Koni Sport Cartridge Conversion for EP3/DC5 Front Struts

Spray every fastener you will touch with PB Blaster and let it penetrate. At the strut housing, unbolt the small brackets that retain the brake hose and the ABS wheel-speed sensor line so they hang clear of the strut. The brake caliper and rotor can stay bolted to the knuckle for the entire job.

Pull the cotter pin from the tie rod end and back off the castle nut. Drive the taper loose with a pickle fork and a few firm blows from a small sledge; it will pop free. Strike only the joint body with the fork, never the threaded stud. The fork usually shreds the tie rod boot, so have a replacement boot ready before you start.

At the top of the strut tower, break the three retaining nuts loose and crack the central rod nut, but leave everything threaded on for now. Underneath, take out the two through-bolts clamping the strut to the knuckle. Pry the knuckle forward to release it from the strut, then lift the complete strut out. Leave the knuckle hanging on the lower ball joint.

Steady the strut on a bench and remove the top center nut, then lift off the top hat and slide the coil spring off. Short lowering springs such as Eibachs will typically come free by hand with no spring compressor, but a full-length stock spring may still hold preload, so use a compressor if there is any tension. Set the bump stop aside.

Find dead center on the bottom cap of the old housing and mark it with a center punch, then drill a small hole. The damper is gas-charged, so expect a brief hiss of escaping pressure as the bit breaks through; keep your face away from the drill. Stroke the damper rod up and down to pump out as much of the internal oil as you can.

Hold the new Koni cartridge against the housing and measure from its top face down to the raised locating bumps on its body. Subtract 7mm from that figure to get the length to trim off the top of the old housing. On this install the measurement was 57mm, so 57 minus 7 gave a 50mm cut. Confirm the number against Koni's printed instructions, wrap tape around the housing as a cut guide, and part the tube with a cutoff wheel or hacksaw, working evenly all the way around. The old damper internals slide out once the cut is complete.

Enlarge the hole in the base of the housing so it will pass the hex-head bolt supplied by Koni; a 1/2-inch bit sizes it correctly. It seats into the base of the new cartridge and pulls the assembly down into the reused housing.

Slide the rubber boot from the Koni kit over the open end of the housing, then drop the cartridge in. With an accurate cut you should be able to start the hex bolt into the cartridge base by hand for a few turns; if it will not line up, withdraw the cartridge and open the hole slightly. Run the bolt in with a ratchet until snug, which draws the cartridge's locating bumps down into the housing and locks it in place. Final-torque to Koni's published spec (roughly 57 ft-lb on this install).

Fit the white plastic spacer disk from the Koni kit over the damper rod, followed by the bump stop. Note that EP3 fronts may carry a hard cone-shaped stop rather than the trimmable foam type found on Integra struts. Reinstall the coil spring and top hat. A short spring can usually be squeezed just enough by hand to start the washer and rod nut; torque that nut to about 37 ft-lb.

Optionally wire-brush the old housing and hit it with rattle-can paint to knock back rust before it returns to the car. Dial in the Koni damping by winding each adjuster fully in, then backing it out one full turn (360 degrees). Reinstall the strut in reverse of removal, torquing the tower nuts, the knuckle through-bolts, and the tie rod nut, and fit a fresh cotter pin. A cartridge swap on its own does not disturb the alignment, so none is required unless you also change ride height or service tie rods, ball joints, or bushings.