This should help. it is for bypass but the process is the same.

 

http://www.foxracingshox.com/dl/offroad/manuals/foxrs-or-bypass-m.pdf

 

 

do you have a 2nd shock ?
if not you shouldn't remove all the valve shims as there will be no control ,

you will need to learn the numbers , they are a messurment of diameter x thickness in thousands of an inch ( 1.000" being 1 inch )
try pasificcustoms.com the have shims available in pre assembled stacks ,

also there should be some numbers on the seal carrier ( where the shafts goes into the shock)
they will be something like 60/40
first number ( 60 ) being compression 2nd ( 40 ) being rebound
you can than order a stack of shims higher ( stiffer ) or lower ( softer )

as for what you need i have no idea its trial and error unless you know someone if a shock dyno

thanks for your help everyone. pacific customs shims turned up yesterday.  read the instructions inthe link twice, then repalced the shims.  was a pretty straight forward job!

You should heed the advice of LIAbility, don't remove anywhere near all the rebound damping.
If you also valve them too lightly you'll end up braking the shims (they rely on each other to maintain integrity).

Are you sure you're actually having rebound damping isuses? Most people I talk to have issues with not enough rebound damping (including myself).
I gather the problem you're having is the rear jacking down under repeating bumps?

That is wild!
You must have some serious shock damping in order to make that weight not return. You sure you simply don't have an issue with binding? Remove the shock, spring and wheel then cycle the hub from full bump to full droop.
You should also be able to cycle your shock without any pressure in it or spring on it.

Out of curiousity, how large a diameter is your Fox shock. Would have thought you'd need at least a 3.0 with some serious valving to even get close to what you describe. With two 2.5's on my lightweight Jimco (considerably less spring than you) I have done nothing but increase my rebound damping.

Sorry Dags, but my vote is there is no way in hell you are over rebound damping with that shock. Something is ary, I just have no idea as to what it is.

If it was that tightly wound you'll fade the shock before you have any issue with rebound.

Front end of my Jimco (middy) is 368kg. With 2 x 2.5 quad bypass and 2 x 2.5 coilovers. We valve the bypass tight and still valve the coilover to minimise fade.

The front end of my Tatum I'm a little worried about. It's 302kg with a single 2.5 internal bypass coilover each side. It's a little bit of a gamble but one that I hope will pay off with the weight reduction of the car over the Jimco.

You sure that it's not doing something under braking? Like deflecting the bushings to the point they bind? Got me stumped, I still don't believe that your 2.0 shock is capible of holding back the spring required for a production 4x4 front end.