I have a 2007 Fox DHX 5.0 air, which has been a fine shock and is in good nick as it only gets ridden a few times a year. I fancied a full sus ride today in the cold Peak so went out over Houndkirk Moor. As I climbed the moor, the bike seemd a bit low, and my pedal was clipping rocks.

I got off and my shock was fully compressed, and stuck that way! I checked the pressures and both main and boost were as they should be.

I wondered if maybe the low temperatures had anything to do with it, but that seems unlikely. Anyone any idea what could be wrong? The fox manual doesn't seem to mention this phenomenon.

It happened to mine, some seal or other has gone. Its a quick trip to mojo (or similar suspension tweaking establishment) for your shock.

Stuck down shock, air in negative chamber. Quite easy sorted on rp2 etc but im not sure bout dhx.

it's easy to fix, you just need to unscrew the air cannister – there are videos around showing you how to do it and warning you of the dangers – it will go bang

a seal service will stop it happening again – this is also easy to do and mojo sell the kits for about a tenner
the method and kit are the same as for other fox air shocks, you'll just have to keep one of the larger o-rings for the DHX Air

Videos? Youtube?

here's one

here

try this ….http://www.foxracingshox.com/fox_tech_center/service_videos/air_sleeve_maint.pdf

I've done this trail-side with an inner tube to grip the cannister a screwdriver in the shaft eye

OK, looks doable. Do I really need a seal kit? It's not been heavily used.

suppose it could be some grit under a seal or something
it might be ok

ive sorted an rp3 without putting in a new seal kit…its got to be worth a try..?

I was under the impression it was caused by an out of spec seal. if that's the case, it's worth replacing the seal in question to stop it happening again. I think they got the elastomer mix wrong and they're not as thermally stable as they should be.

It happened to me yesterday too on my RP3. Its cold and things work differently and can change shape in the cold. Order a seal kit from Mojo they are only £10 and follow these instructions.

1. Let out all the air via the valve.
2. Remove high volume outer sleeve this is held on by a little metal clip.
3. Remove the mounting hardware at the narrow end and push a tea towel through the eyelet so it there is at least 4 inches on each side. This bit is very important.
4. Remove the mounting hardware from the valve end and if you can use a vice to hold this end tight and steady. I used a screwdriver through the eyelet with the mounting hardware still it as this helped me turn it but a vice is easier.
5. With the valve end in the vice and the towel in the eyelet at the other end start to unscrew the air can. This will be stiff but it will come off.
6. Don't crap yourself when the air can bangs and pops off. The tea towel will catch the air can and stop it from going through your garage door.
7. remove the towel and pull the air can off. You will now be able to give it a good clean and see what seal popped and if it is damaged.
8. Pop out old seals and replace with the new ones.
9. Apply plenty of the oil that is supplied with the seals and reassemble. The air can will be difficult to thread at first but that is because the negative air is pushing it.
10. Pump it up and go riding.

Does the Float seal kit fit the DHX air? Anyone know? Mojo don't make it clear.

Yes the seal kits are the same, the problem was due to a batch of dodgy seals, if the shock is under 12 months old and you have a proof of purchase they should do it under warranty, might not if you got it of crc or similar as maybe an o.e item.

oh and DO NOT let the air out of boost valve/piggy back chamber only the main air chamber as this may cause it to cavitate. The best thing for removing the air can is a Rubber air filter removal strap after having cleaned the can.

I just twisted the air can off with my hand. But those air/oil filter rubber things would make it easier if you already have one, no need to buy one especially unless you plan to do it a lot.

some come off easy and others can be a nightmare hence the strap, try and avoid the decal if it's really tight as they can 'ruck' up with the strap.

oh that's another thing when refitting the air can with the shock clamped in a vice/ work mate e.t.c put the rebound on full slow and compress the damper as much as poss. and then put the air can on and do up that makes it loads easier.

My 7 yo Float RL (still on original seals and bushes) did this last year, a quick strip down and clean and it was fine for another 12 months.
Did the same again last week, I was prepared this time and replaced the bushings and seals, hopefully should sort it this time.
Seems to be a factor that it always happens when its pretty cold. Suspect the main piston seal stiffens up in the cold and doesnt maintain a perfect seal, allowing air past the piston into the negative chamber, thus sticking it down.
The bang it makes when you release the pressure from the air can is ace though!! 😈

Screewing it back on is the fun part as you are trying to compress the small amount of air in the negative chamber.

Put it back on the bike if you struggle closing the can, use the frame as a lever, also helps line the thread up correctly. Just make sure no muck drops in the can.

Put it back on the bike if you struggle closing the can, use the frame as a lever, also helps line the thread up correctly. Just make sure no muck drops in the can.

Or turn rebound up to max compress shock screw can on easier.

I emailed Mojo about it. They said I should send it to them for repair as it's dangerous. Mmm…nah. Think I'll have a go meself.