Suspension Tips, for those who want to lower this car.
 

Tips for Scion FRS owners #1:

For those who are contemplating on suspension upgrades to make that horrible ride height reduced to handsome looks of many tuner upgraded ones. Take a serious consideration and heed to my advice.

The Scion FRS/ Subaru BRZ (and Toyota 86) has a fairly stiff suspension already from the factory to cater well to the owners who visit the race track. The car is a very refined, -low gravity, center-mass balance car that requires a pretty hefty load of weight shifting to make it whip and turn (a trait of a true sports car, but at the same time, takes a pretty advanced skill set).

Now having said this, installing shorter stroke, stiffer set of suspension will easily overload the stock tires, and the result will be a car that is really difficult to rotate well, and more prone to initial under-steer, making it less entertaining to drive, and a bit more risky.

My advice is therefore, to purchase a proper set of higher grip tire if upgrading the suspension all at the same time, and to choose a spring rate that is mild and soft, so that the agility of the car is not lost due to unwilling suspension, that might be too stiff. Set your shocks very soft if it's adjustable and increase it only if you can drive it without much "push" or initial under-steer. The FRS and BRZ needs all the suspension travel and shifting of the weight to flick vectors under braking (dive), and depriving it will reduce the fun factor and increase the efforts for the driver to drive it faster.

Stiff, low, suspension and stock tire is about the worst combination you can have in the FRS. Soft compliant suspension and mild drop and healthy set of fairly grippy tires is the only way to NOT ruin a great car, if this is a mild build. 235 width Yokohama S-Drive, Falken FK453, etc equivalent level grip tires, come to mind on a good balance to use for mild street suspension upgrade from most reputable firms.

Full race suspension will almost guarantee you will have a really slow, unwilling car, if you are not a really seasoned driver, and riding on nothing but appropriate RACE compound track slicks.

It's a really well balanced car, an excellent platform, and because of that, it's just that much easier to completely ruin it if you don't do this RIGHT. Needless to say, choose your suspension kits wisely, as the FRS/BRZ is a VERY difficult car to re-tune properly, and the manufacturers must take very careful R&D unlike most others, to properly design a suspension that will actually improve on the platform for this application.

Have FUN!!

Moto-P,
Club4AG.com

Summary, if you are not very versed in dynamic tuning of a sports car like the FRS.
I can elaborate on definition of soft as "compliant, well damped, and allowing enough stroke at low loads" OF course that can be had in different combinations of factors but generally, the suspension on this car needs to MOVE.

Stock Tires + Stock Tires = pretty darn good.

Low+ Stiff+ Stock tire = bad, hard to rotate, easy to understeer (plow)

Soft + mid-height -20~30mm (or plenty of stroke built into coilver) + medium grip street tire = FUN, Fairly quick, easy to handle, and close to original setup.

Low+Stiff+Race tires = proper race car setup, but requires a lot of driving skills to make it go fast.

I'd also like to add that STICKY tires on STOCK suspension REALLY DID WELL at the race track... (but that won't solve most people's peeve of ugly ride height, right?

Just keep in mind though, the peculiar trait of the stock FRS/BRZ is that it comes with already stiff suspension, enough to take on demands of most raceways with really nice stability. This is very different from most previous stock car. SO upon lowering this car, one needs NOT stiffer setup, just lower is the cosmetic element is what's bothering you. Any stiffer and the car will ABSOLUTELY need very grippy tires to balance, and with that, some really good driving skills as well.

The PRIMARY reason I got this car is because I wanted a car that would handle well in stock form. This is because my last car I knew was slow and knew it would cost too much to make fast so I bought some coilovers to make it fast in turns. Well this started the rabbit hole and I knew my next car must have a stock suspension I wouldn't need to modify for the street. So even though it may need a small drop for aesthetics, I won't do it. I am only going to modify for power and upgrade the drivetrain and brakes/tires to handle it.

I agree with you OP. :)

Thanks for the tips, I was considering springs or coils down the road. Don't like the wheel gap at all but I might just deal with it to avoid messing up a great thing!

Great post moto. I agree with all the thoughts in here. I too have thought about lowering this car to make it look better but dont want to risk ruining a very well engineered and set up car. Hopefully TRD can release some coilovers that will drop the car by the recommended 20-30mm and still retain its perfect factory balance.

What springs do you recommend if I just want lower it slightly with stock shocks (btw I have a brz).

I say those wanting to lower their cars wait for Swift Springs to release theirs. They usually do it the right way and actually do extensive R&D to make sure the right spring rate is chosen to work with stock shocks/struts.

+1. What he said except I will be needing advice for the GT86.

RCE has developed some springs that lower 20mm but do not diminish the OEM handling and suspension. Check out the thread

http://www.ft86club.com/forums/showt...?t=8823http://

I've sampled Cusco Street, RS*R Sports-i, and both of them were extremely well behaved and designed for medium grip to high grip tires. Both worked really well at FULL SOFT setting on both ends, even with track radials like the Azenis RT615K. So going stiffer is only needed perhaps, to compensate for wear of the dampers, and also to settle the car at really high speed tracks where stability is in order over quick vector changes.

Both do come at a price of nearly $2000 but with the ability to be 30mm lower, and unlike lowering springs on stock shocks, that allow maybe 20mm max on short rear shocks of the FRS/BRZ, the fully-tapped coilovers can go a full 35mm lower with all of the original stroke range, and has adjustability to actually make the ride more comfortable with more sophisticated valving that is not cost-constrained like the stock shocks.

So if budget is the key, Racecomp's 20mm drop springs are really ideal.

If ride qualities of the stock is a bit harsh for you, you can use either of the more expensive setup to improve that while retaining all the of the nice handling capability with much lower height around 30~35mm drop.

I've also found that 20mm drop is ideal for dynamic alignment (as designed), and 35mm still retaining pretty good alignment as well.

Yes, that should work fine. :D

Most of the major difference (which is still very slight) between the BRZ and FRS/86 is in the shock valving, especially at the rear. While the spring rates are not far off.
So the modification for springs should be approached similarly for both cars.

The BRZ shocks at the rear seems to be slightly softer, giving a better ride and less wilder enthusiasm at the track, but because of this, ride height alteration on the very short stock shocks should be approached with a little more care, as you tend to run out of shock travel faster on the BRZ over rough terrain. (ironic huh? since Subaru is the one who's famous for WRC? :D However there is a GOOD reason. Subaru wanted a more mature ride and less peakiness in the handling for the BRZ, which makes sense for their target audience of slightly more adult fan base than Japan's AE86 drivers who are wild drivers, and Scion's younger crowd who don't mind the slightly stiffer ride...;)

For those who haven't test driven both, the BEST way to tell the difference is not from driving these cars like you stole it during a dealer test drive, as you really won't notice much on what you can do in terms of handling on public roads as you don't usually have enough silky smooth asphalt where you can dice the car into a lift-throttle drift into an apex and hammer out in total control...

The difference can be felt much more easily by something much more mundane. Just roll the car over a large bump like parking lot speed bumps or on/off a steep driveway ramp. You will find that the BRZ will soak up the bump slightly more compliantly than with a FRS, where the BRZ will tread over it, while the FRS feels like it wants to hop over it slightly. And if you are not sensitive enough to feel this, then there is no need to push the car to it's limits as that won't really help you feel this either at speed.

Imo, it's not that simple. At first glance I noticed the spring rates were increased both front and rear. The front has been stiffened and now match the rear. Stiffer front springs will generally create more understeer. This is why toyota designed it to have stiffer rear springs than front.. To oversteer.

It's all personal preference.. But I believe that until the end user makes his/her own educated decision, making blind recommendations is not good advice.

I am going to first try some Tein H-tech springs and go from there. They keep the oem f/r balance and increase spring rates slightly. More so they keep the front softer sprung.

Good post Moto-P, I'm glad to see there are other people that really stay true to keeping proper suspension geometry and ride dynamics. I have been, and still am, thinking long and hard about what I want to do to the suspension since for most of us our FR-S wont be a track only car, we still have to get to work without a stiff back all day :burnrubber:

I fail to see how installing stiffer suspension with the stock tires will induce understeer. Sure, if you mess with the F/R spring rate ratio, increasing the front drastically more than the rear, then I could see this happening. But if you increase the rates such that the F/R balance stays the same, or even makes the rear more aggressive than it is now, than why would it understeer more?

Good question. It shouldn't mess with the balance, however stiffer springs can make a tire lose traction sooner. Coupled with poor driver influence, like too much steering input, can cause understeer (or oversteer).

This is a good point and something people should watch out for when buying coilovers. I've already seen some show up for this car that are way stiffer in front than in the rear. I'm guessing those are for drifting setups, but will really destroy the balance of the car if you're going for grip. Darren's guide in the suspension section lists the spring rates for the coils.

I'm trying to explain how the rsr coils work to him, but he doesn't seem to understand that they aren't ever off of the shelf unless a shop buys them that way. You talk to RSR and choose the spring rates, 6k-9k for front and back, and then they ship them to you in that configuration. Moto and I both have 6k F 7k R and it feels extremely close to stock, but better. The balance is still there, the. At really eats away at the curves still.

What's the advice on tire setup. If aesthetically pleasing springs aren't available for appropriate balance, would increasing tire width be advisable. Would a 245 tire fit well with stock suspension and maintain balance?

The front of the FRS/BRZ like any car, needs to dive, to increase the front weight distribution upon deceleration, allowing the car to grab at the front, and loosen at the rear for the car to get a firm grip of the road with the steering tire. This has a lot to do with, and depends on the ability for the tire to GRIP and CREATE the G forces that allow this dive. With stock tires, there isn't enough traction to decelerate the car enough, and thereby reducing this ability. When you increase the suspension stiffness, it takes even MORE grip to make it dive, and without this grip, the tires will not get enough weight on it to steer.

This is just an example in ONE vector and direction, but this holds true for all axis of the motion, and the car needs to transfer weight back and forth, and side to side to make this happen. The FRS/BRZ is a very light and centered car with low center of gravity, thus making this very difficult since there isn't a huge overhanging weight like most cars. While this is a trait that allows physically, a very acute and responsive car, it is also very sensitive to changes like this.

This is why, overly stiff suspension on the FRS/BRZ tends to create less ability to motion the car correctly when changing vector of travel, and also the direction of the car, and wheels, if the tires can't hold the G-forces necessary to do it efficiently and readily.

Tada's design of equipping it in such way and balancing the car, with mild grip tires is exactly this, to challenge the driver to develop the skills to do this, and to give gratifications to those who can drive it well, and be rewarded the speed that comes along with it. That is what a true sports car should provide.

Yes, again, the lack of dynamically distributed weight on the front tires is the culprit for the quick loss of steering feel, and resulting loss of traction. Stiffer springs, and shock compression settings, can prevent the car from planting the front tires to initiate a turn.

Poor driving skills is a whole different matter as this is simply the inability for the driver to feel and maintain the contact patch at nice, gradual, stable level of grip at any given speed and abrupt and violent inputs and rebound forces, creating a havoc on the dynamics of the vehicle. :D This is also why I recommend a long-stroked (taller) suspension with soft, compliant, and slow moving parts on the suspension for novice drivers, so all of the dynamics of the car are accentuated, and things happen slowly and more predictably. Fast, stiff, grippy setup requires the driver to be much more sensitive, quick, and extremely accurate, and feed-backs happen a lightning speeds where they might not understand at all, what is happening with the vehicle as controls are lost.

Increasing, or changing tires sizes both in width and diameter has consequences that change many different variables, and simply raising the contact patch should not be taken lightly or be treated as a fix-all solution. Increased tire contact patch also means less ability for the tires to reach proper temperature, and reduced grip over loose surface as rain and snow, and even dirt.

I think to keep the inherent balance of power and handling of the FRS/BRZ, the tire size change should be minimal, regardless of going with 16", 17" or 18" to keep the same diameter, and relatively small widths. 225's and 235 width should be plenty for a light FRS, to be fun and agile as universal car. Going beyond this only if there is a specific purpose in various field of REAL racing.

I feel that GRIP and DRIFT setups should be really similar. AS handling and ease of control of a car at any dynamic action, should be a very refined and singular in point. Sure in Pro-Drifting there is a big difference from standard alignment setting, but most D1 cars, in early days before entire sub-frame change was allowed, usually had similar rate equipment. Only set a little stiffer overall, to stabilize the violent flicking of direction. Drift cars still need a LOT of traction in both braking and accelerating vectors, as speed is lost more in a drift than in a grip situation, as you are taking a SLOWER approach to any corner.

Anyway, back to topic, that FRS should have a compliant balance of suspension, that is closely matched to the tires, and no more. For this car, we just need to find that balance where the driver skills are up to the task, before making anything "higher performance" as this car is so demanding of the driver, that if the car is overbuilt for the driver, he will simply be going slower in a higher tuned setup.

totally agree. my last track day all i worked on was braking and loading for cornering. this car is faster using weight transfer and tire slip without a doubt. the oe setup is very good at accomplishing this and when you do it right you know it because you get the tires singing but not screaming. i also learned this car is really good at letting you know when you do it right. if you over brake and have to unload the front a little early it totally messes up the cornering rotation and exit speed. blindly, i'll agree that 20-25 mm of drop would be ok if you're doing it for further cog reduction or aesthetic reason. i really like the stock setup, it's fun and educating. they only thing about changing to a stickier tire is if you don't have a well developed sense of weight shift, a sticky tire will stunt development of it as you'll stay closer to the grip side of things instead of walking that grip slip line. getting the car loose tells you alot about what you are doing. i spun twice on track this wknd working on my trail braking and front loading.


for my purposed the stock tires are good. when i go to a different compound i will either stay at 215 or only go up to 225. but that wont be until i get more consistent with this car. and i hope my coilover choice doesn't affect my learning pace.

I really liked progress coilovers on my B13. They are only height adjustable. Progress took the time to tune the shock and spring combo so the customer couldn't mess up the handling of the car.

To me it's not about the wheel gap... it's about the wheel being concentric with the fender! And the FR-S/BRZ does that quite well, so IMO the FR-S/BRZ isn't too high at all. The ride height is perfect. In fact, lowering the car will ruin the already concentric wheel/fender look from the side. Who else agrees with me on this? There's no need to worry about scraping your car either as a bonus! And besides, the car's center of gravity is already low enough.

yeah, that makes sense. So essentially, unless you add decent front grip with better tires, don't mess with the suspension. I suppose doing a sticky 235/40/17 on an 8" rim would do the trick, and then upping the spring rate would be ok so long as you don't go overboard.

Yes, I understand. I am a vehicle dynamics specialist. I setup and tune clients car for circuit, auto x, etc.

:respekt: I enjoy reading your posts as they are on point and educational. I believe that suspension tuning is an art, not always a science.

Thanks guys, this thread has helped me out a lot in figuring out what I'm going to do.

I wanted to chime in beyond thanks and say that as a purely aesthetic matter, this is where my eyes go as well. When something is out of round or non-concentric, it sticks out like a sore thumb. I've never understood the preoccupation with "wheel gap." "Wheel-doesn't-look-like-it-belongs" is way more obnoxious.

Excellent post Moto! Tire choice is the first question I ask when discussing suspension options with a client as it dictates how firm we need the suspension to be.

One thing to keep in mind is that if you increase the front and rear spring rates by an equal X amount OR by the same ratio, the balance may change. Just keeping that same ratio doesn't mean the car will keep the same balance, and this is especially true when lowering a car with a Mac strut up front. Roll centers and dynamic alignment changes are not identical at both ends and change at different rates with lowering the car.

Our goal was max grip for a sporty street tire with good ride quality and a fast, fun, easy to drive neutral balance. We did try a few other configurations... :)

- andrew

so it would seem that the general consensus is that lowering the car about an inch and a half while keeping the spring rates close to stock and the dampers softer rather than harder will allow you to bring the car down some while not destroying the inherent handling properties?

Doing that would be a disaster!

An inch and half drop with spring rates similar to stock is going to leave you with extremely little suspension travel and if the spring rates are close to stock it will use it up very quick. Bad news. Awful ride and handling.

With regards to the dampers, it's more complicated than just softer or harder.

- Andrew

ok, thats what i was thinking, and why i wanted to ask because i knew i couldnt be understanding that right.

re-reading also helps. i was looking at that first quote and just reading "soft soft soft". but now that i look at the second quote more carefully i see where i was just confusing myself after reading everything and my initial understanding was fine. :bonk:

i use the same setup on my is300, but it didnt handle anywhere near as well as the fr-s from the factory, so there wasnt much worry about making it worse.

How do you define really well? Sticky street tires overpower the stock suspension. The stock dampers are nice for sure. But they were designed to work with wooden wagon wheels for tires. In my experience, a Hankook RS3 had enough grip to make the stock suspension sway around like a top heavy boat and get into the bumpstops at the limit. What track did you test on and what tires did you test to get good results with the stock dampers?

Sorry to ask for definitions again, but how do you define "full race suspension"? Last weekend we tested AST 4150's at buttonwillow (see my blog in my sig for details if you want). Those dampers can be tuned for good street tires as well as slicks. Good dampers make the car easier to drive. Not harder. Even less experienced drivers would be faster on these than on the stock ones. And while we didn't test it, the car would have likely been significantly faster on these dampers with stock tires than on the stock set up. These are the same shocks that are going to be standard equipment in Grand Am's Continental Challenge next year. Definitely full race. I think maybe what you meant was "really cheap, really stiff dampers will be harder to drive and be slower"

I appreciate the education you are trying to provide people, but suspension tuning isn't a scary endeavor. Yes, you can do it wrong, and there is no replacement for quality when it comes to part selection. But while the stock setup is good, there are plenty of ways to improve upon it without being a "pro".

Goodluck to everyone on your setups!
Matt Andrews

Agree with Andrew here. First thing I always ask when someone asks for suspension suggestions is "What tires do you plan to use with the car?", quickly followed by (or even preceded by) "What do you plan to do with your car?"

For me there seem to be two basic directions for suspension setup out there: "Aesthetic" or "Performance". Oftentimes people's parts choices and setup are the result of wanting to achieve a "look" or aesthetic. Nothing wrong with that. But its important to keep in mind that what looks cool doesn't necessarily mean it will handle well nor, for the track oriented, improve your lap times. So what Moto has been trying to get across is that the typical tuning notion of "lower/stiffer" does not equal "faster" or better handling. Unfortunately, just because the car "handles like a go kart" doesn't mean it actually handles well. The "Performance" oriented folk set their car up for the best handling possible for their situation, the look of the car will be what it will be. Their ride height comes from properly analyzing the tire type, spring/swaybar rate, geometry compromise and suspension travel.

Warning Rant :) :

As an aside, an interesting dynamic I'm seeing on this board is the cynism and mistrust many have with vendor input or claims. I guess its bad experience from other boards. I can understand that, because in the end, they all "just" want to sell you something. There are however, a few vendors out there who are enthusiasts first and foremost and I think people will see that over time through the quality of their posts and the kind of neutral information that benefits this growing community. From my experience with them on the Subaru and Evo boards, Race Comp Engineering is one of those vendors. Am I an employee? Nah, but I do like their proper approach to the development of parts. I don't think I've actually ever bought anything from them. :lol: For example, they don't just pick a random amount of lowering like "I think 30mm will look dope on this car". Performance is always utmost on their minds. They take the time to properly dyno test the dampers to see what they are capable of, measure the stroke, map out the geometry of the car and THEN consider what spring rate and amount of lowering will actually improve the handling of the car. And they are totally transparent in the development of these parts. You just need to search their threads on NASIOC to see how they went about developing their Bilstein setup for the current WRX. What we get as consumers are parts that work well FIRST, they MAY happen to look good.

The kind of lowering spring offerings is honestly something I'm surprised at living in Germany. Its ironic but here the "lower/wider" crowd really drives the aftermarket rather than the "peformance" crowd. Pretty much all lowering springs are minimum 30mm and often times 50mm recommend for stock dampers! And these are from reputable manufacturers like Eibach and H&R. You'd think they'd know better here. I just shake my head and wonder, have they even measured the stroke on the car's damper? 50mm easily sits most car's on their bumpstops. And then the spring rate is not much stiffer than stock (to maintain stock comfort levels). I just sit in disbelief sometimes.

Sorry for the rant! Back to the topic at hand.

This is a great discussion happening.

In my case I'm somewhat knowledgable about suspension setup (no pro) and my needs are a blend of looks, comfort and serious performance on a budget (yeah, unattainable holy grail, I know) so I'm finding this information very useful. Very grateful to everyone who has taken time to contribute.

Side note: The level of intensity here is nothing compared to Miata.net or the SCCA boards which is GOOD! Considering that this is a young board with a diverse audience revolving around a new car I think we're doing fine here.

The main points that I'm taking away from is thread are that:

1. You need to consider your needs carefully before proceeding in a particular direction.

2. You need to face the reality that you'll have to compromise as each approach will have definite pros and cons.

3. It takes a combination of discussion and experience to gain good knowledge about exactly what the pros and cons of certain approaches are.

4. In the end you need to make up your own mind.

Neither 1. or 2. are exactly rocket science but they're both VERY easy to forget no matter how experienced you are!

The better you do at 1,2 and 3 the less likely you are to end up being broke and unhappy once you reach 4.

:)

:)

:happy0180:

Valid point, but unfortunately much of the aftermarket is geared toward "buy this it's better!" where many consumers assume that something will automatically make an improvement because it worked on a previous car, they saw an ad, want to be unique, or their friend said so. Matt is dead on that basic suspension tuning isn't a black art, but the underlying maths can be quite mysterious for those of us who aren't suspension engineers... It is pretty easy for a novice to "tune" a car into poorer handling without knowing it, simply because the experience and knowledge isn't there yet. Knowing who to trust is key. No matter what the goal, we need to understand what it is we're trying to improve upon, and what else is affected before going about purchasing parts. Just because the car came from the factory with (fill-in-the-blank-OEM-part-here) doesn't automatically mean the part needs to be upgraded.

Too many people assume that a faster machine will make them a faster driver... It may change the experience, lap times may improve, but the best upgrade that can be made to ANY car is the driver.