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Perrin sway bars 22mm or 25mm?


Pricci09

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i have 22mm in the front and 25mm in the rear with perrin reinforcement brackets. i love them car handles very well now with s/type springs. Took me about 2hrs or so to do both. Looks good and preforms very well for country backroads

 

 

Is it true that if u have a set up like yours (thicker in the rear, than in the front) that it will help with subarus terrible understeer?

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Subscribed. I was wondering the same thing. I am going to be buying some Perrin bars soon but haven't decided on diameter. I have also heard that theory that a thicker/stiffer rear bar would help with oversteer.
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Exactly, you want it to be neutral.

 

Or even neutral, with a tendancy to understeer at the limit.

 

Have you ever tried to recover from a turn you were taking too fast where the front end was just pushing? I'm talking one of those panic situations where you were driving home a bit too aggressively?

 

It is *typically* much easier to recover from an understeering situation than an oversteering one, for the average driver. This isn't a commentary on your driving skills, just a general observation.

 

I would recommend trying the 22mm rear bar first and maxing out the camber on your front wheels (-1.5 should be attainable). After a few thousand miles, post back here and let us know what you think. This approach tries to improve your front grip and addresses one of the weak points of the OEM suspension, the weak rear bar. You can always add other/stiffer bars later.

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Great info UD, and yes, that has happened to me and it's scary as shit! :lol:

 

So if i'm understanding you correctly, a thinner rear bar (22mm rear, 25mm front) would maintain the cars' tendency for the front end to plow before the rear would kick out?

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It is hard for me to talk in absolute about a product I haven't used, but yes, generally that is the case.

 

The reason we put a stiffer rear swaybar in is this: The car is front heavy which means the front wheels lose traction first when turning (understeer). By putting in a stiffer rear swaybar we can make the rear tires lose grip at roughly the same rate as the fronts. Really, you are just trying to counteract the front heavy nature of the car.

 

If you go too stiff, your rear tires will lose traction first, which can be really scary if you're not used to it. At this point you need a stiffer front swaybar to help your front tires lose traction as quickly as your rears. See a trend here? You are whittling away at your ultimate traction in favor of having less and less body roll. The ideal solution would be to increase your front traction to match the rear tires. This is where playing with camber, tire pressures, suspension damping, etc... will help. Now I can't imagine there are any easy way to cure the understeering nature of our cars strictly with the above tweaks, so a mild rear bar is probably still a good idea. Just be aware that it is taking away traction, not improving it.

 

Ideally you would want to change the weight distribution to improve the cars handling. Removing weight from the front would reduce overall weight and shift the F/R ration more towards 50/50 which is the ideal way to cure understeer.

 

For my setup I went with Whiteline adjustable bars. The front bar is 22mm and the rear is 20mm, I have them both on the soft setting. BTW, the "settings" are just two different mounting holes for the endlinks. One hole is closer to the axis of torsion, the other one is a bit further (maybe 1"). The hole that is closer creates a short lever arm on the bar, which means the bar will be more "effective", this is the stiff setting. Conversely, the further hole has a longer lever arm which makes the bar less "effective". Since each bar has two settings, there are 4 different combinations achievable. This setup is slightly only stiffer up front versus stock, but a vast improvement for the rear. The car still understeers a bit, so I am going to set the rear bar to stiff this summer, or try the Whiteline rear bar paired with the stock front bar.

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^What is your front camber?

 

If you've maxed it out, you could try LCA Bushings that give you more caster. Increased caster will improve your dynamic camber, which counteracts your tire turning over itself during a turn, and improves traction. This is preferable to getting camber/caster plates since they add so much NVH... the bushings do a dd a little bit of NVH mostly in the form of vibration. You can feel stuff through the floor/pedals but it's not awful.

 

LGT-NY's Perrin PSRS is probably much more intense since it's spherical bearings with no isolation at all.

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Um my suspension mods are.

 

The sway bars(22mm perrin front and rear)

a front tower brace bar

cobb sport springs.

 

My performance mods are

 

Header

up/downpipe

greaddy evo2 exhaust

(no cats)

cai

Turbo inlet hose

bov

protuned at 19psi

 

Im not a "car smart" kinda guy, i just have the need for speed.

 

I take it 2 the subaru dealer and have them align it.

 

You mention tire pressure as well, i have no clue what the psi of my tires should be i have the dunlops dirreza z1

 

Dont worry about preaching, i need 2 be preached 2, only way i will learn things

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Um my suspension mods are.

 

The sway bars(22mm perrin front and rear)

a front tower brace bar

cobb sport springs.

 

My performance mods are

 

Header

up/downpipe

greaddy evo2 exhaust

(no cats)

cai

Turbo inlet hose

bov

protuned at 19psi

 

Im not a "car smart" kinda guy, i just have the need for speed.

 

I take it 2 the subaru dealer and have them align it.

 

You mention tire pressure as well, i have no clue what the psi of my tires should be i have the dunlops dirreza z1

 

Dont worry about preaching, i need 2 be preached 2, only way i will learn things

 

Wow, that is a lot of car! I have to say I'm glad you have upgraded tires... There are too many people who will dump money into the suspension without addressing their tires.

 

Depending on your priorities, I would recommend you verify your alignment to be maxed out negative front camber (should be able to hit -1.5) but even on both sides. -1 degree camber in the rear (you can go more for better grip, but it's all about balancing front/rear grip, remember?). Zero toe all around. Tell the guy you want zero, not "close to zero"... you can change the behavior of the car by toeing in or out the front or rear wheels, but to get a baseline you should start with zero.

 

I use a Subaru dealership for my alignment, but I've established a good relationship with the tech and trust the quality of his work.

 

Set your tire pressures to the spec on your inner door-jamb. (I forget what the stock spec is) You can experiment with pressures to balance the handling (fine tuning, not drastic), but make sure you are measuring pressures when the tires are cold and with a good gauge. Bias the front tires a few PSI higher to reduce understeer. You can do the stock setting +2-3PSI in the front, or the stock setting -2-3PSI in the rear, or split the difference. Going too far over or under will hurt tire wear, gas mileage, and grip. Keep a notepad and record any impressions you get so you'll remember later on.

 

Doing these things will help you be aware of what is going on with your car in terms of performance and long-term maintenance (replacing tires).

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No worries man... I'm on mandatory 2-week shut-down from work, so coffee, *cough cough*, and LGT.com is my 9-5.

That's amazing! Where do you live again? MA?

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You said that i should put the tire psi at what it says in the door jam but,

 

Doesnt it matter more of what tires u have?

 

I ask this becuase before i got these dunlops i went threw a pair of gforce kdw2's, and i kept them at the psi of what the door jam said but i had extreme wear on the outside of my tires.

 

Thats the main reason i got these dunlops was becuase my cords were showing on the outside of the bfgoodrichs but had tons of tread in the middle.

 

ATM i have my dunlops at around 45/42 psi instead of the 35/32 psi i had before on the gforce, and the stock tires.

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Hey, if you are monitoring tire-wear and adjusting pressures based on that, more power to you. I am not going to tell you that 45PSI is wrong if you aren't wearing down the middle of the treads too fast, it was just a rule of thumb.

 

I have never run anything stickier than my Toyo T1-R's which are happy around 37PSI. Never used the BFG's but 32PSI does seem a bit low... How was the wear on the tires @ 35PSI?

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