TBK's Time Attack Build: MK-BRX

[TBK]

Are you sure that is correct? 343 lbs/in front is insanely soft. 800 lbs/in rear is about 425 lbs/in since it's divorced. That is an insanely soft setup. The front is about half the rate of what I run and some people think my setup is "soft".

Stating what you already know but there's a lot more to how stiffly sprung it feels than just the spring rate.

OEM is 188/343. The Ohlins i'm currently running are 400/685. I'm now going slightly softer in the front and slightly stiffer in the rear. That's going to give me better rotation, more planted exit, sharper transient etc... Any stiffer than that and i'd need to be running more aggressive aero and ideally slicks. I'd be raising the frequency towards 2.2hz+ range, which i don't want to do. With the rates i'm opting for i'd be around the 2hz range both front and rear. That's high track car territory, but not race car territory. That's where i want to be. I would lose mechanical grip and curb confidence with stiffer springs and my current aero/tires. We're running similar tires, but your aero is a bit more aggressive than mine.

The Nitron valving does the heavy lifting.....

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[razorlab]

I ran 550 front / 500 rear (true coilover rear) when i was stock power and no aero. Still was on the soft side.

Now I run 650/600 with baby aero and 600whp+, and I am planning on upping F/R rate +100 this winter as it's still a bit soft.

3xx lb front springs on this car is not a track car setup.

 

[TBK]

I ran 550 front / 500 rear (true coilover rear) when i was stock power and no aero. Still was on the soft side.

3xx lb front springs on this car is not a track car setup.

You can't look at spring rates without factoring in damper architecture...

Also, you can move these numbers around a bit, but roughly speaking, this is the math i'm using:

• 1 Hz = soft GT car / comfy road car
• 1.5–1.8 Hz = sporty street / fast road
• 1.8–2.2 Hz = track-day / semi-slick sweet spot
• 2.3 Hz+ = race-car stiffness (slicks, aero)

With my rates/setup, i'm at the 2Hz mark. It doesn't make sense to call that insanely soft. I think most people have tendency to "overspring", or just rely on springs and pay less attention to the rest of the suspension setup and how it can make the car feel stiffer/softer

Here's an old, but good read. if you get the chance to read this would be very interested in your thoughts.

https://www.tracktuned.com/feed/2016/11/27/overspring-spring-frequency

 

[razorlab]

You can't look at spring rates without factoring in damper architecture...

Also, you can move these numbers around a bit, but roughly speaking, this is the math i'm using:

• 1 Hz = soft GT car / comfy road car
• 1.5–1.8 Hz = sporty street / fast road
• 1.8–2.2 Hz = track-day / semi-slick sweet spot
• 2.3 Hz+ = race-car stiffness (slicks, aero)

With my rates/setup, i'm at the 2Hz mark. It doesn't make sense to call that insanely soft. I think most people have tendency to "overspring", or just rely on springs and pay less attention to the rest of the suspension setup and how it can make the car feel stiffer/softer

Here's an old, but good read. if you get the chance to read this would be very interested in your thoughts.

https://www.tracktuned.com/feed/2016/11/27/overspring-spring-frequency

You will be one of the few going this type of route so I look forward to hearing about your experience.

I run MCS and have owned probably 20 different coilovers at this point so dampening is not that foreign to me. While I am def not a suspension nerd like I am a tuning nerd, I do tend to think I have experience. I am currently running double the rate as you, and I wouldn't call MCS dampening bad. In fact, it's by FAR the best riding track capable car setup I have owned. Many people think my setup is soft. I drive my car so it's setup for me and I am fast with the current setup. I have grip, I do not feel I am "oversprung". As I stated before, I could use some more rate in the front.

Are you sure you are at 2hz? What are you using to calculate that? Calc I am using has me at 2.1

 

[Nugs]

I just received my Nitrons R3s yesterday, they are beautifully made.

Spring rates were supposed to be
16kg front (895lb/in)
17kg rear with true coilovers. (951lb/in)

But they sent me a divorced rear spring set up so asking them what's up before I install.

I currently have 24kg (1343lb/in) rear springs in the car so could just use those.

I have decent aero, Sydney composites dual element wing and diffuser, Triple 7 hood vent, canards and a custom splitter are currently being made.

 

[razorlab]

I just received my Nitrons R3s yesterday, they are beautifully made.

Spring rates were supposed to be
16kg front (895lb/in)
17kg rear with true coilovers. (951lb/in)

But they sent me a divorced rear spring set up so asking them what's up before I install.

I currently have 24kg (1343lb/in) rear springs in the car so could just use those.

I have decent aero, Sydney composites dual element wing and diffuser, Triple 7 hood vent, canards and a custom splitter are currently being made.

Now that sounds more proper.

 

[i3igpete]

Sydney composites dual element wing and diffuser

 

[Nugs]

I should update my build thread.

 

[TBK]

You will be one of the few going this type of route so I look forward to hearing about your experience.

I run MCS and have owned probably 20 different coilovers at this point so dampening is not that foreign to me. While I am def not a suspension nerd like I am a tuning nerd, I do tend to think I have experience. I am currently running double the rate as you, and I wouldn't call MCS dampening bad. In fact, it's by FAR the best riding track capable car setup I have owned. Many people think my setup is soft. I drive my car so it's setup for me and I am fast with the current setup. I have grip, I do not feel I am "oversprung". As I stated before, I could use some more rate in the front.

Are you sure you are at 2hz? What are you using to calculate that? Calc I am using has me at 2.1

Slightly off track comment....these are the conversations that keep me coming back here. So, thanks for that.

Def agree that MCS makes an excellent damper. Imagine thinking otherwise.

I haven't said that your setup isn't soft. What i'm saying is that it's not exclusively your spring rates that are the cause of that. This is also where we get into setup philosophy debates, and what i've noticed is that Americans tend to favor higher spring rates in general vs others. A very funny tell is that my Nitron springs in the US are classified as "fast road" and the higher rates as "track day"....the same ones in Europe are classified as "fast road & track" and the higher rates as "track & race". Same spring rates, different philosophies.

The Supra’s multilink geometry and electronic diff make it really sensitive to damping curves, sway bar balance, and compliance. You can run a 500 lb spring and still have a soft feeling car if your rebound control or roll stiffness isn’t where it needs to be. Also, a well-valved damper and properly matched bar setup can make a 300 lb spring feelreally sharp on turn in

e.g....

Rear bar stiffness has a bigger effect on rotation than a 50 lb spring change
Low speed compression...That’s where the chassis actually ‘talks’ to you mid-corner. Nitron being 3 way adjustable gives me separate control of that, which has more lap time impact than a small spring jump
Rebound balance... Too much rear rebound locks the rear in pitch, making even stiff springs feel lazy on transitions.
Corner weights & rake...0.5% cross imbalance or 5 mm rake change shifts entry/exit balance more than 50 lb/in of spring rate

You get where i'm going with this. More than 1 way to skin a cat. So i'm not dismissing your "soft" feeling claim, i'm just saying that spring rates are 1 lever to pull to that end.

Will def share my thoughts post-install, especially since the weather is pretty good now and so i'll be at the track (or racing) almost every weekend for the next few months.

I've tried, and failed to log btw....i hate BM3 so much. Bluetooth off, connected, data being displayed on the dashboard, tried logging, and would only log 1-3 seconds. Repeatedly. Hopefully the race capture thing goes on this weekend.

I just received my Nitrons R3s yesterday, they are beautifully made.

Spring rates were supposed to be
16kg front (895lb/in)
17kg rear with true coilovers. (951lb/in)

But they sent me a divorced rear spring set up so asking them what's up before I install.

I currently have 24kg (1343lb/in) rear springs in the car so could just use those.

I have decent aero, Sydney composites dual element wing and diffuser, Triple 7 hood vent, canards and a custom splitter are currently being made.

nice, would love to hear your thoughts as well. We're obviously playing in very different fields. I'm running mid shelf aero...APR, and you're running a $6,000 DRS wing. Delicious

 

[Nugs]

nice, would love to hear your thoughts as well. We're obviously playing in very different fields. I'm running mid shelf aero...APR, and you're running a $6,000 DRS wing. Delicious

I'll let you know when I get back on track.
The wing is nice but not DRS.

 

[TBK]

I'll let you know when I get back on track.
The wing is nice but not DRS.

Oops. But yeah, nice is an understatement.

 

[garudathree]

low ride frequency works if the car has good camber curve. your car does not. You use dampers to control cpl variation, not to replace appropriate spring rates.

 

[TBK]

low ride frequency works if the car has good camber curve. your car does not. You use dampers to control cpl variation, not to replace appropriate spring rates.

Yes "low" ride frequency only works if the geometry can keep the tire upright through travel. But the Supra’s camber curve actually isn’t terrible. We're talking 0.6–0.7 degrees per inch of compression up front, and close to 0.5 degrees at the rear. Yeah it's not double wishbone levels, but with -3.5 degrees static front camber, I’m still sitting in the 4.0–4.2 degree range at mid-corner, so the tire’s contact patch is solid even with a bit of roll

I can stiffen low speed to hold platform attitude (curb control, aero stability) while letting high-speed stay compliant over bumps. So i get a flat car without having to jack the spring rate and lose mechanical grip

 

[garudathree]

you need to fire the suspension shop that made up those numbers to you. look at your own videos, with the front outside completely collapsed, you’ll barely run -1 in the front in mid corner. The Supra front gains positive camber after an inch of compression from stock height. In the rear you’re at the point of crab walking. low speed compression does nothing in mid corner once the chassis has settled.

 

[razorlab]

Hold up. Did you just say your APR aero is mid shelf? Mid shelf at AutoZone?

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