More on valving.Sean - I had my shocks rebuilt and revalved a year ago. Did they give you a sheet with the shim stack information on it? They hadn't been done prior to that as far as I'm aware (bought them used). I had them adjust the valving so the low speed compression was improved. The shop that rebuilt them said that I couldn't change the digressive valve to a progressive. You can change the rate of the valving by swapping the shims, you can also (probably) swap the pistons from the fox shock to the icon shock, basically they need to have a similar height and the same wear band size. FOA shocks can take some king parts for instance. The pistons aren't terribly expensive anyways. I ordered Icon shafts when I did my rebuild and they were like $60 each. Pistons are ~$20-40. Basically you can only make a 2.5" shock for the same application different from any other in a few ways. If you make the ID of the body different you have to run different seals and you have to machine the ID more or less which costs money. The way the piston sits on the shaft could be different as could thread size and things like that but there is not really anything special about any brand other than QC. I don't know enough about this to know if that's correct or not. The ride remained basically unchanged, which tells me the springs are likely the problem. I would be interested in what the current valving is before making that statement but you could be right.
The more I look at it and read up on it, I'm leaning towards swapping my 700 lbs springs to 650 lbs. I have the original #650's that the Icon shocks came with and might try to swap them over. They are 13", which is kind of annoying, but a swap would tell me if I could get my ride height back and have an improved ride. If I'm understanding all this correctly the spring length doesn't necessarily matter, more just the rate. I should still be able to preload the 13" #650 springs to get to my ride height (2" above stock) and they should theoretically be softer than the #700's at that height. Not necessarily, spring length is sort of independent in that excess is not needed. If you go too short thought you will fully compress and block out the springs. If you have uncompressed spring at the fully bottomed out point after the preload is applied you are ok and extra length doesn't help.
Here's some decent reading I found: https://accutuneoffroad.com/articles/coilover-spring-rates-for-toyota-tacoma-4runner/. Since the 1st gen Tundra is heavier than a Tacoma I'd say 650 for me would equal 600 for them. Maybe? I don't have immediate plans to add full skids, and will be keeping my bed open and clear. I don't think I'll have much more weight than I already do. Rate depends on the length of the control arm, the position of the shock from the control arm pivot, and weight that the truck needs to support.
The FOA reservoir has me intrigued. When I had the shocks rebuilt I inquired about adding a remote resi and the cost just didn't make sense. If I could add them myself I'd really consider it. I'm sure I can find a place that works with hydraulics around here....tons of tractors for farming in this area. That can come later though. I ought to be able to get a decent ride with what I have now if I can figure out what I need to do. I looked into just using the stock icon DR fill port to add a resi and the hole was on the small side. If you are ok punching that out for a 1/2" NPT hydraulic fitting then you can run the resi I linked above. I almost went that route but opted to wait because I plan to sell the DR/Icon's I have once I secure a LT kit.
I'm not following you here. Did you mean to say I have too little rebound damping? Bucking would be a decent way to describe what I'm feeling. Lots of feedback from the rear end. The only way to adjust this is to revalve, correct? This is what I have on there currently: http://iconvehicledynamics.com/shop/943-2000-2006-toyota-tundra-vs-25-series-pbr-rear-shocks-wcdcv-0-3-lift.html
bucking is when you compress the rear then feel the rear end bounce back up really quickly, the wobble or sliding loose feeling is when the back sort of sinks or slides because the springs don't extend back down quick enough.
My tire pressure is 35 front and 33 rear (chalk test), and they are E-rated (285-75/16)
seems about right.
AccuTune Off-Road’s Experience: Our Founder and author of this article, Ryan Raker, has been designing, tuning, and manufacturing shocks with digressive, linear and progressive damping curves since 2001. During that time he used state of the art shock dyno’s to design and/or tune premium shocks...