Shocks are by far one of the most important parts on any RC car, and oftentimes they’re the most overlooked when it comes time to do regular cleaning and maintenance. A well-maintained set of shocks will not only preserve but sometimes even improve your RC car’s performance and handling, making regular service and maintenance a must. In this article we are going to go over the basic tips and cover a few tricks on how to thoroughly clean and service your RC shocks.
For this article I decided to use the shocks from my B74 as the example. Associated’s design on the B74 shocks may have some specific design elements that others don’t, but overall, just about all RC shocks use a similar design when it comes to the basics. The basic anatomy of a shock consists of the main shock body, the shock piston and shock shaft, the top cap, and the lower cap that helps house the internal seals. One thing to keep in mind is that the B74 shocks use “emulsion” style top caps, meaning it has a bleed screw and no air bladder.
Dirty shock, clean shock
Remove the spring seat and the coil spring from the shock body as well to give them a good cleaning on the side. Removing the seat and spring are always necessary to properly change fluid or completely rebuild a shock, but it can also help to get all the gunk off when doing a simple exterior cleaning. Take the extra couple seconds to remove these pieces, it’s worth it.
Before I disassemble any of the sealed components, I always make sure to give the outside of the shock body a good spray with some electric motor cleaner. This, along with some thorough cleaning with a rag, will ensure that no dirt or debris gets inside.
Once the outside has been properly cleaned take off the top cap and drain the fluid. Notice how dirty that fluid looks? Shaft seals can only do so much to keep out fine particles of dust and dirt, which is one of the reasons regular shock maintenance can be so important. I usually pour the shock fluid into a small paper cup, making it easy to clean up later. Make sure to move the shock shaft back and forth to get as much of the old fluid out as possible. If you’re simply replacing fluid, you can skip to the Filling & Bleeding section because next we’re going to go over a full teardown of the shock.
Remove the eyelet from the shock shaft, using either a set of plastic-jawed pliers or specialty shock pliers to hold the shock shaft in place. Once removed be sure to clean off as much dirt or grime as possible from the shaft threads. Remove the bottom cap, and then the piston and shock shaft. I use the very bottom of the shock shaft to gently push out the inner seals and spacers from the shock body. This way I don’t risk damaging the shock body with a pick or other sharp tool.
Give the internal bore of the shock a good cleaning with a cotton swab, making sure to remove as much dirt and residual oil as possible. I suggest avoiding the use any kind of cleaning solution or spray when cleaning the inside of the shock body, mostly because of the potential to leave residue and ruining the new fluid and seals over time.
Cleaning & Greasing
Now it’s time to give all of the internal parts a good once-over, cleaning as necessary. If your shocks have internal plastic spacers between seals, it’s a good idea to get them as clean as possible. The shock seals and o-rings are usually the most common maintenance item to get overlooked when worn out, allowing dirt and debris inside the shock, usually resulting in a leak, and even sometimes causing internal damage.
For the V2 shocks I clean the shock shaft and piston, the outer o-ring for the bottom cap, as well as the internal plastic spacers.
Shock shaft seals and o-rings take a lot of abuse, so they tend to wear out quicker than you might think. If your shocks aren’t leaking, that doesn’t necessarily mean they don’t need replacement. Any noticeable change in performance warrants taking out the seals for inspection on your next tear down.
It may be a bit hard to see, but the old seal’s inner diameter widened with use, which potentially allowed in more dirt and debris. In the interest of restoring the shock to its former performance, I opted to install new o-rings.
Some shocks, like the ones off the B74, have a special tool to hold onto the shock body, but if this isn’t something available on your shocks a set of plastic-jawed pliers will do the trick.
Reassembly is the reverse of disassembly, with a few minor details to pay attention to. First thing, make sure you reinstall the shock seals carefully, ensuring each seal and spacer is seated properly, then reinstall the bottom cap. After that carefully reinstall the shock shaft and piston into the shock body. It’s rare, but also entirely possible to damage your shock seals with the threads on the end of the shock shaft if not installed carefully. As long as you are careful when installing and your seals are greased, you should be ok. Once that’s done simply reinstall install the eyelet and you’re good to go.
Filling and Bleeding
Fill the shock body with fluid slowly so you don’t trap excess air in the fluid. The B74 shocks use a bleeder, or emulsion style cap, so I fill the fluid almost to the top. For Bladder style shocks, usually slightly less fluid is necessary. Move the shock shaft up and down slowly, you’ll start to notice small air bubbles coming to the surface. Now you can either set it aside for a few minutes to let the air escape, or you can use a specialty shock bleeder which helps to ensure that almost no air bubbles are left.
Once the excess air is removed, reinstall the top cap with the bleed screw removed. Fully compress the shock shaft keeping a rag around the shock to catch any excess fluid. Simply reinstall the bleeder screw and you’re all set.
After filling the fluid and tightening the cap I usually give the shock another spray of electric motor cleaner to take off any residual oil.
Once assembled, the shock shaft should not move from its fully compressed position. If the shock shaft moves, this means there may be excess air in the shock, which can cause inconsistencies in performance.
And there you have it, a fully refreshed shock!
Fresh shock fluid has more air in it than you might think. Look at just how many bubbles are forced out of the fluid by the shock bleeder.
When is Maintenance Needed?
Regular maintenance can mean different things to different people. For an RC racer this might mean a tear down and rebuild of the shocks after every race weekend, while for casual bashers it could be as simple as once every couple of months. If you notice any damage or leaking, replace the damaged parts, if you notice leaking then installing some new seals and o-rings is highly suggested. Ultimately, the interval of when and why is up to you, but hopefully this guide shows you just how easy shock maintenance can be.
Text and Images by Lauren Short