Questions about suspension geometry improvements

[M3n2c3]

So I've been researching more suspension bits that I can't really afford. . .

This will be a bit of a read, but please bear with me.

Preface: I want to improve handling for daily driving and the occasional autocross (I'll be running RNP so rulebook legality is not really a concern at this point). I had coilovers for a while, and replaced them with Prodrive springs that I intend to keep on the car. Given that there are so few options available for strut upgrades, I will most likely continue to run on stock struts until one or more go bad and I am forced to replace them. I have "upgraded" the RSB with a stock 17mm WRX bar, and may or may not decide to move up to 20mm depending on various factors, one of them being the results of this thread. I'm also running the following alignment: -1.3f, -0.8r (and no toe iirc).

My reluctance to screw with sway bars stems partly from my own experience with them and partly from observing a thread regarding Scott's sway bar troubles and the idea that they are simply a suspension "band-aid," i.e. a cheap, moderately effective but double-edged suspension option when considered versus all the other aspects available for improvement.

So here's what I want to do: I am comfortable with the ride quality, body roll, and overall balance of the car in terms of spirited driving and hard cornering. I want to increase steering response and turn-in without really adding any more stiffness and without reducing roll at the cost of impairing suspension travel (hence my reluctance to go with stiffer sway bars). I don't want to get the back end out - I want to get the front in more without really sacrificing rear-end grip.

I've seen and researched a couple of bits available that really interest me.

The first is Whiteline's anti-lift kit (also called a caster kit or positive steering response kit by some manufacturers). Given that I am on softer suspension, I like the idea behind this: adding positive caster to improve dynamic camber, and reducing front end lift by altering the control arm geometry. Whiteline also offers these with a "comfort" bushing that would serve to minimize NVH increases. Color me "Tickled Pink."

The second is the relatively new front roll-center adjustment kit. There was a thread about this a while back, but it died off before Whiteline released their kit. Fortunately, there's a huge amount of feedback on a thread on NASIOC, and the response seems to be incredibly positive. Most folk who have installed this on their car say that the change to the suspension geometry (lowering the attachment points of the control arms and tierods to a more optimal position on a lowered car) has resulted in a near-complete loss of the usual turn-in understeer, improved mid-corner control, and far less scrubbing overall. Apparently their tester "complained" about having to adjust his driving style - he was used to having to compensate for the usual turn-in push and kept hitting the inside rumble strip early with the kit on due to the improved grip.

A combination of these two kits sounds like a great idea to me: no great increase in NVH, no "swaybar-esque" loss of suspension travel, no loss of rear-end grip, and much improved turn-in.

The price is also fair: $400 for the combo (~$225 for the ALK and ~$175 for the roll-center adjustment kit) versus ~$500-$600 for a full swaybar upgrade (front, rear, mounts, and endlinks).

Thoughts?

[Dean]

Sway bars are not a nightmare, and definitely not a band aid. They perform a very specific function, control body roll/transfer weight side to side. There are those who will start a religious war of sway bars vs. springs, but most sane folks realize they both can and should be used in appropriate amounts.

Sue just put a set of COBB hollow bars on her otherwise stock suspension WRX wagon and really likes the reduced roll.

ALK = good...

WL roll-center adjust is a big ??? The 6 Gun Racing one is probably much better, but 2.5X the price.

[MikeK]

Originally Posted by Dean

The 6 Gun Racing one is probably much better, but 2.5X the price.

I thought they had a lot of failures. Has the design been changed to address this?

[Dean]

Originally Posted by MikeK

I thought they had a lot of failures. Has the design been changed to address this?

Yes

[M3n2c3]

Originally Posted by Dean

Sway bars are not a nightmare, and definitely not a band aid. They perform a very specific function, control body roll/transfer weight side to side. There are those who will start a religious war of sway bars vs. springs, but most sane folks realize they both can and should be used in appropriate amounts.

I'm not saying they're are bad, just that upgrading excessively can do more harm than help, and that there are other options available that may be more appropriate. I'm pretty sure I phrased my thoughts on them effectively. Again,

Originally Posted by me

My reluctance to screw with sway bars stems partly from my own experience with them and partly from observing a thread regarding Scott's sway bar troubles and the idea that they are simply a suspension "band-aid," i.e. a cheap, moderately effective but double-edged suspension option when considered versus all the other aspects available for improvement.

As far as the "band-aid" thing goes, it was a quote from that thread, used in reference to the fact that too many people mistakenly want to view it as a quick-n-easy suspension upgrade that will magically cure your understeer. See the RS25.com forums for many examples.

My key thought is that having upgraded to a moderate sway bar size, and given that I want to improve turn-in without the effects of an increase in swaybar diameter, there are now upgrades that I view as being more effective rather than simply saying, [get'erdone voice]"still too much understeer? Slap a bigger sway bar on there!"[/voice]

And the 6gun kit is waaaaay out of my price range. There's a reason I have an RS and not an STi.

[Kevin M]

J, I would recommend to you a mild sway bar upgrade. 20mm rear and ~22mm front with poly-bush endlinks like Whiteline would not require swapping the rear mounts and would make a noticeable difference in improved handling and steering feel. Really, this should be your next step since coilovers are out of the question. Sway bars get negative rep because people who are building dedicated track cars are generally better served with stiff springs than the compromise of moderate springs and large, stiff bars. But for your street driven car, it's the ideal solution.

ALK works wonders, but wave goodbye to any thoughts of ever being class competitive, since you're now in F Modified (however, that's an empty class so maybe it would help ). Get the comfort version and it will be an improvement without a massive increase in harshness, though you will be able to notice it.

The Whiteline balljoint kit is pretty new, and I'm tempted to grab one for my own FSP car. The 6Gun kit is way overpriced for a street car, and not a tremendous bargain for race cars either, really.

[M3n2c3]

Originally Posted by BAN SUVS

J, I would recommend to you a mild sway bar upgrade. 20mm rear and ~22mm front with poly-bush endlinks like Whiteline would not require swapping the rear mounts and would make a noticeable difference in improved handling and steering feel. Really, this should be your next step since coilovers are out of the question. Sway bars get negative rep because people who are building dedicated track cars are generally better served with stiff springs than the compromise of moderate springs and large, stiff bars. But for your street driven car, it's the ideal solution.

I've been looking to go that route for a while (and swap the 17mm that I have on to the Forester ), but Kostamojen recently installed the Whiteline balljoint kit and said:

Driving wise, it gives a little more steering response when cornering and perhaps some snap oversteer if you are not careful.

Given this info, I think I'd like to go with the balljoint kit first and then step the swaybars up from there as needed.

[Dean]

Sorry, did not mean to seem to be offensive, or defensive, and do not want you to be either. There a a bunch of people with a lot of real life experience in getting these cars to handle on this board which I assume is why you made your post.

Again, ALK = good for a number of reasons. Go read the white papers and/or Unibomber stuff on it if you want more details.

But it is only so good. The base strut geometry of the car is less than ideal, and the ALK alone cannot compensate for it.

Since you have lowering springs, the roll center adjuster of either flavor is only going to get you back to the neighborhood of stock suspension geometry which still sucks, especially since your springs are not significantly stiffer than stock and are slightly underdamped and thus transfer weight faster than is likely ideal.

Will either of these items help? Maybe, but the question is will they accomplish what you want, and that is debatable.

My earlier point was that properly sized bars can mitigate and resolve issues and have a proven track record in doing so. Not sure I agree with Kevin's reasoning on why they get a bad rep. Most anybody who actually knows about tuning suspensions knows springs and sways have to be sized appropriately for the given application. Most folks who say one is better than the other are likely not actually aware of how they operate and interact.

By removing your higher spring rate coilovers, you have significantly reduced your roll resistance which forces you into bad roll geometry land and your springs which lower you to some degree have pushed you further into that. Without increasing spring rates, sways are the only way to minimize roll. These other items may make a difference, but I am not convinced they will make the difference you are looking for.

In this instance, I would say they are a "band aid" as they are not actually directly addressing the primary issue which is roll.

I just don't want you to spend $400 and not get the results you are hoping for.

[Kevin M]

Frankly, Steve doesn't know what he's talking about when it comes to suspension. He's the guy who spun at Buttonwillow 4 times in *2* sessions. After the first session, he said the car was loose, so he stiffened his rear struts.

You're not going to crash your car because of sway bars if you're not an idiot. I don't think you're an idiot. Are you an idiot?

[M3n2c3]

All good points. This is why I was looking for the discussion.

Of course, it's tough to know for sure what I'll prefer without actually doing it. My experience with coilovers was pretty poor due to my inability to get them set up properly, but it definitely showed me that simply minimizing roll would not make my car handle like a dream. That's not to say I discount the value of reducing roll - I'm just thinking about taking a shot at fixing a few other aspects of the car's suspension before I stiffen it up.

I know this will sound silly, but I've been screwing around with my STi in Forza 2 and while I can dial various amounts of understeer, snap oversteer, throttle oversteer, etc, the one thing that's a bitch to find is actual turn-in grip. No amount of spring rate, damping, and sway bar adjustments will counteract the game's insistence that Imprezas just understeer at turn-in by default. It got me thinking, and that's why I researched these upgrades for my RS.

I think it's just a matter of how I decide to set priorities. My concern is that I'll go with a sway bar upgrade and decide that I still want the extra turn-in that the geometry kits provide, but then do those only to find that they don't really match my sway bar choices. I'm leaning towards improving the geometry first, and then adding sway bars based on how the car handles at that point. . . after all, I can choose sway bar sizes to fine-tune, but these kits are pretty much on-off, one size fits all. It may not matter, but given that I'll probably do both eventually anyway, I'd hate to find out the hard way.

Originally Posted by me

too many people mistakenly want to view it as a quick-n-easy suspension upgrade that will magically cure your understeer.

Originally Posted by Dean

In this instance, I would say they are a "band aid" as they are not actually directly addressing the primary issue which is roll.

Touche. Well played, sir - exactly why I'm posting here instead of just reading NASIOC and going out to buy.

And I am not an idiot, but I cannot say truthfully that there has never been evidence to the contrary.

[AtomicLabMonkey]

Originally Posted by Dean

Without increasing spring rates, sways are the only way to minimize roll. These other items may make a difference, but I am not convinced they will make the difference you are looking for.

Raising the roll center height at either end will reduce overall body roll, and probably give you a more favorable camber curve. The tradeoff is increased jacking forces.

You can always lower the C.G. or increase the track width to reduce roll, too.

Using stiffer bars to limit roll/suspension travel to mask the effects of poor geometry is pretty much the definition of "band-aiding" a suspension.

Of course, what's best depends on what you can afford or are allowed to do within your ruleset.

[Dean]

If your goal is better response at turn in, add some toe out. Be aware this will eat tires quicker though and be slightly disconcerting under braking. I don't think any of the kits are going to significantly change turn in. They mostly effect the outside suspension after it is compressed to some degree.

If your goal is to reduce mid corner understeer... Unfortunately there is no cost effective way to change to unequal length A arms in the front which is probably the only true non band-aid.

Your stock struts make caster/camber plates basically useless, so no joy moving the top of the strut.

The ALK will help Caster and roll center a bit by pushing the rear or the front A arm down and out which pushes the lower ball forward and out.

The taller lower ball and tie rod ends known which WL calls the roll center kit change the compression/roll camber and bump steer curves by increasing the distance from the arm to both balls. The lower ball change is beneficial as long as you can keep the arm below horizontal by some means. As soon as it goes past horizontal, it exacerbates the original issue, and camber goes positive even faster.

People put 32mm front bars on stock Imprezas to try and keep the lower arms from going past horizontal. The increased grip due to retained camber more than compensates for the increased weight transfer.

You really are stuck between a rock and a hard place. The WL RC kit may get your camber curve back close to stock under DD situations, but may hurt you under extreme handling like autocross unless you control roll better.

I just thought of something. you may be a good candidate for the Praxis air suspension system given your requirements especially if combined with the ball relocaters. While it is less than ideal, as you lower the suspension, it will increase toe out, and increase spring rates. I am guessing it is way out of budget though.

[AtomicLabMonkey]

Originally Posted by Dean

If your goal is to reduce mid corner understeer... Unfortunately there is no cost effective way to change to unequal length A arms in the front which is probably the only true non band-aid.

Moving weight from front to back is no band-aid and will reduce understeer, but finding a cost-effective way to do it can be tough.

Originally Posted by Dean

You really are stuck between a rock and a hard place. The WL RC kit may get your camber curve back close to stock under DD situations, but may hurt you under extreme handling like autocross unless you control roll better.

I don't see how it would hurt. Given two front-ends with the same C.G. and roll resistance, the one with a low, unstable roll center and poor camber curve is typically not going to grip as well as the one with a more stable RC & more dynamic camber.

[Dean]

Originally Posted by AtomicLabMonkey

Moving weight from front to back is no band-aid and will reduce understeer, but finding a cost-effective way to do it can be tough.

Agreed, but other than battery they are basically non-existent for anything substantial.

Originally Posted by AtomicLabMonkey

I don't see how it would hurt. Given two front-ends with the same C.G. and roll resistance, the one with a low, unstable roll center and poor camber curve is typically not going to grip as well as the one with a more stable RC & more dynamic camber.

I'm not convinced they are significantly moving the RC, and the camber curve is shifted and multiplied, not necessarily better. Under autocross type conditions, once the arm goes past parallel to the chassis, the evil positive camber attack is increased due to the offset ball.

I admit I am extrapolating all sorts of stuff with insufficient data. Without a lipstick cam under his car, I am basing my statements on the theory that the ball extenders are mostly designed to compensate for drop associated with coilovers that also typically have significantly higher spring rates, camber plates, etc. I am just not sure the Prodrive springs are significantly stiffer than stock to allow the RC kits to work optimally. I am not saying they won't do something, just not sure they will do what he wants at under the extremes of autocross.

[Kevin M]

Dean, I'm not sure that full compression on coilovers is significantly different in terms of geometry than full compression on standard drop springs like Jeremiah's Prodrives, since the coilovers start so much closer to the bumps.

[Dean]

Originally Posted by BAN SUVS

Dean, I'm not sure that full compression on coilovers is significantly different in terms of geometry than full compression on standard drop springs like Jeremiah's Prodrives, since the coilovers start so much closer to the bumps.

Huh?Lowering springs put you closer to stock bumps, but coilovers if they have even bumps are dependent on their design and throw.

Hitting bump stops in any configuration is going to cause drastic near instantaneous understeer.

The difference I was describing was related to spring rates of his prodrives vs. typically higher rates on coilovers in terms of roll resistance.

[AtomicLabMonkey]

Originally Posted by Dean

I'm not convinced they are significantly moving the RC, and the camber curve is shifted and multiplied, not necessarily better. Under autocross type conditions, once the arm goes past parallel to the chassis, the evil positive camber attack is increased due to the offset ball.

I admit I am extrapolating all sorts of stuff with insufficient data. Without a lipstick cam under his car, I am basing my statements on the theory that the ball extenders are mostly designed to compensate for drop associated with coilovers that also typically have significantly higher spring rates, camber plates, etc. I am just not sure the Prodrive springs are significantly stiffer than stock to allow the RC kits to work optimally. I am not saying they won't do something, just not sure they will do what he wants at under the extremes of autocross.

Having run many many suspension simulations for strut front ends using many different combinations of pivot positions, I'll say with confidence that I would much rather auto-x a car that has the balljoints lowered 1/2"-1" from an extender kit than a car that doesn't.

Now, if you gave me the x-y-z coordinates for the pivots of an Impreza front end, I could tell you exactly how it will respond in both cases.

[Dean]

Originally Posted by AtomicLabMonkey

Having run many many suspension simulations for strut front ends using many different combinations of pivot positions, I'll say with confidence that I would much rather auto-x a car that has the balljoints lowered 1/2"-1" from an extender kit than a car that doesn't.

Now, if you gave me the x-y-z coordinates for the pivots of an Impreza front end, I could tell you exactly how it will respond in both cases.

Sorry, don't have them. But the WL one is 10mm lower, the 6gun is 45mm. I'm not convinced 10mm does a whole lot of good for cars that are lowered 25-40+mm

[AtomicLabMonkey]

You own an Impreza, don't you? If you want hard data instead of educated guessing, man up, get the plumb bob and measuring tape out, and get me some coordinates!

[markcjr]

I'm running the prodrive p1 springs, and also have the whiteline alk (with comfort bushings). I think that it helped turn in, at least it feels like the car will go quicker into a turn, as in instead of feeling like the car is swinging into a turn, it feels like you driving into it more.
Also, if you're talking about spending $400, you could pick up some koni adjustable inserts. I have those as well and if you run them on 1 click rear, 1/2 click front, it is excellent for daily driving. also, you could click them up to the 3rd or 4th setting if you were tracking your car. I got mine for ~440 from alexperformance.com. I had these done first with my springs, and then did the whiteline alk afterwards. I feel more jarring and clunks i think due to alk than i used to without it.
mark

[JC]

If all you are looking for is improved steering response, you always have this option too...

http://www.q-rack.com/r2qrack.htm

[Kevin M]

Actually that can make the problem worse.

Also, why does the WRX in the top photo have a Rev-Lab sticker on it? Did they change their name?

[JC]

Originally Posted by BAN SUVS

Actually that can make the problem worse.

Do explain. I know my EVO feels a hell of a lot snappier than an STi.

Originally Posted by BAN SUVS

Also, why does the WRX in the top photo have a Rev-Lab sticker on it? Did they change their name?

They definitely used to be Rev-Labs so I would assume so.

[Kevin M]

Originally Posted by JC

Do explain. I know my EVO feels a hell of a lot snappier than an STi.

The Evo doesn't suffer (as much) from the ills of McStrut suspension compromises, largely because the steering rack is in a dramatically different place than on a Suby. Apples and Oranges. If you had an STi ratio steering rack, your car would still "feel" better on turn-in.

Originally Posted by JC

They definitely used to be Rev-Labs so I would assume so.

That's not nearly as awesome as I had hoped.

[JC]

Originally Posted by BAN SUVS

The Evo doesn't suffer (as much) from the ills of McStrut suspension compromises, largely because the steering rack is in a dramatically different place than on a Suby. Apples and Oranges. If you had an STi ratio steering rack, your car would still "feel" better on turn-in.

That doesn't really answer my question about how it will make an STi feel worse.

http://www.iwsti.com/forums/showthread.php?t=78804

This thing is absolutely amazing. It's incredible how much of a difference this steering rack makes over stock. I finally feel that what happens to the steering wheel translates into what happens on the road.

It's tight and heavy, steering response is instant and not a lot is required for something to happen.

It's a very confidence inspiring feel now. Before I felt that the steering was too light and pretty vague in certain areas. That and the dead play when the wheel was dead center drove me crazy. You'd turn the wheel an inch and nothing would happen, then a bit more and all of a sudden the wheels would turn. Obviously you get used to it, but this is just sooooooo much better.

As soon as I get to Andrewtech, Andrew asks me where I got the rack because all the guys in the shop want one! At this point I knew it was going to be a drastic change. As I got in the car to leave, it immediately felt different, mostly because I was backing out of a parking spot and only turned the wheel one full turn before it was at full lock At slow parking lot speeds, the steering felt heavier and more direct than stock, but not too heavy by any means. Then I got out onto the open road...

Luckily my drive to work today included some twisties as well as straight highway driving. In the twisties, the car is just amazing. It simply goes where you point it, no dead spot in the center, no sawing at the wheel, just direct. The weighting is perfect, heavier than stock but purposeful. Almost, dare I say, Porsche-like. During lane changes, etc. the car is NOT at all twitchy or temperamental. It's not a "sneeze and change lanes" type of deal, I can drive casually on the highway with one hand on the wheel no problem. The on-center feel is very solid, but instead of being able to turn the wheel a few degrees before you get any feedback, it's instant. Overall, I couldn't be happier with this mod. I'm really glad I decided to go with the 11.5:1, and I would venture to say this is one of my favorite mods to date.

I had a chance to drive an Evo 9 today with Swift springs and although the Evo has a 13:1 ratio, the steering felt NUMB compared to my STi with the 11.5:1. Granted my STi is more heavily modded and has more aggressive alignment numbers, but based on steering feel and feedback alone, the Evo was no match. A stock STi is even further off, and a stock WRX is not even in the same time zone. Just thought I would add this, since it is sort of inevitable that an Evo will be brought into a conversation about steering ratios.

About the rack, I just love it!! I don't have to shuffle my hands anymore on most turns, and the car is so much more responsive to steering inputs due to the quicker ratio(mine is 11.5:1). And the steering feel seems to be greatly improved as well. If you don't have it, you should get one! I can't wait to go out to the track and/or auto-X now.