[Rick205]

After rebuilding my boxxer WC and re-installing it on the bike the forks have now developed 5-10mm of 'dead' travel:

When you pick the front end up the fork will drop 5-10mm - with the fork dissasembled you can push / pull the solo air pistion in and out with very minimal resistance 5-10mm even when there is 150psi in the chamber.

My thoughts are the negative spring is not doing its job but all of the o-rings look to be in good condtion.

Have any of this sites many boxxer geeks heard of / experienced this before?

Thanks, Rick

 

[w00dy]

Is it still being damped for that portion of the travel or is it loose?

 

[BigHitComp04]

Mine is doing the exact same thing but i never rebuilt mine. First 5-10mm are completely dead, as in no compression, completely loose. After that it feels perfect though, so its really not noticeable at all when riding, its just annoying and shouldnt be doing that. My seals seem kinda dirty and have constantly been leaking minimal amounts of oil onto the stanchions since i got the fork. Could cleaning the seals or possibly buying new seals solve the problem?

 

[Commencal-guy]

My only explanation to this is that the O-ring in the solo air piston needs to be changed out.

 

[Rick205]

Its not an issue with external seals or damping as thats a seperate leg completely.

The o-rings in the solo air assembly 'look' as if there ok - i suppose changing them is the next step.

Socket or UDI or any of the other boxxer gurus care to chime in?

 

[John P.]

I've got the exact same problem with my Totem (air). No damping in that ~5 mm of dead travel.

No idea what's going on here as I've never taken it apart, but I'm assuming it's the same issue you guys are having with the Boxxer.

 

[Steve M]

Ok got a couple of questions here:
1. What on earth does FAO mean?
2. Is the free play in terms of spring rate or damping? Like is there no SPRING force for 5-10mm or no damping force?

If there's no damping force, that's quite likely because your oil level is too low, easy fix. However it doesn't sound like this is the case, so if it is indeed the spring side, I'm going to guess that what's happened is you've somehow gotten too much air trapped in your negative spring. Since the air pressure only equalises between the +ve and -ve chambers at hard topout, if the negative spring pressure is higher (like you reinstalled the seal head with the piston pushed a long way in or something) than the positive spring pressure, it might never top out properly, and thus never equalise the pressures properly, resulting in a negative spring force that's higher than the positive spring force (because the negative spring force obviously increases as it gets closer to topout). Try forcibly topping it out by hand (this might take a LOT of force - 150psi on a 1" diameter piston is like 117lbs of force, this isn't a small amount!) or rebuild the solo air assembly with the piston closer to the seal head.

Failing that, check that the solo air piston is tight on the shaft.

Disclaimer: these are just GUESSES based upon a basic understanding of the solo air system - I don't own a solo air assembly myself and haven't seen this problem before. Hope it helps but no guarantees!

 

[Rick205]

Thanks for the reply.

erm, FAO means for attention of

I am talking about the solo air side - this isnt damping related.

I have tried what you suggested socket - no joy, i have narrowed it down to the movement of the spring washer on top of the solo-air shaft moving up and down when you lift the fork - the whole spring assembly is moving the length this spring washer compresses giving you this undamped travel.

I suppose this could mean there is a problem with the negative spring - even with 150psi in the fork i can easily pull it to topout.

Ill get some o-rings together and give that a go.

Thanks for taking the time for the detailed reply.

Rick

 

[Commencal-guy]

Does your fork make a bit of a clicking sound when you push it down 1-3 inches and pull it back up? If it is your Air piston moving freely you probably need a new spring washer

 

[Hack On Wheels]

Thanks for the reply.

erm, FAO means for attention of

I am talking about the solo air side - this isnt damping related.

I have tried what you suggested socket - no joy, i have narrowed it down to the movement of the spring washer on top of the solo-air shaft moving up and down when you lift the fork - the whole spring assembly is moving the length this spring washer compresses giving you this undamped travel.

I suppose this could mean there is a problem with the negative spring - even with 150psi in the fork i can easily pull it to topout.

Ill get some o-rings together and give that a go.

Thanks for taking the time for the detailed reply.

Rick

Damn, I just started having this exact problem the other day. I'm interested to see what you find the source of this to be. It really is odd having no (noticeable) damping and no spring force (either pos or neg) for the first little bit of travel. It actually felt/feels more like the lowers are ridiculously loose and about to fall off than anything else. ...and yes, I did check and the bolts are all tight. I can't seem to even get half a season out of this fork without something breaking or being weird... :huh:

 

[Dr Phil mmkay]

I've got a Boxxer Team, soft spring, with both preload spacers still in. Mine does the same thing... weird.

 

[BigHitComp04]

Ok got a couple of questions here:
1. What on earth does FAO mean?
2. Is the free play in terms of spring rate or damping? Like is there no SPRING force for 5-10mm or no damping force?

If there's no damping force, that's quite likely because your oil level is too low, easy fix. However it doesn't sound like this is the case, so if it is indeed the spring side, I'm going to guess that what's happened is you've somehow gotten too much air trapped in your negative spring. Since the air pressure only equalises between the +ve and -ve chambers at hard topout, if the negative spring pressure is higher (like you reinstalled the seal head with the piston pushed a long way in or something) than the positive spring pressure, it might never top out properly, and thus never equalise the pressures properly, resulting in a negative spring force that's higher than the positive spring force (because the negative spring force obviously increases as it gets closer to topout). Try forcibly topping it out by hand (this might take a LOT of force - 150psi on a 1" diameter piston is like 117lbs of force, this isn't a small amount!) or rebuild the solo air assembly with the piston closer to the seal head.

Failing that, check that the solo air piston is tight on the shaft.

Disclaimer: these are just GUESSES based upon a basic understanding of the solo air system - I don't own a solo air assembly myself and haven't seen this problem before. Hope it helps but no guarantees!

In answer to question 2. For myself there is no compression. There is still some spring (air) resistance. Also i notice that it tends to get stuck in those last 5-10mm Both when compressing the fork and when the fork is rebounding. It just feels awful

 

[Udi]

Visually inspecting o-rings doesn't usually always cut it.

There's also one o-ring in the solo-air assy that you probably didn't look at, it's the one that seals between the positive and negative chamber... this one is coincidentally the only one that I've ever seen fail. To get to it you have to remove the solo air piston, which involves circlip pliers for the circlip, and then sliding off the wave-washer + piston. The o-ring is pressed into the base of the piston. I'd remove all o-rings and take them into an o-ring shop to get replacements. If there's no joy there, I have all solo-air o-ring numbers listed somewhere here, just ask.

There is naturally a small amount of dead travel inherent in the solo air assembly (3-4mm) but it shouldn't really be noticeable (and especially not more than at a previous time). This is due to the way the mechanism works, when the fork is forced to topout the piston compresses the wave-washer, allowing the chambers to equalize in pressure.

For the damper side, the biggest issue I've found is that measuring containers are inaccurate, so if you lock the fork out and there is dead-zone before the damping kicks in, add 5ml of oil (at a time) and try again until the damping kicks in pretty much instantly.

 

[Rick205]

I did completely strip the solo assembly and clean the whole thing inspecting all the o-rings - including the one you mention - it does 'look' fine but as you say it may be the one causing problems.

The compressing of the spring washer is what im feeling as dead travel but i am feeling it when i just lift the front wheel up and place it back on the ground - the shafts moving up and down this distance before the solo air assembly is moving - indicating no negative air spring?

Ill change the o-rings and report back as it seems a few people are having similar issues - the fork works fine except for this.

Rick

 

[DTLogic]

I have the same dead spot with my FOX40 after a rebuild & and my FOX Float 36. My LBS said it is a problem alot of FOX's have, I guess this is not so.

 

[gratiflying]

same problem with Boxxer WC... never noticed this in past year on fork... first 5mm of fork travel requires very little force to compress (almost feels like play somewhere in the fork)... continue compression and then you "hit" solo air compression abruptly which at 150psi requires significantly more force to compress than the first 5mm...

any updates?

 

[clockworked]

I've got a Boxxer Team, soft spring, with both preload spacers still in. Mine does the same thing... weird.

same - but with a heavy spring. I don't remember it doing it before i changed the spring - am i being paranoid?

 

[SylentK]

Are you guys sure you just don't have a stiction-free, well working fork? My current 888 (as well as my old Shiver) sit about 5mm into thier travel with no force. I thought this was/is a common thing. I thought it just meant there is not enough resistance in the spring or stiction to keep the fork fully out. Sure, if I increase my spring rate, the 5mm goes away, but then my preload will be off. Maybe I'm taking crazy pills...

 

[Rick205]

For those mentioning this problem with Boxxer teams or Fox forks its not the same issue - you all run coils: just add some preload by means of spacers or external adjustment (or there may be other issues causing this).

This is a solo air / boxxer wc issue - just an update - changed the o-rings in the solo assembly and its no better im afraid - but my issue may be compounded by the 'loose' lower of the solo air shaft (needs re-punching).

All in all, i have ridden the fork and its smooth as, well damped and riding very well - i only notice this issue when the front ends lifted and dropped or when topout is reached and then the fork is recompressed - even then its a small issue.

I dont know what else to do now - the movement is still there - its not like the 888's you mention - i used to run 888's and know what you mean.

I put it down to the solo air shaft moving up and down when the spring washer under the clip on its head compresses - this is moving before the solo air spring head itself moves creating this few mm of dead travel - I dont know the answer - maybe ill just buy a new solo air spring at the end of the year as my forks pretty beat to be fair.

Rick

 

[Commencal-guy]

To be honest can't this problem be all because of the little spring washer on the solo air piston? I had this play before as well, probably a bit worse since the fork made a knocking noise. I got it rebuilt at the Bromont wc by Sram, and they said they gave me a new (thicker spring washer) after the first time they tried to fix the problem. It was so the Solo Air piston didn't play as easily knocking up and down at top out. After the knocking noise was gone as well as my 3-4mm of play. It never hurts to try but get a new spring washer.