Suspension Coilover Tuning for the Touge. (Similar to Autocross?)

[treerexaudi Official]

As the title says above, suspension and/or coilover tuning for the touge, which may very well be similar to auto cross. I do apologize for my lack of knowledge on this subject, and I do understand suspension and coilover setups are only the tip of the iceberg. Strut bars, a stickier tyre compound, breaks, and a good balance between horsepower and weight are just to name a few of course. However this is mainly about suspension and coilovers only as I understand a ton of thought goes into this one part, and I don't want to make this to length of a question (However if you do have some other bits of info to offer anything is very much appreciated).

Now for the actual question. I recently have gotten into these mountain racing videos, and was curious about the suspension coilover spring setups they may run. I am again, quite a newbie when it comes to this so anything helps, but heres what I know.

The pring rates for for the FR-S are.

Spoiler: FR-S Spring Rates

Various measurements
Front OE Spring Rate: Scion FR-S 23 N/mm (131 lbs/in) (2.3kg) (~2300k)

Rear OE Spring Rate: Scion FR-S 37 N/mm (211 lbs/in) (3.8kg) (~3800k)

Source and credit from BRZ Club and Eibach Springs

And the spring rates for the BRZ.

Spoiler: BRZ Spring Rates

OEM Subaru BRZ Front 0.0"/2.7k

OEM Subaru BRZ Rear 0.0"/3.5k

From both of these spring rates I have found out that the FR-S tends to be a more tail happy vehicle, and the BRZ more planted. Another strange thing however is that the FR-S tends to have a very slightly faster 0-60 just because of the suspension? Please correct me if I am wrong, but this is what I have heard, and I do know that the BRZ does have an upgraded gearing for better launches which is odd for the FR-S to be slightly faster. Anyways I was curious about suspension tuning in the first place because of the tight mountain road driving (spirited driving with stability in a way), and the fact that I have found myself a set of KW V3's which I do intend on putting on the car with a slight lowering. What concerns me though is the tuning that should be added once they are installed. For example.

The KW V's have the ability to.

Spoiler: KWs

Adjust the rebound, bump, spring rates, and damping, and probably a few other things i may not know about because then again I am a newbie to this.

So a another major question I guess, would be the effects of a stiff vs soft suspension. I have heard from many that a stiff suspension is more prone to cause the car to become unstable when hitting the apex due to the shocks not being able to compensate for it thus losing traction and/or control of the vehicle. With soft suspension being prone to more body roll and basically all around bad handling, but probably only comfort. I myself don't understand the rebound, bump, and damping, but maybe you can get what I am trying to ask here.

Enough of the talk though. Heres is the type of racing/handling I am talking about. This 86 also got one of the best times on this track which is what really got me going about looking into this.



Before you comment I do apologize that this may seem like a messy wall of text, but there is a decent amount of stuff that I do know and I guess a few very similarly related questions.

 

[r3k1355]

Theory can only take you so far, you actually have to go out and spend a lot of time setting up suspension for the car and the individual driver.
If you're working off a modified road car you'll probably spend a bunch of time chopping and changing parts around to get a setup you like.

 

[s13silvia]

Agree with above, then you have the issue that money and parts can only take you so far because more than 50% is down to driver skill. If I was starting for fast road and entry motorsport then id buy a set of adjustable coilovers that arent too stiff, a rollcage and some poly bushes all round (if you can afford adjustable arms etc then get them). Make sure no balljoints or suspension components have play. Lighten the car some. Buy some uprated pads/discs. Buy some tyres that are good in BOTH wet and dry if you cant afford pairs of both. Id then take the car to a guy who aligns motorsport or rally cars and get him to set the suspension up as best HE thinks. You will then have a bloody good starting point.

 

[mint]

Ok lets clear something up first. The word Touge doesnt mean a type of motorsports. The word Touge literally means 'Pass', in this reference Mountains.
When it comes to Mountain Touge, You have either Grip, Or Drift. So the first and most important question is what is it? Grip or Drift, because both are totally different and both can benefit from the drive train first and foremost.

If its Drift?..
From my own understanding of being on the Touge roads of Japan; suspension is not really a big topic of discussion. Its tyres. Tyres are by far the most important element to having a fast and controlled run. Take for in my example multiple chassis all being the same. All suspension setups being totally different, all tyres being the exact same. From the width to the brand. These guys were running a full grip setup for drift. A simple difference of a slightly more expensive brand was meaning the gap between lead and follow were massive. So much so it blew my mind to see the difference in a simple tyre can actually make. This is taking into consideration both driver skill levels were basically evenly matched being their local Touge. (Running for 15+ years)

All night discussion was on Tyres, Gear ratio and power. Nothing at all to do with suspension, springs or strut bars.

If its Grip driving your talking about, Then I would say suspension does indeed play a big factor when it comes to setting times. Have a look at the Touge Showdown videos. FWD chassis also tend to perform very well in this. Im not saying a GT86 would be a poor choice, but actually on one of the most recent editions of Dori Ten, The touge grip times on the GT86 from Stock to full HKS tune, were poor compared to less powered MR2 / S2K setups. There is a reason, That the title 'Touge Monster' goes to an S2000..

https://100vids.com/video/9vRX8aF4kuM/TOUGE-Showdown-300-Round-2-5-of-5

https://100vids.com/video/dz2dxLLOl...irst-Ever-Touge-Battle-Ends-in-a-SADDEN-DEATH

To quote Hideki Tanabe (Founder of Powerhouse Amuse) "I dont think clocking the fastest time is everything or the most important thing."

Tanabe San cared alot about Suspension, and it showed. His orange s2000 was considered, 'The Perfect' touge car.

My best advise would be to go and drive. Unless your running a slammed car and want to maintain maximum use, then spring rates wont 'really' make much of a difference for drift. For example, The reason for that is the cars running Touge in Japan which I encountered were not slammed, or even crazy low for my standards. Thus they had squat. Which again aided in gaining grip.
For me personally, My style has been low. So Its important to me, to have the stiffest spring I can run to reduce as much squat and roll as possible to save the rear wheel from contacting the arch on drift. This will however influence the result of how the car will perform but its called compromise.

It did however open my mind to a grip setup and to focus more on fast driving. One quote I will never forget from these sessions was the following..

"Anyone can drift, Anyone can get big angle and lots of smoke.. If you are getting smoke, then your not going fast enough."

Touge drifting was faster, more extreme and more ground roots than ANY circuit event I have ever been to. 265's, 400hp. S bodies. Perfect definition of sheer fun.