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4.0" fully suspended
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Discussion Starter · #1 ·
On air chamber I have noticed that I need to replace the oil after about 15- 20 hrs of use- otherwise bottoms out way easier and have inconsistent force along the compression stroke.By that I mean it feels normal at the begining of stroke but halfway in it shudders.The force required to compress through the stroke is fluctuating at this point. Air pressure at schrader valve is fine and stable, I keep it at 110-120 psi and it stays there.

I weigh 175 Lbs., typically run 35-42mL of 7.5w oil in air chamber on a 29er setup.The oil i am using is Spectro golden (dirt bike cartridge fluid). I am trying to maintain the duc32 to match the high volume fox rp23 I am running on my dw link sultan. I prefer progressiveness over linearity but dont mind bottoming out the fork for the occasional super big hit the front end may take. I have found the right set-up but just would like to do this for more than 4-5 rides. I do notice that when draining the oil to replace there is a large amount of air in the oil- leading me to suspect potentially this oil doesn't have the ability to degas well ( if that makes sense or is the air in the oil a symptom of stroking the shock to expel the oil when bike is upside down?)
I just got done draining and replacing the oil and fork feels great buttery smooth and right amount of progression at the bottom of the stroke. Love it, just how long is it going to last- I'll be riding some techincal stuff tomorrow so I hope it lasts. Any thoughts?
 

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I am somewhat at a loss as to why any quality oil would wear out that fast or retain air to that level..

There is a upgrade that can be done to the fork that inserts an additional piston in the fork that keeps the air away from the oil similar to the rear shock (poor description but all I know sorry!).. Kevin at Suspension Experts installed it on one of my DUC32's and I love it. Not only does it make the fork more progressive and smooth it also makes it quieter and you loose most of the "squishing" noise when the fork is working which is mostly air being forced to mix with the fluid I suspect.

While your at it have him throw on the Anno caps and custom tune the fork (shin stack, fluid volume/weight etc.) for your weight and riding style. Well worth the cost... Then you should be able to ride a full year or two between service intervals depending on how much you ride. Best money I spent in awhile...

http://www.mtbsuspensionexperts.com 866-788-2456 Kevin is the owner and a great guy.
 

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dirtydoug said:
... typically run 35-42mL of 7.5w oil in air chamber on a 29er setup.
[edited as my initial response was entirely erroneous ... ]

the usual max oil level is 18cc - (according to the maverick support pdf for fitting the 29'er spacers) another 5 to 7cc can be added for a 29'er set-up, although there is a "DUC 29er" thread here where the progression oil on a 29'er set-up "can be up to 40cc" ... 40cc sounds like a lot to me, and you're definately no clydesdale!!

the weight of the oil in the air spring side of the fork plays no role.

ragetty
 

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thank you for quietly pointing out my error ...

jezuz, what a phuqwit i am - i was obviously not thinking straight ...

ok, well - 40cc / 40ml still sounds like a lot to me ...

ragetty
 

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Schipperkes are cool.
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ragetty said:
the usual max oil level is 18cc - (according to the maverick support pdf for fitting the 29'er spacers) another 5 to 7cc can be added for a 29'er set-up, although there is a "DUC 29er" thread here where the progression oil on a 29'er set-up "can be up to 40cc" ... 40cc sounds like a lot to me.

ragetty
:skep:

Max oil in air chamber in 26" wheel mode is 18ccs

Max oil in air chamber in 29" wheel mode is 44ccs

:drumroll:
 

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the context was:

ragetty said:
40cc sounds like a lot to me, and you're definately no clydesdale!! ...
he's still no clydesdale ;)

but the initial set-up suits him, so i won't question his judgement ...

ragetty
 

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4.0" fully suspended
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Discussion Starter · #8 ·
baha_boater said:
There is a upgrade that can be done to the fork that inserts an additional piston in the fork that keeps the air away from the oil similar to the rear shock
Cool didn't know about this sounds good. Is it still user serviceable? Seems like inserting a piston would require additional work or would not allow one to modify the amount of oil easily if one wanted to tune for different trail conditions. That is one of the major pros of this fork- easy for user to tune and it is kind of fun playing around and seeing what works. I remember someone in a thread a long time ago described this fork as a "works" fork, drawing some parallel to how car racing use to be. This design feature works well for me.
Knew about the cups- been thinking about those cause I did have a seal blow this season and dump oil all over my pads and rotors.
 

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Discussion Starter · #9 ·
post-ride update

rode for 3 hrs toay at Pueblo south shore in Colorado today. duc32 performed well- did notice that as day went on got easier to bottom out- so in my words it went from progressive to more linear. Pueblo is a mix of steep short rockie goodness with buff rolling singletrack so conditions were such that it was rough for a little bit but then smoothed out.

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dirtydoug said:
Cool didn't know about this sounds good. Is it still user serviceable? Seems like inserting a piston would require additional work or would not allow one to modify the amount of oil easily if one wanted to tune for different trail conditions.
I've got it (oem in my DUC) and it's easy to deal with. It's just a plastic floater, and adds no difficulty (albeit a step) to the fork maintenance.
 

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Fortes Fortuna Iuvat
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Such gorgeous shots... and I thought the scenery around here was superb!
 

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cyco biker
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Still no solution

I just got my Durance a hopped up DUC as it's tasty morsel for 2010 so I apologize ahead of time for ignorance that comes from reading rather than experience. I'm learning as I go.

The original post talked of oil in the air side taking on bubbles & effecting the progressiveness of feel. Mav's site has this 29er pdf (http://www.maverickbike.com/cms_images/file_359.pdf) for set up. Looks like you're doing what you can correctly. The "degassing" (sounds like a personal problem to me - maybe a byproduct of excessive holiday indulgence :eek: ) solution that Baha mentioned seems like a great upgrade for the forks performance but this extra piston (internal floating piston or IFP - info here...http://forums.mtbr.com/showthread.php?t=471026&highlight=internal+floating+piston), which does help separate air from oil, I believe is on the damper side, so it won't manage the problem stated. Maybe you have a faulty O ring in there somewhere that is allowing air & oil to improperly mix without effecting the pressure. The air chamber schematic in the pdf for the fork ( http://www.maverickbike.com/cms_images/file_15.pdf ) shows at least 7 O rings. Since you are comfortable going inside the fork, possibly if you look at the pdf, you may be able to figure out what is the culprit.

If you figure it out, let us know. Thanks
 

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Discussion Starter · #14 ·
yes- always the simplest thing and should have just listened to Dave at redstone. He mentioned just replacing schrader valve core from the get go- I just replaced it not to long ago so ruled it out.
So I had three problems occasional slow leaking core, bad shock pump due to age, and bad pressure testing method. The plastic seat for shock pump schrader fitting was disintergrating causing small bits of plastic debris to work its way down into schrader. Hence a variable leak sometimes there sometimes not.
My pressure testing method left the shock pump installed so it never was testing integrity of schrader valve. :thumbsup:
Designating this duc as back-up and occasional use on my singlespeed or for another project I have in mind.
I got a spare duc and sent it into get the Sex seal cups installed too btw since I've had the seals blow all over my caliper before.
 

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cyco biker
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Thanks for the update & the added info. :thumbsup: Darn those schraeder valves.

I decided to go with the red wiper seal covers & the added protection combined with the she-she, style is pretty cool. The red goes great with my warranty XO rear d railleaur.

Imagine that, My 8 year old, been thru plenty of nastiness, XO rear der. had the TI spring break in it as the hanger broke & SRAM was awesome enough to deem it a warranty. I already like the way it works but they got my business for life.

Oh wait, that's for another forum.
 
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