Thread: Guide: Building Custom Koni Shorts (CSKs)

Jimbo, I've been researching quite a bit, and I think you're right on most counts.

1. 8610-1409SPORT is a correct part number that will fit inside B13 front strut housings.
2. People do use front strut housings to utilize the Koni inserts in the rear. People seem to use the same Koni part number.

Now, about shortening the rears: I believe the process is the same, but I've read from multiple sources that doing the shortening process is less necessary in the rear, since it has less chance to bottom out with the reduced load compared to the front. Yes, the springs will be softer, etc. but risk of bottoming out is still less.

3. I don't believe that using front strut housings in the rear regains any suspension travel compared to oem rear struts, so if you want to keep as much stroke as possible while lowering your car on RMs (or any other spring) you will want to do the shortening process.

OK, I've got a plan now at least. Will be picking up a set of front B13 struts at the local salvage yard next trip, and will compare against the rears when I pull them off to see what the lengths look like. I know that the top gets cut off to allow for the strut to be inserted, hence some minimal shortening from that, and will see how things look from there on further shortening by cutting that nub at the bottom of the insert for the rear.

The Road Magnet springs I'm looking at will drop the rear 1" from stock, and if the front struts are already about that much shorter than the rear, then I may be good. As always, will get pics as I go and add those to my build thread, and will link it back here when that's online.

Note: for track use, you're going to want the rear rate higher than the front. I'm currently 100lbs higher in the rear.

The other thing to remember is that when you lower the car you give up some *total* travel, no matter what. By shortening, you gain back some bump travel at the expense of droop. This is esp important in the front.

Thank you for adding that information.

I have Road Magnets on my B13. Below is a quote from Steve in a 2007 thread regard OEM style springs like Hyperco and Road Magnet on the rear of a B13.
Am I correct in assuming that the only insert I can use in the rear is the Koni Red 86-2465 or has anything changed in the past 9 years. KYB AGX rears are no longer available.

Custom Shortened Koni INFO Discussion - SR20 Forum

Rear Option B13
Standard Koni B13 rears- This is your only option for those running lowering springs (such as Hyperco and Road Magnet) on a B13. You can not use any other Koni in the back on a B13 with those lowering springs. It is 1 inch shorter then oem standard so you don’t even need to do any tricks to lower the things. Just install them as the instructions say. They work fine with lowering springs but I don’t pair them with the Maxima fronts. Max spring rate is in the 275# range. Another option for those with lowering spring is to just use AGX's in the back with Koni in the front. The front is the place that we have major travel issue, the rear is not as big of a deal. With a under 1 inch drop you are fine in the back with AGX's with Hyperco. I have no experiance with Road Magnet springs.