Upgrading to Swift Springs... lengths/diameters?

[shibui]

Hi all,

Upgrading my coilover springs to Swift Springs and looking for insight on spring lengths. Divorced (not true) coilover setup.

Original springs that came with the coilovers

F: 180mm (7.087 inches), 2.5 inches ID
R: 135mm (5.31496 inches), 2.5 inches ID

Looking at what's available on Swift's website, the front seems straightforward. I'll get:

F: 7 inch, 65mm/ID65 (brown), 448 lbs/inch

But for the rears unsure if I should go with the shorter (5 inch) or longer (6 inch) spring from original 5.31 inch length?

R: 6 inch, 65mm/ID65 (brown), 840 lbs/inch

or

R: 5 inch, 65mm/ID65 (brown), 896 lbs/inch

I called up Swift and a few other spring companies, and was essentially told that if there is still adjustment in the rear to go lower (which there is, I'm not maxxed out), then to just go with the taller 6 inch spring.

Thoughts?

[cobra]

It's not a straightforward answer. General rule of thumb is you always want to go with the longest spring possible that you can fit while still getting the ride height you desire.

-How much space do you have to fit the spring in terms of tire clearance and adjuster range?
-What is your desired ride height?
-How much shock travel do you have from ride height?
-How much travel are those springs rated for before they coil bind?

Assuming nothing out of the ordinary...
450/840 rates are pretty dang stiff. You might be okay with 7 and 5 inch lengths, but definitely try to get 8 and 6 if you can fit them.

Personally I am running 8" front and 7" rear lengths with 400/630 rates at nearly stock ride height and it just barely works. The stock springs are large diameter and very long for a reason.

[shibui]

It's not a straightforward answer. General rule of thumb is you always want to go with the longest spring possible that you can fit while still getting the ride height you desire.

-How much space do you have to fit the spring in terms of tire clearance and adjuster range?
-What is your desired ride height?
-How much shock travel do you have from ride height?
-How much travel are those springs rated for before they coil bind?

Assuming nothing out of the ordinary...
450/840 rates are pretty dang stiff. You might be okay with 7 and 5 inch lengths, but definitely try to get 8 and 6 if you can fit them.

Personally I am running 8" front and 7" rear lengths with 400/630 rates at nearly stock ride height and it just barely works. The stock springs are large diameter and very long for a reason.

I'm pretty happy with my current height and don't really want to change it at all. I'm at the standard 13.5 F and 13R with my current spring lengths. Shock travel feels good, never bottoms out. The springs it came with are just not that good though. The valving is set up for track.

Since the upgraded front Swift spring is the same length, I assumed it would be an easy swap-in there.

For the rears, it sounds like the 7" front and 6" rear would be best combo then? To get more spring length vs. putting the 5" back there.

I got the 448/840 rates using the Flat Ride calculator and inputting my suspension data - I know it's more complicated than that but this will at least allow me to upgrade the springs and provide a base point moving forward, since the stock springs my coilovers came with are not good.

Thanks!

[cobra]

I'm pretty happy with my current height and don't really want to change it at all. I'm at the standard 13.5 F and 13R with my current spring lengths. Shock travel feels good, never bottoms out. The springs it came with are just not that good though. The valving is set up for track.

Since the upgraded front Swift spring is the same length, I assumed it would be an easy swap-in there.

For the rears, it sounds like the 7" front and 6" rear would be best combo then? To get more spring length vs. putting the 5" back there.

I got the 448/840 rates using the Flat Ride calculator and inputting my suspension data - I know it's more complicated than that but this will at least allow me to upgrade the springs and provide a base point moving forward, since the stock springs my coilovers came with are not good.

Thanks!

What's not good about your current springs?

[shibui]

What's not good about your current springs?

Current frequencies give pitched and not flat ride + they're lower build quality vs. something like a Swift or Hyperco.

[mrgizmo04]

What are your current rates and on what coilovers?

Sent from my SM-S911U1 using Tapatalk

[cobra]

Current frequencies give pitched and not flat ride + they're lower build quality vs. something like a Swift or Hyperco.

"Flat Ride" isn't going to magically fix the ride if your dampers are not tuned accordingly. 850-900lb in rear is quite high.
What brand are they and what makes them low quality? If it holds up your car and is reasonably close to the stated rate, what's not to like?

[shibui]

"Flat Ride" isn't going to magically fix the ride if your dampers are not tuned accordingly. 850-900lb in rear is quite high.
What brand are they and what makes them low quality? If it holds up your car and is reasonably close to the stated rate, what's not to like?

The dampers/valving is pretty aggressive and set up for track, so think it can handle that read spring rate. Seems pretty popular to run that high of a spring for track cars from what I've seen.

Most springrates that come with coilovers give a pitched ride and can be improved - right? I thought it was common for people on here to upgrade their springs?

[cobra]

The dampers/valving is pretty aggressive and set up for track, so think it can handle that read spring rate. Seems pretty popular to run that high of a spring for track cars from what I've seen.

Most springrates that come with coilovers give a pitched ride and can be improved - right? I thought it was common for people on here to upgrade their springs?

The aggressive damping doesn't necessarily mean it will be well suited for much stiffer or softer spring, it has a lot to do with the shape of the damping curve. It might work fine, just something to keep in mind.

From what I've seen, coilover kits come with all different rates and damper technologies, so I can't really say. For a track car, you probably want to prioritize grip and handling balance while seeing where your driver feel and control requirements intersect. In fact it might make sense to have softer springs than you think if you want to be able put down power on a bumpy track. It's a combination of tire type, tire size, aero, roll bar stiffness, track condition, etc. The line between "pitched" and "flat ride" is blurry...