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Old 09-13-2012, 09:48 PM   #29
SubieNate
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With the stock ride height, the lower control arms are pointing down from inside to outside, so when cornering, body rolls, then outside of your car sinks, then the lower control arm will push the low side of your wheel out, to automatically gain some negtive camber for your outside wheels, that's very good and useful.

But after lowered ride height too much, your lower control arms may be already level or even pointing up, so when cornering, the body roll will make the lower arm pull the low side of your wheel in, to gain some positive camber, that's bad! More worse is, when standstill, your negtive camber is too much yet, cause you have used that dynamic camber in advance by lowering, then you wants to reduce it, that's your current situation.

In short, don't reduce stock camber, if even the stock camber is too much for you, then you must have done something wrong.
Is this still true with a multilink setup? It's not a McPherson strut in the rear.

Nathan
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Old 09-13-2012, 10:59 PM   #30
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Is this still true with a multilink setup? It's not a McPherson strut in the rear.

Nathan
I believe it must be true. To my understanding, the major difference between McPherson and double-A is the top pivot point, upper arm bushing or strut top mount.
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Old 09-14-2012, 02:17 AM   #31
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@Borden - I am lowered on KW's and have taken it down farther than I like for this car. In doing so I've seen what the effects of lowering does to the camber on this vehicle as well as how it handles corners. I haven't aligned it just yet and am only guessing that the camber for the rears is verging on -3 based on visual appearance. I am going to bring it back up a bit to correct this to some degree but want to maintain about a 1.5" drop all around. This car has no camber adjustment built in, none. The only way to adjust and get the car where you want it is to buy something aftermarket. I originally posed the question because I was searching for information. You suggest in your post to know what it is you are doing before moding the car. That is why this thread was created was to explore the two options for my situation. I will not know exactly where the alignment specs should be for my driving until I try it out.

There are 2 options available. Camber Bushings or Adjustable Rear Control Arms. Camber Bushings will give me an advertised adjustment up to +/-.75 and stated by users to be more in the +/-.5 range. Control arms will give me a very wide range and are easily adjustable. If I go with bushings I may still need the arms to achieve an acceptable (to me) camber spec due to the narrow window of adjustment offered with bushings. If I go with arms I can adjust over a large range and if it changes the geometry too much I can add adjustable toe and swap trailing arms. An alignment will tell me if this is needed if the toe can't be corrected or things simply won't fit.

I am DDing this car until spring and at that time I will start putting it on the track. I may or may not turn it into a dedicated track car eventually but it will at least be out there on occasion. I want to set it up with -1.5 in the rear and -1.75 in the front as a starting point and see how it drives. To do this I will need camber plates up front to get to -1.75 and adjustable arms in the rear to be able to get back from the -3 I think I am at. Bushings wouldn't even get me back to -2.

I think there will be a lot of users on here who are looking for a great stance and still trying to achieve great performance. There is no boxed solution for this so we must ask questions, modify, adjust, and modify some more if necessary to achieve what we are looking for. With a new platform, trial and error is how we learn.
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Old 09-14-2012, 04:21 AM   #32
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@Borden - I am lowered on KW's and have taken it down farther than I like for this car. In doing so I've seen what the effects of lowering does to the camber on this vehicle as well as how it handles corners. I haven't aligned it just yet and am only guessing that the camber for the rears is verging on -3 based on visual appearance. I am going to bring it back up a bit to correct this to some degree but want to maintain about a 1.5" drop all around. This car has no camber adjustment built in, none. The only way to adjust and get the car where you want it is to buy something aftermarket. I originally posed the question because I was searching for information. You suggest in your post to know what it is you are doing before moding the car. That is why this thread was created was to explore the two options for my situation. I will not know exactly where the alignment specs should be for my driving until I try it out.

There are 2 options available. Camber Bushings or Adjustable Rear Control Arms. Camber Bushings will give me an advertised adjustment up to +/-.75 and stated by users to be more in the +/-.5 range. Control arms will give me a very wide range and are easily adjustable. If I go with bushings I may still need the arms to achieve an acceptable (to me) camber spec due to the narrow window of adjustment offered with bushings. If I go with arms I can adjust over a large range and if it changes the geometry too much I can add adjustable toe and swap trailing arms. An alignment will tell me if this is needed if the toe can't be corrected or things simply won't fit.

I am DDing this car until spring and at that time I will start putting it on the track. I may or may not turn it into a dedicated track car eventually but it will at least be out there on occasion. I want to set it up with -1.5 in the rear and -1.75 in the front as a starting point and see how it drives. To do this I will need camber plates up front to get to -1.75 and adjustable arms in the rear to be able to get back from the -3 I think I am at. Bushings wouldn't even get me back to -2.

I think there will be a lot of users on here who are looking for a great stance and still trying to achieve great performance. There is no boxed solution for this so we must ask questions, modify, adjust, and modify some more if necessary to achieve what we are looking for. With a new platform, trial and error is how we learn.
Wow, if there's any offence, I'm so sorry, I don't mean that

I'm from China, as you can see, my English is not good, so maybe there's some unintentional bad words in bad tone, don't mind In my place, this car haven't even release, and I'm waiting eagerly, cause I know it's a great one, I love it and have done many research about it, but never have my hand on

From my experience, the camber judged from bear eyes is very inaccurate, you may have an iphone lean again your wheel with a protractor app to get a rough number.

And stance and performance can not be both achieved with just camber adjust kit and coilovers if you going too low, you need roll center adjust kit to lower the ball joint of the lower control arm too, to raise the roll center. And in case of front wheels, that's better done with tie rod adjust kit too, or you will get crazy bumper steer.

Anyway, the suspension of FRS is very similar to WRX's, so basically I think there's not too much unknown mystery left, all we need to do is to learn from antecessors' experiences. I found motoIQ's "The Ultimate Guide to Suspension and Handling" and "A Tech Look Under the Scion FR-S!" are really great, I've read them all thoroughly and learn a lot about this car
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Old 09-14-2012, 04:27 AM   #33
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Again, I believe bringing your car up till getting a satisfied camber is a much better solution than camber bushings or adjustable control arms, you have more than 2 options, in fact
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Old 09-14-2012, 08:34 AM   #34
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True. That is another option but I don't want my car riding that high.
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Old 09-15-2012, 12:18 AM   #35
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I believe it must be true. To my understanding, the major difference between McPherson and double-A is the top pivot point, upper arm bushing or strut top mount.
McPherson don't have an upper arm. Just the lower and the strut. Double-A arms don't have camber change with compression unless they're unequal length a-arms.

Still wondering about multilink. Is it considered an unequal length type setup?

Nathan
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Old 09-15-2012, 12:54 AM   #36
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That's not true. If two equal length a-arms are non-parallel you will have camber change with travel.

But yes, you could consider the multi-link setup "unequal length," the camber changes pretty significantly with bump after all and that is the problem people are running into (which is nothing new for Subaru owners since the 08+ impreza has the same stuff).

Anyway, the problem is that the rear gains quite a bit of camber with compression and the front does not. So the car needs very little static rear camber while the front needs a lot, and when you lower the car the opposite happens. So yes, you need an arm or bushing or something to take camber out of the rear, and then you need a camber plate/bolt/offset top and roll center adjuster for the front to add camber. Ideal numbers would need to be determined with a tire temp gauge but starting at -2f/-1.5r is a pretty safe bet for street car.
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Old 09-15-2012, 04:16 AM   #37
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McPherson don't have an upper arm. Just the lower and the strut. Double-A arms don't have camber change with compression unless they're unequal length a-arms.

Still wondering about multilink. Is it considered an unequal length type setup?

Nathan
Yes equal length double-A won't get camber gain with compression, I think that's why normal mass production cars don't use that setup All we can see is unequal double A or McPherson in reality. I agree with @jamal, cause upper A arm has shorter motion radius than strut, so double-A setup has greater camber gain with compression.

I haven't had a fully understanding of multilink, it's too complicated and too many variants... But surely the rear setup of FRS can be considered as a double-A setup according to many experts' explanation.
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Old 09-15-2012, 12:22 PM   #38
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If I remember correctly, multi-link is a doubla A including a trailing arm that influences the geometry as things move. So really a modified double A.

I hadn't thought of non-parallel equal length.

Camber gain with compression isn't a bad thing right? Do people like equal length double A just because it feels consistent (I.E., no camber change with compression)? If McPherson is good enough for the 911 it's obvious it can be tuned to be very, very good.
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Old 09-15-2012, 12:59 PM   #39
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It was probably more just what they came up with to meet packaging and design requirements. The whole rear suspension is really low profile compared to the older Subaru rear strut setu[ so the rear floor is a lot flatter and wider. The old strut towers used to be up right behind the back seat at shoulder level (really long struts are good for rally), and now they are at floor level.

You could consider the rear suspension similar to an unequal length double a-arm because there is one upper a-arm and then a longer lca. Then in addition to the toe link there is a trailing link. I haven't really thought about it but I suppose this was for anti-squat or something. Here are some pretty good articles about the rear suspension:
http://www.iwsti.com/forums/gr-suspe...-i-travel.html
http://www.iwsti.com/forums/gr-suspe...bumpsteer.html

You definitely want camber gain with compression to compensate for body roll and tire flex in a corner. Like I said, the rear does a much better job than the front. The front suspension will only gain about half a degree from stock ride height and then go back to where it was at full bump. Essentially this means that for every degree of roll you need a degree of camber to keep the front tires happy and optimize grip, except that you need to be able to brake and want the tires to wear evenly. A stock car probably rolls around 5-6 degrees under max cornering.

So for a McPherson to work well you basically need a lot of caster and camber and a big swaybar.

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Old 09-16-2012, 02:00 AM   #40
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^ @jamal, thanks for that article. It's a good read and it seems to suggest dropping on coilovers and also that dropping negatively changes stock-dynamic camber/toe... so don't drop if wanting to maintain dynamic alignment / do a minimal drop?
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Old 09-17-2012, 05:15 PM   #41
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I'm not going for stock ride height.

Ended up picking up these for the time being. They allow 0-3 Degrees of camber either +/-. For the rear bolts you will need to take off about three threads from the inside to make the smooth potion of the shank match the width of the control arm.
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Old 09-19-2012, 09:33 PM   #42
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Which sti/wrx control arms are compatible with ours?
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