I ditched the coil over idea and decided to go with Koni Sport Yellows and RSR Race Springs. The car is a 1997 240SX base model. The springs I am using is RSR’s highest uprated performance springs. Rated at 5.0 kgf front and 4.2 kgf rear, these springs are the stiffest I was able to find at the moment. I also have a set of Espilir springs rated for 4.0 kgf front and 3.6 kgf rear just in case the first choice is too stiff. Afraid at first, but soon realize that the Koni shock absorbers do match the RSR Race Springs quite well.
First impression compared to stock shocks and springs. Rebound is left at soft setting from factory. On the first day, an immediate difference was noticed on regular streets. The body roll and lean have tremendously reduced. There is less wavy and bouncy body movements. Compression stroke dampens small bumps quite well. There is small amount of harshness, but the ride comfort was maintained. On freeways, the high speeds digressive valving really helped and ride harshness is almost non-existent.
Second impression. After a 3-4 days, the shock absorbers have finally wear in and the damping have changed a little. On the streets, the shock absorbers seem to absorb more “low speed” bumps. The shock was able to dampen the first bump and consecutive bumps easily. The overall handling of the car remains the same. However ride comfort have increased thanks to the better low speeds damping. Also, the springs are setting in slowly and the height of the car will lower a little bit. Current front height is 14-14/16″ and rear is 13-9/16″.
Comparing to coil overs. I have used coil overs for many years on my S13 and have driven on other cars with coil overs including Apexi, Tanabe, and Stance. My S13 had the Apexi N1 EXV on there. This is a low budget coil over similar to Megan Racing, Stance, or Ksport. The Apexi N1 EXV have very short shock travel giving very little damping on both low speeds and high speeds. Front travel is about 2.5″ (Koni is 4-5″ stroke) and rear travel is 3.5″ (Koni is 5-6″ stroke). The springs are 8 kgf and 6 kgf. The result is a harsh ride if you have performance low profile tires. On 50 and 55 profile, the car’s comfort is much better.
Normally the N1 EXV is set to soft settings for daily driving. It has trouble damping on the streets especially ones with a lot of bumps and dips. The valving feels like linear. As the car moves faster and faster, the bumps get harsher and harsher. The N1 EXV feels better on freeways, but an unexpected dip can send the passengers upward hitting the roof of the car. It would feel like the car had dropped 5 feet. The drop would feel very blunt and harsh. The Koni shock absorber on the other hand does not have a problem damping at either low or high speeds.
Look, it’s an adjustment knob! The N1 EXV has 32 ways adjustability. I assume it’s rebound only. Playing with the knob on the streets show no definable difference. Most of the time the ride will still feel stiff although the setting is at full soft. On the track, the difference is noticeable. However the difference from one click to another will be different depending on what click setting you’re on. I will assume that the valving is linear, the rebound adjustment is very narrow and the range is limited. The adjustment does not make any difference whatsoever at low speeds. It is also possible that the adjustment knob may not do what it’s supposed to do. The adjustment knob is unpredictable and unusable in most cases.
Koni Sport Yellow shock absorbers will be far superior in handling in both streets and track (excluding drifting) compared to any similar priced or low budget coil overs on the market. There are many high end coil overs out there that will be even better, but at a price of an arm or leg. For what it’s worth, Koni Sport Yellows will be comparable in performance for the fraction of the price.