20mm 2.5GT front swaybar installed

[jamal]

Like a month ago I bought a front swaybar out of a 97 Legacy 2.5GT, which is 20mm compared to the 18mm bar on my 93 Legacy. It was only $50 and that 2mm makes a 53% increase in stiffness. That reduces body roll, and due to the tendancy of the Subaru's suspension to lose negative camber with enough compression, keeps the suspension in the sweet part of the camber curve and increases grip.

Oooh, ahhh:



Being from a newer Legacy, I had to buy new bushings to fit it to my car. The 2nd gen Legacy has a slightly different front crossmember which has bigger swaybar mounting brackets. I called up Racecomp Engineering and they said they cound get me some whiteline bushings. I ordered all four for the hell of it. After a week of not hearing from them after they took my information and credit card number, I called them up to see what the deal was. They were like "oh, sorry, I think there's something wrong with our system and it didn't automatically send you an invoice, but they should get there today or tomorrow." And when I got home I had a sweet package:



Here are the 1st gen bushings compared to 2nd gen:



They were something like $38 shipped and I didn't have to wait for them to come from Australia. Also a sweet sticker was included that will go in the drawer with all my other stickers.

To clean up the swaybar I bought some sandpaper, rags, underbody coating, and steel wool:



I found some bbq cleaner downstairs which did a great job cleaning off all the grime.

Here is my new bar before and after mostly being cleaned and sanded:





The new bushings fit like a charm:



The rubberized underbody coating turned out fairly well:



Goddamn was the bar a pain in the ass to get out. I ended up having to drop one side of the exhaust manifold to fit it past the powersteering lines. On the plus side all the flange bolts came out without a problem which is good because I'm planning on getting a new exhaust in the near future.

Looks like it will fit:



it doesn't look much bigger but it is.

Then it was simply a matter of snaking it back through betweein the exhaust manifold and power steering lines, greasing up the bushings, and bolting everything down. The swaybar will not go in and out without removing a wheel.





Then I replaced the rear bushings on my 18mm Legacy turbo bar, which took a wrench and all of five minutes:





Notice the sweet Kartboy endlinks.

Now I've taken quite a bit of compliance out of the suspension, installed bigger swaybars, STi struts and springs, and have quite a bit of camber (-2deg f -1.5deg rear) thanks to drilling out the bottom front holes to run two sets of oem bolts. Next up is probably the exhaust and I'd like to eventually replace the control arm and lateral link bushings with polyurethane. Also I should ditch the RE92s for a real summer tire but that will wait until after ski season.

I think I will go driving in the mountains later to see how it feels. Hooray for the angeles crest highway being only 15 minutes away.

[jamal]

Trip Report:
I took a quick drive up the angeles crest to upper big tijunga and then back down. Upper Big Tijunga is becoming one of my favourite roads.

Flatter cornering? Check.
Quicker turn in? Check.
More responsive? Check.

Am I completely happy? Not sure.

A swaybar is twice as effective at increasing roll stiffness as springs. So basically I can relate this to trading my 225lb/in front springs for 450lb/in springs while keeping the 194 lb-in rear springs and 18mm front and rear bars, but without the increase in ride harshness. So, not quite an optimum balace anymore and it's more understeery. I've heard a lot of good things about putting on a bigger front bar from nasioc forums, but I'm starting to think equal sized bars is best. In conclusion, I just took my very well balanced car and messed it all up. Looks like I need a new rear swaybar.

I love how much flatter it is though. I'd much rather upsize the rear than put the 18mm bar back on. As much as I'd like whiteline 22mm front and 20-24 rear bars, I don't really want to go spend $400. Hmm... maybe I should see exactly what it takes to make an Impreza bar fit. A 20mm WRX rear bar can be had on the cheap.

[Legacy777]

Yeah,

That's what I have the whiteline bars....and it's pretty neutral handling, but can be made to over or understeer depending on how you drive it.

[Subtle]

Front and rear bars ++

[jamal]

Actually I think the next thing I want are new seats. I really get tossed around in mine. There are usually a few sets of RS seats for sale locally on nasioc.

[Legacy777]

That's really the thing I need to fix. My seats sucks monkey nuts.

I just picked up a set of WRX seats for the OBS due to old ones sucking so much. I may play around with the WRX seats in the Legacy at some point and time.....

[ultrasonic]

A swaybar is twice as effective at increasing roll stiffness as springs. So basically I can relate this to trading my 225lb/in front springs for 450lb/in springs while keeping the 194 lb-in rear springs and 18mm front and rear bars, but without the increase in ride harshness.

Not sure what you base the "twice as effective" concept on. Do you have a reference for this? When left and right are equally loaded, the sway bar does not matter, of course. So you'd only have the increased effective spring rate when turning or something.

So, not quite an optimum balace anymore and it's more understeery.
...
I love how much flatter it is though. I'd much rather upsize the rear than put the 18mm bar back on.

I agree, to an extent. Personally, I loved the addition of the 20mm front, even with the stock 18mm rear. Less roll and more grip is worth a little change in driving style to take advantage of it. Of course adding the 18-22mm adjustable rear bar made it even better. Right now, with the STi struts and springs, it makes for a very neutral set up- very balanced in steady state turns with essentially no throttle induced rotation. Smooth and forgiving.

I would add more front before adding more rear bar. Even though more rear bar biases towards the oversteer that feels good, more front bar would create more overall grip.

Cliff's Notes:
Agree with jamal = Increase both front and rear bars, go for balance.
Disagree with jamal = I'll take all the front bar you can give me!

[jamal]

Not sure what you base the "twice as effective" concept on. Do you have a reference for this? When left and right are equally loaded, the sway bar does not matter, of course. So you'd only have the increased effective spring rate when turning or something.

I guess I worded it kind of funny, but what I mean is that a swaybar is twice as effective at resisting roll than the springs because it acts on both sides of the suspension. I was just using that to describe what putting on a bigger bar does to the roll stiffness.

A 50% increase in swaybar stiffness does pretty much the same thing to your roll stiffness as doubling the spring rates. So basically I have the same front roll stiffness as a car with 450lb springs and an 18mm bar.

I read that somewhere anyway. Possibly in How to Make Your Car Handle by Fred Puhn or on nasioc somewhere.

It has to do with the geometry and suspension mounting points but I remember it being around 2:1 for our cars at least

[scottzg]

I would add more front before adding more rear bar. Even though more rear bar biases towards the oversteer that feels good, more front bar would create more overall grip.

eh? oversteer happens when the rear end runs out of grip, understeer happens when the front end runs out.

[ultrasonic]

I would add more front before adding more rear bar. Even though more rear bar biases towards the oversteer that feels good, more front bar would create more overall grip.

eh? oversteer happens when the rear end runs out of grip, understeer happens when the front end runs out.

Yes, but more front bar increases overall grip because it maintains better contact patch in turns. It's all due to the fairly lousy camber curves inherent in the front suspension. True, there may be more tendency towards understeer at the limit, but because there is more overall grip that limit is higher.

Also, under/oversteer is not ONLY present when one end or the other "runs out of grip." The slip angle (I think that's the proper term, I'm not an expert) changes even as you are approaching the loss of grip. That's the reason you can feel the effects of sway bar changes even though you are not literally skidding the tires sideways.

Again, I'm not an expert, but I have tried to read enough to understand why my vehicles behave they way they do in reaction to the changes I have made.

There is a reasonable explanation here:

http://forums.nasioc.com/forums/showthread.php?t=920405

but there is another thread at NASIOC that goes into more detail. I just don't have the time to find it right now.

Another significat advantage to increasing your front sway bar is that you can even out the front tire wear. As our suspension compresses, the camber changes towards the positive, i.e. the top of the wheels leans out. Most people who drive somewhat agressively get increased outside edge wear. The stiffer front bar maintains better contact patch in cornering, thereby putting less wear on the outside edge of the tread, which equates to longer tire life. Plenty of negative camber in the front helps also.

[scottzg]

True, there may be more tendency towards understeer at the limit, but because there is more overall grip that limit is higher....

your evidence is contrary to your conclusion.

All that other stuff you regurgitated is only true in a steady state turn on a perfectly smooth surface with no throttle or steering imputs. Not even NASCAR cars experience that.

[jamal]

Yes, but more front bar increases overall grip because it maintains better contact patch in turns. It's all due to the fairly lousy camber curves inherent in the front suspension. True, there may be more tendency towards understeer at the limit, but because there is more overall grip that limit is higher.

I suppose it is kind of contradicting to say that you have more grip but also more understeer.

Like I said, it would be nice to compare them on a skidpad or slalom, but Dr. Biggly seems to make sense, and I do feel like I'm getting more grip out of the RE92s than I ever have.

Also, the camber curve isn't as horrible as people make it out to be. For the first ~two inches of stock travel, camber increases by about half a degree, for then next to it goes out about half a degree.

Camber is basically the same under full compression as it is at stock ride height, of course you've got a boatload of body roll to go along with it.

no that's wrong

so then how does it work?

[Adam West]

This is the greatest link for freaking ever!


http://forums.nasioc.com/forums/showthread.php?t=920405

Thanks!!!!

++for large 20 in front and 20-24 adjustable (set to 24 in back)...

There's a road test of it on the Whiteline site - not scientific but a fun read regardless.

http://www.whiteline.com.au/articles/AS ... ails_1.pdf

Work backwards to read the rest of this article on the site. Cheers!

[jamal]

Here's a good one too:

http://forums.nasioc.com/forums/showthr ... ?t=1152714

And this post:
http://forums.nasioc.com/forums/showpos ... ostcount=4

Oh and I'm picking up some RS seats Saturday.

[ultrasonic]

True, there may be more tendency towards understeer at the limit, but because there is more overall grip that limit is higher....

your evidence is contrary to your conclusion.

Maybe I'm not communicating very effectively. I beg your forgiveness. It certainly reads the way I intended it. I hope the misunderstanding isn't on the part of the reader.

All that other stuff you regurgitated is only true in a steady state turn on a perfectly smooth surface with no throttle or steering imputs. Not even NASCAR cars experience that.

Scott, the way you use the term "regurgitated" here sounds petty and condescending. I have thought better of you up til now.

By the way, have you made the specific change that I'm talking about? Have you changed to a heavier front sway bar on a Subaru and driven it before and after the change? I did, I felt the difference, then searched to find concepts that explain what I percieve first hand. I put a stiffer front bar on my car, along with the stock rear bar, and I percieved an increase in cornering grip. So have many others.

If your experiences run to the contrary, please state the circumstances. I'm sure we would all love to learn.

[ultrasonic]

Also, the camber curve isn't as horrible as people make it out to be. For the first ~two inches of stock travel, camber increases by about half a degree, for then next to it goes out about half a degree.

Camber is basically the same under full compression as it is at stock ride height, of course you've got a boatload of body roll to go along with it.

Yes, and the body roll is where the camber goes away, isn't it?

Take static camber (say -1.5 degrees) then give away a half degree because of suspension compression. So far so good. But then look at the amount of body roll on a stock sway bar. Another 2 degrees of camber given away to body roll? More? I don't know exactly, but I'm pretty sure it puts you into positive camber which makes for understeer and outside edge tire wear.

I think this is the thread I was looking for previously:

http://forums.nasioc.com/forums/showthread.php?t=879235

[scottzg]

ultra, you dont seem to understand that if the car is tending to understeer more, that means you've reduced grip at the front end relative to the rear. It the most fundamental concept in suspension tuning. That's all ive said this whole thread.

[ultrasonic]

ultra, you dont seem to understand that if the car is tending to understeer more, that means you've reduced grip at the front end relative to the rear. It the most fundamental concept in suspension tuning. That's all ive said this whole thread.

The balance of the car may have shifted towards understeer at the limit. But, the overall grip of the car has increased, and that limit is significantly higher.

Yeah, it's counterintuitive, I know. I thought the same thing until I discussed it with some local autocrossers (the most experienced suspension guys that I know of), and read some of those links I regurgitated above. Now I understand it, and I take advantage of it every time I drive.

In any event, props to jamal for taking the initiative to fit the '97 front bar, and for the excellent write up with photos. I hope readers are able to get some value out of this thread, even with the distractions.

[jamal]

In any event, props to jamal for taking the initiative to fit the '97 front bar, and for the excellent write up with photos. I hope readers are able to get some value out of this thread, even with the distractions.

Aww you are so sweet.
I don't think they're really distractions, more of good discussion relating to the mod. Much better than just the write up.

And understeer is definitely more pronounced in the rain, where the grip is less and I guess the weight transfer overrides the roll. I'm very tempted to pick up the 20mm wrx bar for sale locally. I'm pretty sure I can make it fit with creative use of a jack to the spare tire well...

But wow does this car change direction in a hurry. I cranked it over hard through a transition and was amazed with how it just immediately changed directions and stayed settled.

+abillionty for solid endlinks and p/u bushings. I want to do the lateral links and control arms now. But damn will that be a pain in the ass.


EDIT: I got an open run around the onramp on the way to work, and can't go any faster than I could before. Looks like I don't have quite enough tire to see the full benefits.

Solution: I'm thinking stickier tires.