[Pearson II]

Interesting. Eddie said he couldn't get anything even close to that with his car in stock form. If I remember correctly. As far as dynamic camber I wish I could speak with some knowledge on that, but I'm not 100% on what that exactly is and how it is measured. Help on that topic would be great. Thanks for adding some good food for thought Digitalfiend.

[RdRacer301]

Yeah, I did the alignment about 2 wks I bought the car(MY05). IIRC, the front cambers were actually in the positive and the most I could get out of stock adjustment was -.8*~-.9*. Castor at even 4.5* or so.

[Digitalfiend]

Originally Posted by Pearson II

Interesting. Eddie said he couldn't get anything even close to that with his car in stock form. If I remember correctly. As far as dynamic camber I wish I could speak with some knowledge on that, but I'm not 100% on what that exactly is and how it is measured. Help on that topic would be great. Thanks for adding some good food for thought Digitalfiend.

I really don't think your castor is 1 deg. Perhaps the tech didn't setup the alignment sensors properly. You could always go back and get them to redo it or try another reputable place and see what they can get. My alignment was done on one of those Hunter racks (apparently a pretty good machine.)

As for camber, I've had my STi aligned three times over the course of 3 years and my camber has been pretty consistent between -.89 to -1.14.

[Pearson II]

Check out post #24

[Digitalfiend]

Originally Posted by Pearson II

Check out post #24

lmao. Sorry, by "reputable tech" I simply meant "another" reputable tech. I wasn't implying that your tech (in this case you) was a dufus. Different machines, calibrations, skills etc, can lead to different results.

Anyhow, keep us posted.

[Pearson II]

HAHA...I will try to get to my old shop and use their machine this comming weekend. In the mean time could you explain dynamic camber at all? That would be a great.

[homer09]

dynamic camber is the camber your wheel has as it travels up and down while cornering. static camber is the camber reading at rest (on the alignment rack).

as a car turns hard, the body rolls. this roll lowers the camber of the wheel relative to the ground. tires usually grip best at about -0.5 camber relative to the ground. so if your car rolls 3 degrees and your static camber is -1.5, you are now at +1.5 degrees and you are not exploiting your tires properly.

this is where dynamic camber comes in, the suspension can be designed so that as the wheel compresses or the steering is turned, more camber is added through the geometry. castor is one easy and simple way of doing this. the more castor you have, the more negative camber you get as you turn the steering wheel. this effect is especially noticeable on mercedes when they park. you can actually see the wheels incline quick a bit.

so castor is a good thing. and impreza need it badly because mcphaerson suspension do a bad job at adding dynamic camber.

[RdRacer301]

Originally Posted by homer09

dynamic camber is the camber your wheel has as it travels up and down while cornering. static camber is the camber reading at rest (on the alignment rack).

as a car turns hard, the body rolls. this roll lowers the camber of the wheel relative to the ground. tires usually grip best at about -0.5 camber relative to the ground. so if your car rolls 3 degrees and your static camber is -1.5, you are deep in the positive and you are not exploiting your tires properly.

this is where dynamic camber comes in, the suspension can be designed so that as the wheel compresses or the steering is turned, more camber is added through the geometry. castor is one easy and simple way of doing this. the more castor you have, the more negative camber you get as you turn the steering wheel. this effect is especially noticeable on mercedes when they park. you can actually see the wheels incline quick a bit.

so castor is a good thing. and impreza need it badly because mcphaerson suspension do a bad job at adding dynamic camber.

Makes so much sense. Thanks.

[Pearson II]

Great answer Very simple and to the point. Now we come back to why did SOA remove an a$$ load of caster from the 07's? Or is it that my rack at work is reading it wrong? I seriously dout that it is though. It's only 6 months old. I guess until I can get on another rack and check it or another person with a 07 gets their alignment done we'll just have to wait.

One more thing on caster. I know the more positive caster you have the harder a car is to turn. So, why is it that adding caster(like when you install an ALK) STi's turn in better? That doesn't make any sense to me. Can you please explain more on this topic?

[RdRacer301]

Originally Posted by Pearson II

Great answer Very simple and to the point. Now we come back to why did SOA remove an a$$ load of caster from the 07's? Or is it that my rack at work is reading it wrong? I seriously dout that it is though. It's only 6 months old. I guess until I can get on another rack and check it or another person with a 07 gets their alignment done we'll just have to wait.

One more thing on caster. I know the more positive caster you have the harder a car is to turn. So, why is it that adding caster(like when you install an ALK) STi's turn in better? That doesn't make any sense to me. Can you please explain more on this topic?

The purpose of adding castor with ALK is to prevent the car from "rocking" forward when you lift mid-corner, thus losing some traction in the rear... possibly inducing lift-oversteer... Basically, it reduces lift-oversteer... not so much better turn in.

[homer09]

Originally Posted by Pearson II

Great answer Very simple and to the point. Now we come back to why did SOA remove an a$$ load of caster from the 07's? Or is it that my rack at work is reading it wrong? I seriously dout that it is though. It's only 6 months old. I guess until I can get on another rack and check it or another person with a 07 gets their alignment done we'll just have to wait.

One more thing on caster. I know the more positive caster you have the harder a car is to turn. So, why is it that adding caster(like when you install an ALK) STi's turn in better? That doesn't make any sense to me. Can you please explain more on this topic?

it doesnt matter how new your rack is, if its not properly set up, it wont give the right results. im almost 100% sure that the reading you got is wrong. maybe have someone else double check your work, it's sometimes something overlooked.

adding caster influences turning in two ways: 1-better dynamic camber, 2-heavier feeling in the steering wheel, and more tendancy to recenter itself.

the dynamic camber advantage that more positive caster brings i already explained above.

for the weight, think of a shopping cart's front wheels. you know how they are not mounted with the vertical turning axis directly over the center? how they kind of dangle behind and follow the turns? well this is equivalent to negative castor (which for this component, reacts pretty much the same as positive castor). what the castor on a shopping cart allows is easier control and steering. the wheels follow the movements of the cart. if the wheels were mounted without the offset, they will not only roll, but also rotate round and round making the cart impossible to drive.

back to the car, castor tends to force the wheels to align with the direction the car is going. because of that, the steering feels heavier since more effort is required to fight the effect. most people like this because it gives you a more positive feedback of where the car wants to go, and inspires more confidence to the driver.

the downside, is the car will tend to track more. it will follow holes and ruts and be more "darty" especially over bumpy roads. this is what i guess subaru wanted to counter by dropping some castor off the new sti. BUT, i highly doubt they dropped 4-5 degrees off, that would bring it below the wrx's castor and probably almost any other car on the road. i think they dropped about 1 degree off the 07, to bring it level with the wrx.

oh, and if you are wondering why cars have postive and not negative castor, it's simply because of the dynamic camber. negative castor would have the opposite of the desired effect: it would REDUCE negative camber as you turn. positive camber is what you want because it increases negative camber as you turn.

[homer09]

Originally Posted by RdRacer301

The purpose of adding castor with ALK is to prevent the car from "rocking" forward when you lift mid-corner, thus losing some traction in the rear... possibly inducing lift-oversteer... Basically, it reduces lift-oversteer... not so much better turn in.

no i wouldnt agree with this. the ALK kit bypasses the anti-lift effects subaru designed into the suspension.

the end result of the alk is a SOFTER front suspension (without changing the springs). this means that it grips better over bumpy roads. the front wheels will remain in better contact with the ground. if you increase the front grip, you improve turn in and increase over steer. the downside is you will have MORE nose dive and lift with with the ALK, but this was measured by WL to be less than an 1" on the softer wrx springs. (should be even less on sti springs).

the other result is the added castor, its advantages explained above.

[Pearson II]

I know that I've read on more than one thread that it is also supposed to help with turn in mostly b/c it allows for more suspension travel.

[homer09]

Originally Posted by Pearson II

I know that I've read on more than one thread that it is also supposed to help with turn in mostly b/c it allows for more suspension travel.

yeah thats kinda right. its mostly because a softer front will allow the wheel to travel more easily over bumps and grip better.

but the alk in no way increases suspension travel. this is fixed by the spring/strut combo alone.

[Pearson II]

I think this thread should be added to the "Threads of Interest" sticky. We are covering many different areas in one thread.