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carpe mañana
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Discussion Starter · #1 ·
So, long time ago I made a suggestion to the guys bottoming out their DHX air on the Packs too easily to fill the air sleeve with oil to take up the air volume. Jerk Chicken suggested filling up the sleeve with something thicker, like Prep M. Then came along Tscheezy who figured out that the RP3 air sleever fits the DHX air. Finally JNC reported that Fox sells the RP3 sleeve for $35. I couldn't resist.

So, I ordered the supplies. The RP3 air sleeve, part number 806-29-041 (you'll need it as noone at Fox seems to know the part number without digging through their parts list for a while), and the FLOAT/RP3 air sleeve rebuild kit, part number 803-00-142. It comes with all the seals and a Float fluid pillow pack for $6. I got some stickers, too, but the kid that serviced my ordered put in the DHX decal kit for the reservoir not the main body, so I'll have to call Fox and get it straightened out.

Getting ready for the swap:




The stock sleeve is off:


Here's the interesting part. Everyone's reporting the stuck down problem with their Floats, RP3s and DHXairs. My negative spring had no air pressure what-so-ever. I unscrewed it from the shock body, prepared for the loud pop, and it never came. I then stuggled to pull it off due to the vacuum I was creating. But it did come off just fine in the end.

So, I was checking out the air sleeve up close, once it was off, to see exactly how one could pack grease in there, if one wanted to do the mod I originally suggested and I came upon something REALLY interesting. The air sleeve on the DHX is composed of 2 air cambers held together by a C-clip.



There is a small air port in the inner sleeve which allows for the air to pass between the two volumes. The hole is very small, I wonder why, but it appears to work fine, so whatever.



Here is a comparison of the RP3 sleeve (left) and the inner DHX sleeve (right). You can see that these don't differ very much. The DHXair sleeve has just a little larger ID.





This brings on another idea. If anyone of you wants to try the lower volume air sleeve, on the budget, you can just thread in a small set screw into the opening with some coating to make that air tight, or just fill in the hole with JB Weld, and you'll have almost the same volume DHXair as the one modified with the RP3 air sleeve.

Here is a shot of the old seal (left) and the new seal (right). The material is different, softer.



The new seal installed:



All done:



So, how does it feel once on the bike? I was able to drop my main chamber pressure by 30psi and remained with the same sag (boost valve volume and pressure unchanged). The shock definatelly does a better job resisting bottomout without added compression damping caused by increased air pressure in the boost valve or decreased chamber volume. The fact that I now have a negative spring definatelly helped, too. The shock was buttery smooth compared to how it felt before the swap. The rear felt far plusher than the front. I will now have to devote my attention to the dual air PIKE.

_MK
 

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Nice work. I've wondered about that second sleeve on the DHX-A. Does it have a set of seals as well? And what does your cryptic remark about the Pike mean? A little retune to match the modified DHX-A or a mod for the Pike itself? That's too much of a tease!

Incidentally I tried the idea of reducing the air volume by adding something thicker to the main chamber. In my case I wadded a couple of teaspoons of Slick Honey under the main cap and on top of the large nut (or whatever its called). This was in addition to the Float Fluid I put in. The effect was subtle; kind of like adding more BO. For about three weeks I had an extra 1/8th of an inch left on the shaft after rides. Then as the seals weeped it returned to normal. This was done also to avoid the stuck down issue. It was an idea worth trying.
 

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carpe mañana
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Discussion Starter · #3 ·
Yeah, the outer sleeve has its own set of seals. If you were to pack that full of thick grease, it would never weep out. It does equal extra weight, though. This is something I forgot to mention in my original post, the RP3 air sleeve is about 40g lighter than the DHXair original sleeve. Subtle, but a weight saving in any regard.

I don't know if you'll be able to see the seals in the photo, as it isn't the best one, but here's a close out of the outer sleeve:


As of the PIKE, it definatelly feels harsher than the rear end right now. And I did bottom it out on a couple of drops today, whereas the rear did not. And I didn't land nose heavy. There are a couple of things I am thinking of doing. One is an overdue oil change, which might make the compression damper work better, so it is less harsh, while it will aid with bottomout better. The other is possibly adding a few ccs of extra fluid to the positive air chamber. I might also need to refine my tuning skills with the floodgate. Anotherwords, nothing fancy, but a little bit of work.

_MK
 

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Lay off the Levers
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This was very informative _MK thanks! Now I have a much better understanding of what folks are talking about.
And I hope that Pike isn't too difficult to tune, I just finished bolting mine up.:D

A quick Q: removing the air chamber is just a matter of airing down the shock and unscrewing it? I also just bolted up a mothballed RP3 and I think I'd like to grease up the insides incase it got a little dry with disuse.
 

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Zilla,
You're right about the procedure to remove the sleeve. When airing down, you have to take note of the extent to which the damper shaft goes back into the body. If it's a slight amount, it's fine, but if it's like 25% or greater, you have stuck down and should use some caution when opening to not lose a finger or damage the air sleeve on the reducers at the bottom. The first time you remove the sleeve, it's pretty tough to unscrew. It's easier after that. And disuse won't dry out the insides. Don't worry about that.

I saw this link from you sram thread. It's got a video on it.
 

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Beautiful work!!!

MK_ said:
Yeah, the outer sleeve has its own set of seals. If you were to pack that full of thick grease, it would never weep out. It does equal extra weight, though. This is something I forgot to mention in my original post, the RP3 air sleeve is about 40g lighter than the DHXair original sleeve. Subtle, but a weight saving in any regard.

I don't know if you'll be able to see the seals in the photo, as it isn't the best one, but here's a close out of the outer sleeve:


As of the PIKE, it definatelly feels harsher than the rear end right now. And I did bottom it out on a couple of drops today, whereas the rear did not. And I didn't land nose heavy. There are a couple of things I am thinking of doing. One is an overdue oil change, which might make the compression damper work better, so it is less harsh, while it will aid with bottomout better. The other is possibly adding a few ccs of extra fluid to the positive air chamber. I might also need to refine my tuning skills with the floodgate. Anotherwords, nothing fancy, but a little bit of work.

_MK
Do you think the guys at Push can use the RP3 sleeve to push a DHX Air 5.0?

I admire your work. Excellent. Also thanks to Tscheesy for thinking outside the box.

You guys rock!
 

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carpe mañana
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Discussion Starter · #8 ·
Bikezilla said:
This was very informative _MK thanks! Now I have a much better understanding of what folks are talking about.
And I hope that Pike isn't too difficult to tune, I just finished bolting mine up.:D

A quick Q: removing the air chamber is just a matter of airing down the shock and unscrewing it? I also just bolted up a mothballed RP3 and I think I'd like to grease up the insides incase it got a little dry with disuse.
I deflated my shock, cycled it a few times, deflated, cycled it again and deflated one last time, then with the suspension fully compressed and a shop rag under the shock, I unscrewed the air sleeve. When the shock is compressed, the negative spring volume is the largest possible, which results in lowest possible pressure, which reduces the likelyhood of it shooting down.

I would open it up and grease it up. My DHXair was bone dry on the inside and it has less than a season of riding.

_MK
 

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restless minds create a good solution. well done MK and tscheezy.

MK -- I think the better term would be "improved" rather than "upgraded." "Improvement" means tangible thing. "Upgrade" is a salesman's term.:cool:

(I'm assuming that the result will be as planned. If not, maybe "upgrade" is more appropriate.)
 

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carpe mañana
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Discussion Starter · #10 ·
gonzostrike said:
(I'm assuming that the result will be as planned. If not, maybe "upgrade" is more appropriate.)
Exacly. I'm leaving myself a little window ;)

_MK
 

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Zion Rasta said:
Do you think the guys at Push can use the RP3 sleeve to push a DHX Air 5.0?

I admire your work. Excellent. Also thanks to Tscheesy for thinking outside the box.

You guys rock!
Maybe this should be a niche of a niche and be an MK Tuning service. Well something anyway, Tim Flooks probably likes his TF Tuning name as it is and wouldn't be seeking name copycats.

Doesn't sound to me like it's so hard that you'd need to send to PUSH.

MK, what did you think of the process? Something most of the folks who are reasonably handy with bike wrenching could handle?
 

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carpe mañana
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Discussion Starter · #12 ·
gonzostrike said:
Maybe this should be a niche of a niche and be an MK Tuning service. Well something anyway, Tim Flooks probably likes his TF Tuning name as it is and wouldn't be seeking name copycats.

Doesn't sound to me like it's so hard that you'd need to send to PUSH.

MK, what did you think of the process? Something most of the folks who are reasonably handy with bike wrenching could handle?
The procedure does not require any special tools nor any type of precision. Very easy. The hardest part is mustering the courage to unscrew the air sleeve. Otherwise a small pillow pack of Float fluid is all you really need.

I would definatelly get the $6 air sleeve maintenance kit, which also comes with the pillow pack, to repace the rubber o or q ring (whatever Fox refers to it) on the air piston to eliminate the possibility of the stuck down shock, although mine was actually stuck up :cool:. And no, there will be no MK Tuned service. :p

_MK
 

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What do you charge?

MK_ said:
The procedure does not require any special tools nor any type of precision. Very easy. The hardest part is mustering the courage to unscrew the air sleeve. Otherwise a small pillow pack of Float fluid is all you really need.

I would definatelly get the $6 air sleeve maintenance kit, which also comes with the pillow pack, to repace the rubber o or q ring (whatever Fox refers to it) on the air piston to eliminate the possibility of the stuck down shock, although mine was actually stuck up :cool:. And no, there will be no MK Tuned service. :p

_MK
MK,What would you charge me if I send my DHX to you and do the mods. Parts + Labor + Shipping= ???$$
 

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Thanks for the info MK_ and folks.
Can other oil be used in place of the Float fluid? How about Pedro's syn-lube, slick honey, Prep-M?
 

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carpe mañana
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Discussion Starter · #15 ·
Bikezilla said:
Thanks for the info MK_ and folks.
Can other oil be used in place of the Float fluid? How about Pedro's syn-lube, slick honey, Prep-M?
Just get some fully synthetic gear lube, 80W or greater from an automotive supply store like NAPA.

_MK
 

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I wondered about plugging that hole in the inner sleeve too, but I wonder if the piston head passes it when you approach bottomout. It would make sense for it to do that since it would suddenly reduce the chamber volume being compressed and provide an extreme end-of-stroke pneumatic bumper. If the piston passes the hole and you plugged it and any material were protruding into the inner cylinder wall at the hole, your piston seals would not be happy. Then again I don't know if the seals even go as far as the hole.
 

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carpe mañana
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Discussion Starter · #17 ·
tscheezy said:
I wondered about plugging that hole in the inner sleeve too, but I wonder if the piston head passes it when you approach bottomout. It would make sense for it to do that since it would suddenly reduce the chamber volume being compressed and provide an extreme end-of-stroke pneumatic bumper. If the piston passes the hole and you plugged it and any material were protruding into the inner cylinder wall at the hole, your piston seals would not be happy. Then again I don't know if the seals even go as far as the hole.
Yeah, you're right, I didn't think about that aspect of it. The piston definatelly doesn't pass the hole, since if it would, the air from the auxilary sleeve would pass into the negative chamber, but maybe it comes up to it and would make contact with a protruding piece.

Good observation.

_MK
 

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Is this a crazy idea?

MK,

Based on the great results from your mod, what's your opinion about using an AVA sleeve rather than an RP3 one? First, let me tell you that I have no idea is such replacement is possible and how RP3 canister volume compares with Max/Min AVA sleeve, but if feasible, it could add even one more "tuning" setting to this shock.

I guess it could even make more complicated to find the right setting for this shock, but I must admit that it sounds tempting to me! :thumbsup:

Edited: Typo
 

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carpe mañana
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Discussion Starter · #19 ·
Tavinho said:
MK,

Based on the great results from your mod, what's your opinion about using an AVA sleeve rather than an RP3 one? First, let me tell you that I have no idea is such replacement is possible and how RP3 canister volume compares with Max/Min AVA sleeve, but it feasible, it could add even one more "tuning" setting to this shock.

I guess it could even make more complicated to find the right setting for this shock, but I must admit that it sounds tempting to me! :thumbsup:
Exactly. If the minimum setting of the AVA sleeve is close to the RP3 and the max is close to DHX, then you can just play around by popping off the auxilary sleeve off the DHX and filling it with grease or oil. The DHX sleeve is actually a tad bigger than RP3 one, so it would be close.

_MK
 

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Dhx-ava

MK_ said:
Exactly. If the minimum setting of the AVA sleeve is close to the RP3 and the max is close to DHX, then you can just play around by popping off the auxilary sleeve off the DHX and filling it with grease or oil. The DHX sleeve is actually a tad bigger than RP3 one, so it would be close.

_MK
I have run the DHX with the RP3 air can, as well as the RP3 with the DHX air can. Dont like either set up that much the way I do the DHX stock. So I would really be interested in what the outcome is running the DHX with the AVA can. I dont have one here to try so some feedback once ridden by someone would be good to hear.
 
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