service and changing the DHX5 alone

No don't do that.
The compression valving on the DHX5 is already very soft, so the last thing you want to do is reduce support in the stack anywhere.

First thing to ask is - what pressure, propedal, and bottom out settings are you currently running?

The DHX can be setup to be quite a progressive shock simply with a combination of those adjustments, what it lacks (if anything) is support in the early to mid stroke, so you just have very little support and then hit a wall towards the end.

Make sure the oil you are using isn't too thin as well, because stock oil in the DHX5 was Silkolene Pro RSF 10wt (~47 cSt if I remember correctly, check it)... and that's quite thick. You could very easily have used a thinner oil in your rebuilds and reduced damping support.

AFTER you have considered all those factors, I would start by replacing the shims in the main stack with thicker ones, especially the larger diameter ones. I think the stock ones are 0.1mm, if they are you'd probably do well to replace say the 3 biggest ones with 0.2mm instead (maybe even 0.25mm) and go onwards from there. Try to keep the overall thickness of the stack the same (you may have to reduce thickness of the smallest diameter spacing shims at the base of the stack) Believe me when I say the stock stack does very little (compression damping is mostly provided by the propedal/boost valve assembly in stock guise).

No one will give you a magic combo, experimentation is key - but having played with quite a few of them, that would be my advice.

Alternatively - I'm running a CCDB in one sunday, and a BOS Stoy in another... they will give you all the adjustment range you need externally. $$ though.

160 psi for progression
15wt oil for firmer damping
and rebound 2 clicks from full open

Didn't Fox change oils and/viscosities at one point?

Having spoken with a mate of mine on a 224 with a DHX-5 they found the most effective way to increase the progressiveness of the shock was (as you've already mentioned) to reduce the initial volume of the air chamber by pushing the IFP in a smaller distance. This won't give you support through the entire range as Udi has mentioned, but it will feel like a brick wall towards the end if you fiddle with it enough.

saruti said:

p.s.
I am using the recomended settings
110 psi
3 clicks of propedal
4 clicks of rebound from full open

Click to expand...

Yeah, probably not enough for hard riding. Id try 5 clicks PP, 130-140psi and see what you think of that first. I suspect it might help a lot. Just out of curiosity, what is your body weight and springrate?

Also make sure you check the cSt value of the oil you are running, rather than just the weight. I'd recommend using Redline or Silkolene RSF oils where possible because they have a high VI (less viscosity change over a heat range) - important for shocks.

Stock IFP depth is fine too, I don't really see a big need to mess around with that given that the external adjustments focus on progressive damping anyway.

So in short - try different external settings, make sure the oil matches the stock specs (~47cSt, 300+ VI), and after that worry about making internal changes. If you decide to reconfigure shims, you will also want to find a good supplier for shims in the exact size you want (sometimes hard).