Legacy understeering

[yapko]

Hi,

I'm thinking about some experiments with suspension of my 1993 Legacy GL. It's quite understeery so I suppose some stronger rear sway bar should help a bit. I wonder if Legacy turbo have different sway bars? Or could sway bar from another Subaru fit in? Thanks for any advices.

[Legacy777]

Yes the legacy turbo does have a bigger rear anti-sway bar, and does help balance out the car. I'd also recommend some KYB GR2 struts if you haven't replaced the struts.

[jamal]

I have a t-leg rsb when I originally had nothing and am pretty happy with the balance.

 

Something I've been hearing a lot of is that a bigger front bar is better. Increasing the front roll stiffness will actually improve the camber curve and provide better contact to the point where it more than cancels out the added weight transfer.

 

The problem is that the people who say this didn't just put on a front bar and nothing else. They've probably already done significant suspension modifications and don't really have a good baseline to relate to.

 

It's important to keep in mind that an awd inherently understeers under power and there isn't much you can do about it. Think of it this way: You have 4 wheels driving the car, and the front two have the additional task of steering it. Which end is going to lose traction first?

 

You can compensate by messing with relative roll stiffnesses, but an awd car that tends to oversteer is going to be very scary in transitions and under braking.

[firstwagon]

I've read about a number of people replacing the rear sway bar to balance the car more.

 

An 18 mm seems to be the popular choice for non racing use.

 

Some links I saved...

 

http://www.legacycentral.org/library/rear_sway.htm

 

http://www.pdm-racing.com/products/subaru_corner.html

 

http://www.legacycentral.org/library/literature/kevin_suspension.htm

 

http://bbs.legacycentral.org/viewtopic.php?t=2153

[yapko]

Thank you very much for your replys!

I'll see what can I do. And yea, I know that awd with 50/50 torque split will always understeer under the power, and its just nature of the car. but suspension of the car seems to me to be set to understeer too (as majority of ordinary road cars, i think), and thats what I want to change.

Thanks again.

[Setright]

WAIT!

 

 

All you need to do is get an alignment. The front end allows you to dial in some negative camber. You should be able to get at least -0.5 degrees. The difference over the factory spec 0.0 is phenomenal!

 

Did this to my Impreza - which doesn't even have a rear ARB - and understeer is a thing of the past. As long as you don't turn-in on full throttle. Just slowly squeeze the gas pedal once you're in the curve and the car will move toward very mild oversteer.

 

Try this cheap and simple mod first. Or, fit new struts then do the needed alignment.

 

 

ARB mods may become redunant.

[jamal]

I would suggest as much negative camber as you can get. I have -0.7 degrees up front with STi struts, and plan to drill out the bottom holes in the knuckles to run oem camber bolts top and bottom. Hopefully that will get me close to -2. Even with that much you don't have to worry about added tire wear (provided you go around corners with some regularity). There are more precise ways to determine how much negative camber you should have, but in the case of a Subaru having the stock bolts maxed out is a good start.

[Virrdog]

Something I've been hearing a lot of is that a bigger front bar is better. Increasing the front roll stiffness will actually improve the camber curve and provide better contact to the point where it more than cancels out the added weight transfer.

 

The problem is that the people who say this didn't just put on a front bar and nothing else. They've probably already done significant suspension modifications and don't really have a good baseline to relate to.

 

I put on a whiteline front sway bar with intentions of putting on my rear soon after. That didn't happen for a while and I loved the car with just a bigger front bar. It was a slight improvement with a rear bar set stiffer with solid endlinks. The front bar was night and day.

[jib]

I would suggest as much negative camber as you can get.

 

That's all well and good for turning more effectively, but how much does it accelerate wearing of the inner edge of the tread on a Subie?

 

jack

[jamal]

Having something like a degree of camber won't cause noticable tire wear on the inside edge, especially if you like to drive on twisty roads. From what I've heard, it doesn't become much of an issue until you have more than 2 degrees, and even then probably only if you do nothing but drive in a straight line.

 

I just checked my treadwear. With -0.7 up front and -1.5 rear the depth is even all the way across on all corners although the front outside blocks are a little more worn than the inside. Also I found out I should rotate my tires.

[Legacy777]

Yeah,

 

If you drive any bit agressively, you'll wear evenly. Even if not, you'd still probably be fine.

[jamal]

I went on a fun mountain road drive that lasted about 70 miles longer than I'd planned last weekend. The outsides of my front tires are not looking too good. I think I'm going to drill out the knuckles and run stock camber bolts in the bottom holes.