Fox shock pellet to Schrader valve conversion

It was time to rebuild and screw around with the valving on my Fox Factory 2.5 coil overs as the truck nose dives on hard stuff (due to the plate bumper and winch up front). What I didn't know at the start was that these shocks have rubber plugs and 3/8 x 24 hex plugs with a pin hole in them as fill valves (a.k.a. pellet valves). I hoped to find a ready made Schrader valve to thread into the existing 3/8 x 24 hole. Wrong! I could not find one. I stiffened up the compression valving and resealed deciding to stick with the pellets (I put new in). I also decided to install 14" x 650# King springs in place of the Eibach 13" x 600# ones that came on the shocks. I bought a needle fill tool online opting for the softer priced offering (not the Fox one). I knew to be very careful with the relatively tiny needle as far as lining up with the hole, but try as I might, that needle would not go through, and eventually, I bent it up. I WILL convert to Schraders!!! I picked up some reservoir fill valves having a 1/8" pipe thread. I took the shock back apart and headed to the mill.

I drilled to the bottom of the existing hole using a 21/64 bit, reamed for 1/8" pipe taper, and threaded by hand after starting tapping in the mill. Cleaned and re-assembled. I had to mill a recess in the top mount plate to clear the new valve. The top plate is running up side down per Fox. When installed with the top plate right side up, the shock is 2" too long.
I had to make a spring compressor too....works nicely.

More...
Sure is nice to have Schraders!!!!

 

Can you double check the thread size on the drilled set screw that retains the pellet. You mentioned 3/8-24.

Any chance you meant 5/16-24?

Tap drill size for the 1/8 NPT is very slightly more than 5/16, suggesting if oem Fox used 3/8, the existing threaded hole might be too large.

 

The plug is 3/8" fine thread. No taper. Just like a 3/8" fine bolt. Fox used this size on purpose knowing there were no valves out there which would thread right in. Fox had to use the plug method for the Tacoma as when the top plate is flipped upside down, a Schrader of any type will not fit nor could you access it. You can't add nitrogen to the shock once installed on the truck unless you modify it as I did. The only std. valve sizes which will work (you have to machine the shock) are 7/16" 'O' ring base and 1/8" pipe. 5/16 would fall into the hole. I chose the pipe thread as I trust an interference fit using Locktite red more than an o ring as far as preventing long term seepage.
Tap size Threads per inch Drill size w/ taper pipe reamer

1/8" 27 TPI 21/64" drill.

 

21/64” is .328”.
So you sized the hole to .328” for 1/8-27 NPT.

3/8” is .375”
Tap drill for 3/8-24 is also 21/64”.

Seems you would be cutting threads over threads.

The really odd thing though, on other Fox Shox the pellet set screw with the hole is 5/16-24, and those valves are available and screw in without mods.

 

The hole is stepped inside. it goes from 3/8 to a 1/4 hole for the pellet. The 3/8" hole is roughly 1/2" deep. I'm drilling the 1/4" hole out to 21/64 as that's the drill size for this tap then reaming for 1/8" pipe (the ream cut runs from about mid hole to 3/4" down). The topmost 1/8" of threads end up shallow. The rest is cut fine. I have no doubt that I have a good fit.

 

What do you mean "the shock was 2" too long"? For the valve to fit properly or for the King springs to fit properly?
Your spring compressor worked well on the 14" 700lb. coils?

 

If you looked online for my shocks you'd see photos with the top brackets like this (left set):

When I got these 5 years ago I could not install the shocks brackets up as shown. I called Fox and was told to turn the brackets over (see photo above of my install). I took the first shock and flipped the bracket up as shown in the photo above yesterday just to make sure it can't be done. Without lengthening the height of the top mounting bucket or going long travel, it can't be done (at least with this set of shocks). I checked to see if the bottom mount could be moved out, but it can't as it would hit the CV boots on the front axles. The 14" springs went right on with my compressor. Had to compress about 2" to get the keepers in. I need to hit the trails to see how these run.

 

I have the same coil overs as you, but the newer version with the single lock collar. My top hat came factory flipped the opposite as what’s in the pic.