BC Racing Coilover Spring Change & Preload Adjustment
Please follow these steps in order to isolate the problem you are experiencing.
Verify the top nut is secure and tight.
You can do this by removing the dampening adjustment knob located at the top of the shock shaft. To remove: Take a 14mm or 17mm wrench (depending on top nut size) and loosen the part of the knob or loosen by hand for V1 design under the black dial. After the knob is off, you can tighten the nut by either using an allen key to hold the shaft from spinning and an open-end 17mm or 21mm wrench(depending on top nut size). The other method would be to use a low powered impact wrench and tighten until the shock shaft begins to spin.
Verify all mounting hardware is tight and secure.
This includes but is not limited to the lower mount bolt(s) top plate bolts, sway bar end links, control arm bolts, as well as the lock, rings on the Coilover itself.
Verify that the pre-load is properly set at the factory specifications.
The front should be set at the 3-5mm we recommend. To do this, tighten the lower spring perch by hand until the spring is now captive ie located and not able to move upwards or downwards. Then you will need to run the locking ring up to the lower spring perch nut, from there you will tighten the spring perch with your spanner wrench until there is a 4mm gap between the locking ring and the lower spring perch (this should be just enough to fit the spanner wrench in.) You can refer to this video above as a reference.
Separate Spring and Shock Preload
Verify that the suspension bushings are not binding.
This will normally result in excessive squeaking, but it could also be the cause of a knocking noise.
To resolve this, put the car on a drive-on lift or jack stands.
If you are using the jack stand method, you will need to jack up one corner suspension at a time to simulate the car being on the ground. You will then loosen and re-tighten all of the control arm bolts so that the bushings reset to a manner where they are at zero flex at static height and can flex down with the suspension droops and up when it compresses.
If the problem persists, and you are within the warranty period, please email us back with a copy of your original purchase receipt and the serial number for your kit. The serial number is located on the ends of the outer brown box the kit shipped in, and also the warranty card included in the kit. These serial numbers are required for us to proceed further with your inquiry when contacting BC Racing HQ so please ensure these details are supplied.
Please attach pictures of the suspension kit installed on your vehicle so that we can verify it was installed correctly. A video that portrays the problem you are having is also extremely helpful so that we are able to assist you as best as possible.