Shock Setup
Shocks…. Let’s talk about shocks. Shocks are, in my opinion, one of if not the most important part of an RC build. Whether you are building a trail rig or comp crawler, a garage drifter or full spec drift car, well built shocks are the key to successfully enjoying your ride. The shocks directly translate the weight and motion of you car to the road.
There is a lot of opinion and personal preference to how folks like their shocks to feel. With that said, this is how I build Yokomo SLF drift shocks for the feeling I like. Most of the techniques I use can be done with any bladder style shock. Use it all, leave it all, or take what you like. I just want to share what I’ve learned and what I like in my drift car shocks.
So here we go! First thing I like to do is make sure I have a nice clean work space. I use Scott blue shop towels and I always lay a fresh one on my work surface. Since we’ll be working with oil and lube grease, you don’t want dirt and debris getting into any seals or in the shock body itself. Building shocks is messy, no way around it for best results.
“Most of the techniques I use can be done with any bladder style shock.”
A good pair of shock shaft pliers is an absolute must.
There are tonnes of options out there and most aren’t expensive and will last a long time. I got mine from Amazon and I have zero complaints. You never want to leave tool marks on the shock shaft. The tiny burrs will eat the o-ring and cause leaking over time.
For my build, I also highly recommend a good Pin Vise and shock piston drill bits.
O-ring grease…. I use Protek Blue, green slime is just as good.
Now that we have a clean work space and tools gathered let’s get started. The first thing I do is assemble all four shaft and piston assemblies. Have fun with the E-clips…. This next step is personal preference, but I use the four hole piston. The stock holes are 1.1mm, I drill mine with the Pin Vise to 1.6mm to decrease the damping rate. If you do decide to drill the pistons, do it over a trash can or anywhere but directly over where you are building your shocks. Clean the shavings off the assemblies before going on.
At this point, I prep the shock bodies. Install the thin, black o-ring in the pre-load collar and thread them onto the bodies. Now you can drop the piston assemblies into each body. The next step is install the O-ring followed by the lower retainer. I apply just a small amount of o-ring grease as shown below.
Evenly smear the grease around the entire o-ring. Once you are done, seat the o-ring into the body, set the retainer, then screw on the lower shock cap. DO NOT USE the .5mm spacer as shown in the directions, this compresses the o-ring too much and makes the shocks stick.
NOTE - I do not recommend installing the o-rings and caps into the body THEN pushing the shock shaft through. The newer blue Yokomo and red Reve D O-rings are very soft and the threads of the shock shaft will tear the o-rings as they pass through as the seals are now compressed and seated in the shock body.
Using your shock shaft pliers, hold the shafts steady and thread the rod ends onto the shock shaft. I like to measure each shock as I do this, SLF shocks will be 11.5mm - 12mm of exposed shaft. As I finish each rode end, I hang the shocks in a shock stand for servicing. I 3D printed this one years ago from a file on thingiverse, there are several to choose from or you can but one premade. Always a good idea to lay a shop towel under your shock stand, you ARE going to spill some oil and thats perfectly fine.
Fill the shocks all the way to the top as shown here.
Once full, gently run the piston all the way to the top, then pull the piston out slowly. You should see some tiny bubbles rising though the oil. I usually perform this step 2-3 on each shock, when you are no longer seeing bubbles rise from under the piston, let the shocks rest with the pistons fully extended. This is a great time to take a breather as the bubbles rise and pop. If you want to keep on going, you can use a small pin to work the bubbles out.
Take a break or keep working, for smooth, consistent feeling shocks, this is a VERY IMPORTANT step. Make sure there are NO BUBBLES in the oil before you move on.
With no bubbles in the oil, it’s time to instal the bladders. This is my method and it’s the best way ive found to seal the top of the shock and not introduce air back into the shock oil.
With all the excess oil squished out, the bladders should be resting in their natural shape neatly sealed. All the hard stuff is over but be careful to not lift the bladders off the shoe bodies as you finish up. Next to last is placing the ball caps on top of the bladders for each shock.
I use my thumb and forefinger to “taco” the bladder and let the bladder push the excess oil out of the shock body. As the bladder is released, it should settle cleanly on the top of the shock body and make its own vacuum seal with the oil. You may need to gentle work the lip of the bladder to let any excess oil out so it sits level on top of the shock body.
TAKE YOUR TIME WITH THE LAST STEP. Rounding third and heading home, dont let the catcher tag you buy letting the bladder slip as you seat the collars on. Place them gently over the ball cap and it will push evenly over the bladder. Screw the cap on HAND TIGHT and clean the outside of the shock bodies and wipe the last of the oil away.
So here you are, completed dampers ready for your choice of springs and cups. I am a huge fan of the Yokomo SLF Big Bore shocks. They are easy to build, easy to tune, and very versatile. The techniques and steps I do can be used on pretty any bladder style shock. We are also only just at the tip of the iceberg with shocks…. Hopefully this helps you get pointed in the right direction. Cheers!
