STI flexible draw stiffener experience anyone?

[JDM4E]

Originally Posted by wheelhaus

This all sounds like marketing and voodoo. Anyone have any actual sources of test results or analytics that describe how flexible bracing actually works?

The grimmspeed bar is the only I've personally seen with actual testing, and it's as straight as a bar can get so it's absolutely as rigid as possible. It is on my car and the difference was noticeable. I cannot imagine any curved/arched/flexible bar being worth even half a pile of rat dung in the functionality department. (Just because it's on some car with sponsor stickers on the side doesn't convince me of anything). I am very interested to be proven wrong, however.

for starters
[ame="https://www.youtube.com/watch?v=0r8xW03PVow"]STI flexible tower bar movie - YouTube[/ame]

[Gunman]

Originally Posted by nikitopo

You don't need to go extra stiff with this car. The flexible tower bar has been used even on the dedicated (Subaru sponsored) track car. It wasn't meant to be used only on road cars and it works very well:

I can only say from my experience, I have only seen one car drop lap time, by going softer with the chassis. It was running coil bound, so the only compliance it had was in the tire, and the chassis, so softening the chassis helped.

So, that said, the flex brace may be an improvement over no brace, but it's still offering more compliance than a solid brace.

[nikitopo]

Originally Posted by Gunman

I can only say from my experience, I have only seen one car drop lap time, by going softer with the chassis. It was running coil bound, so the only compliance it had was in the tire, and the chassis, so softening the chassis helped.

So, that said, the flex brace may be an improvement over no brace, but it's still offering more compliance than a solid brace.

Well, there is a tendency to read here that the stiffer is usually the better. Personally, I would say that it depends the case. For example, on the suspension towers you might need some compliance on vertical forces (generated from road unevenness or from potholes) and no compliance on horizontal forces (generated when cornering). As already mentioned, STi is using these flexible braces in their racing cars. They were using the flexible tower bar alone in the 86/BRZ one make race series and together with the draw stiffener in the Nurburgring 24h STi race car. In both cases they were quite successful and managed to win podium positions. This doesn't mean that everyone has to agree and you are free to choose the other camp.

[norcalpb]

The top chart is the 86, and the lower chart is an e46 on a track. Positive numbers mean the chassis is spreading apart, and negative means the chassis is spreading inward. The STi bar can prevent these motions, but what these graphs don’t show is when you hit a bump and part of the chassis moves up relative to the other. A stiff strut bar makes these bumps pretty brutal (looking at the Focus RS) but a bar that flexes during these kind of movements makes the ride more compliant, which can actually handle better over rough roads or imperfections on the track.

[gtengr]

Originally Posted by Gunman

So, that said, the flex brace may be an improvement over no brace, but it's still offering more compliance than a solid brace.

A measure of compliance seems pretty standard when it comes to sti parts. It's nice to have options.

[why?]

just like the chassis of a car, or even simpler, a soda can, they are designed to be flexible in only certain directions, and rigid in others.

[JIM THEO]

The more friendly/compliant a car is at the limit the more easier you reach your personal limits, this is my personal experience.
By the way just found another flexible strut tower bar from SYMS made also by Yamaha as TRD/STI one:
https://syms.jp/car_category/bodysupport_brz86zczn/

[leevanf]

Sorry to revive this thread, but is this the conclusion?

To mod an other-wise non Ts Car,

1. Best for DD, just slap on a Flexible V-Bar
2. Best for DD, and some more stiffness, Flexible V-Bar + Draw Stiffener
3. Iciing on the cake thats not as necessary: Tower Bar + V-Bar
4. All the way - Tower Bar + V-bar + Draw stiffener?

[nikitopo]

Just keep in mind to keep the stiffness balance front and rear. I had option 1 and I was quite happy. I installed recently the thicker rear oem sway bar and now I am going for option 2. So, it depends the total balance of the car ...

[JIM THEO]

Originally Posted by leevanf

Sorry to revive this thread, but is this the conclusion?

To mod an other-wise non Ts Car,

1. Best for DD, just slap on a Flexible V-Bar
2. Best for DD, and some more stiffness, Flexible V-Bar + Draw Stiffener
3. Iciing on the cake thats not as necessary: Tower Bar + V-Bar
4. All the way - Tower Bar + V-bar + Draw stiffener?

I would follow what STI fitted on last gen tS, option 2.

[nikitopo]

Originally Posted by JIM THEO

I would follow what STI fitted on last gen tS, option 2.

If you have the latest chassis changes (+'17), then yes option 2 is recommended. Leevanf has the '14 model which is weaker on the rear. He could still go with option 2, but I believe only if he makes some changes on the rear too. Of course all these would be noticeable when driving on the limit and with stickier tires. Otherwise, there will not be visible any weakness.

[JIM THEO]

Just installed draw stiffeners and STI flexible tower bar in my MY18 BRZ.
I do feel the front end to follow faster the steering inputs and the car feels comfortable than before believe it or not!
That's very interesting and explains why the flexible bar is better than any aftermarket bar (independent vertical movement of each front strut towers) while I feel the need to add the harder STI steering rack bushes as the response of the front end is probably more than the feedback - or at least this is my feeling - so I should equalize them, bear in mind I also have the tS suspension so very close to this setup.

[leevanf]

Originally Posted by JIM THEO

Just installed draw stiffeners and STI flexible tower bar in my MY18 BRZ.
I do feel the front end to follow faster the steering inputs and the car feels comfortable than before believe it or not!
That's very interesting and explains why the flexible bar is better than any aftermarket bar (independent vertical movement of each front strut towers) while I feel the need to add the harder STI steering rack bushes as the response of the front end is probably more than the feedback - or at least this is my feeling - so I should equalize them, bear in mind I also have the tS suspension so very close to this setup.

Thats awesome. I dropped my suspension mod route on favor of getting forged wheels first. What made you decide to get the flexible tower instead of the flexible V bar?


Sent from my iPhone using Tapatalk

[JIM THEO]

Originally Posted by leevanf

Thats awesome. I dropped my suspension mod route on favor of getting forged wheels first. What made you decide to get the flexible tower instead of the flexible V bar?


Sent from my iPhone using Tapatalk

Cost and only cost, I'd like to use the exact same parts with tS but as I bought the draw stiffeners new but cheaper I choose the flexible tower bar in order to keep the total cost low, plus where I read about it the final result is almost the same!

By searching the net I found also that STI steering rack bushes are quite difficult to install so I may install aftermarket ones say Whiteline etc.