Cygnus Performance

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Loose Top Hat Nuts

When you first install height adjustable coilovers it’s pretty common to have a loose top hat nut. This is not because the nut was improperly tightened at the factory during production. We have a special clamp that holds the shaft, and every top had nut is properly torqued to the same specification before the coilovers get shipped to the customer.

The reason that this can be an issue is because when you initially adjust ride height the spring can put a lot of force on the upper perch causing the nut to slightly back off. This issue is not unique to our product. Every height adjustable coilover set in the world including $15,000 coilovers will exhibit this issue once in awhile depending on a number of variables.

If you are experiencing this issue you will notice a clunking noise. Typically whenever the suspension un-weights the spherical bearing will slide up on the pin and then bang down on the shaft as the suspension comes back under load. The good news is this is a very easy issue to fix. Usually tightening them one time will be sufficient to permanently address the issue.

No matter how many times I tell people this many of them don’t seem to understand that ***THE TOP HAT NUT CANNOT BE TIGHTENED BY THE END USER USING HAND TOOLS.*** This is because the shaft and piston assembly will freely rotate within the shock body as you try to tighten this fastener. There is no way to incorporate a hex inset into the shaft of a rebound adjustable coilover (unless it’s inverted) because of the rebound adjustment clicker assembly. If you don’t have the special clamp that we use at the factory during initial assembly the only way to overcome this rotation is with inertia. Therefore, the nut must be tightened with an electric impact gun rather than hand tools. The speed at which the impact gun spins the top hat nut will overcome the rotation of the shaft which will sufficiently tighten the nut within a couple of seconds.

In order to successfully tighten this nut without damaging anything you will need the following:

– Electric impact gun

– 19mm or 21mm deep socket (dependent on which of our top hats you are running)

– 2mm hex key

Although it is preferred to do this under load while the car is on the ground it really doesn’t make a big difference either way. Start by removing the rebound adjustment knob which is attached via 2mm hex set screw. This is to avoid damaging the rebound adjustment clicker with the impact gun. From there you simply tighten the nut using the deep impact socket and electric impact gun. A couple of seconds is all it takes. Although none of this is going to damage the shock in any way you don’t really want to spin the piston more than necessary.

If you experience clunking that is not resolved by tightening this fastener please contact me for further troubleshooting. It is not common for these coilovers to make noise, but the good news is when they do we can always resolve it. If you are experiencing a clunking noise this is by far the most common culprit. Thanks for reading and let me know if you have any questions.

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