In this article I install the Swift Springs and take measurements to prep for air cup suspension
I’ll measure the Swift Springs (linear) and BC strut assemblies (ID and OD) to prep for Stanceparts air cup lift system. This information may be helpful to anyone that is pursuing this same exact setup.
Introduction
My goal is a more comfortable ride. I ride about 1-finger gap on all corners. I have the adjustable dampening offered by BC Racing BR series coilovers and wanted to pair them up with Swift springs Default spring rate – 10k in the rear, 7k in the front.
I ordered these from SpringRates.com and they were drop shipped direct from BC Racing. I ordered the Swifts after the initial BC coilover purchase. Essentially I have 2 sets of springs, the Swifts and the BCs.
Update
It turns out Stanceparts does not make an air cup design for the rear top hat style coilover. I’ll leave the photos and measurements below in case anyone needs them, for whatever reason.
Advantages of Swift Springs
From the manufacturer:
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Swift Springs are manufactured using (H5S.TW.) which is far superior to silicone chrome steel and allows us to wind our springs with less coils, resulting in reduced un-sprung weight and increased stroke.
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Swift Springs ride smoother to a comparable spring rate. For example, if your coilovers have 10K spring rates and you upgrade to 10K Swift Springs, the car will perform better AND ride smoother. For this reason, many enthusiasts increase the spring rates slightly when upgrading to Swift Springs.
Installation
The short version
- Remove the coilovers
- Spin OFF the bottom assembly
- Install the new spring from the bottom up
- Reassemble using antiseize on threads
- Reinstall on car, adjust ride height as needed
The front Swift springs are 7k rate, linear design.
Rear installation and measurements
The rear Swift springs are 10k rate, linear design. I used the same process as the fronts: I removed the coilovers, spun the bottom assembly off, then installed the new spring from the bottom up.
Here are photos and captions
Adding photos of the markings here so I can refer to them if needed.
Remove the bottom mount and take off the pieces one by one, take note of the order and orientation of the parts. Be sure to also get the 2 spring seats at the top and bottom of the BC coil. I will transfer these on to the Swifts
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Widest part of the rear strut piston 12.5mm
Let’s now measure the Swift 100 (10k) springs OD and ID. The OD of the spring is 84mm.
Final rear strut assembled. She’s a beaut!
Driving Impressions
The biggest noticeable difference was in the rears, where we went from an obvious progressive spring to a linear design. Much softer in the back for the compression and allowing for less bounce or wheel hop in the back. BUT, overall my entire chassis is on the stiff side. The rears softened up with the Swifts in the back.
For the fronts, there was not much difference. I would say nothing noticeable. I suspect they need to settle in more but off the bat it was not very perceivable by me. Regardless, I have the measurements for the front now when it’s time to get the Stanceparts Aircup kit for the front. More details soon, stay tuned!
