Building Shocks
We did an article a while ago where we addressed "the worst part" of building a kit. While I hate building turnbuckles, most people here seem to hate building shocks. I actually enjoy the process, and find comfort in ending up with a silky smooth damper. Although shocks vary in style--some with bladders, foam, or just air in the oil--the principles are the same. In this article we're going to tackle building both a bladder style shock and the emulsion-type shocks that welcome the intermingling of oil and air. The end result should be a newfound love for building shocks, and one item off our "we hate to build" list.

Words: Derek Buono

Issue 136 - March 2007

It's All In THE PREP
This is the one step that many just skip over, but it's here where you'll gain results for a small amount of effort. Most plastic parts are injection molded and that means flashing. In shocks, flashing is the worst thing you can have on the spacers, as it deforms, rips o-rings, and scratches shafts. Spending a few minutes with a file or sandpaper will work wonders.

STEP 1: Remove the plastic parts from the tree. Some parts have a certain way they are designed to be snapped off, to reduce the amount of flashing from the edges of the pistons and spacers. Pay attention, but if there isn't a pre-defined way to do this, use an X-Acto knife and carefully remove all of the parts required for the build.

STEP 2: A magnifying glass reveals wonderful things, and in this case, the flaws. Under the glass, use a fine file like a nail file, or some fine grit sandpaper, and remove all the flashing from the spacers and pistons. You don't want to change the shape of the part, but you want it to be smooth so it fits into the space it was designed to fit into without deforming the part.

STEP 1: Install the piston on the shock shaft. Be sure to keep in mind that the front shafts and bodies may be different lengths than the rear. Keeping the pairs separate will avoid confusion. [1]

STEP 2: Lay out the order of the o-rings and spacers in front of each shock. Lubing the parts with oil will help things go together easier and avoid tearing the o-rings. Team Associated sells "Green Slime" which is used in-between the o-rings and spacers to help eliminate air caught in the spaces.

STEP 3: Lube the threads of the shock shaft and slowly insert it into the body. This is a very critical part of the process because the threads are usually still sharp, and they can tear an o-ring if you're not careful. Slide the shaft all the way down to the bottom of the body. Repeat this for each shock.

STEP 4: This step can be done last, but I like to get it out of the way early. Attaching the shock end is something that is more difficult than it seems. Lots of shocks have such a tight fit and hard plastic that it's hard to get a grip on the shaft. I use wire cutters to grab the last thread on the shaft. Unless it's a cheap shock, you can really put some force on the cutters to hold the shaft as you thread the end on.

STEP 5: Pull the shock shaft all the way out.

STEP 6: Fill the shock with oil. Tilt the shock on an angle to avoid getting air bubbles in the oil. Fill it to the top of the shock or just slightly below.

Here's where the "hard" part happens. Filling the shocks with oil is easy, but it's also easy to add too much or not enough, and this will alter the performance and consistency of the shock, possibly throwing the car out of balance. The next steps are specific for bladder and emulsion-style shocks. There are only a few differences in building the shocks, and this is noted where applicable.

Emulsion STYLE

Emulsion, by definition, means one liquid is suspended in another, and in shocks that's air and oil mixed together in a "frothy" like mixture. Because the oil and air are not separated, as in a bladder system, the volume needed to allow full stroke of the shock is found in the oil. As the shaft enters the emulsion, the air is forced to the sides and the shaft has room to enter. This also slightly affects damping, as air will slightly lessen the thickness of the oil. Therefore, to really check damping, you have to pump the shock vigorously to get the consistency of the emulsion to race conditions.

STEP 7A: Wait. Here's when waiting a few minutes pays off. Slowly pump the shocks to try and get all the air that may be trapped under the piston out of the oil and to the top. If you can get the shocks to fit in the Ride Shock Pump, this will speed the process (see sidebar). Otherwise, after pumping the shocks a few times, letting each one sit will allow most of the air to float to the top. Thicker oils will take longer.

STEP 8A: Place the bladder on the shock and press on the edges. You're trying to bleed some of the oil out of the body, but not create any bubbles.

STEP 9A: Put the cap on and tighten the cap all the way down. Remember to use any o-ring around the cap.

Bladder STYLE

Bladder-style shocks are ones that use a rubber diaphragm to separate the air from the oil. During compression the air at the top is compressed to allow the shock shaft the volume to enter the shock. If too much oil is used there won't be enough airspace to allow the shock to function properly, and the damping rate is altered. This separation is more consistent than the non-bladder because of the separation of air and oil.

STEP 7B: Insert the cap or bottom-loading cartridge, and tighten it almost entirely. At this point you need to bleed out the excess oil, and leave enough air in the body to allow room for the volume of shaft.

STEP 8B: While the shaft is fully depressed, tighten the cap completely.

STEP 9B: This is where emulsion shocks will differ. By their design you should hear air in the shocks when you pump them. Pump them several times to get the air and oil mixed (emulsified), then test to see if there's the correct amount of oil mixed (emulsified), then test to see if there's the correct amount of oil in the shocks. Press the shock in and feel for resistance. The shaft should be able to be pushed all the way in and rebound slowly out.

STEP 10: Check oil level by pressing the shock shaft all the way in the shock body. There should be no air in the oil. To check this, listen to the sound of the oil. If it's filled correctly you shouldn't hear air in the oil. If there's too much oil, the shaft will resist being pushed in all the way and will snap back at you.

STEP 11: Measure the shock lengths to ensure that they are built to the same length. Adjust shock end if necessary.

STEP 12: Complete the shocks using the remaining items that are shock specific. Put the spring retainers on the body, insert the spring, and finally add the spring perch to the bottom.

When you repeat this process four times--or eight times if you've got one of the trucks that uses double the pleasure--you'll end up with some super smooth and consistent shocks. After you build more than a few shocks, you may even learn to love the art form of building shocks.