How To Rebuild QA1 Monotube Circle Track Shocks

Rebuilding or tuning shocks might sound complicated, but surprisingly enough, the procedure is fairly simple.

When you feel your shocks are worn and not performing the way they did when you first installed them, maybe it is time to do something about it. Shocks are one of those items that are consumable on all types of cars. Race cars, especially dirt track cars, tend to be rough on shocks. The abuse a dirt track car puts on shocks is amazing. Despite this, shocks are a very dependable and essential part of the suspension system.

When your shocks are not performing like new, you’ll know it. Your lap times will get slower and the car’s handling will be a challenge. Most of the racers we know will buy quality shocks like the QA1 Monotube or Twin Tube shocks because they are rebuildable. Rebuildable shocks allow the race team a better return on their investment in the long run and give race teams more control on how their suspension will handle on race day.

These are the tools that many of the pros use when working on shocks.

For many racers, QA1 circle track shocks can be rebuilt in their shop with access to some special tools. We’re going to take a look at how QA1’s monotube shocks are rebuilt, so you can see what it takes and let you decide if this is something you want to do.

Rebuilding QA1 Circle Track Shocks

If your shop does any welding, chances are you already have tanks of argon, helium, oxygen, or other mixes of gases. It will be necessary to have a cylinder of nitrogen and a QA1 fill tool in order to fill the shocks during the rebuild process. A shock vice and some common hand tools will also be required.

Hyperscrews on the top and bottom must be removed to begin the rebuilding procedure.

While many may use a traditional vice instead of a shock vice, our contacts at QA1 recommend a shock vice if you plan on rebuilding shocks regularly. A shock vice is the best way to secure a monotube shock and prevent any damage while working on the shock body. If you choose to use a traditional vice, ensure the vice is fitted with soft jaws or covers.

You will also need a closure-nut wrench, small pick, soft-blow hammer, and a Phillips screwdriver to rebuild the shocks. Finally, a supply of fresh shock oil will be necessary — depending on the condition of your shock. At a minimum, serious racers will want to rebuild shocks with fresh fluid and look for any parts that need replacing after a hard season of racing.

Tools Recommended For Rebuilding And Tuning QA1 Circle Track Shocks:

  • Vise with soft jaws (aluminum or plastic) or shock vice
  • Torque wrench with 17mm socket
  • QA1 shock oil (part #SF04)
  • QA1 rebuild kit and/or tuning kit
  • QA1 monotube inflation tool (part #7791-140)
  • Snap-ring pliers
  • Phillips screwdriver
  • Soft-faced mallet
  • Clean rags

Rebuilding QA1 Monotube Circle Track Shocks

After mounting the shock in the shock vise with the body up, make sure the shock is fully extended. You’ll then want to remove the hyperscrew to release the nitrogen in the shock, and then compress the shock to make sure all the gas ha escaped. After re-extending the shock, flip it over so the body is now in the vice.

Removing the snap ring that retains the gland-retaining ring.

Around the shaft, you’ll notice a small snap ring that will need to be removed so you can undo the gland-retaining ring. This retaining ring looks like a steel washer.

Pro-tip: Use a binder clip to hold this washer up and out of the way.

On the inside of the shock body, you’ll notice another hyperscrew in the gland. Slowly remove it. If the floating-piston O-ring has failed, nitrogen gas will be mixed with the oil, and oil can shoot out of the hyperscrew port. With your fingers, push the gland down into the body of the shock roughly a 1/2-inch. Then, remove the snap ring that keeps the gland in place.

With firm pressure, pull up on the entire piston and rod assembly while rocking back and forth to remove it from the shock body.

Note the black binder clip on the shaft of the shock assembly. This is a quick and easy way to hold the steel gland-retaining ring up and out of the way.

Now you can change out the valving, replace seals, or do any other upgrades that might be necessary. Pour the oil out of the shock body and use new oil when reassembling. You can reuse the oil if it’s new.

Assembling QA1 Monotube Circle Track Shocks

Before starting reassembly, you’ll want to reset the floating piston. This is accomplished by taking a section of pipe — or the end of a hammer — and pushing down on the bottom of the inside of the shock body. This piston will slide down about 1-inch, and you’ll hear the air push out around it.

The next step is to add a specific amount of shock oil. The amount of oil required is based on the stroke of the shock. In the case of a 7-inch shock, you’ll need 320ml of oil. If you are working on a 9-inch shock, the oil volume is 400ml.

With the shock tube filled with the correct amount of oil, slide the piston assembly into the shock body until the piston is submerged in the oil. Then, slide the gland assembly down into the shock body until it is approximately 3/8-inch below the large snap ring groove on the inside of the shock body.

Re-installing the hyperscrew.

You’ll want to push the piston down until enough fluid fills up on top of the gland to the small snap ring groove on the gland itself. Now, go ahead and install the screw back into the gland body. With the screw back in, tip the shock over and dump out the small amount of oil that’s on top of the gland.

Slide the gland-retaining ring back down and install the snap clip to hold it in place. Flip the shock back over and install the hyperscrew on the bottom. The best practice is to install the screw all the way in, then back it out two revolutions.

Add The Nitrogen Charge

In order to charge the shocks with nitrogen, you’ll need the QA1 refill tool. In essence, this tool allows you to fill the shock and tighten the hyperscrew at the same time. To use it, slide the tool into the bearing mount on the shock, and then push the tool down onto the shock body over the hyperscrew. With the tool over the hyperscrew, use it to loosen the screw a tiny bit more. Then, fill the shock with nitrogen, and tighten down the hyperscrew before removing the fill tool.

To make sure the shock is properly rebuilt, slide the travel indicator on the piston shaft up, then compress the shock all the way down. It should return to fully extended on its own. If the shock does not fully compress, there is either too much or too little oil. If there is too much, the gland hyperscrew can be loosened and a small amount of oil bled out. If it is too little, the reassembly process needs to start over, including resetting the floating piston.

The average Saturday night racer operates with a lean operation. There are no shock specialists and no money in the budget to be shipping out shocks every week to be dyno’ed and rebuilt by the pros. QA1’s efficient and maintenance-friendly monotube shocks can be rebuilt in your shop or race trailer with a minimum of specialized tools. Just use due care and follow these easy procedures.

For more information on these or the other products made by QA1, visit them online at

Article Sources

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
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