Bilstein b6 + Stock springs

[lutfy]

Just keep in mind the Bilstein B6 will (or I should say "may" in this case) raise the car a tad. Reasoning: older shocks tend to sag so expect a slight ride height increase with stiffer newer shocks. At least this was the reasoning when I went with the setup on both my E36 and E90 M3. My take is that the shocks are stiffer than OEM with higher compression. In both cases I went with slightly lowering springs (Eibach Sport or such) and the ride height was tad lower or 'identical' to stock from my experience. This car may vary but something to know...

On my race car (BMW I Stock) I had Bilstein revalve for higher spring rates and dispite the adjustability, was very happy with it.

Lutfy

[Gforce]

You're talking millimetres not inches. Only high pressure gas shocks have this effect and only they can lose enough pressure to sag. Springs sag but only when very old and usually starting to corrode.

[OND]

Originally Posted by Gforce

There's no doubt the stock chassis is tail happy and that this slows down the car. Equally, there is no doubt the Subaru engineers designed this deliberately. As the market for this car matured so did the chassis set up, most likely to keep sales going.

Drive aggressively in the wet or on snow or ice and the 2013-2016 factory chassis set up is pretty clearly too much oriented to front grip. As it comes from the factory the rear can be induced to step out without much effort from the driver. I am sure the 2017 is better in this respect but I have not driven one.

There's no doubt you can drive this car without the rear stepping out. There is also no doubt that the car is slower in stock form than it is after a simple mod or too.

Sticking a stiffer front bar on helps a lot.

The steady state cornering behavior of BRZ is understeer, in both wet and dry. Please stop spewing out this "stock BRZ is oversteery" BS in every possible thread.

I asked you in another thread and you avoided the question, but do you even track your car or have you ever been to a skidpad to suggest people with stock'ish cars to decrease front end grip with larger swaybars? If you do, I'd love to see a video of the oversteering issues that you had with a stock BRZ.

OP, I'd also think about front camber bolts or adjustable top hats before shocks if you haven't done those yet.

[JMon85]

But really tho.. The guys in the Toyota 86 racing series cars under/oversteer.. its going to happen no matter what.. in any vehicle.. okok they're ametuer/semi-pro/guest pro (a level I'll never attain with my DD) I get it.. diver induced blah blah lol.. I'm just harmlessly inquiring for suggestions for more grip w/o lowering the ride height.

[strat61caster]

Originally Posted by OND

to suggest people with stock'ish cars to decrease front end grip with larger swaybars? If you do, I'd love to see a video of the oversteering issues that you had with a stock BRZ.

To be fair in autocross stock classes a stiff front swaybar is preferred to help the car in transitions. I think the sentiment that increasing the front roll stiffness helps the car (why so many off the shelf setups have a stiffer front vs. rear than stock) and that has a grain of truth, but man the lack of camber up front is priority number one to making the car faster and more balanced imho.

[OND]

Originally Posted by strat61caster

To be fair in autocross stock classes a stiff front swaybar is preferred to help the car in transitions. I think the sentiment that increasing the front roll stiffness helps the car (why so many off the shelf setups have a stiffer front vs. rear than stock) and that has a grain of truth, but man the lack of camber up front is priority number one to making the car faster and more balanced imho.

Those are all good points. I bet increasing front roll stiffness helps with various setups, but it's just not what I'd consider a necessary first mod to a stock BRZ.

[Gforce]

Originally Posted by OND

The steady state cornering behavior of BRZ is understeer, in both wet and dry. Please stop spewing out this "stock BRZ is oversteery" BS in every possible thread.

I asked you in another thread and you avoided the question, but do you even track your car or have you ever been to a skidpad to suggest people with stock'ish cars to decrease front end grip with larger swaybars? If you do, I'd love to see a video of the oversteering issues that you had with a stock BRZ.

OP, I'd also think about front camber bolts or adjustable top hats before shocks if you haven't done those yet.

No, I don't track my BRZ. I have driven proper race cars on a track. Yes I've used a "skid pad". They're called parking lots where I come from.

Roll bars do not create or destroy grip. Tires deliver grip. Roll bars affect how quickly the weight transfer torque is put into the springs. Steady state chassis behaviour isn't very important when cornering. What matters is what happens when you try to increase power in the corner and when you can do that. The sooner you can put all the available engine torque to the wheels in a corner the lower your lap times will be. You cannot increase the acceleration of your car but you can influence for how long you can use it.

By moving roll stiffness forwards you can put more power down earlier in the corner. That's how the stiffer front bar delivers more front axle grip. By allowing higher cornering speeds before the inside rear wheel loses traction.

Camber adjustment delivers more grip entirely differently. It only works if camber is incorrect to begin with.

For my money the first mod needed by this chassis is rear subframe bushing inserts and the second is a transmission mount insert. These reduce unwanted rear axle alignment changes and wheelhop effects on the shift lever.

[Gforce]

Originally Posted by OND

Those are all good points. I bet increasing front roll stiffness helps with various setups, but it's just not what I'd consider a necessary first mod to a stock BRZ.

You will find that front roll stiffness on the BRZ chassis is insufficient relative to the rear, until the 2017 model year when Subaru themselves fixed this issue. You're not arguing with me you're arguing with the Subaru engineers. Good luck with that.

[OND]

Originally Posted by Gforce

No, I don't track my BRZ. I have driven proper race cars on a track.

Roll bars do not create or destroy grip. Tires deliver grip. Roll bars affect how quickly the weight transfer torque is put into the springs. Steady state chassis behaviour isn't very important when cornering. What matters is what happens when you try to increase power in the corner and when you can do that. The sooner you can put all the available engine torque to the wheels in a corner the lower your lap times will be. You cannot increase the acceleration of your car but you can influence for how long you can use it.

By moving roll stiffness forwards you can put more power down earlier in the corner. That's how the stiffer front bar delivers more front axle grip. By allowing higher cornering speeds before the inside rear wheel loses traction.

Camber adjustment delivers more grip entirely differently. It only works if camber is incorrect to begin with.

For my money the first mod needed by this chassis is rear subframe bushing inserts and the second is a transmission mount insert. These reduce unwanted rear axle alignment changes and wheelhop effects on the shift lever.

Some of those statements show an obvious lack of understanding of vehicle dynamics. Like "Roll bars affect how quickly the weight transfer torque is put into the springs", wth????

Stiffer front bars don't create more front axle grip. They help transfer load to the rear axle under lateral loading, thus increasing rear grip and reducing front grip.

A stock BRZ on track with 0 front camber will start plowing at the corner exits before the rear end starts sliding, unless the driver has terrible throttle modulation. Your modified car might be struggling to put the extra power down and you might like the stability of a FSB, but that is a totally different scenario.

If you don't think 0 front camber is "wrong" for performance driving, I dont know what to tell you. I'll just be waiting for the "Destroyed tire outer shoulders after tracking" thread, just like the one I created last year

Increasing front springs rates have many effects other than the roll stiffness that you seem to be obsessed with, so please stop using Subaru engineers' decisions to support a totally different point.

[strat61caster]

Originally Posted by Gforce

Camber adjustment delivers more grip entirely differently. It only works if camber is incorrect to begin with.

As @OND mentioned, this is what happens if you actually drive an 86 hard with stock camber:

http://www.ft86club.com/forums/showp...82&postcount=1

That looks like correct tire wear to you? I get it, I've done a lot of research and studying on vehicle dynamics too, some things that work on this car don't make sense to me mathematically, but statements like stock camber is adequate and steady state cornering is irrelevant are just not grounded in any kind of reality.

[ApexEight]

I've got the Whiteline rear subframe, diff, and tramsmission mount inserts as well as the Perrin steering rack locks. Stock suspension otherwise. So do you guys recommend front camber bolts in the lower strut holes and take the stock bolts from the lower strut holes and put them in the top holes? What should I be looking for alignment wise in terms of attainable specs? As much negative camber as possible with zero toe or maybe a touch toe out? How about the rear, a touch toe in? Car is a daily and will be autocrossing this weekend. 2014 FR-S on all-season Toyos. May pick up some MPSS in 225/45. To me, the rear doesn't have enough grip and I want a more planted feel all around. Also thinking about 1" lowering springs and a front bar.

[Gforce]

Originally Posted by OND

Some of those statements show an obvious lack of understanding of vehicle dynamics. Like "Roll bars affect how quickly the weight transfer torque is put into the springs", wth????

Stiffer front bars don't create more front axle grip. They help transfer load to the rear axle under lateral loading, thus increasing rear grip and reducing front grip.

A stock BRZ on track with 0 front camber will start plowing at the corner exits before the rear end starts sliding, unless the driver has terrible throttle modulation. Your modified car might be struggling to put the extra power down and you might like the stability of a FSB, but that is a totally different scenario.

If you don't think 0 front camber is "wrong" for performance driving, I dont know what to tell you. I'll just be waiting for the "Destroyed tire outer shoulders after tracking" thread, just like the one I created last year

Increasing front springs rates have many effects other than the roll stiffness that you seem to be obsessed with, so please stop using Subaru engineers' decisions to support a totally different point.

I think you have much of this backwards. For example, a stiffer front bar transfers grip capacity to the rear axle by resisting more of the weight transfer torque. This allows more power to be applied to the rear axle. For fwd you would not tune the chassis in this way, you would increase rear roll stiffness instead and for the same reason.

Roll bars transfer spring rate from the outside spring to the inside spring, or put the other way, engage the inside spring to resist compression of the outside spring relative to the inside spring. They work by, in effect, lowering the car. They cannot deliver more grip than the tires can deliver. They do change the point in the suspension travel that the tires are asked to deliver grip, which may or may not increase total grip delivered. With street suspension in general reducing roll increases tire grip by reducing camber change.

To visualize this just imagine how the roll bar would work with no springs.

To understand chassis dynamics you need only consider a go kart.

[Gforce]

Originally Posted by strat61caster

As @OND mentioned, this is what happens if you actually drive an 86 hard with stock camber:

http://www.ft86club.com/forums/showp...82&postcount=1

That looks like correct tire wear to you? I get it, I've done a lot of research and studying on vehicle dynamics too, some things that work on this car don't make sense to me mathematically, but statements like stock camber is adequate and steady state cornering is irrelevant are just not grounded in any kind of reality.

I'm not sure I said either of these things. Stock camber is what it is unless you fit adjustment parts. I have rear crash bolts but only to get camber close to equal left to right. I have no camber adjustment on the front struts, but I'm thinking of adding crash bolts.

McPherson struts produce more camber change than mulitlink, generally speaking. Subaru inclined the BRZ struts more than in the Impreza upon which it is based. Subaru also fit much stiffer springs than it does to the Impreza. The BRZ also has no drive to the front axle. Net result is Subaru doesn't need to set any negative front camber. The grip limitations for this Impreza based suspension are all at the rear axle.

The reason steady state cornering isn't relevant is there are no steady state corners. I mean Parabolica at Monza is close but even there the racing line has an apex, (two actually).

Plus all cars built for road use understeer at maximum lateral g achievable in steady state. They have to to be safe to drive.

[strat61caster]

Originally Posted by ApexEight

To me, the rear doesn't have enough grip and I want a more planted feel all around.

More seat time imo, enter corners faster.

The spc bottom and stock bolt top will get you max camber, I've heard some say -2 or more with that setup but ymmv. To start I'd ask the shop for -2 degrees up front or as close as they can get, zero toe up front, rear toe in is dependent on how they measure it, could be 1/32" in or 0.1 degrees toe in (total) for a minor toe in effect. Maybe less if the rear end starts feeling super planted, you can free it up a bit. Your current alignment could explain what you're feeling.

Play with that for awhile, if you still feel the car is too oversteery go for the front bar or springs. I'd suggest racecomp as they increase the front spring the most which sounds like what you want.