Setting Pre-Load on your BC Racing Coilovers
The proper way to set pre-load on a BC coilover-
- Loosen both lock rings under the spring (spring seat ring(top) and spring lock ring(bottom)) so that the spring is loose and can move up and down slightly.
- Tighten up the spring seat ring so that the spring is snug, but do not tighten it down past simply holding the spring snug, this will be "0" preload.
- Now bring the bottom lock ring up so that it is just touching the spring seat ring, but do not tighten to lock, you will be moving the spring seat ring next.
- Now tighten up the spring seat ring so that you are now preloading (compressing) the spring.
- Measure the distance between the bottom ring and the top ring as you are tightening, once there is a 3-5mm gap between the two rings, you have 3-5mm of preload on the spring. The thickness of the lock ring wrench is 4mm, so when you can slip the wrench in between the lock rings, you're good to go.
- Tighten up the lock ring to lock your preload in place
- Repeat for all 4 corners.
You also may want to check and make sure the top center nut is tight. It is best to check this nut with an impact gun if you have access to one. A quick hit with an impact gun is all it should need to stay tight and snug. If you do not have access to an impact gun, you can use an allen key to hold the shaft in place and tighten the nut with an open socket or wrench. You don't want the shaft to spin while you are tightening it,otherwise it will not tighten or tighten enough. A few other areas to check are the lower mounting bolts, the allen bolts that adjust camber if fitted with camber plates, and the 4 lock bolts underneath the pillowball bearing if fitted with pillowball mounts. Make sure all fasteners are tight as they can cause problems later down the road if not properly tightened.
Sometimes noise can come from somewhere else. Endlinks, swaybars, and chassis contact can all be the source of a noise issue. Make sure that since the car is now lowered and stiffer, that you do not have any exhaust contact anywhere down the exhaust system. These are all common noise issues.
Quick and easy way to measure travel:
Measurement A - The amount the piston rod that can go into the strut body.
Measurement B - Center of hub to fender lip at your ride height with car on the ground.
Measurement C - Center of hub to fender lip with the car in the air (both front or rear wheels up in the air)
Total Stroke = A
Droop Travel = C - B
Bump Travel = A - Droop Travel