One of the most intimidating tasks in fixing up a truck has to be working on shocks. Shock absorbers seem to take on a stigma of being an intricate part only to be worked on by a trained professional. Well I am here to tell you that they are in fact nothing to be feared and can be easily worked on in your very own garage!
To show how easily shock work can be done we are going to walk you through a simple revalve on a set of 2.5" RaceRunner by Sway-a-Way race shocks. For this we took a trip over to Sway-a-Way's shop in Chatsworth California and meet up with Engineer Brian Bell.
The list of tools you need to disassemble your RaceRunner shock is very minimal and there are no specialty tools. All you need are a 5/32" Allen Wrench, small flathead screwdriver, pair of pliers, a 7/8" wrench (closed or open, your choice), a bench vise, and some clean rags (shop rags, not dish rags as I'm sure your wife wouldn't like that too much).
Start by placing the shock upside down in your vise and secure it by clamping onto the cylinder cap. It is a good idea to place a rag between the cap and the vise so that you don't scratch or otherwise mare the caps surface. You are going to want to make sure that the shocks shaft is fully extended since this will make removing it much simpler. At this point you need to remove the nitrogen from the reservoir to depressurize the shock. Do this by simply pressing the Schrader valve just like letting air out of your trucks tire.
You are now ready to start taking the shock apart. Start by removing the three Allen screws in the wiper seal cap. After you slide the wiper seal cap up the shaft and out of the way the seal carrier will be visible. Press this piece down just enough to see the circlip and remove it using your small flathead screwdriver (or a small pick if you happen to have one). With the circlip removed the entire shaft assembly will be ready to come out. Remove the shaft slowly and steadily to avoid spilling the oil inside. We can now start the revalving!
To begin revalving you will need to remove the shock body from your vise making sure again not to spill any of the oil inside. Place the shock against a wall or in a corner where it won't be disturbed while you work on the valving. Place the shaft assembly into the vise and secure it using the rod end. You can also secure it via the shaft by using a hogged out block of soft wood or soft metal such as aluminum. Never clamp the shaft in the vise by its self as this will cause scratches and/or gouges in the shaft which will lead to premature seal and shock failure. Next remove the 7/8" locknut that is located at the end of the shaft, with this off you can now remove the piston and valving shims. Be careful not to lose any of the valving shims when you remove the piston from the shaft and make note of which way the piston came off. Remember, Compression is on the bottom and Rebound is on the top. Once you have installed your new valving shims place the piston back onto the shaft and tighten the locknut. The shaft is now ready to go back into the body.
Don't get too excited yet, there is still one more step that needs to be done before the shocks can be reassembled, this is setting the floating piston depth in the reservoir. Doing this ensures that you have the proper oil level, proper pressure, and helps to prevent hydraulic lock. To set the depth simply press down on the Schrader valve side of the reservoir exposing a circlip, remove this circlip and remove the end cap with a pair of pliers (be sure the Schrader valve cap is on to prevent damage to its threads). Press the piston down to a depth of 9" below the end of the cap. It may take some force, don't worry this is normal. Also be careful not to press too hard or fast or you may end up with a shock oil volcano spewing from the body.
Now you can reassemble your shock. With the body placed back into the vise fill the oil level to about 1" below the circlip groove inside the cylinder. Place the shaft back into the cylinder by rotating the shaft clockwise and lowering it slowly into the oil. Next press the seal carrier into the oil, if oil overflows out of the shock before you sink the seal cap o-ring you know you have the right amount of oil in the shock. Press the seal carrier far enough in to expose the circlip groove and replace the circlip, pull up on the shaft to seat the seal carrier against the circlip. Now you can slide the wiper seal cap back into place and secure it with the Allen screws, snug, not tight. Lastly you must press the shaft completely into the body, then charge the shock with 200psi of Nitrogen. This will ensure that the shock is not seeping oil and that it is cycling correctly. If everything checks out refasten the Allen screws and the shock is now ready to go back on your truck!
And you see, you thought valving a shock was hard! We will discuss how to choose the proper valving for your shock at a later time.
Note from Sway-A-Way:
A couple years ago we redesigned and improved our 2.0" and 2.5" pistons providing better oil flow and damping characteristics. However, with the current valving in the shocks the shock is approximately five to ten percent softer. You might find the current setting satisfactory but you may consider valving your RaceRunner shocks about five to ten percent heavier depending on your application. See the photos below to tell which piston you have.