Swift sport springs kit for Datsun 240Z

Swift sport springs for Datsun 240Z. 

Engineered by ZSM Custom, these springs were specifically designed and developed for the Datsun 240Z chassis. Although any shock absorbers can be matched to these springs, we got the best results from using the Kona Yellow sport shocks offered by Motor Sport Auto (MSA part number 23-1031 fronts and 23-1032 rears). Please note the actual color of the springs will be in signature Swift bronze orange.

Swift Company:

Swift is a material science company that makes springs.  They do extensive study on metallurgy to create their own steel.  Through R&D, they have developed many alloys of steel that they can use to achieve different goals, depending on the application.  Unlike other spring manufacturers, Swift have their own in-house foundry to manufacture their own springs to their desired specifications.

Since Swift is an engineering and data driven company, they have extensive data through analysis of different spring specifications which gives them far more advantage than competition. 

Swift company extensively research spring compression and rebound rate which differentiates from their competitors.  While Swift springs rebound and compression rates are linear (both rebound and compression rates mimic each other), other competitors were significantly different in rebound and compression rates. The linear consistency in compression and rebound spring rate is very important to the suspension performance. 

Swift vs Competition:

The linear spring rate will allow for more consistent dampening.  Using a progressive spring, the rate increases exponentially with compression.  This is detrimental to ride quality and even performance.

The valving on the S30Z shock inserts were never designed for a progressive rate springs and causes the damper to work much harder than it is capable of, resulting in a loss of dampening control.  While dyno testing the S30 dampers with progressive rate springs, we witnessed a loss of damper control on the dynograph.

With Swift’s linear rebound and compression rate springs, the tire contact with the road is optimized.

The faster reacting rebound of the springs will directly translate into a better ride quality.  The higher reacting spring will improve tire contact with the road resulting in increased performance. 

In the case of driving over a pothole, the spring will react quickly to maintain road contact.  This is important because the entire chassis of the car will not “fall” or “drop” into the pothole, reacting to the road deformation, just the suspension.  

This will also have an effect with smaller bumps as a concession.  Think “Rumble Strip” / “Stutter Bumps”.  In this scenario, a spring can compress on the first bump, but not rebound completely for the second and so on.  This leads to a condition we call “packing”.  

Since the damper cannot fully recover before the next bump, it keeps compressing into its travel until it bottoms out.  This will cause the spring rate to go to Infinity and act as if there is no damper at all.  At this point you may see the entire car step out to the side because it still needs to deflect the incoming forces.

With a consistent performing Swift spring, the rebound side of the spring will react quicker and maintain that tire contact patch.  What this allows for, is the cars chassis to remain stable as the suspension works underneath it, maintaining the chassis balance.

Our Drop-in Springs:

Our drop-in spring from Swift is a true linear spring.  The quality of the materials used to construct the springs will never sag or change rates, even after years of abuse.  

Furthermore, our springs have a built-in helper spring.  The helper spring is required to prevent any slack (spring float) while the suspension is unloaded. 

A performance benefit of the helper spring is to improve the transition from an unloaded spring to compression.  It eases the transition without affecting spring rate.  The technical term for this is a “2-step linear spring”. This will offer better performance and ride quality.

The spring rates we chose are calculated for optimal balance with the shock inserts available on the market today.  With competitor’s drop-in springs for the S30z platform, you will find that they are simply “over-sprung” for the shock valving, negatively affecting ride quality and performance.  

Our drop-in springs were primarily tested using the cartridge insert type Koni shock absorbers made for the S30 for maximum performance and ride quality. However, other brands of shock absorbers will yield similar results.  

Real world testing:

Extensive real world testing and adjustments were performed on our springs prior to the release of the product to ensure our customers are getting the highest quality drop-in springs available on the market today.  

We have done numerous testing by daily driving on street and highway roads with multiple road conditions. We have done extensive performance driving at circuit road courses and winding canyon roads to ensure our products will meet every demand.

While competitor’s drop-in springs are not designed for 240Z, creating a “negative rake” effect (front ride height is higher than the rear), our springs are specifically designed for 240Z chassis and carefully configured for the balanced front/rear height. This suspension is lowered -30mm (+/-5mm) from the factory ride height to achieve a well balanced performance, ride comfort, and aesthetics. 

Completion of high performance drop-in springs:

These Swift springs were created because we want to take the S30 to the next level of performance and quality without resorting to cut and weld type suspension unit. 

R&D, real world testing, quality of the product, all reflects how much we love and care about the S30 chassis to create this Swift drop-in springs. 

We strive in providing the highest quality and performance on every product and this drop-in springs by Swift definitely shows our commitment.  Our research continues…