Actual Spring difference GR86 vs BRZ
 

Here are the factory spring rate differences per car model. Source is the official SACHS Performance Coilover distributor in Japan, so it looks to be a quite reliable source.

Car model Front spring rate (N/mm) Rear spring rate (N/mm)
TOYOTA 86 ( MY 2021 ) 28 39
TOYOTA 86 ( 1st model ) 23 33

Car model Front spring rate (N/mm) Rear spring rate (N/mm)
SUBARU BRZ ( MY 2021 ) 30 35
SUBARU BRZ ( 1st model ) 23 35

Actual Spring difference GR86 vs BRZ
 

EDIT: FIXED IN POST #6

This is confusing.
Is this formatting correct? The values are an order of magnitude low for Newtons/mm too. Could it be N/cm or kg/mm?
I tried to make sense of the formatting but the units are definitely wrong:

2022 TOYOTA GR86:
F: 2839N/m - 2.839N/mm - 0.290kg/mm - 16.2lbf/in
R: 2333N/m -2.333N/mm - 0.238kg/mm - 13.3lbf/in

2022 SUBARU BRZ:
F: 3035N/m - 3.035N/mm - 0.310kg/mm - 17.3lbf/in
R:2335N/m - 2.335N/mm - 0.238kg/mm - 13.33lbf/in

Yes. It should be N/mm. I edited the first post. Keep in mind that these are the rates for the Japanese market. They might get revised in other regions.

Those OG numbers don't seem correct.

We know from Subaru/Toyotas press kits on release that the spring rates on the front of the 86 were softer than the BRZ, and that the rear spring rates were supposed to be the same.

In this its kind of the opposite, as if the BRZ has the slightly more oversteer setting...? Perhaps its the 16+ refresh?

Yes. 1st model spring rates are from the model '17 refresh were both cars had almost similar spring rates.

I see, I got confused about the no spacing and units.

Useful to know the 2017-2020 spring rates, I’ve never seen them confirmed. Looks like they mostly softened the rear and didn’t touch the front much for the facelift, contrary to what the press was reporting at the time.

Nice to see a healthy jump in front spring rates on the BRZ, that should help a lot with dynamic camber loss up front.

Converted the numbers into a new table, N/mm may not mean much to others:

https://uploads.tapatalk-cdn.com/202...07fc041eb3.jpg

Looks like they sacrificed the improvement in ride quality that the more rigid chassis would have made possible (by allowing lower spring rates) in favour of improving the handling.

That is a big delta between the front-rear differences - 63 for the GR86 vs. 28 for the BRZ. All else being equal that should be enough to make the GR86 far more tail-happy. But are the ARB rates the same? Also the differences in rear ARB mounting points between the two may make a difference here.

The RSB mounting point won’t change the rate of the bar. Sway bars are measured by overall thickness, wall thickness, length, and arm length. The line from Subaru on it is more of a direct feel. Kinda makes sense since the mounts shouldn’t flex as much most likely and won’t move with the subframe. Motion ration could have changed but check post 50 on this thread, same mounting location so this shouldn’t be the case.

https://www.ft86club.com/forums/show...=146965&page=4

Curious to see what the bar rates are too though.

It absolutely affects the *effective* rate on the bar. It will resist the roll motion of the body better than the same size bar mounted to the subframe. How much better? That depends on lots of things and could range from barely noticeable to the difference between hollow and solid bars, maybe even more. Without knowing a TON of factors it’s impossible to find out until people test the cars thoroughly.

I'm still confused.
Which rates are you saying they used for 13–16 and 17–20?

Looks like they made the Toyota rear softer and the Subaru front softer to get both to ~the same setup. Doesn’t line up 100% with what the press was publishing at the time but they never had actual numbers. The BRZ’s rear actually got stiffer with the facelift.

13-16:
FRS: 2.3k 3.8k
BRZ: 2.7k 3.5k

17-20:
86: 2.3k 3.4k
BRZ: 2.3 3.6k

2022:
GR86: 2.9k 4.0k
BRZ: 3.1k 3.6k

I have TRD springs and sway bars on my 2013 that were bought when they first came out, what are those numbers?

https://www.ft86club.com/forums/showthread.php?t=8739

Looks like 3.5kg/mm F and 5.8kg/mm R

Thanks for the reference numbers. It's good to know to compare.
Along with my TRD springs and anti sway bars, I had installed;

TRD door inserts

Bilstein B-6 Shocks (OEM size, recommended for the TRD lowering springs)

Whiteline bushings
KCA416 Camber adjusting bolt
KSR210 Steering- rack & pinion,
KDT926 Gearbox- positive shift kit
KDT925 Differential- mount in cradle & support outrigger insert bushings
KDT922 Rear Crossmember- mount insert bushings

Cusco Power Braces
Front Tower Bar (Type ALC OS)
Front Lower Control Arms
Front Crossmember bar (Type ll)
Rear Crossmember bar

With this suspension package, my FRS handles so much better. I Love it!!!:thumbup: