KW and Mountain Pass Performance provide this kit with physically larger and unlabeled springs making it difficult to swap them out without replacing more things. We cant say exactly what the default spring rate is, but we believe its in the range of 8-10k front and 10-12k rear range.
That's great for the street but for Autocross or Track its really soft. If you a natural frequencies to gauge effective stiffness of the suspension, This gives the OTS frequencies of;
- Front (8-10k) : 1.45-1.65hz
- Rear (10-12k): 1.50-1.65hz
This is the upper end of comfort and low end of performance typically used when picking spring rates. For competition use, we start at 2hz and go up from there depending on need and tolerance. For reference, a standard 992 GT3 is 2.0hz and GT3rs is 2.5hz.
We found right around 2hz front and rear were completely comfortable with the wide range of valving in the KW V3 shock and made for a great street/track car with our use.
This gives a spring rate range of;
- Front: 800-900 lb/in or 14-16k
- Rear: 1000-1100 lb/in or 18-20k
Those rates sound high, but hopefully the above explanation helps indicate they are completely within a normal "sporty" range.
The technical details used for Tesla Model 3 calculations are the following;
- Motion Ratio
- Front: 0.66
- Rear: 0.605
-
Unsprung Corner Weight (roughly)
- Front: 905
- Rear: 905
Ok, how does the kit work.
The front is relatively easy, you just need a 70mm (2.75") spring, 7-8" long, and in the desired rate. The larger diameter makes selection harder, but Swift makes them and I got mine from tougefactory.com (no affiliation). You also need a 2.5" helper or assist spring to take up free length.
The extra free length is just due to range of travel of the shock relative to ride height and spring rate. As you get stiffer, there is less droop needed and less static deflection. So a long travel shock will end up with an un-captured spring. Very common situation.
The rear is where this kit comes in. This has a lower and upper adapter;
- Lower: A coupler to adapt a 2.5" spring to the spring opening in the factory control arm. While this does move in an ark, its relatively level at normal lowered ride height.
- Upper: This coupler captures the helper spring needed to keep things assembled at droop. The helper is absolutely necessary to hold the KW upper adjustment and main spring all in place.
Here is the stack up;
- KW/MPP Ride height adjustment perch
- SSB Upper adapter (smaller piece)
- Hyperco 2.5" helper spring (CS100)
- Hyperco 2.5-2.5" coupler (plastic piece that comes with the helper spring)
- 2.5" x 6" spring of your choice. MUST BE 6"
- SSB Lower adapter (thicker piece)
- OEM Control Arm.
*Contact us if you need help sourcing the springs. We can get hyperco, but Swift is less available.