Bilstein b6 + Stock springs

[JMon85]

Hi, Would Bilstein b6 (or equivalent) with stock springs be a significant upgrade over OEM? Has anyone else done this? I'm looking for an increase in cornering performance and not interested in lowering my car. If anyone has any other suggestions, I'm all ears. I'd like to stay under $1000. Also I'm on 17x8 225/45 Michelin PS. Thanks~

I apologize if this has been covered, search forum button isn't working for me.

[nikitopo]

The stock suspension has been studied very well and you can get very minimal gains even with advanced coilovers. You say that you have a 2015 car, so your suspension is also the upgraded one. Additionally, your stock springs are fine for a 225 Michelin PS tire. Do you want to increase cornering performance on a track or on the road? Also what kind of corners are you interested? Low speed or high speed corners? On high speed corners, you might try to stiffen a bit the chassis. An example is the flexible draw stiffener by STI. Some guys that installed it said that afterwards it corners on rails.

[JMon85]

Awesome thanks for the great info

I really enjoy the way the car feels now with the new tires but for some reason I just want a little more grip, particularly in the rear, w/o totally disturbing the natural balance of the chassis. If that makes any sense..

I'll definitely look into that STi draw stiffener. Mainly low - med speed cornering, eventually track for fun.

I guess my goal really, if possible, is just dial out some oversteer while retaining ride quality.

[Gforce]

I have done exactly this. Subaru has in effect done this for 2017 and on by fitting Sachs dampers which are a marketplace equivalent to Bilstein.

Bilstein B6 control the springs much better than stock, especially at the rear axle. Cheapest mod for the results that you can make.

225/45 tires are the tyre this car should have come with from the factory. Special factory versions of these cars have been fitted with the wider profile to good effect.

Again, this is a very effective and cheap mod, especially if your stock tires need replacing. Fitting better tires does spoil the goofy but entertaining stock handling though.

In order, I would now choose better dampers first, then a set of rear subframe bushing inserts (every BRZ needs a set of these very cheap parts to become a serious car), then a transmission mount insert (also quite cheap and if you fit better tires you will make wheel hop off the line much worse) and only then fit better tires. I fit better tires first and now think that was a mistake. Subaru made a good decision fitting relatively non grippy tires as stock, they work better with the other design limitations. I also have crash bolts in the rear LCA to allow rear camber to be increased slightly and, more importantly equalized left to right.

Finally, I would move roll stiffness forwards in the chassis. As you drive faster and harder the chassis benefits from a bit more initial understeer. Mind you, I fitted an eForce Supercharger which puts a lot more torque through the rear axle. More front roll stiffness is pretty much essential if you start upping the power.

Subaru also did this for 2017 by increasing the front spring rate while decreasing the rear spring rate. Some roll stiffness was added back at the rear for 2017 by increasing the rear roll bar by 1mm (15 mm instead of 14mm).

I decided to fit a 20 mm (2 mm larger than stock) front bar and then a set of 2017 rear springs. The front bar went on last winter just after the eForce and it works very well especially in snow or on wet roads. The softer rear springs improved wet road and snow handling this winter. It remains to be seen how the warm dry road handling may be affected.

If unsatisfactory, I will install a Whiteline adjustable rear bar at 16 mm (2 mm larger than stock and 1 mm larger than 2017 stock) and play around with the rate. A set of front camber crash bolts would also be considered if more front grip was needed. These cars can tolerate quite stiff roll bars if you wish to reduce body roll. I don't really care about body roll since grip is all I really focus on. Body roll has very little effect on absolute grip within the limits of driving a street car. Fitting grippy tires is the cause of body roll so you may find stiffer roll bars work better with a set of let's say Michelin Supersports. Now superseded by the Pilot 4.

All the mods I have made except the eForce can be added within your budget now you have made the big outlay for better tires. I highly recommend you follow this path or similar before contemplating any coilovers or lowering mods. All these mods will also work if and when you decide to go lower. I'm not because I really like driving my BRZ year round very fast in all weather conditions. If you get no snow then a 0.5 - 1.0 in suspension drop can be fun by all reports. Rather than coilovers which are usually never adjusted after install anyway, to drop your car after all these mods you simply add a set of Toyota lowering springs or one of many competing sets of just lowering springs designed to fit stock shock spring perches.

Instead of lowering the car you can achieve similar effects with a set of camber crash bolts for the front struts to allow some negative camber to be added and a set of MCA traction brackets at the rear to, in effect, lower the rear suspension from a geometry perspective without actually lowering the car.

https://mcasuspension.com/traction-mod

Again, these are relatively cheap mods and cheaper than a set of good lowering springs. You get some lowered geometry effects without actually lowering the car. The BRZ isn't particularly close to the ground but the driver's seat sure is!

Oh, and if you can save enough buy a Supercharger!

[JMon85]

Very informative!

Thanks guys. All these suggestions are exactly what I'm looking for and yes, fit nicely into my budget! Much appreciated. I also don't want to lower my car for those same reasons. I'll definitely add a review of the outcome.

[Chad_W]

Awesome, this the mod I'm doing in the near future. I feel like the car is a little under-dampened from the factory, which might give it a more "exciting" feeling, but I think bilsteins would probably improve ride quality slightly as well too (that's been my experience with other platforms). Can anyone relate how they felt this combo effected the ride quality?

[Gforce]

Originally Posted by Chad_W

Awesome, this the mod I'm doing in the near future. I feel like the car is a little under-dampened from the factory, which might give it a more "exciting" feeling, but I think bilsteins would probably improve ride quality slightly as well too (that's been my experience with other platforms). Can anyone relate how they felt this combo effected the ride quality?

Rear Bilstein B6 improve ride quality noticeably. 2017 rear springs even more so.

[strat61caster]

Originally Posted by JMon85

Awesome thanks for the great info

I really enjoy the way the car feels now with the new tires but for some reason I just want a little more grip, particularly in the rear, w/o totally disturbing the natural balance of the chassis. If that makes any sense..

I guess my goal really, if possible, is just dial out some oversteer while retaining ride quality.

I found the stock setup to be very understeer prone when driven at the limit, only sloppy or aggressive driver inputs made the rear step out. A lot of it has to do with how you approach the limits when driving the car, on track us amateurs typically enter a corner very slow and use a lot of throttle on exit, I think that's why most journalists and amateurs say it oversteers and call it "tail happy".

But if you put it on a skidpad and slowly approach the limit, the front loses grip first. If you're too aggressive on the brakes and overdrive on corner entry it will understeer hard (one of my issues, still is to an extent). In the end the car does what you tell it to do, which is a blessing, but can be a mild inconvenience if you're not a skilled tuner with regards to handling.


I'd second the rear subframe bushing inserts, they made a big difference in helping the rear end feel planted which might be some of what you are feeling. The Bilsteins shouldn't change the balance of the car by much, but I'd hold off on changing the balance of the car for awhile, get a bit more seat time before massively changing swaybars, springs, alignment, etc.

[JMon85]

Yeah.. I decided to hold off on purchasing shocks for now and went with a few bushing kits instead. Should get'em in next week. Great feedback thanks!

[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.

[Gforce]

Originally Posted by JMon85

Yeah.. I decided to hold off on purchasing shocks for now and went with a few bushing kits instead. Should get'em in next week. Great feedback thanks!

You will enjoy those. A lot.

[Hyper4mance2k]

By far the best value per dollar I have spent on my car was the $40 Whiteline rear subframe bushing inserts. The next best investment was the Strano front sway-bar and stock WRX rear sway-bar. Third would be my Bilstein B6's. I have ran multiple combinations of 2014, 2015, stock, and the Bilsteins. With and without the WRX rear bar, Strano Bar. The B6's are a huge upgrade over the stock struts with the 2014 or 2015 BRZ springs. If you upgrade your sway bars, but keep the stock struts, the car will handle better, but it will ride worse over poor surfaces.

Remenber, any changes to the overall spring rate of the car, chassis stiffening, new bushings, larger sway bars, etc., will greatly benefit from an upgrade to the factory struts. When you stiffen the chassis, remove compliance from bushings with inserts, etc, you're putting a larger work load on the suspension, and the stock struts are at their limit from the get go.

[Gforce]

This is very, very good information.

[JMon85]

Indeed!