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2014 Fox 40 issue

muddyfox

Monkey
Feb 13, 2002
167
0
North Vancouver, B.C.
I seem to have a problem with my new 40, anyone else having the same issue, or anyone have any suggestions. I set the sag @ 50 psi and set the fork legs in the crowns with about 1/2" stick above the top crown last week. I changed a headset bearings tonight, set the height again, and checked the travel, only getting about 7-1/4" and almost an 1" is negative. I can hold the arch and the wheel and fully extend it. If I add more air it extends further. I took all the air out compressed it all the way, fork is set at the right spot as i have about 1/4 inch left on the stantions before they would bottom out. Filled with air, same deal, at 50 psi which allowed the right sag for me I'm not getting full extension, increase air and more of the fork comes out of the lowers, it's around 80 psi that i get the whole fork out. Anyone have any thoughts??
 

joeg

I have some obvious biases
Jul 20, 2011
198
137
Santa Cruz CA
I seem to have a problem with my new 40, anyone else having the same issue, or anyone have any suggestions. I set the sag @ 50 psi and set the fork legs in the crowns with about 1/2" stick above the top crown last week. I changed a headset bearings tonight, set the height again, and checked the travel, only getting about 7-1/4" and almost an 1" is negative. I can hold the arch and the wheel and fully extend it. If I add more air it extends further. I took all the air out compressed it all the way, fork is set at the right spot as i have about 1/4 inch left on the stantions before they would bottom out. Filled with air, same deal, at 50 psi which allowed the right sag for me I'm not getting full extension, increase air and more of the fork comes out of the lowers, it's around 80 psi that i get the whole fork out. Anyone have any thoughts??
for setting height, i recently learned a good measurement from syndicate mechanic jason marsh. measure from the top of the bottom crown to the top of the fork leg. set it at 155mm as the lowest you should go (for 2014 model). that measurement is from the stankshun itself, not including the top cap parts, just the kashima bits. this may not help anything with your stroke issue if you have it, but as a starting point it might be helpful
 

tacubaya

Monkey
Dec 19, 2009
720
89
Mexico City
Sounds like your fork has a very stiff negative spring.. I thought the Float 40 came with different negative springs to suit different rider weights?
 

muddyfox

Monkey
Feb 13, 2002
167
0
North Vancouver, B.C.
I have the height set correctly, but thanks for the info. with 156mm top of fork leg to top of lower crown i only have 18.9cm (7.5") of stanction from bottom of lower crown to top of the lower leg seals, I can pull the rest out or pump the fork up to 80 psi and it's all available, but lower the psi to 50 for my proper sag and its back aroun 7 - 7.5 "......, should have known better than to be first on the wagon?
 

Steve M

Turbo Monkey
Mar 3, 2007
1,991
45
Whistler
There is nothing wrong with your fork as such - the Float spring system runs a coil negative spring (which acts to compress the fork, by opposing the air positive spring). Because the coil is of a given stiffness (unless you change it out - Fox make coil negative springs available in different rates), the point where it equalises against the force of the air spring (essentially your soft top-out point) is determined by how high your air pressure is. This means that the higher the pressure, the more you'll compress the negative spring, and the more travel you'll get out of it.

If the lack of travel concerns you, get hold of a softer negative spring from Fox. However, the fork is completely safe to use in the meantime (unless there are other issues, which it doesn't sound like there are). I would recommend NOT relying solely on sag measurements on any air fork though - ride the thing and adjust the pressure to suit you rather than being concerned with the sag - it is difficult to measure accurately at the best of times, and the funky initial rate of air spring systems means you can't compare the sag in an air fork directly to the sag in a coil fork anyway.
 

muddyfox

Monkey
Feb 13, 2002
167
0
North Vancouver, B.C.
There is nothing wrong with your fork as such - the Float spring system runs a coil negative spring (which acts to compress the fork, by opposing the air positive spring). Because the coil is of a given stiffness (unless you change it out - Fox make coil negative springs available in different rates), the point where it equalises against the force of the air spring (essentially your soft top-out point) is determined by how high your air pressure is. This means that the higher the pressure, the more you'll compress the negative spring, and the more travel you'll get out of it.

If the lack of travel concerns you, get hold of a softer negative spring from Fox. However, the fork is completely safe to use in the meantime (unless there are other issues, which it doesn't sound like there are). I would recommend NOT relying solely on sag measurements on any air fork though - ride the thing and adjust the pressure to suit you rather than being concerned with the sag - it is difficult to measure accurately at the best of times, and the funky initial rate of air spring systems means you can't compare the sag in an air fork directly to the sag in a coil fork anyway.

Thanks Steve,

but I'm now totally confused. With the bike suspended in the air set at 50 psi I'm only able to get a max of 7-1/4" of travel the rest is simply not available and does not come back unless I pump up the pressure to about 80 psi which makes the fork extremely stiff for my weight. Sorry if I'm not explaining this well. If I set sag to the recomended amount (1.6" for soft) I have less than 5-3/4" of travel available. I simply cannot get the full 8" of travel out of the fork unless I crank up the air pressure.

Am I supposed to only get partial travel out of the fork because I don't weigh 200 lbs? Seems stupid, or am I totally missing what you're saying??
 

time-bomb

Monkey
May 2, 2008
957
21
right here -> .
for setting height, i recently learned a good measurement from syndicate mechanic jason marsh. measure from the top of the bottom crown to the top of the fork leg. set it at 155mm as the lowest you should go (for 2014 model). that measurement is from the stankshun itself, not including the top cap parts, just the kashima bits. this may not help anything with your stroke issue if you have it, but as a starting point it might be helpful
:rofl:
 

buckoW

Turbo Monkey
Mar 1, 2007
3,776
4,695
Champery, Switzerland
Thanks Steve,

but I'm now totally confused. With the bike suspended in the air set at 50 psi I'm only able to get a max of 7-1/4" of travel the rest is simply not available and does not come back unless I pump up the pressure to about 80 psi which makes the fork extremely stiff for my weight. Sorry if I'm not explaining this well. If I set sag to the recomended amount (1.6" for soft) I have less than 5-3/4" of travel available. I simply cannot get the full 8" of travel out of the fork unless I crank up the air pressure.

Am I supposed to only get partial travel out of the fork because I don't weigh 200 lbs? Seems stupid, or am I totally missing what you're saying??
Forget sag and run the fork with 50psi to see if you are bottoming or not getting full travel. How much do you weigh? 50 psi is not much and I would think you need a bit more. Floriane Pugin was running 55psi the other day and she is not very big. Have you bottomed the fork while riding at 50 psi?
 

muddyfox

Monkey
Feb 13, 2002
167
0
North Vancouver, B.C.
I don't think I've explained this very well. I'm not getting full travel because about 1" of the available travel doesn't extend out of the lowers. The only way I can get it to extend so full travel is available for me is to grab the lowers and the crown and force them apart or put about 80 psi in the fork. With 50 psi (regardless of my weight it should fully extend without any weight on the bike) I only have 7" total of stanctions showing between the crown and the lower. I have set the crown height properly. I had this same thing happen years ago with WC boxxers. Fork has been sent away for warranty.
 
Apr 25, 2011
32
0
Pacific Northwet
You have explained it fine, the negative spring is to stiff for 50 psi to overcome the springrate of the negative spring you have. You need to call fox and ask them what negative spring you need if you want/need to run that low of pressure in the fork. Steve's post above explains this perfectly.
 

muddyfox

Monkey
Feb 13, 2002
167
0
North Vancouver, B.C.
Thanks guys, the only problem is it worked fine with the supplied negative spring when I received it and after a full day in Whistler to break it in a bit. Last ride it made a couple "clunks", didn't pay much attention and thought i might need a new headset bearing, replaced that and realized it wasn't working right..., see what Fox says I guess. Another friend has the fork as well, set the PSI at 50 and it's fine, something else is going on.
 

Beef Supreme

Turbo Monkey
Oct 29, 2010
1,434
73
Hiding from the stupid
Try a different shock pump, maybe? My fox pump is extremely inaccurate at 50lbs. Also check to make sure you have enough bath oil. It may have trouble overcoming the negative spring if it is running dry.
 

Lelandjt

Turbo Monkey
Apr 4, 2008
2,508
821
Breckenridge, CO/Lahaina,HI
The only thing that could possibly go wrong to cause this is air to leak from the positive chamber into the negative spring's chamber. It sounds like you need a softer neg spring but weird that it was fine at first. Also, 1.6" is too much fork sag.
 

Lelandjt

Turbo Monkey
Apr 4, 2008
2,508
821
Breckenridge, CO/Lahaina,HI
Some of us here are pros. Others are fast amatuers. I know some people here are much slower but I give the benefit of the doubt. No need to follow my advice but I still thought it was worth sharing. A rider tuning a fork should at least be aware that 20% fork sag isn't a strict rule. Ty 10% & 20% to see what you like better.

OP: I'm really interested to hear if something was wrong with the fork or just too firm a negative spring. Please follow up if you hear anything from Fox.
 
Last edited:

jonKranked

Detective Dookie
Nov 10, 2005
85,558
24,181
media blackout
Some of us here are pros. Others are fast amatuers. I know some people here are much slower but I give the benefit of the doubt. No need to follow my advice but I still thought it was worth sharing. A rider tuning a fork should at least be aware that 20% fork sag isn't a strict rule. Ty 10% & 20% to see what you like better.

OP: I'm really interested to hear if something was wrong with the fork or just too firm a negative spring. Please follow up if you hear anything from Fox.
wait i forgot, on the internet everyone's a pro
 

muddyfox

Monkey
Feb 13, 2002
167
0
North Vancouver, B.C.
20% for Whistler park is a nice sweet spot, picks up all the little chatter & braking bumps, and 15% for shore is perfect for me. I can't see going down to 10% unless I was racing. Was a big reason why I wanted the fork in the first place, easy to dial it in depending on what/where I'm riding.

There was something very wrong with the fork, not sure what though. The Canadian distributor was asked to send it to Fox so they could figure it out as they hadn't seen this happen before. If it was just the negative spring this would have shown up when the fork was first set up and it was fine initially.
 

Lelandjt

Turbo Monkey
Apr 4, 2008
2,508
821
Breckenridge, CO/Lahaina,HI
I just finished ordering one. First time I've paid for a fork in nearly a decade so I hope it's the sh*t. I agree that being able to fine tune spring rate and sag is the biggest benefit of air. In my 888 I'd vary between 100-110psi depending on the track. That results in about 20-30mm of sag when on flat ground and standing fairly centered.
 

the law

Monkey
Jun 25, 2002
267
0
where its at
I find it kind of interesting that everyone was quick to blame the OP -- you are doing it wrong or that is normal -- before Fox decides to fly him out a new fork. Just food for thought. It is not always that easy to diagnose a problem over the internet.
 

blindboxx2334

Turbo Monkey
Mar 19, 2013
1,340
101
Wets Coast
Some of us here are pros. Others are fast amatuers. I know some people here are much slower but I give the benefit of the doubt. No need to follow my advice but I still thought it was worth sharing. A rider tuning a fork should at least be aware that 20% fork sag isn't a strict rule. Ty 10% & 20% to see what you like better.

OP: I'm really interested to hear if something was wrong with the fork or just too firm a negative spring. Please follow up if you hear anything from Fox.
please forgive me as i am a tard and dont want to make another thread..

can someone please give me a quick and dirty run down of (generally) how much sag i should be running on certain types of terrain (rock/gnar, 'bike park'/jumping, etc)? or is it just more or less what you prefer?

(since this is my first DH im building) i was going to start with either 20 or 25% sag, first couple of rides would be at n* or some trails up in foresthill/auburn area, but more than likely n* to keep it simple and get her all dialed in.

again, yes i know i am newb.
 

tacubaya

Monkey
Dec 19, 2009
720
89
Mexico City
Try different sag amounts and choose whichever suits your riding style and terrain the most. 20% works great for most, but I know people that run 10% and some that run as much as 35%.
 

blindboxx2334

Turbo Monkey
Mar 19, 2013
1,340
101
Wets Coast
great thanks! ill start at 20 and work around that! my dj usually has no sag, so this is going to take some getting used too.

oh, and the same is to be said for the rear shock too? start with 20% and go from there?
 

Lelandjt

Turbo Monkey
Apr 4, 2008
2,508
821
Breckenridge, CO/Lahaina,HI
great thanks! ill start at 20 and work around that! my dj usually has no sag, so this is going to take some getting used too.

oh, and the same is to be said for the rear shock too? start with 20% and go from there?
For the rear shock almost everyone likes about 30% so start there. "Firm" is considered 25-28% and a few riders/frames like 35%.
With the fork sag gets complicated because you can slide the legs up and down in the crowns so that combined with sag determines the ride height and headtube angle. You want to find a ride height/headtube angle that balances stability with front end grip and a sag point that maintains traction and some plushness but doesn't dive excessively into the travel.
 

blindboxx2334

Turbo Monkey
Mar 19, 2013
1,340
101
Wets Coast
cool thanks for that info, as well taking the time to explain it to me! i will take note of that, much appreciated.

as for the crown height. i was just going to take note of where it was when i bought it and just put it back in its original spot.. now that i know this, ill take note of it and probably fiddle with it when i start riding. ive got a lot of button pushing/turning to do :D
 
Mar 20, 2014
8
0
Hey guys

I have exactly the same issue as the OP. Has anyone managed to get hold of a different rate negative ti spring from Fox USA? In the UK I'm told they aren't available.

Cheers