'93' Forks 1st Cartridge type

Sorry the 1990 forks were of the older style and do not have the cartridge. 1993 were the first cartridge type put on the KDX they were also the first of only two years that the KDX had USD or upside down forks. I'm going riding this weekend and will be trying my 93 out with two shims removed. I'll give some feedback next week. :cool:

 

[captbly99]

Sorry the 1990 forks were of the older style and do not have the cartridge. 1993 were the first cartridge type put on the KDX they were also the first of only two years that the KDX had USD or upside down forks. I'm going riding this weekend and will be trying my 93 out with two shims removed. I'll give some feedback next week. :cool:

Wish you were going today, I got my forks apart right now wondering if I should do that mod while I got it apart :think:

 

[flop2]

well worth it

hey guys, sorry for the lack of feedbacks. I have finally done my forks, and this is the best free mod I have done so far. now the bike is a lot more stable. It doesn't try to throw me out whenever I hit a rock, roots at high speed. thanks again to Andrew for posting the info.

flop

 

[Porter]

Fork shims

Wow. Just when I thought all the easy,cheap mods where exhausted. I just came back from my regular short trail ride turned into a longer than normal ride. The shim stack adjustment mod is awesome. I never have had the money to send out my suspension. I may never do that now. That one simple mod added 10 mph to my trail speed. I reached a point where I was trying to lose the front end on rocks,bad angle roots,etc. Hard to believe they are that much better. My ride has gone from trail bike to something you point & shoot (CEJ needle w/ modified slide). A well set-up suspension gives you great confidence. Happy Days.

 

[captbly99]

Wow, will the two guys who did this mod and liked it please tell me what wt. oil and also the level.
I just changed the oil in mine, refilled it with 7.5 wt., 100mm.
But, I did not remove any shims! I am thinking about doing it while they are on my bench and I do not have the caps on yet, I am thinking about redraining them and doing this mod. Also, when I took mine apart and took the cartridge out, I wasn't exactly sure where to remove the shims, that's why I didn't, is it from the one that attached to the 14mm allen end with the clicker adjustments?(does that make any sense) It was my first time doing forks, I was skeeered! :laugh:
Thanks!

 

[flop2]

shim stack

yes, there are attached to the 14mm bolt. first you need to remove the nut from the 14mm, then you will have to remove the holder (looks like a cap with legs). after that, the shims are right underneath. I'm telling you, they are kinda hard to see.they are stack so well and with the oil they tend to come out together. at first I thought It was a bushing. but they are 1mm thick shims.

The mod is really worth it.
good luck

Btw, I have taken pictures of the procedure. perhaps I could email them to you.

Flop

 

[captbly99]

Thanks Flop,

I don't think pictures will be necessary I know exactly what you are talking about now. BUt, I am very interested in the type you used and how much. Thanks again.

 

[flop2]

oil

100mm, mobil atf (red cap). now, if only I could get the rear end that smooth.

flop

 

[80elkster]

Woohoo!!!!!!!!!!!!

I finally got around to pulling the cartridges out of my 93 USD forks and found that they have only four shims (3) .005" and (1) .008" thick. I pulled one of the .005" shims, about 21 percent change to the shim stack and slapped em back together. Went riding today and WHOLY @#$% what a difference, the roots and rocks I used to slow down for, I could jam over the top of and not even feel them!! Even the worst roots 6" plus felt like I was running over a piece of foam. This was definitely one of the best changes to my suspension so far. Don't wait to do this find someone with an impact wrench and an aircompressor and get those extra shims out of there!!!

Homemade tool: I welded a 14mm nut onto the end of a 14mm bolt and put either end into the cartridge and used a socket on the other. Didn't have to go out and buy a 14mm allen socket.

PS: Hints for stubborn cartridges that don't want to come out 1) Take a socket that is just smaller than the cartridge body turn it upside down and place it on top of the cartridge then smack it (the socket) at least three times with a hammer. This breaks loose the locktite used to hold the cartridges in.
2) Use only short quick bursts with the impact wrench with the fork leg compressed as much as you can. DON'T and I Repeat DON'T spin the cartridge too much as it could damage the inner workings of your fork. :nod:

 

[QLD_KDX]

Well y'all, I think we may have started something here..! Glad y'all like the mod ;) Lets pass it around...

Andrew

 

[tptp]

Hi, I have done one of the forks today, will do the other one tomorrow. But when doing this mod I think it is some shims on the rod also, with the same type of finger cap as on the valve in the absolute bottom. Are they for rebound or?? Is there anything to do with them?