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How to Build R5-Style Shocks

This tutorial demonstrates how to build/rebuild the R5-style pan car micro shocks. The shocks on the R5 series of cars differ greatly from other styles of micro shocks on the market, and there are a few "gotchas" to look out for when building them. Hopefully this tutorial will teach you how to build smooth, trouble-free shocks consistently.

To build your shocks, you'll need the following items-
• A 1.5mm allen wrench
• A 3.0mm allen wrench
• Shock oil
• Fresh shock o-rings if rebuilding a shock.
• Paper towel
• X-acto knife with a fresh blade
• An old toothbrush or similar brush for cleaning the outside of the shock
• A shock building stand (In a pinch, a touring car wheel works perfect)
• You may also need a pair of pliers for one of the last steps
The first step when rebuilding the shocks is of course to disassemble the shock. Use your 3.0mm allen wrench to remove the shock from your car, and then use the 1.5mm allen wrench to remove the lower shock eyelet and spring cup.
Once you have the spring, spring cup, and lower eyelet removed, use your cleaning brush to remove as much dust and dirt as possible. You want to get the shock as clean as possible. Make sure that you check the lower seal cap of the shock for debris, as well as the cutout in the upper shock cap.
When you've finished cleaning up the shock, it should look like this. Now we're ready to start rebuilding.
Start by removing the upper cap from the shock and placing it to the side. Check the hole where the shock shaft passes through for more debris and remove it with the cleaning brush. Next, push the upper seal and spacer out of the top of the shock using the shock shaft. Go ahead and throw away the o-ring, as we will be using fresh seals from the rebuild kit. You can reuse the spacer, or use a new one from the rebuild kit.
Pour out any oil remaining in the shock body and dispose of it properly.
Continue fully disassembling the shock by unscrewing the lower seal cap and pressing out the lower o-ring and spacer using the shock shaft. Again, throw away the o-ring as we won't be reusing it. Check the lower seal cap hole for debris just like you did the upper cap and make sure that it's spotless.
Examine the shock shaft for scratches or pitting. If the shaft has a satin finish or if there are scratches, I recommend polishing the shaft by chucking it into a Dremel or hand drill and using some metal polish and a rag. I use Mother's aluminum polish to smooth out my shock shafts. This can make a huge difference in the smoothness of your finished shock, so I recommend not skipping this step unless you're in a rush at the track. Even if you are building brand new shocks, the shafts will benefit from being polished.
Your rebuild kit will include all of the plastics for the shock, as well as a smaller bag of small parts. For the rebuild, you should really only need the smaller bag of parts.
In the smaller bag of parts, you'll find new seals and spacers. One rebuild kit includes enough parts to rebuild two shocks.
Before you start reassembling your shock, check the black spacers for mold flashing. In the picture to the left you can see a little bit of plastic left over from where the spacers was molded on its parts tree.
To remove the flashing, use your x-acto knife to cut off the side of the spacer that has the flashing. Notice how much I'm cutting off in the picture to the left. You actually want to make a flat side on the spacer. Even if your spacers don't have any flashing, I recommend trimming off one side of the spacer. More on that later.
Once you're finished trimming the spacer, it should look like the picture to the left.
Start out reassembling the shock by putting a spacer into the bottom of the shock body. Use your 1.5mm allen wrench to make sure that the spacer is seated correctly into the shock.
Next, place one of the o-rings and make sure that it's seated correctly against the spacer. Some people like to use Associated Green Slime on their shock seals, but with shocks this small I don't recommend it. Excess slime could contaminate the shock oil, and these shocks have a very small volume of oil to work with. Also, the polish job you put on your shock shaft earlier should help cut down on any stiction.
Finish up the bottom of the shock body by screwing on the lower cap. This cap just needs to be finger tight - don't gorilla grip it.
Take your shock oil and place a drop on the longer end of the shock shaft. This is to help lubricate the shaft as it passes through the lower shock o-ring. If you skip this step you may tear your o-ring, which would lead to a leaking shock.
Place the shock shaft back into the shock body long end first. SLOWLY push the shaft past the lower seal.
Pull the shaft down until the piston reaches the bottom of the shock body.
Fill the shock body until the oil is about 2-3mm from the top of the shock body.
SLOWLY work the shock shaft up and down a few times to allow trapped air to escape out from under the piston. You'll see the bubbles rising up in the oil.
Leave the shock sitting on your rebuild stand until all of the air bubbles have escaped from the oil. Add more oil if needed to bring the oil level back up to 2-3mm from the top of the shock.
Take your remaining spacer and slide it down into the shock. Again, use your 1.5mm allen wrench to make sure that it's seated correctly. As you insert the spacer, you'll notice that excess oil will escape out from under the spacer through the opening we made when we trimmed the spacer. See, I told you there was a reason for doing that. ;)
This step is optional, but if you have a large amount of oil remaining above the spacer, you can use the corner of a paper towel to "wick" up the extra oil. When doing this, be careful that you don't lower the oil level in the shock too much. You still want a minute amount of oil above the spacer.
Slowly slide your remaining o-ring over the shock shaft and down into the shock body. The o-ring will push out some extra oil when you do this. Make sure that the o-ring seats fully down into the shock body. If there's excess oil keeping the o-ring from seating correctly, use your thumbnail to press down on the o-ring, working your was around it in a circle to force out the excess oil. What you want to do is "burp" the o-ring.
When viewing the shock from the side, you shouldn't be able to see the o-ring at all. If you can, you're more likely to cross-thread or strip out the upper shock cap. This is the biggest problem that I've seen people have with these shocks. Making sure that the upper seal sits correctly in the shock body will save you a lot of grief later on. This is also why you need to use fresh seals every time you rebuild your shocks. Over time, shock oil causes the seals to swell. This prevents used seals from seating correctly in these shocks. To see this, look at one of your old seals compared to a fresh one. The used seal will look bloated compared to the new seal.

Seating this o-ring is probably the most important part of building these shocks. Make sure that you take your time and get it right!
Once you've correctly seated the upper o-ring, CAREFULLY screw the shock cap on. Screw the cap on until it just bottoms out, but don't tighten it any tighter. Any more pressure on the threads and you'll strip out the cap. If you've previously overtightened the cap, go ahead and use the replacement cap from the rebuild kit. You can look at a cap and tell if it has been overtightened before. Stressed caps will look like they're flared out at their opening. Toss these caps in the garbage- don't even keep them around as spares. Once a cap has been overtightened, it will easily pop off in a collision on the track. Replace them and save yourself the heartache of losing a race due to a blown-out shock.

Go ahead and test the shock to make sure that there's no air in there. If you hear ANY squishing noise, remove the top of the shock, o-ring, and spacer to add more oil. The R5 shocks are a "dead" shock in that there's no rebound, and the displacement of the shock shaft doesn't change as the shock is compressed. There needs to be zero air in these shocks for them to work correctly. Again, take your time and get it right.
Now that the main part of your shock is built, wipe off any excess oil from outside of the shock and reassemble the spring, spring cup, and lower eyelet. To make tightening the lower eyelet easier, slide your 3.0mm allen wrench into the opening in the upper shock cap to prevent the shock shaft from fully compressing into the shock. Tighten the set screw in the eyelet with your 1.5mm allen wrench.
Now that you have a smooth shock, you need to look at the mounting points that hold the shock onto the car. Use your 3.0mm wrench to work the pivot balls in the upper shock cap and the lower eyelet around in every direction. If the balls feel tight in their sockets, you can loosen them up by squeezing the cap or eyelet from the sides with a pair of pliers. It's a good idea to check this every time you put your shocks back on your car, since a binding shock mount will negate all of the work that you've done to build a smooth shock.
That's it. You should now have a smooth shock that when mounted to your car should be free and move through its full range of movement without any binding.

One last important note about building shocks- If you are racing outdoors and the temperature differs from indoors by more than a few degrees, build your shocks outside. The reason behind this is that shock oil is affected by changes in temperature. If you build your shocks indoors in a cool, air conditioned room and then race in 90+ degree weather, the pressure in your shocks will differ. The same goes for racing outdoors in the winter. Your shocks need to be built in conditions similar to those they will be raced in. If you're racing indoors, you should be good to go.

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