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fox 40 owners,

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
something to think about the next time you are fiddling with your settings on your fork. the HSC settings effect the LSC a LOT.

i always though that the HSC setting is actually what it says, a high speed compression adjuster. but go set you LSC at max, with your HSC at min, push down on your fork. then crank the HSC all the way in with the same LsC setting. feel the difference?

its actually more accurately a LSC threshold adjuster like on a boxxer moco. thanks to socket aka steve for explaining this to me.

and no, this is not just from parking lot test. just spent a day doing runs at cwmcarn messing with the settings. so i ended up setting the LSC roughly where i wanted it, then left it and adjusted the HSC until the fork wasn't bumpy on the smaller high speed bumps. really stoked with it now.


the reason i have been setting my 40 all over again is because i just got it back from mojo, its got new lowers after wearing out the old bushings, cracking the arch and bending the compression rod. i was so used to riding the old fork, its now way to plush for my liking at my old settings, i have to start from scratch again. i am loving my 40 all over again.

hope this will help ppl out there have a better understanding of how the adjustments work and set their forks to how they want them.



and socket- you should try adjusting the LSC on a 40 with the HSC is all the way in, its a huge difference. not quite like a boxxer, but still a big difference. something you will feel with a push down test. and i definitely agree that you cant feel the difference between the min and max setting of LSC if the HSC is set pretty low. it was still something i felt on the trail tho, then i cranked up the hsc to see if what you said would make sense, and WOW. what a big difference.
 

buckoW

Turbo Monkey
Mar 1, 2007
1,572
319
Champery, Switzerland
I think they are related as well. I usually run a minimum of 4 clicks on LSC to get the HSC to work better. Suspension Center in Switzerland has a new cartridge for a 40 that uses air pressure to set the HSC and it ramps up sooner in the travel than the RC2 cartridge. Do you have the 2008 cartridge? That one works much better than the 2007 cartridge, IMO.
 

big cal

Monkey
Nov 18, 2001
177
0
Melbourne, Australia
That's good to know, i've always thought the comp. adjustments were pretty useless, because i only ever really played with LSC ... but i also spent a year riding it over sprung.. so my tuning enthusiasm is quite low...
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
mine is a 05 cartridge, its just got some love from mojo tho. :thumb:

my settings right now are: purple spring (125lbs rider) no preload, 3 clicks rebound, 8 clicks LSC, 10 clicks HSC.

all clicks are counted from fully open.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,995
23
Whistler
something to think about the next time you are fiddling with your settings on your fork. the HSC settings effect the LSC a LOT.

i always though that the HSC setting is actually what it says, a high speed compression adjuster. but go set you LSC at max, with your HSC at min, push down on your fork. then crank the HSC all the way in with the same LsC setting. feel the difference?

its actually more accurately a LSC threshold adjuster like on a boxxer moco. thanks to socket aka steve for explaining this to me.

and no, this is not just from parking lot test. just spent a day doing runs at cwmcarn messing with the settings. so i ended up setting the LSC roughly where i wanted it, then left it and adjusted the HSC until the fork wasn't bumpy on the smaller high speed bumps. really stoked with it now.


the reason i have been setting my 40 all over again is because i just got it back from mojo, its got new lowers after wearing out the old bushings, cracking the arch and bending the compression rod. i was so used to riding the old fork, its now way to plush for my liking at my old settings, i have to start from scratch again. i am loving my 40 all over again.

hope this will help ppl out there have a better understanding of how the adjustments work and set their forks to how they want them.



and socket- you should try adjusting the LSC on a 40 with the HSC is all the way in, its a huge difference. not quite like a boxxer, but still a big difference. something you will feel with a push down test. and i definitely agree that you cant feel the difference between the min and max setting of LSC if the HSC is set pretty low. it was still something i felt on the trail tho, then i cranked up the hsc to see if what you said would make sense, and WOW. what a big difference.
haha cheers.

Yeah I did try winding the HSC in then adjusting the LSC, and it made some difference, but really compared to how I like to run my LSC it's still nearly nothing. I'd like to pull a 40 cart apart and see if there's much you can do to fix that though.
 

MttyTee

Monkey
Jun 20, 2007
209
0
Back on the east coast!
haha cheers.

Yeah I did try winding the HSC in then adjusting the LSC, and it made some difference, but really compared to how I like to run my LSC it's still nearly nothing. I'd like to pull a 40 cart apart and see if there's much you can do to fix that though.
You should pull one apart, you'd geek out for sure as it's pretty well engineered. May be tough to explain in detail but as you go from Min to Mid to Max on the HS adjuster you change the clamp diameter on the shim stack as well as change the preload on the spring. The 08' cartridge has better low to mid speed control b/c the compression check shim on the main piston is restricted from opening as far as the older version. Though in typical Fox fashion it is damped on the light side. I have an old version and with some modding I am getting a considerable amount of LSC out of it.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,995
23
Whistler
You should pull one apart, you'd geek out for sure as it's pretty well engineered. May be tough to explain in detail but as you go from Min to Mid to Max on the HS adjuster you change the clamp diameter on the shim stack as well as change the preload on the spring. The 08' cartridge has better low to mid speed control b/c the compression check shim on the main piston is restricted from opening as far as the older version. Though in typical Fox fashion it is damped on the light side. I have an old version and with some modding I am getting a considerable amount of LSC out of it.
So that preload cone for the shim stack actually widens somehow to hold the shim from a larger diameter as you wind the HSC on? That's pretty nuts.

I still don't get why they haven't just made it so that you can actually wind in the LSC adjuster alone and have some actual LSC control without pulling the thing to bits first though... the Fox rebound dampers are absolutely second to none IMO, and the adjusters on those work beautifully so it's not like Fox are incapable of making a decent adjustment range if they want to.

That said - nobody has ever really produced fully stock suspension that works "exactly" as it should anyway I guess. Always gotta mod something.
 

MttyTee

Monkey
Jun 20, 2007
209
0
Back on the east coast!
So that preload cone for the shim stack actually widens somehow to hold the shim from a larger diameter as you wind the HSC on? That's pretty nuts.

I still don't get why they haven't just made it so that you can actually wind in the LSC adjuster alone and have some actual LSC control without pulling the thing to bits first though... the Fox rebound dampers are absolutely second to none IMO, and the adjusters on those work beautifully so it's not like Fox are incapable of making a decent adjustment range if they want to.

That said - nobody has ever really produced fully stock suspension that works "exactly" as it should anyway I guess. Always gotta mod something.
It's a stepped adjustment, with the HS adjuster all the way on Min the spring backed cone doesn't touch the shim, it clamps on a smaller diameter that the cone slides over. Then after about a turn the cone touches the shim and the spring is preloaded as you turn the adjuster until you max it and at Max the cone is locked against the shim, not allowed to push against the spring.

I've known some of the guys involved with development at Fox since their RS days and they've always preferred light damping.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
mtty tee, do you have any pics of the part that changes the clamp area on the shims? coz the only way it can have variable geometry that i can think of is if it was made out of an elastomer or something similar.

and do you have any tuning tips for light riders? i remember you saying start with the HSC all the way out, would that be with the LSC all the way in?
 

redride

Monkey
Sep 23, 2007
215
0
Kuala Lumpur
man, i'm still struggling with my 40. love it to bits but want to learn how to tune it. thanks for the tips. will try it out this week on the trails.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
yea man, when i first got my 40 in 05, was a grom, knew fak all about tuning, just whack. 06 started to tune, but very vague, 07 understood LSC and started using it. 08 only learned what the adjustments really did. hahaha.

if you are still having trouble with it i'll help you out when i see you on the 6th of march.:weee:
 

MttyTee

Monkey
Jun 20, 2007
209
0
Back on the east coast!
mtty tee, do you have any pics of the part that changes the clamp area on the shims? coz the only way it can have variable geometry that i can think of is if it was made out of an elastomer or something similar.

and do you have any tuning tips for light riders? i remember you saying start with the HSC all the way out, would that be with the LSC all the way in?
Picture a sleeve inside of another sleeve. The inner sleeve is fixed and the outer sleeve is backed by a spring. When the adjuster is on Min the shims bends around the inner sleeve. When the adjuster is wound about 1 full turn in the outer sleeve contacts the shim and the shim needs to overcome spring force to open. As you turn the adjuster in more it preloads the spring until you get about 1/4 turn from Max. Then the outer sleeve locks against the shim. Pretty sweet little adjuster IMO. It wouldn't be as light but I'd like to see a bigger volume cart. that flowed more oil, then you would have more tuning ability.

As far as settings I don't have much info other than what I've used. I'm about 160 w/ gear and have been fooling with steeper head angles (67 degrees). With the stock pre-07 cart I was using LSC max and HSC 1 turn in from Min. If your HA is slacker you may want to use less LSC to allow the fork to settle more and help turn initiation. I made some changes similar to the 07 cart changes and ended up backing the LSC out about a full turn, though the effective amount of LSC damping is more than what I had before.

I don't know if that really helped, are you having specific issues with your fork settings?
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
cheers for the explanation as always.

i have seen detailed pics of it an have a better understanding of it now. is the inner preload hat (as its called in the fox schematic drawings) fixed? i understand how the outer preload hat works now, its spring backed and the HSC adjuster works by changing the spring preload as you explained.

i will have to get an old cart to fool around with, i dont want to mess with my current cart so i can keep it as a control to compare to.

is the changes to the 08 just a higher rate spring on the return valve on the rebound piston or is the travel of the shim limited?

my current set up on the 40 is LSC all the way in, HSC 1.5 turns from full open, rebound 3 clicks from full open. i am using a purple spring with no preload, i weigh 125lbs. bike HA is 65.5.

my problem is that i want more LSC, but i am already at max. i am running as much HSC as i can with the fork being acceptable on the small high speed hits.

me next move is to try going down a spring rate to the black spring and running more HSC and see how that goes.
 

MttyTee

Monkey
Jun 20, 2007
209
0
Back on the east coast!
...is the inner preload hat (as its called in the fox schematic drawings) fixed? i understand how the outer preload hat works now, its spring backed and the HSC adjuster works by changing the spring preload as you explained.
Yup, inner hat is fixed and the outer hat actually locks against the shim when the HSC adjuster is almost maxed (1/4 turn or less if my memory is good)

the changes to the 08 just a higher rate spring on the return valve on the rebound piston or is the travel of the shim limited?
If the spring rate changed it's not noticeable. Yes, the travel is limited.
my problem is that i want more LSC, but i am already at max. i am running as much HSC as i can with the fork being acceptable on the small high speed hits.

me next move is to try going down a spring rate to the black spring and running more HSC and see how that goes.
Depending on what exactly your trying to accomplish you might try opening the LSC adjuster a touch and going in on the HSC adjuster, don't be fooled by the names, they both affect the whole range. If you really get into it, try limiting the check shim even further, I had good luck with this.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
yea, for me, i am using the HSC adjuster to get the amount of LSC i want since i am max on the lsc.

my old setting was 10 clicks from full open on the LSC, then 2 turns from full open on the HSC, had far less LSC back then. and just half a turn more of HSC and i would have the same problem on the fork with the smaller high speed hits. so i am inclined to think that 1.5 to 2 turns is the max i can run on the hsc with any reasonable amount of lsc.

my settings had to change since i got my rear shock back from push with my old settings the front end was diving more then the back in berms.

what do you think of dropping the spring rate and upping the hsc for the time being? my sag on the front end is in the low to mid 20s (%).

and how much do you actually limit the travel on the check valve by?
 

MttyTee

Monkey
Jun 20, 2007
209
0
Back on the east coast!
I wouldn't lower the spring rate. From what you describe that would be going in the opposite direction from what you want. The front end would want to dive more and need more damping to hold it up, which in turn would increase your "spikey" problem on HS hits. If your going to change springs I would increase the spring rate to help hold the front end up and then lower the damping to compensate.

Since I didn't have anything else at my disposal at the time, I packed 2 o'rings under the check shim. I'll have to check on the size. It worked amazingly well for me but unfortunately it's all but impossible to say how far the shim checks and what clamp surface it bends over.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
go up the a spring rate? i am only getting sag in the low to mid 20s right now. wouldn't that make the bike pretty unbalanced?

its not that i was bothered by the fork diving before, i was ok with it. but after sending my dhx to push, i had to change the compression settings on the fork so that it matches the back better.

when i first rode the bike with my old set up, it was like a hard tail, the front end diving like mad with out the rear end diving.

anyways, i'll give it a go, also means i can use the ti med spring. mmmmmm...
 

MttyTee

Monkey
Jun 20, 2007
209
0
Back on the east coast!
F sag has always been tough to quantify for me. In general when trying to fine tune, I don't mess with spring rates much b/c , like you said, it changes the initial balance. But try it out and see. I def think you'd like it better than going down in spring rate.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
ok, now for the sake of e-engineering :D what would you think about if i added a second smaller shim behind the one shim on the hsc circuit? (sockets idea) he was saying that it would limit the flow through the hsc circuit so that the lsc circuit might actually give some useful adjustments.

i also found out that the shims from the dhx and 40 are of the same id. got to love standardization. :)
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
i used them in my dhx before i sent it to push. now i have two sets of shims. :weee:

i think i am going to get another dhx so that i continue to learn about tuning and stuff.

again, thanks for the shims!!
 

MttyTee

Monkey
Jun 20, 2007
209
0
Back on the east coast!
ok, now for the sake of e-engineering :D what would you think about if i added a second smaller shim behind the one shim on the hsc circuit? (sockets idea) he was saying that it would limit the flow through the hsc circuit so that the lsc circuit might actually give some useful adjustments.

i also found out that the shims from the dhx and 40 are of the same id. got to love standardization. :)
I wouldn't add a shim that is any smaller than the OD of the outer "hat" as that would be similar to adding preload to the HSC spring and would reduce the amount of oil flowing during high speed hits. If you have one try adding another shim that is the same OD as the current shim. That way the tips of the shim will be held shut longer and you can back off the HSC adjuster to try to match the HSC you had before.
 

tlproject7

Monkey
Nov 15, 2005
520
0
i know this is a rookie question but i have a forty to, trying to make sense of everything and wanted to know when "full open" is said for high or low speed compression, does that mean compression is set at the max or min?
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
I wouldn't add a shim that is any smaller than the OD of the outer "hat" as that would be similar to adding preload to the HSC spring and would reduce the amount of oil flowing during high speed hits. If you have one try adding another shim that is the same OD as the current shim. That way the tips of the shim will be held shut longer and you can back off the HSC adjuster to try to match the HSC you had before.
ok, i just measured the shims that i have, the closest one i have is a 15.5 od, the compression shim on the 40 is a 16.6 od.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,359
0
Malaysia
paging mtty tee again. :D

its been on the blue (medium spring) for two months now. unfortunately i think i have to go back to the purple, soft spring.

i didn't measure the sag i am getting on it, but its a fair bit less. the problem i am getting is that i am washing out on the front, mainly rougher corners. smoother flat corners its absolutely fine. (well, i think that problem is because i am not getting enough sag, could be wrong)

diving wise, it does dive less, which i really like. but at of the day i am running the same amount of damping that i was when i was on the purple spring too. this is so it feels decent and you can really be aggressive on the faster speed stuff. the really slow speed stuff, i can run less compression, but then i dont like it when i have to get aggressive.

i just want more damping. arrhhh. going to try and get my hands on an 08 cart. not in the mood of opening up my cart again as i dont have any spares if anything goes wrong.

when i go back to the purple spring, would backing off the LSC a bit lessen the spiking at high speed? ie instead of what i was running, 3 turns of HSC from full open, LSC fully closed. => open up the LSC a few clicks, and run more HSC. would that somehow give me more damping while being able to address the spiking bit?

otherwise, i am still just going to run it as the spiking only occurs on really really fast stuff, so its not going to bother me all the time.




steve- feel free to go on about how 40's dont have any comp damping. i totally agree. :p