A Technical Look Under the Scion FR-S! Chassis,Brakes,Suspension, Differential

[import_nation]

A Tech Look Under the Scion FR-S!
By Mike Kojima

Recently the Scion FR-S or Toyota 86/Subaru BRZ has been officially unveiled to the motoring public. Most of the stuff about the car on the web has been pretty pictures and cool videos of Ken Gushi sliding around in the rain. Now that the first close to production Scion FR-S’s have been officially rolled out and press embargos have been lifted we will give you a technical look at the car's underpinnings with some engineering commentary.

The FR-S suspension is conventional MacPherson strut. The Greddy car had a prototype set of Greddy coilovers. The only adjustment in the front alignment is the toe which is typical. No provision for camber or caster adjustment is present on the stock car, at least this stock prototype! The front suspension has a good amount of caster, king pin inclination and trail which is good for camber gain under cornering, straight line stability, good on center feel and good self aligning torque with minimal scrub. These aspects of the front end geometry are reminiscent of the Nissan S Chassis and older BMW's, good things.

You are probably dying to know more about the chassis and suspension. Is the car the real deal or is it marketeering hype riding on the DNA of the old AE86. Is it or isn’t it? Well let’s go and take a look. The car we got to see carefully is the black street car built by Greddy which was on display at the official Scion reveal a few weeks ago.

The prototype coilovers may have little droop travel as the car was not lowered much but the position of the lower control arm and ball joint indicated a pretty low front roll center, at least with these particular coilovers. The front control arm was perpendicular to the ground under full droop. This means that the roll center when plotted will most likely be under ground . Implications of this are a high roll couple and lack of negative camber gain under roll. This means that the car will need stiff front springs and or anti sway bars and a lot of static negative camber when lowered or the car will tend to lose front grip at the limit, at least when lowered significantly. A lowered FR-S is going to benefit from extended stud ball joints and tie rod ends like those that Whiteline sells for the EVO and WRX.

At the event our freelancer John N. Frink and Annie Sam got a fleeting view of the undersides of the car and managed to snap a few pictures. A few days later we managed to look at the underneath of the Greddy car while picking up some stuff for Project EVO X. Since the car is no longer a secret and the specs have been released, the nice folks at Greddy let us take some pictures of the underside.

The tie rod is out of plane from the lower control am and the inner tie rod joint is out of line from the pivot. It looks like the FR-S will toe in under dive and roll which is good for stability but not necessarily the best for steering response. The Nissan S chassis for instance has a close to ideal steering rack and tie rod location for little bump steer. The FR-S's location is more indicative of stability under braking.

[import_nation]

Over the last 87 weeks, the slow, agonizing reveal of the Toyota FT-86 (show car)/Toyota 86 (JDM production model)/Toyota GT 86 (Europe)/Scion FR-S (U.S.)/Subaru BRZ (everywhere) has been dribbling a Chinese water torture of information on us. Today's drop, the official U.S. unveiling of the Scion FR-S version, revealed almost no new information. The only true surprise was the fact that we don't have to order the trick 86 boxer badge (above) from Japan. The FR-S will wear the badge even here.
We did get closer to the car than ever before, though, and we've learned a few things about the innards over the last few days, so here's the full MotoIQ brain dump:

First of all, it's the right size. Just a hair bigger than a Miata, but with more space inside. So stop comparing it to that behemoth from Hyundai!
Second, it's reasonably close to the right weight. Japanese versions are supposedly 2689 pounds, but the Japanese tend to weigh their cars dry, offer more stripped-to-the-bone versions (like no stereo, no A/C), and have lighter bumpers and door beams. All indications are that U.S. models will be about 100 pounds heavier.
Third, it was developed with the right attitude. Chief Engineer Tetsuya Tada was quoted saying
“There is a Toyota standard for designing new cars. This standard was to a large extent ignored. Why did we do this? There are cars that are accepted by a lot of people. Practical cars that are easy to drive and that do not break easily. These are standard Toyota cars. The 86 is not a car like that. We had to change our design approach for this car. We may have to do this again for other cars.
It is impossible to develop a sports car that appeals to everybody. If you try to please everybody, the car would be half-baked for everybody, and not particularly good for anybody. This car is not developed by a committee, or by consensus.”
Do yourself a favor and go read the rest of that story at The Truth About Cars. We'll still be here when you're done...

Under the hood we know some interesting things.
1: There is no engine cover. You can see the engine when you open the hood! This Tada guy obviously gets it.
2: The engine is a unique mish-mash of Subaru and Toyota technology. The bottom (middle?) end is supposedly based on the new FB20, but the square 86 x 86mm bore and stroke (the standard FB is undersquare) calls that little factoid into question. When Toyota wants to make horsepower, they pick up their red phone and call Yamaha. Yamaha did the 2ZZGE head, the 3SGTE head, and if you go back far enough, they even did the engine in the 2000GT. Word is Yamaha is responsible for the heads on this one too.
Toyota's bizarrely complex but very effective direct and port injection system is in place, with fuel delivery split between two parallel sets of injectors, one in the intake ports and one in the cylinders.
Those Yamaha heads and direct injection are apparently pretty damn knock resistant. Compression is 12.5:1
You already know this, but just for the record, Scion is saying 200 hp at 7000 rpm, 151 lb-ft of torque at 6600 rpm, and redline is 7400 rpm. Those numbers are all very slightly different than we've seen before, but are close enough not to matter.
Other things we can tell from this picture of the engine bay:
The big hose teeing off the intake looks like it's piping sound to the interior. This is a relatively common thing these days. When the intake is placed way up in cold-air land forward of the radiator, the only way to get good intake honkus sounds to the guy making the payments is to pipe the sound in through a membrane (kinda like a rugged speaker cone with no driver) that lets sound pass through without letting unfiltered air slip by. Miatas use these, Mustangs use these, and they're quite common in Europe where drive-by noise regulations make it nearly impossible for a car to sound good without one.
The lack of a power steering pump indicates electric power steering. The fact that it's nearly 2012 also indicates electric power steering. Hope it doesn't suck.
There will never be an all-wheel-drive version. Never.
How can we tell? The front diff needs to be roughly in line with the front wheel centerline, and with a Subaru layout, the front diff sits behind the clutch. In this car, the middle of the engine sits on the front wheel centerline. The engine would have to move forward nearly a foot to make all-wheel drive possible, and that's just not going to happen.
And that's fine with us. The weight distribution is already 53/47. We don't need it any more front heavy.

We were planning to bring you fresh information on the exhaust manifold layout (will the primaries be paired Subaru-style for that off-beat sound, or will they be properly paired for good breathing?) and subframe clearance for future turbo models, but this undercover foiled that plan. At least the car will be slippery.

UPDATE: Tip of the hat to MotoIQ Nerd @Jamal, who pointed us to Hellafunctional, who stole this image from someone over at FT86Clubwho snapped this shot in the Subaru booth at the Tokyo Motor Show a few days ago. Looks like the engine uses a proper 4-2-1 header, which means it will sound like a proper 4-cylinder, not like a WRX. Love that fact or hate it (I'm on the fence) this manifold is surely a large part of why this engine is capable of 100 hp per liter.

MORE UPDATES: Jay Kavanagh over at InsideLine.com posted these pictures of the Subaru 1.6 turbo sitting right next to the BRZ/86/FT-S engine. Though there are no claims this will go in the 86, it doens't take much imagination to see it being done, either by them or by us. This turbo packaging is very friendly for the 86's FR layout, since there will be tons of room in front for a bigger turbo. This packaging makes a twin-scroll a no-brainer, since you could essentially have the same manifold as the non-turbo engine, but with a turbo flange right after the 4-2 collectors. It would also be much easier to simply put the intercooler in front, where it belongs, and connect to the already forward-facing throttle body.
It's not clear how Subaru is dealing with oil drainage, since the turbo's oil drain is down below the oil line in the pan, but the fact that Subaru already worked it out for us makes it much easier when we turbocharge one of these ourselves.
The dual direct/port injection system now makes perfect sense. It's easier for tuners to leave the direct injectors alone and add bigger port injectors for boosted fueling.

5

There doesn't appear to be any camber adjustment in the MacPherson strut front suspension. The top mounts (visible in the engine shot) look suspiciously like Impreza top mounts. That's just fine, since Impreza mounts are indestructible, but there's no adjustment there.
Down here, the lower control arm is an L-arm, with the steering rack in the back and the L part of the arm pointing forward. If there was going to be camber adjustment down here, it would be on that lower control arm bushing just below the steering arm. No such luck.

The arm itself is a simple steel arm. It's a single stamping that should be lightweight, cheap, and easy to bend if you try to do traditional Subaru things with it.

The last chance for camber adjustment would be here, at the strut mount. There should be an eccentric on one of those bolts, but again, no luck.

The front calipers are two-piston sliders. These look a lot like Impreza calipers to us, which would mean there's already a huge array of performance pads available for the 86 before it ever hits the showroom. Assuming they were nice enough to carry over mounting points, there will be brake upgrades galore as well.

The multilink rear suspension does appear to be from an Impreza, as suspected. Long lower control arms look the same. Forged steel upper A-arm looks the same. Stamped steel trailing arm looks the same. The differential in an Impreza, though, is a Hitachi R160. Subaru has been using versions of this diff since the '80s, and Nissan started using it back in 1967 (when they built the first 1968 510s). This is not an R160, though.
Imprezas only put 50% of their power to the back, so a diff ready to handle 200 hp would be on a 400 hp Impreza. Sadly, Subaru doesn't make such a thing. When they make a 300-hp Impreza, though, they use an R180 (Same diff Nissan used in 1969 on the 1970 240Z). This is also not an R180...

If anyone recognizes this diff, shout it out. We've never seen it before and fear it might be new. Carryover diffs are always good, since they mean abundant selection of gear ratios and limited slips.
UPDATE: Thanks to @AKADriver for pointing us in an IS direction for the diff. This IS300 diff looks like the same one. That's all good news. Lots of ratios available, lots of different LSDs, plus word is the FR-S will come with an LSD of some sort from the factory anyway.


Finally, wheels and tires are mixed news.
The wheels appear to be 17x7.5, and the bolt pattern is, sadly, Subaru's standard 5x100. There has been rampant speculation on this subject in the last few days, but I got on my knees and measured. This bolt patern severely limits wheel selection, which is a damn shame.
The 215/45-17 tire size is actually good news. 225/45-17s will slap right on, and that's a well supported size, with lots of performance tires available. The factory tire is a Michelin Primacy HP. No idea how bad that is. Factory tires are always engineered to the manufacturer's specs, so even if you've had experience with a tire that claims to be a Primacy HP, it's unlikely to be the same tire. The 240 treadwear rating is the only hint we have.
Other than the fact that it actually looks better in person and that we all want one now, that's all the info we have on the 86. There are a few more shots being processed and uploaded, so we'll update this page as soon as we have them.
Expect the car to go on sale in March or April.

[modelo420]

It goes on sale March or April....thats alll I got from this post...lol. I loved the post, good info in it...but as soon as I saw the sale dates...I forgot everything I just read:P

[cfrp]

The underside is pretty well covered. Is it just me or do those lower control arms look pretty flimsy..