[patrik]

I'll make it quick and easy to answer: Is injecting oil into the main chamber doing what buying a smaller volume air can would do? Is a Dhx air the wrong shock for an SWD psycho 7 (single pivot, highish leverage ratio I think)? That is all, thanks

 

[Udi]

A smaller volume aircan or more oil volume in the air chamber will do the same thing, merely increase springrate progression.

What's the leverage ratio on the bike exactly? A high leverage single pivot would indeed be the wrong bike for the shock. Any regression in the first half of the stroke is also undesirable (so it doesn't belong in a morewood or any orange).

 

[JDA]

So it would become more progressive or ramp up more? because I have to run a fair bit of air in my boost valve to stop the shock bottoming out even though the bottom out adjuster is full clockwise all the way in.

 

[Udi]

Yep.
FYI - Adding air to the boost chamber essentially adds compression damping throughout the stroke, and the bottom out adjuster has very little affect on anything from full out to full in (nowhere near as much as people would think anyway). Adding oil to the (spring) air chamber on the other hand increases spring rate progressivity while making no changes to damping. Before you go there though I'd check your sag and make sure you aren't getting more than say 34%, if you are, run more air pressure (in the air spring).

 

[JDA]

Thanks mate, I'm running it exactly 35% sag (190psi main chamber) which is right where I want it but I have 140psi in the boost valve to stop it bottoming out which is much more than I'd like really, I used to run my coil at around 115psi.

Whats involved with adding oil to the main chamber? I've done the air sleeve service myself before but thats as far as I've gone with taking it apart.

Sorry for the hijack

 

[patrik]

No problem, the oil in the air chamber is super easy if the way I've been up to it is correct: Just remove the valve from the main chamber with your standard valve core remover and use a syringe that threads onto the valve to pump some higher viscosity fork oil in there ~10wt (I'm using a stans syringe, got it at the LBS) About 10-20ml from what I've read, I haven't noticed a dramatic change in performance but I've had very little time on the shock with oil in it as the bikes been in the shop. I was just wondering if I should go the whole smaller volume air can route or if this would do fine. I also may try another mod that involves isolating the inner part of the main chamber from the alleged outer sleeve by clogging a little hole in the main chamber with some epoxy. This is all hypothetical at the moment as I've yet to pull the shock apart.

***SPAM*** If it doesn't work, anyone want a nearly brand new, one time used 2009 Dhx Air, 8.5x2.5? ***SPAM***

 

[patrik]

Also, the leverage ratio's almost identical to an orange I think, so looks like this may well just be a new shock issue