2022+ Suspension MEGA thread - Shock dynos, suspension frequencies, travel, more!
 

Super big shout out to @trippinbillies40 for sending us a set of OEM dampers early on! Massive help!

This thread is a work in progress and we plan on updating/adding more over time. We still have a lot of work to do...this is an exciting time for us over here at RCE. We are still waiting on our own car (:thumbdown:) but it's coming soon.

There is some background reading at the end of the post.

Travel:
https://live.staticflickr.com/65535/...53532800_h.jpg
https://live.staticflickr.com/65535/...692fbb81_h.jpg
^Front struts, new vs old

https://live.staticflickr.com/65535/...4d45442a_h.jpg
^Front strut overall stroke/travel ~122mm (old was ~149mm) BUT this is not the full story.

Front droop travel appears to be shorter, but it's actually the rebound spring pulling the shaft back in. Overall travel is about the same as 1st gen.

Rears appear to be the same dimensions as previous cars in terms of travel.

Bumpstops are the same as before and 59mm long front, 57mm rear. Again, this is a very bumpstop active car so you’re using the bumpstops over essentially every bump and in every corner. They’re designed that way. Lower the car a lot with lowering springs and you’re compressing the bumpstops before you even sit in the car.


Valving:
Shock dynos! These are BRZ dampers…we do not know for sure yet if the GR86 dampers are identical. I would not trust magazine quotes.

https://live.staticflickr.com/65535/...46cc1d0b_b.jpg

https://live.staticflickr.com/65535/...8202e1e3_b.jpg

It’s a nice looking curve for a factory Subaru/Toyota damper at this price point and better than what you see in some aftermarket coilovers. It’s not heavily ultra rebound biased which is nice. Actually more compression than rebound til around 2 inches per second.

Good low speed compression, little bit digressive. More front compression than rear.

Rebound has a little progressive to digressive shape to it, which isn’t uncommon. In front, at 2 inches per second you’re at about 85% critically damped with the BRZ springs and 90% with the GR86 springs. Just a little softer in the rear. At higher piston speeds the front never really gets too out of hand (stays above 60% until 8 inches per second) but the rear does go to 50% and lower around 5 inches per second.

All that is to say the shock valving is pretty decent and IMO better than in the past.

And the dampers can support slightly stiffer spring rates. The rear is again a little more sensitive to increased spring rates like last time, so you can’t go too stiff in the rear and expect the dampers to keep up.

Large drops from lowering springs will still cause problems due to available bump travel as on previous cars. In general the previous factory shocks didn’t last super long when ran hard and that will probably still be true, but we’ll see if they’re a little more durable over time.

Springs:
We have not measured spring rates ourselves yet but they are posted elsewhere on the forum:

GR86
2.9 kg/mm front (162 lbs/in)
4.0 kg/mm rear (224 lbs/in)

BRZ
3.1 kg/mm front (174 lbs/in)
3.6 kg/mm rear (202 lbs/in)

This is a little bit firmer overall than the old cars, but not a drastic increase. And remember, the bumpstops are a big part of how these cars handle and those are not included in these rates. Still, the more rearward bias is why the GR86 wants to oversteer a little more than the BRZ.

Motion ratios:
These are the same as before, although I’d like to double check the rear. About 1 (really like 0.97) in the front and 0.76 in the rear. Multiply spring rates by the motion ratio squared to get wheel rates.
*double checking these soon.

EDIT: looking like rear motion ratio is ~0.78

Suspension frequencies:
Using a 55/45 weight split and 3000 lbs with driver, we get roughly:

BRZ – 1.47 Hz front and 1.42 Hz rear.
GR86 – 1.42 Hz front and 1.50 Hz rear.

A slight difference between the 2 cars and overall that’s somewhat soft compared to coilovers. But remember, this doesn’t include those bumpstops. Of course, overall weight and distribution will vary from car to car and driver to driver. You can discuss flat ride amongst yourselves if you like :lol:.

Swaybars:
A big part of handling balance is swaybars. This time the sway bars differ from car to car.

The BRZ has an 18.3 mm hollow front bar and a 14mm solid rear bar.
The GR86 has an 18mm solid front bar and a 15mm solid rear bar.

We don’t know what the hollow front bar measures out to, but if someone wants to cut their bar in half for wall thicknesses that would be great. We will eventually have the spring rates of the front bar. Remember swaybars have their own motion ratios too.

The other difference is the new rear swaybar mounting points on the BRZ. We don’t yet know how much of a difference this makes in practice.

Geometry and other things:
Slightly wider rear track.
Slightly longer wheelbase.

Bushings:
Need a little more time here too. The same as before up front at least.

Factory adjustments:
Same as before…meaning nothing but toe adjustment from the factory. Add camber/crash bolts or camber plates to the front and adjustable lower or upper control arms in the rear for camber.

Chassis stiffness:
It's stiffer! More on this soon.

Dump of other notes:
1st gen lowering springs do not work on the 22+ shocks (specifically the rear spring).

You can probably swap complete 1st gen damper/spring/tops assemblies with 2nd gen and vice versa (untested).

We are developing new springs for the new car.

Coilovers are more straightforward and will swap without issue at least in terms of fitment.

The rear upper shock mount is different...appears to be harder rubber but not sure. SHOULD swap over fine, unclear if there is a stack height difference.

All new RCE parts are being developed for new and old cars concurrently (except springs as mentioned).

Thread on 1st vs 2nd gen parts compatibility
https://www.ft86club.com/forums/showthread.php?t=147698

Tech background stuff
Basics on motion ratios:
https://www.instagram.com/p/B3cDzqOD..._web_copy_link

Basics on suspension frequencies:
https://www.instagram.com/p/B6TKG6Un..._web_copy_link

Basics on shock dynos:
https://www.instagram.com/p/CJd5GH4H..._web_copy_link

The reduced droop travel disappointed me….it’s still a strut though.

If bumps stops play such a large part in the stock suspension setups of both the old and new car why is no one offering different bumpstops to improve handling or comfort? Are they just not sexy enough from a marketing point of view? It seems like it would be a good OEM+ kind of mod.

No money to be made, many options on the shelf for those that want to, easily cut 'em to length or add spacers to modify what you're looking for for way cheaper then springs.

Eibach and kw and ST give them to you for free when you buy their springs/coilovers. Googling now I saw some OEM rubbers for <$5.


https://www.summitracing.com/parts/e...xoC8pIQAvD_BwE

https://shop.penskeshocks.com/product/bump-rubber/

https://www.speedwaymotors.com/Speed...oft,59316.html

https://www.fcpeuro.com/products/aud...RoCxM0QAvD_BwE

I know what you're saying but what lengths and rates improve my handling? I'd rather pay for the experience and time of professionals to find the right combination. I mean I could pay for custom springs if i want but I'd rather buy springs from Racecomp as they have put in the time and effort to come up with a length and rate that works.

I wonder if the reduced droop travel is due to the rebound spring in the front shocks. Can you extend it further by pulling on it?

This is correct!

- Andrew

Excited to see further development from you guys. i will be waiting for the new coilovers for my GR86 when time comes. both SS1 on my old BRZ and STi has been flawless.

On my GR86 Struts, there appears to be a rebound spring, because when I pull on it, it extends another 1/2in or so.

Interesting. Wonder if they're really that different than the BRZ. Thanks!

I think they're the same and I think Myles just needs to pull harder. :lol:

I'll have a look again...we used that first set for something special but I do have another set to play with now too.

- Andrew

Random update that may interest someone...

In between testing some 3 way coilovers and other fun stuff, I've put the 2022 BRZ dampers and springs on my 2016 BRZ. Just for kicks. The car is otherwise now almost completely stock suspension wise (boooring) with the exception of OEM crash bolts, my bling STI strut bar, and rear Whiteline subframe + diff bushing inserts.

The ride quality is very good, better than OEM 2016 dampers by a significant margin. It's downright comfortable. This is on really awful Baltimore city roads and long trips to the mountains. It's likely better than 2017-2020 dampers too. Better than Bilstein B6, Koni, etc. Almost like a normal car.

Which...I do not love in terms of handling and feel. It's a little sloppy and not very confidence inspiring, especially the rear. This isn't just me going from those 3 ways to an OEM suspension. I would still prefer the 22 dampers to any of the 1st gen OEM dampers and a lightly used set of these would be a good choice for someone looking for more comfort.

Just some quick thoughts.

- Andrew

Also, posted this elsewhere on the rear swaybar mounting method for BRZ...reposting here:

Yeah I was surprised at how comfortable the oem suspension on the 22 BRZ was compared to my returned-to-stock 13 FR-S. The 2013 feels almost crashy and dare I say overdamped in comparison, but firmer and more responsive when pushed.

I’m constantly tempted to throw my RCE T2’s on my 22 BRZ (they’ll go on eventually), but for now I’m enjoying the comfort level on the oem 22 suspension.

When you say 2017-2020 dampers you mean Showa base or PP Sachs?

I think it rides better than both.

- Andrew

But does the 22 suspension oversteer when you sneeze like the 13 FRS does stock?

It does not lol. I would not describe it as prone to oversteer at all.

- Andrew

Do you know the bar rate on the RSB for the GR86? I found you post elsewhere the 14MM is 113lbs in reference to the old cars but having trouble with googlefoo on the 15MM bar the 17+ cars had.

I believe sway bars increase stiffness with the 4th power of thickness, so 15/14 = 1.071 (or 7% increase in diameter) results in a 31.6% stiffer bar.

AWESOME thread and data, thanks @Racecomp Engineering. I started working the frequency ratios on my own and stumbled on this — I appreciate the detail.

Hi, with the MY22 suspension does the ride height increase or decrease on the MY16 BRZ? Asking this since I read somewhere the MY22 rides 10mm lower.

Hmmm...I didn't measure ride height unfortunately and don't have any pics. It looked "stock."

I may have been overselling the comfort just a tad...it's good and better than anything first gen by a little bit...but not amazing/plush.

I do think it's worth replacing old and tired first gen parts with 2nd gen BRZ parts if you get a good deal and don't want to try anything aftermarket.

- Andrew

Andrew I know you said in the other "shared parts" thread that the rear tophats are different, but is there a combination of parts that would allow me to pair gen2 dampers with gen1 tS springs on my 2019 BRZ?

I want to pair the 2024 tS Hitachi dampers with my tS springs - hoping it will be more comfortable than my current Bilstein B6 & tS spring combo which tosses me around quite a bit on broken roads. My buddy and I compared his 2022 BRZ with my car and the new car is definitely more comfortable.

-David

Hmmm not sure of the exact difference in the rear top hat, but I haven't tried putting a rear 1st gen spring on 2nd gen shocks. It's not "supposed" to work.

We're interested to see how the Hitachi dampers do and how they'll compare to standard and also the GR86 Sachs dampers.

- Andrew

I believe the top hat is the same but I know for sure that the perch on the shock is different.

nuts, okay thanks

Here are GR86 OEM rear struts and springs with 2013 model top hats. Fitment seemed fine to me.

cant get the pics to embed. link is https://imgur.com/a/kUEgiV6
https://imgur.com/a/kUEgiV6

So if I were to put the 2022+ strut assemblies in a 2013 brz, would I be able to use the 2013 stock end links? What about if I also added the 2022+ jdm sti springs? Thanks!

The assemblies are the same, just droop travel and valving have changed.

OEM endlinks are the same for 1st and 2nd gen.

If your endlinks are 12 years old I'd plan on replacing them!

- Andrew

Gotcha, thanks! Yes I need to replace them, just trying to figure out which ones to get. Would you recco stock or adjustable? Only suspension mod I have at the moment are TRD sway bars, and plan to do a slight lower at some point, but probably no more than 15mm. (Sorry slightly off topic, I know)

With OEM (or similar) struts and shocks I recommend OEM endlinks....except in some cases an adjustable endlink is helpful with certain adjustable sway bars.

I'm not familiar enough with the TRD bars to make a recommendation though. If you're okay right now with the OEMs you'll most likely still be okay later.

- Andrew

Got it, thanks!

Speaking of endlinks, I really need to get around to changing the fronts on mine after adding coilovers.

My Perrin OEM length ones don't clear the inner fender / body with -4 degrees of camber, so I went back to stock. Perrin's bushing's are wider. Either way, both too long and the swaybar touches the control arm slightly, which I can't imagine is great for handling.

I highly recommend the Perrin OEM length ones for use with regular struts and stock / stock-ish ride height. They held up great through 2-3 seasons of autocross and I still have their front ones on my WRX after about 10 years. They'd be a nice little upgrade / replacement along with the 2022+ suspension.

I bought RacerX front endlinks to solve the clearance problem (MCS 2wnr with -4* camber). They have gobs of clearance. But the sphericals got creaky fast. Not sloppy, but just creaky. Not sure I'd get them again. The price is very good, though.

-Mike

We have some coming very soon. :)

Very good quality sphericals.

- Andrew