Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

[theNewman]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

One of the guys I used to work with at Sewell reported pulling up next to one on his way home last night. It had paper tags, so I doubt it was a presser or manufacturer owned . . .

[Draco-REX]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

The pictures, measurements and comments from my little BRZ post are spreading like wildfire... I've found them on over a dozen forums so far (and only put them on 5 of them). Crazy. Of course since I said a few negative things about the crap stock tires that come on these cars, I defaced a sacred cow, and have been tarred and feathered by many. But I'm used to that.

I don't think the tires are sacred, just that some may think you're not keeping with the spirit of the BRZ (low power, low grip). NO biggie. If everyone were on the same page when it came to cars we'd only be watching NASCAR.

I'm planning on increasing the tire grip anyways. But I'm keeping an eye towards minimizing weight gain at the wheels. Since I'm not looking to compete for points with the BRZ, 225/40-18 is looking like a good size for the weight.

I'm pretty much decided on the Enkei PF01 rims 18x7.5+45. Excellent weight for the cost and the offset will widen the track by 20mm.

But I'm currently undecided between three tire choices.
Dunlop Z1*specs are an obvious choice. Excellent grip and turn-in. But the heaviest at 25lbs. (Stock tire is 21lbs)

Hankook R-S3 has excellent grip, but softer turn-in feel and horrible wet characteristics. I wasn't all that happy with the R-S2's feel. But these are only 23lbs.

Continental ExtremeContact DWs are my third choice. Very good grip, excellent wet grip, but soft feel again. I have a set on my spec.B and they're great DD summer tires. But I think the BRZ deserves something a bit sharper. I'm considering these because they weigh in at a very light 21lbs.

In theory, adding 4lbs to the tire carcass would make a noticeable difference on a 200hp car. But what would your take be on 4lbs per tire on the BRZ?

I got a call yesterday from a shop that is having an open house on March 24th (COBB Tuning Plano - shop expansion) and they will have a BRZ on hand that day. I am going to scale the sh!t out of that car that day - corner weigh it with and without a driver, weigh the trunk junk, note the fuel level, and pull a wheel and take some more measurements. I might even have some 17x9" wheels that could possibly fit the car on hand to test with.

So that's as soon as I can scale this car. March 24th. Three weeks. They might even be on some streets by then - who knows. If I can get my hands on one sooner I'll post up, but look for real a BRZ "race weight" RIGHT HERE on the evening of March 24th.

Can't wait. A lot of people are interested in this.

Yea, suspension tuning isn't as glamorous as engine tuning, but what good is a lot of power if you cannot put it to the ground? There are very few forums that have excellent suspension tuning threads... luckily there are two suspension based companies that post here, but this is still a small forum. For additional in depth suspension theory discussion with a large number of at least semi-knowledgeable users go to http://forums.corner-carvers.com/index.php... just read the new user guide first.

At least here you won't get tossed off the forum for misspelled words.

Thanks,

I'll have to check that forum out. I try to keep my misspellings to a minimum.

[Fair!]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

The pictures, measurements and comments from my little BRZ post are spreading like wildfire... I've found them on over a dozen forums so far (and only put them on 5 of them). Crazy. Of course since I said a few negative things about the crap stock tires that come on these cars, I defaced a sacred cow, and have been tarred and feathered by many. But I'm used to that.

I got a call yesterday from a shop that is having an open house on March 24th (COBB Tuning Plano - shop expansion) and they will have a BRZ on hand that day. I am going to scale the sh!t out of that car that day - corner weigh it with and without a driver, weigh the trunk junk, note the fuel level, and pull a wheel and take some more measurements. I might even have some 17x9" wheels that could possibly fit the car on hand to test with.

So that's as soon as I can scale this car. March 24th. Three weeks. They might even be on some streets by then - who knows. If I can get my hands on one sooner I'll post up, but look for real a BRZ "race weight" RIGHT HERE on the evening of March 24th.

Ok. Focusing mostly on SCCA RAllyX and tuning my cars for street use, I deal with a lot more suspension travel. The word "moderation" figured heavily in what I've done so far. The tough part with suspension tuning is knowing where to draw the line. Not just in part selection, but the line between theory and real world. So it's instructional to see where you guys draw that line. Very cool.

I enjoy suspension tuning a lot more than engine tuning. So theory/real-world discussions are very interesting. Unfortunately, suspension talk just gets blank looks and awkward silences at car meets.

Yea, suspension tuning isn't as glamorous as engine tuning, but what good is a lot of power if you cannot put it to the ground? There are very few forums that have excellent suspension tuning threads... luckily there are two suspension based companies that post here, but this is still a small forum. For additional in depth suspension theory discussion with a large number of at least semi-knowledgeable users go to http://forums.corner-carvers.com/index.php... just read the new user guide first.

At least here you won't get tossed off the forum for misspelled words.

Thanks,

[Draco-REX]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Ok. Focusing mostly on SCCA RAllyX and tuning my cars for street use, I deal with a lot more suspension travel. The word "moderation" figured heavily in what I've done so far. The tough part with suspension tuning is knowing where to draw the line. Not just in part selection, but the line between theory and real world. So it's instructional to see where you guys draw that line. Very cool.

I enjoy suspension tuning a lot more than engine tuning. So theory/real-world discussions are very interesting. Unfortunately, suspension talk just gets blank looks and awkward silences at car meets.

[hancheyb]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Granted, in AutoX trim, the suspension will probably be so stiff that the changed geometry won't matter as much. But it seems to me that the sweet spot will be an inch or less of a drop.

That was my point. Camber plates just change your starting point of where you start your useable camber curve. They don't really give you "more to lose". The suspension is going to travel through its arc based on the pivot points of the arms and strut. The static camber added in a plate does not have a large effect on those arcs. It does move the strut, but that's not where the problem is. And in most setups you're talking about 1" of compression travel. No car is going to lose too much camber in any race condition.

Look at the hundreds of pictures Terry has taken at autocross events showing the reality of camber curves with cars loaded up in a corner. BMW, Mustang, Subaru, and Evo (all strut cars), all of them with 3-4* of static camber, none go past 0* loaded up. Most of those cars have more than 1" of compression travel too. More like 2.5" of compression travel. Look at all the BRZ videos and the front camber is positive in any loaded up picture or video.

Rate of change with regards to roll center is just a fact of life with a strut car. There's not a good one out there in OEM form. MotoIQ's analysis doesn't reveal any earth shattering news about strut cars. It is a simple fix. Don't let the control arm go past horizontal. And if you have to, add a bunch of camber and spring rate. We're dealing with cars never designed to be race cars. After all, Toyota has said many times this car is made with the aftermarket in mind. Meaning they built a good baseline. If you want it to act like a race car, you'll have to go the aftermarket to fix it.

The assumption should be if you lower any car for a perceived performance improvement (or looks), you're exceeding the parameters the manufacturer's design intent. Therefore you're going to have to fix just about everything, camber, toe change, roll center, etc. Or just lower it and go slower.

[Fair!]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Camber plates compensate by giving you more to lose. But they don't fix the rate of loss.

I'm interested in their conclusions about the toe changes through the front suspension's motion and the high rate of roll center drop.

Granted, in AutoX trim, the suspension will probably be so stiff that the changed geometry won't matter as much. But it seems to me that the sweet spot will be an inch or less of a drop.

These posts are more fodder for the battle between suspension theory and the reality of lap times.

These roll center changes, camber curve changes, etc are great for internet debates, and in a perfect textbook setting you would never lower the ride height in almost any car. But in the real world, when competition is at stake, lowering the Center of Gravity has such a dramatically positive effect on handling (and lap times) that its very often worth it in times to go beyond 1" of lowering. Everything on a racing car is a battle of compromises, and real track testing will prove what ride heights work and where there is a drop off in lap times when you go too far.

You will never see a race car at stock ride height, or anywhere near it, unless class rules dictate that for some unusual reason. If you could alter the pick-up points then you could compensate for the changes in camber curves/geometry from dramatic lowering, and many racing classes allow that... but many do not. For a 100% street car we do normally recommend staying within 1" - 2" of stock ride height, depending on the car model and factory geometry. Some cars are sensitive to bump steer and other adverse effects when lowered too far.

Don't worry - we're not a bunch of stance-tards trying to go for some artificial "slammed look". If it makes the car faster, we'll keep pushing the envelope until it slows the car down, then we'll back off. A bit of knowledge coupled with real testing always trumps internet theory.

Thanks,

[Draco-REX]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

It's no different than every other modern strut car out there. They all lose camber as they go beyond a horizontal control arm. Just like a Subaru (same suspension), you'll be limited on lowering it unless you can put roll center relocation kits on it. That or high spring rates to keep it from losing camber. Oh, and camber plates fix this too.

Camber plates compensate by giving you more to lose. But they don't fix the rate of loss.

I'm interested in their conclusions about the toe changes through the front suspension's motion and the high rate of roll center drop.

Granted, in AutoX trim, the suspension will probably be so stiff that the changed geometry won't matter as much. But it seems to me that the sweet spot will be an inch or less of a drop.

[hancheyb]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Very good to hear. I'll be keeping an eye out for it.


As far as dropping the car 2", what is your take on the motoiq conclusions about the stock geometry. It seems like lowering the car much will really mess with the car's handling at the upper limit.

http://www.motoiq.com/magazine_artic...cion-fr-s.aspx

It's no different than every other modern strut car out there. They all lose camber as they go beyond a horizontal control arm. Just like a Subaru (same suspension), you'll be limited on lowering it unless you can put roll center relocation kits on it. That or high spring rates to keep it from losing camber. Oh, and camber plates fix this too.

[Draco-REX]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Yep. We're planning on making a "real" set of full length headers and after-header exhaust routed more efficiently towards the back, around the transmission tunnel on both sides, with a proper Y-pipe. and a lightweight rear system with the muffler mounted inside the tunnel. The stock stuff routed pretty weirdly (turbo style across the front), so this could lose a good bit of weight and unleash some horsepower.

Everything we do is always very very weight conscious.

Very good to hear. I'll be keeping an eye out for it.


As far as dropping the car 2", what is your take on the motoiq conclusions about the stock geometry. It seems like lowering the car much will really mess with the car's handling at the upper limit.

http://www.motoiq.com/magazine_artic...cion-fr-s.aspx

[HIDGolf]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

16" spare is hopeful for cheap snow wheels/tires!

[Fair!]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Great review. Answered some questions I had. I'm very interested in the thought of an exhaust system made with weight loss in mind. I'll be looking to see if any meet these targets you guys have set. Hopefully the "lightweight" nature of the car will make people more mindful of the weight of mods.

Yep. We're planning on making a "real" set of full length headers and after-header exhaust routed more efficiently towards the back, around the transmission tunnel on both sides, with a proper Y-pipe. and a lightweight rear system with the muffler mounted inside the tunnel. The stock stuff routed pretty weirdly (turbo style across the front), so this could lose a good bit of weight and unleash some horsepower.

Everything we do is always very very weight conscious.

Thanks for the info guys! This is minutia, but does the BRZ have the roof rack attachment points like BMWs, Porsches and Subarus?

I've gone back and looked at my pictures... and yes, there are "side channels" on both sides of the roof panel structure, so it might be possible. I did not see the little flip out panels that are made for this purpose, like on the cars you mentioned.

Are you sure that's a full-size spare?

Hehehe... that was kind of a joke, knocking on the skinny nature of the stock wheel/tire (17x7" with 215/45/17 tires). The spare is actually a temporary unit, but not that much skinnier than the stock set-up. Its going to weigh a good deal, being a steel wheel. More trunk junk that gets removed track-side.

The spare is a 135/80/16 tire...

[HIDGolf]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Thanks for the info guys! This is minutia, but does the BRZ have the roof rack attachment points like BMWs, Porsches and Subarus?

Are you sure that's a full-size spare?

[Draco-REX]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Great review. Answered some questions I had. I'm very interested in the thought of an exhaust system made with weight loss in mind. I'll be looking to see if any meet these targets you guys have set. Hopefully the "lightweight" nature of the car will make people more mindful of the weight of mods.

[hancheyb]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

I think the dealerships are still hurting from the tsunami. They are looking at this car like a savior and instead of letting it "play out", they look like drooling wolves. One guy told me they had 9 already sold. Another said they will only see 15 this year. Terry was told he'd be the first to buy one.

Then one of them tells me they only sold FOUR new cars last July. FOUR? No, really. So you know they are hurting to get a sales boost and make up for all the money they lost last year. And they want to do it with ONE car, the BRZ.

My bet is the "15" number is just to get people to jump on it, the paint package is just profit to make up for last year, and the reality is these things will be all over the place in 6 months. Easier to keep that a secret when there's so little (dealer) information around it.

[Redwood]

Re: Subaru BRZ / Toyota FRS / FT86 Chassis Related Tech

Great preview! I am bummed that you guys couldn't weigh it (not as much as you guys, I'm sure). According to the brochure (attached) on the U.S. website, it has a "curb weight" of 2762lbs, but that is a "preliminary estimate" per the fine print. I don't know if that includes a full tank of gas or what. The stuff I read indicates the Premium has all-seasons and the Limited would get summer tires. If that is indeed a final spec U.S. model, they may have changed their minds. I just don't understand that thinking. Matt, if you get one, you have to get the blue pearl color. It's insane that they go on sale in a week and they don't know the price yet. Maybe they will announce in a week. What I have read on pricing is around $24K for the Premium and $27K for the Limited.