Koni products have been considered among the best for quite some time. Although modification to the stock suspension components is required to install these on your 240, the results are arguably worth the trouble.
Time: 4-5 hours
– 2 spring compressors (can be rented from Autozone for $40 refundable deposit)
– Drill w/ 4mm and 12mm bits
– Band saw
– Metric socket set
– Breaker bar
– Floor jack and stands
– Rubber mallet
– A friend
– Wooden blocks
– Koni struts
– Aftermarket springs of your choice
1. You need to get that car up on all four jackstands set evenly on the frame. You might as well set chunks of wood in between the frame and jack stands, because this job should take several hours. Take off the wheels and you will be able to see your suspension components on the front and rear.
2. You might want to start on the front. It is more difficult than the rear, and you might as well get it over and done with. There are 3 bolts connecting the top hat of the front struts to the car body. Just break those bolts and loosen them for now.
3. Next, you are going to get your breaker bar and wrenches ready, because you need to break the 2 bolts connecting the bottom of the strut to the brake assembly. Spray some PB blaster or WD-40 on those bolts if you have any trouble. I found that it was easiest to break the bolts by also using the jack to jack up the breaker bar. Make sure to disconnect the brake lines from the strut BEFORE you remove the 2 bolts, or else you will put too much pressure on the brake lines.
4. Once you disconnect the brake lines from the strut, you can remove the bolts from the bottom, and let the brake assembly hang. You can next remove the top 3 bolts connecting to the strut mount and remove the assembly all together. If some pieces don’t move, be sure to use the rubber mallet…..it will make things SO much easier.
5. Once you have the strut and spring outside of the car, you will want to compress the spring with the tensioners in order to take pressure off of the top hat. When you achieve this, use a wrench and allen key to remove the top hat. It is easier than a socket since it will not spin on you.
6. When you have removed the components, be sure to note how you took it apart, since you will need to put it back together the same way.
7. Now comes the fun part. When you have the front oem strut all by itself, turn it upside-down, and wedge it in the vice between 2 blocks of wood.
8. You will need to take the 3 mm drill bit, and drill a hole in the center of the bottom of the strut. This will release gas pressure, and make your life a little bit easier. After you have successfully drilled through the bottom of the strut, just stick on a piece of duct tape over the hole to ensure that things don’t get messy.
9. The next step is to turn the strut at an angle in which you can use your ban saw (or any other cutting device). The Koni instructions say that you should cut a few millimeters below the top curve. DO NOT. Just make sure to cut down UNDER the larger diameter ring at the top of the strut, since if you cut too high up, you will notice that there are notches and such preventing the insides of the strut to come out. If you do happen to cut too high up, you can always use an angle grinder as well to clear a path for the insides to come out. One straight cut right through the top is all you need. I had to use a vice grip on the piston to make sure it wouldn’t spin around on me.
10. After you cut the top, you should be able to tilt the strut upside down, remove the tape, and hammer the bottom until the innards slide right out. You can also heat the outside of the strut sleeve so they slide out. Worst case scenario: You think that everything is jammed in place, and that since you cut off the entire top, there is nothing to grab onto to pull out the insides………wrong. When you use the rubber mallet and hammer right above the hole you had first drilled out, you will create pressure starting to force the piston or assembly out to be grabbed or whichever. I assure you it is a lot easier than most of you think, lol.
You want to cut as low as you can, or else you get these stubs. If it is not a perfectly round inner circle, just grind them down, or cut again.
11. The next step after emptying the strut, is to go back to the hole you first drilled. Koni struts are secured by a bolt connecting to the bottom of the strut, so use a 12 mm drill bit, and drill out that hole to compensate for it. If you mess up, don’t worry, you can make it larger than it needs to be since the bolt also uses a LARGE washer included with the struts.
12. By now you should have the Konis inside the sleeves and bolted up. Some people will tell you that you might need to file a lot of metal, but s13 oem struts are clamped on, so no huge booger welds inside the strut.
13. Assemble the spring of your choice with the newly fitted Koni struts. Make sure to look at the FSM as to which way to set up the springs and spring perches. The top is always flat, but look at the FSM for factory torque specs etc.
14. Once you have your front piece all together, place the top of the strut back into the 3 top holes, and have a friend just put the nuts back on so it can hang and swing around. Do not tighten them, since you need some play.
15. Next, just line up the brake assembly with the strut. I found this to be quite straight forward, but if you have trouble, have a friend use his foot to press down on the rotor to move it to where you need it to be.
16. Torque down those 5 bolts, then repeat for the other side.
17. Now it’s time for the rear. There are only 3 bolts to worry about, 2 connecting the top of the strut to the body, and one nut connecting the bottom to the brake assembly. Remove the interior in order to get to the back struts.
18. Now take a 12 mm socket and remove both top bolts, then go to the bottom of the strut, and use the 17 mm deep socket, and break the nut free behind the brake assembly. You can’t see it easily, but you will be able to feel it.
19. Once you have removed the bolts, take the rubber hammer, and hammer the strut backwards off of the brake assembly. (I love my hammer)
20. The Koni Struts are almost a direct bolt on. But No one has ever mentioned what needs to be done to the oem rear struts.
21. After removing the top mounts and rubber boots from the oem strut, you will realize that the Konis did not come with the bottom spring perch, and that the only way to get it, is from the oem struts. No instructions or customer support will tell you this, lol.
22. All you need to do, is remove the springs and take apart the oem struts. Hit the bottom of the spring perch upward to break it free, it shouldn’t be on too tight. You will notice a single metal ring preventing you from removing this super vital spring perch. So bust out that ban saw and show it who’s boss!
23. You might think that you need to file the inside of the perch once you get it free so it can slide onto the Koni rear strut…..DON’T. All you need is to tap it evenly with the rubber hammer, and it will slide of perfectly. Consult your FSM diagram and assemble your new springs onto the Konis. And make sure you use the bolts provided with the front and rear struts. I tired using the oem nuts, and was an idiot. I stripped a little bit of my own strut’s top threads.
24. Look at the FSM and make sure you assemble the rear struts and springs the align with the body and brake assembly as you put it back together. This is also a good time to adjust the stiffness of you rear struts. *
25. Get a friend to slide on the nuts to the top of the strut while you begin to hold it in place. Make sure not to tighten it, as you will need it to move around as well. The rear LOOKS hard to reassemble, but I assure you, it is cake.
26. You will probably notice that the strut is too low to slide right onto the bolt connected to the brake assembly. All you need to do, is have your friend step on the rotor and press down while you slide the strut onto the bolt and use the rubber hammer to coax it all the way into its place. Torque those nuts down to FSM specs, and you are done!
*Adjustment of Koni Struts*
The front are pretty straight forward, as most sets of Konis come with a top knob to tell you how to properly adjust the stiffness. Start off by turning it all the way to the low setting until you feel resistance. From there, rotate in 180 degree increments to increase stiffness, I believe you can rotate them up to 720 degrees for the front, but feel free to experiment!
The rears are a different story. While the struts are OUT of the car, place the piston of the strut into the vice, and press all of your body weight onto the strut. What you are doing, is pressing a fork into 2 holes in order to lock the valve mechanism so it can be adjusted. Consult the direction for which way increases or decreases the bump and dampening. While fully compressed and locked, keep your weight on it and turn all the way to low until you feel a lot of resistance. From then on, rotate in 180 degree increments to increase stiffness.
I have both the front and rear on 360 degrees ( two 180 turns up), and the ride feels great.
The springs I have are rated to 6.2 kg/mm front, and 4.5 kg/mm rear.