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Discussion Starter #1 (Edited)
I've been reading a lot on anti-sway bars here over the last few weeks.

It seems many STI owners are scared to run large rear bars because they're afraid of lifting the inside rear wheel, as if this magically and suddenly reduces the car's grip. Obviously a tire not touching the ground can not grip, right? In every thread on rear sway bars, someone always brings up rear wheel lift and why big rear sways are bad.

The popular solution here is to run a smaller rear sway or softer rear springs. Either lowers the effective wheel rate in the rear, which (if the strut allows) gives a longer effective suspension travel. And what does this accomplish? It produces understeer, pure and simple. You're changing the handling bias. It's no wonder so many STI owners complain of understeer. I've never met a crowd so willing to stick with just a huge front sway bar, and the STI is certainly not the only camber-starved car out there.

The only reason this is reducing rear wheel lift is because the softer rear suspension is forcing the front tires to instead control body roll. Since under braking and turning your front tires are already saturated, grip up front is reduced while grip in the rear increases. This would be no different than if you ran softer rear springs or firmer front springs. Running a smaller rear sway does not normally increase the total grip of the vehicle, and the trade is almost never worth it if the handling bias becomes off-neutral.

Increasing droop travel beyond the spring travel and adding a helper spring in the rear does not improve the situation. A helper spring simply makes your linear springs progressive; they work the same as a very progressive coil spring. It makes the end of your suspension travel very soft, and while this suddenly soft rear suspension may keep a tire planted, it'll only do so by changing the car's handling bias towards understeer. Progressive springs are not good for performance as they create jacking forces and can lead to unpredictability. The weight shift of the car has not changed because the center of gravity has not changed (it will have risen, if anything, due to the progressive spring rate).

I've even read someone suggest running using firmer rear springs just so that he/she could run a smaller rear sway bar, thus preventing rear wheel lift. It won't! Sways and springs together make up your wheel spring rate; the wheels don't know the difference. The total weight shift of the car does not change. I've read elsewhere online that sway bars decrease a car's grip by transfering weight to the outside tire, and this is complete BS. The weight transfer is no different than it is with firmer springs, so long as the total wheel rate is the same.

Now, I'll concede that too much inside rear wheel lift can be a bad thing, but only if it's prominent in steady-state turning. In that case, it's a sign of having too much weight transfer, NOT that your handling bias is off. Reducing weight transfer as much as possible is always beneficial and really helps make the most of your tires: that's why we see cars with aluminum roofs and such. But if you're getting lift under heavy braking and turning, then what's the big deal? The rear tires aren't used much for braking anyway, especially on a front-heavy car. On a street car like the Impreza the Cg may never get low enough to prevent wheel lift under all circumstances. Besides, you will NEVER lift a rear wheel under acceleration when you need the rear wheels planted most.

As I said earlier, a wheel lifts for one reason only: there is no weight on it. So, how do we fix this? You can either widen the track or lower the center of gravity. Only the latter is really practical. If you are getting rear wheel lift and, for whatever reason, are troubled by it, lower your car. It's simple. Lowering too much creates its own set of problems, but that's a different topic. The point is this: lifting a rear wheel is a weight shift problem, not a handling bias problem. It should be solved by reducing the weight shift in your car, not by changing the handling bias towards understeer.

Now, lots of people here run big front sways with the stock rear sway, and they're happy with that. Great- I'm sure it is a drastic improvement over stock due to the reduction of body roll. However, running a large rear sway also reduces body roll and will thus keep the front tires on-camber too. However, the rear sway reduces body roll without overwhelming the front tires at the same time, and thus the improvement in front grip will be far more pronounced. Having more front grip than rear creates oversteer, and thus it's important to keep a balance.

From all that I've read, it seems most guys who really love their vehicle's handling run nearly equal front and rear sway bars. This sure makes more sense to me than running a much larger front sway (you stock class autocrosser's aside). Lastly, my own experience says that you want high-quality shocks if you run large sway bars, because your spring rate because much higher in turns than it is on straights. The shocks need to be good enough to dampen this much higher rate or you will feel instability.

Sorry for the rant here, but I got tired of reading about inside rear lift and seeing people run small (or stock) rear sways because of it. There are plenty of good reasons to run a smaller rear sway, but that's not one of them.
 

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My thoughts and responses below. I also have a thread somewhere on here addressing the relationship between spring rate and sways.

stretch said:
I've been reading a lot on anti-sway bars here over the last few weeks.

It seems many STI owners are scared to run large rear bars because they're afraid of lifting the inside rear wheel, as if this magically and suddenly reduces the car's grip. Obviously a tire not touching the ground can not grip, right? In every thread on rear sway bars, someone always brings up rear wheel lift and why big rear sways are bad.
They aren't necessarily bad, you just need to have the springs to accomodate them. The stock springs are awful for trying to run anything 24mm or larger on the rear. Lifting is bad because it happens at the worst possible time - through apex. You can't really get on the throttle effectively until the tire gets back on the ground

The popular solution here is to run a smaller rear sway or softer rear springs. Either lowers the effective wheel rate in the rear, which (if the strut allows) gives a longer effective suspension travel. And what does this accomplish? It produces understeer, pure and simple. You're changing the handling bias. It's no wonder so many STI owners complain of understeer. I've never met a crowd so willing to stick with just a huge front sway bar, and the STI is certainly not the only camber-starved car out there.
As you pointed out this car is camber starved up front. This is the reason for everyone running a larger front bar. You sure as heck don't want to run softer rear springs than what comes stock on the car. It will make it wallow like a hippo. With the cross loading you may get the droop travel for the rear, but you have keep in mind you have the bump travel up front. With so many of the cars lowered for track work you lose some of the bump travel. That's why so much has been written about the idea ride heights of these cars.

The only reason this is reducing rear wheel lift is because the softer rear suspension is forcing the front tires to instead control body roll. Since under braking and turning your front tires are already saturated, grip up front is reduced while grip in the rear increases. This would be no different than if you ran softer rear springs or firmer front springs. Running a smaller rear sway does not normally increase the total grip of the vehicle, and the trade is almost never worth it if the handling bias becomes off-neutral.
This is why I made my suggestions for bars in the other thread. Quite often we see folks come to us asking for the biggest front and rear bars they can get because they just want the biggest bars they can get. They don't consider the relationship with springs. I feel my suggestions keep the car nicely neutral for the type of driving that is to be done.

Increasing droop travel beyond the spring travel and adding a helper spring in the rear does not improve the situation. A helper spring simply makes your linear springs progressive; they work the same as a very progressive coil spring. It makes the end of your suspension travel very soft, and while this suddenly soft rear suspension may keep a tire planted, it'll only do so by changing the car's handling bias towards understeer. Progressive springs are not good for performance as they create jacking forces and can lead to unpredictability. The weight shift of the car has not changed because the center of gravity has not changed (it will have risen, if anything, due to the progressive spring rate).
I completely agree with you on this.

I've even read someone suggest running using firmer rear springs just so that he/she could run a smaller rear sway bar, thus preventing rear wheel lift. It won't! Sways and springs together make up your wheel spring rate; the wheels don't know the difference. The total weight shift of the car does not change. I've read elsewhere online that sway bars decrease a car's grip by transfering weight to the outside tire, and this is complete BS. The weight transfer is no different than it is with firmer springs, so long as the total wheel rate is the same.
I'm in agreement here too. folks need to consider the relationship of springs and sway together. I often suggest firmer springs so that folks can run larger bars (back to the stock springs being too soft), but only up to a point. When you start looking at 14k/12k springs then you really need to start thinking about your sway choice. Even on the adjustable bars there's only a limited amount of adjustability, and if you're running superman springs and getting nice rotation with just those there's not need to go overboard with something like a 27mm rear bar.

Now, I'll concede that too much inside rear wheel lift can be a bad thing, but only if it's prominent in steady-state turning. In that case, it's a sign of having too much weight transfer, NOT that your handling bias is off. Reducing weight transfer as much as possible is always beneficial and really helps make the most of your tires: that's why we see cars with aluminum roofs and such. But if you're getting lift under heavy braking and turning, then what's the big deal? The rear tires aren't used much for braking anyway, especially on a front-heavy car. On a street car like the Impreza the Cg may never get low enough to prevent wheel lift under all circumstances. Besides, you will NEVER lift a rear wheel under acceleration when you need the rear wheels planted most.

As I said earlier, a wheel lifts for one reason only: there is no weight on it. So, how do we fix this? You can either widen the track or lower the center of gravity. Only the latter is really practical. If you are getting rear wheel lift and, for whatever reason, are troubled by it, lower your car. It's simple. Lowering too much creates its own set of problems, but that's a different topic. The point is this: lifting a rear wheel is a weight shift problem, not a handling bias problem. It should be solved by reducing the weight shift in your car, not by changing the handling bias towards understeer.
I'm in total agreement on this one. Keep in mind that you can also help that weight shift by upgrading springs

Now, lots of people here run big front sways with the stock rear sway, and they're happy with that. Great- I'm sure it is a drastic improvement over stock due to the reduction of body roll. However, running a large rear sway also reduces body roll and will thus keep the front tires on-camber too. However, the rear sway reduces body roll without overwhelming the front tires at the same time, and thus the improvement in front grip will be far more pronounced. Having more front grip than rear creates oversteer, and thus it's important to keep a balance.

From all that I've read, it seems most guys who really love their vehicle's handling run nearly equal front and rear sway bars. This sure makes more sense to me than running a much larger front sway (you stock class autocrosser's aside). Lastly, my own experience says that you want high-quality shocks if you run large sway bars, because your spring rate because much higher in turns than it is on straights. The shocks need to be good enough to dampen this much higher rate or you will feel instability.

Sorry for the rant here, but I got tired of reading about inside rear lift and seeing people run small (or stock) rear sways because of it. There are plenty of good reasons to run a smaller rear sway, but that's not one of them.
overall, I'd have to say I agree with what you say. I will say that the folks that I have run into who are running a large front and stock sway are the guys who have inverted the relationship on the spring bias by going stiffer in the rear to jack up their roll resistance that way.

as for the larger front bar - I've run even bars, and I've run large front with decently sized, but small rear. I really like the larger front. heck, check out Javid's numbers for camber curve and you can see why. The front camber curve on these cars sucks.

i guess the cat's out of the bag on widening track. Tony and I have been playing with spacers up front for a while now, and we've been happy with the results.

i really like how this thread started, and I think a lot of valuable information can be learned in an open discussion in it. lets keep it rolling.

-Clint
 

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stretch said:
Sorry for the rant here, but I got tired of reading about inside rear lift and seeing people run small (or stock) rear sways because of it. There are plenty of good reasons to run a smaller rear sway, but that's not one of them.
There's good info here, but there's more to it. There are two possible reasons why you're lifting the rear....

1. you need to restrict weight shift, exactly as you've said. Your inside rear is at the end of it's rope because the suspension isn't low enough or stiff enough. This is probably happening in a situation where you're running stupid sticky tires on a stock-ish suspension.

2. your rear springs are entirely too soft for the big-ass rear sway you have installed and it's got a strangle hold on your droop travel. It is possible for a sway bar to overpower the spring so that the spring can't push the wheel down.

Overall your post is well informed, and well written. But when you're trying to fix a "rear tire lift" situation you have to figure out exactly why the rear tire is lifting before you can do anything to fix it. In a FWD car it really doesn't matter if you hike up the rear a bit. When I'm going from brakes to throttle I want traction, and if one of my driven wheels is off the ground I'm not getting as much power down as I should.

Like Turninconcepts.com said, it's important to understand the relationship between the springs and the swaybars when you're trying to determin how much bar is just right.

stretch said:
I've read elsewhere online that sway bars decrease a car's grip by transfering weight to the outside tire, and this is complete BS.
It depends on what kind of surface you're driving on.
 

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Discussion Starter #6 (Edited)
Turninconcepts.com said:
as for the larger front bar - I've run even bars, and I've run large front with decently sized, but small rear. I really like the larger front. heck, check out Javid's numbers for camber curve and you can see why. The front camber curve on these cars sucks.
Clint, thanks for the huge reply. I was hoping this would start a much more involved conversation. :)

I'm not quite sure I understand your rationale here though- that the front camber curve sucks is actually a reason to run a big rear sway bar in addition to a large front sway. This will result in the largest overall reduction of body roll and thus keep camber at all corners in check. Whiteline's largest bar is 27mm front and 27mm rear: they're equal.

Or, let's put it differently. Let's say a 27mm FSB and 22mm RSB result in the same total amount of body roll as running a 24mm sway front and rear. Thus, the camber of your front tires mid-turn is similar with both setups. Wouldn't the handling bias of the latter setup be more desirable, as the roll stiffness is more evenly distributed?

i guess the cat's out of the bag on widening track. Tony and I have been playing with spacers up front for a while now, and we've been happy with the results.
How much have you been able to widen without getting into trouble with the fenders? 35mm offset wheels would widen the track over the more typical 48mm offset wheels, but at what expense of tire width? I tend to think that the best way to widen one's track is to simply widen your wheels and tires. I'm not sure those with 255's on 17x8.5's can push their wheels out any further without doing lots of fender work.

i really like how this thread started, and I think a lot of valuable information can be learned in an open discussion in it. lets keep it rolling.

-Clint
Thanks!

I unfortunately don't have any STI suspension experience yet, as I created this thread after merely researching what others have done. You might have noticed I do carry some suspension experience with me though!

I've already purchased the Strano FSB (cheaply, used on eBay). I was debating on either the 24mm or 27mm rear Whiteline sway bar.

Personally, since my car is a daily driver, I want the biggest sways I can get in lieu of requiring significantly firmer springs. My goal is to reduce body roll as much as possible to get away with as little static camber as possible: -2 degrees or less. I don't want to run more than this on a street car. I think any compromise due to the large sways on the street will be less than that of running an entire extra degree of camber on the street.

I realize moderate sways with firm springs will result in a more predictable car, but as I'm sure you'll agree, bigger sways offer a better ride quality compromise for a given roll resistance than stiff springs. I just hope I'm not going too big too soon, as the discrepency between my spring and sway rates will create for quite varied loads on my struts.

And that's the problem- I haven't figured out what I'm going to do for shocks and springs yet. I have to stop spending money on this car! I was planning on Koni inserts in WRX housings (for the rear only, since I have an '05 STI) as a stop-gap. Anyway, I'm getting off-topic... back to lifting wheels!
 

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Discussion Starter #7
Mykl said:
2. your rear springs are entirely too soft for the big-ass rear sway you have installed and it's got a strangle hold on your droop travel. It is possible for a sway bar to overpower the spring so that the spring can't push the wheel down.
But this is no different than simply running firm rear springs. For a given wheel rate, it does not matter whether the resistance comes from springs or sways. The amount of weight on that tire is exactly the same.

If a sway adds 250#/in of resistance to 250#/in springs, the wheel rate is 500 pounds per inch. (I'm oversimplifying, but stay with me.) If you removed the rear sway and ran 500# springs instead, your end result would be exactly the same. It would still take exactly 500 pounds of relief to decompress that corner one inch. Since at rest, the rear wheels may only have 750lbs each on them, in either case the tire will be airborn with an inch-and-a-half of travel. Once this happens, you'll know more than 750lbs of weight has transferred away from that corner.

But here's the other thing: reducing pitch doesn't actually change how much weight has transferred before a wheel gets airborn. It just changes how much distance (measured in droop travel) it takes before it happens. If I bumped my spring rates up 50% in all corners to a 750# effective wheel rate, the wheel would go airborn in just one inch of droop travel. It may look like the tire has become less airborn, but really nothing important has changed (aside from the outside tires being more on-camber).

Like I've said, the only way to reduce wheel lift without altering your roll resistance is to lower your center of gravity or widen your track. Doing it with a change of spring (or bar) rate changes your roll resistance and really addresses the wrong problem.

Do you guys really lift a wheel at the apex? How so? Doing the math, I'd have a hard time believing the car would lift a wheel under anything much more than trail braking, which any front-heavy car will do. I hope you're not still lifting or on the brakes at the apex. Perhaps I estimate the Cg to be too low- 20" or so? In a steady-state turn, the rear ought to be planted, and it ought to have plenty of weight on it as you ease on the throttle.

Another thought- if it does take a low rear spring/bar rate to keep the tire on the ground, how much weight could it possibly have on it? Is it worth sacrificing some turn-in and tossibility to put all of 50lbs on a tire?
 

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stretch said:
But this is no different than simply running firm rear springs. For a given wheel rate, it does not matter whether the resistance comes from springs or sways. The amount of weight on that tire is exactly the same.
You're missing one key point. We have fully independent suspensions. A swaybar ties the two sides together, limiting the independent nature of the suspension.

When cornering, the bar will twist with the outside end being pushed down, and the inside end being lifted (just like the body of the car). On the outside tire, this downward pressure helps increase tire traction. However, on the inside tire, the anti-roll bar is pushing up on the suspension reducing the downward force the spring is trying to place to keep the tire on road. If the anti-roll bar is too stiff, it will overpower the spring, prevent it from extending enough to keep the tire on the road, and the wheel will actually lift off the ground.

Your thinking is correct if you assume the car will always run on a glass smooth, very grippy surface like virgin asphalt. In that case you can run stupid stiff springs and no swaybars. The problem comes into play when you tune your suspension to deal with bumps. Then the springs must be compliant enough to soak up those bumps so your car doesn't lose grip going over them. This is what swaybars are for, to provide extra roll resistance so you can run a soft enough spring to deal with surface irregularities.

This is where the tricky part comes into play. You need to choose the right spring for the surface (and tires you're running), and the right bar for the spring. It gets even more complicated if we're talking about tuning a suspension for dirt, ice, snow, gravel, or any non paved surface... because the relationships change.
 

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If your interested in performance and fine tuning, you can't really just focus on the rear and not the front as well. Below may help explain....




stretch said:
I've been reading a lot on anti-sway bars here over the last few weeks.

It seems many STI owners are scared to run large rear bars because they're afraid of lifting the inside rear wheel, as if this magically and suddenly reduces the car's grip. Obviously a tire not touching the ground can not grip, right? In every thread on rear sway bars, someone always brings up rear wheel lift and why big rear sways are bad.

Rear lift being a big deal really depends on wether you want to use the gas in your car. I'm not sure if you've had the experiance of powering out of a turn with only the outside wheels on the ground. It is both very nerve racking and difficult to keep the car on line and not too loose or too pushy. Of course, if you dont get on the gas you can wait for the car to land and it won't matter.

The popular solution here is to run a smaller rear sway or softer rear springs. Either lowers the effective wheel rate in the rear, which (if the strut allows) gives a longer effective suspension travel. And what does this accomplish? It produces understeer, pure and simple. You're changing the handling bias. It's no wonder so many STI owners complain of understeer. I've never met a crowd so willing to stick with just a huge front sway bar, and the STI is certainly not the only camber-starved car out there.

I'm not sure that longer strut travel = understeer. As a general rule of thumb the impreza chassis seems to like wheel rates that are proportionate to the weight distribution. Plus the rear camber curve is not really a curve, teh geometry retains nearly all of the camber through bump.

The only reason this is reducing rear wheel lift is because the softer rear suspension is forcing the front tires to instead control body roll. Since under braking and turning your front tires are already saturated, grip up front is reduced while grip in the rear increases. This would be no different than if you ran softer rear springs or firmer front springs. Running a smaller rear sway does not normally increase the total grip of the vehicle, and the trade is almost never worth it if the handling bias becomes off-neutral.

The above is somewhat true but largely meaningless untill you start to talk about rates. I can assure you that 700 lb springs and a 20mm bar in the rear of an STi is too much rate. I and many other drivers ran it and it was simply faster when we pulled the sway bar, nothing was adjusted at the front of the car. Every driver could enter corners and handle transitions much quicker... Also, the car's mid corner characteristics didn't change.

Increasing droop travel beyond the spring travel and adding a helper spring in the rear does not improve the situation. A helper spring simply makes your linear springs progressive; they work the same as a very progressive coil spring. It makes the end of your suspension travel very soft, and while this suddenly soft rear suspension may keep a tire planted, it'll only do so by changing the car's handling bias towards understeer. Progressive springs are not good for performance as they create jacking forces and can lead to unpredictability. The weight shift of the car has not changed because the center of gravity has not changed (it will have risen, if anything, due to the progressive spring rate).

My helper springs allow me to run the ride height I want (roughly 14/13.5) and have 3.5" of droop up front and 2.5" of droop in the rear. This helps keep wheels on the ground and helps the diff's stay happy. If you buy Tiens or JIC with out helper spring you will not have the same droop travel I have at my ride hieght.

I've even read someone suggest running using firmer rear springs just so that he/she could run a smaller rear sway bar, thus preventing rear wheel lift. It won't! Sways and springs together make up your wheel spring rate; the wheels don't know the difference. The total weight shift of the car does not change. I've read elsewhere online that sway bars decrease a car's grip by transfering weight to the outside tire, and this is complete BS. The weight transfer is no different than it is with firmer springs, so long as the total wheel rate is the same.

With both bars on the car, jack one side of your car up. Meaure the droop. Now jack the other side up as well (all 4 wheels off). Now that your 'outside' wheels (the ones that were on the ground during the first jacking) aren't compressed, the sway bar is not preventing your inside wheels from reaching full droop. If you measure droop you will measure more.

Springs and sway bars are often 'combined' to calculate wheel rate but even that isn't accurate. There are many differences between the two. The most imporatant of which, for the current conversation, would be that a sway bar doesn't effect travel at the other end of the car like a spring does and a spring doesn't limit local suspension travel like a sway bar. Under accel, the rear srpings stop the front from lifting off the ground. Big sway bars on soft spring won't do that.

You are aware of what happens to the front geometry under bump. Given everything else is equal a car with 500 lb srpings up front WILL ALWAYS out brake a car with 250 springs and 250 bars.


Now, I'll concede that too much inside rear wheel lift can be a bad thing, but only if it's prominent in steady-state turning. In that case, it's a sign of having too much weight transfer, NOT that your handling bias is off. Reducing weight transfer as much as possible is always beneficial and really helps make the most of your tires: that's why we see cars with aluminum roofs and such. But if you're getting lift under heavy braking and turning, then what's the big deal? The rear tires aren't used much for braking anyway, especially on a front-heavy car. On a street car like the Impreza the Cg may never get low enough to prevent wheel lift under all circumstances. Besides, you will NEVER lift a rear wheel under acceleration when you need the rear wheels planted most.

My thoughts / experinace comes from lifting on entry (rears), mid corner (both), and exit (front). Your right in that the entry doesn't matter much, it's only when you want to turn and get on the gas that is it rea important but the rear tires and diff do play a roll in braking, especially if you are going to trail brake and want to push the car to the limits and still control it.

As I said earlier, a wheel lifts for one reason only: there is no weight on it.

WRONG, a wheel will also lift if a sway bar is pulling up on it.

So, how do we fix this? You can either widen the track or lower the center of gravity. Only the latter is really practical. If you are getting rear wheel lift and, for whatever reason, are troubled by it, lower your car. It's simple. Lowering too much creates its own set of problems, but that's a different topic. The point is this: lifting a rear wheel is a weight shift problem, not a handling bias problem. It should be solved by reducing the weight shift in your car, not by changing the handling bias towards understeer.

How about "Wieght shift is the source of the energy that lifts a wheel but the geometry CAN be a limiting factor". AKA, you could roll the car so much that no reasonable amount of droop would let the wheel sit back down. Most the time though, at our modests levels of grip the tire could be put back on the ground.

Now, lots of people here run big front sways with the stock rear sway, and they're happy with that. Great- I'm sure it is a drastic improvement over stock due to the reduction of body roll. However, running a large rear sway also reduces body roll and will thus keep the front tires on-camber too. However, the rear sway reduces body roll without overwhelming the front tires at the same time, and thus the improvement in front grip will be far more pronounced. Having more front grip than rear creates oversteer, and thus it's important to keep a balance.

A good point but hard to apply with out discussing rates.

From all that I've read, it seems most guys who really love their vehicle's handling run nearly equal front and rear sway bars. This sure makes more sense to me than running a much larger front sway (you stock class autocrosser's aside). Lastly, my own experience says that you want high-quality shocks if you run large sway bars, because your spring rate because much higher in turns than it is on straights. The shocks need to be good enough to dampen this much higher rate or you will feel instability.

Sorry for the rant here, but I got tired of reading about inside rear lift and seeing people run small (or stock) rear sways because of it. There are plenty of good reasons to run a smaller rear sway, but that's not one of them.
I believe, and I think I have written this before, that soft springs and upgraded sway bars front and rear are a pretty good setup, especially for street or 'light' r-comps.

Once you get really big sticky tires and run in a 'open' suspension group (be it a class or you have the money to go faster at your HPDEs by buying suspension) you will have enough *weight transfer* that limitations in your geometry (flaws in your setup) will become much more apparant / hard to deal with.

FYI, one other way to combat with rear lift is to reduce rear out side grip (increase toe or reduce camber). The car may become harder to turn in but might be faster mid corner and more predictable on exit vs a traditional alignment with wheel lift mid corner.


Of course, there are many ways to setup and drive a car. Try telling a DSM owner that they need a front bar and they'll spit on you.
 

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Just so I am aware, what are the stickiest tires you have run on your setup and where have you run the car (autoX or tracks?). Not trying to call you out but just want to make sure I understand what degree of weight tranfer you have experianced.
 

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I'm not quite sure I understand your rationale here though- that the front camber curve sucks is actually a reason to run a big rear sway bar in addition to a large front sway. This will result in the largest overall reduction of body roll and thus keep camber at all corners in check. Whiteline's largest bar is 27mm front and 27mm rear: they're equal.
Traditionaly thinking, and all the books in the world will agree with this, but experience over time has shown it to be different. These cars really like a larger front bar than rear. I think Javid covered this one too.

Do you guys really lift a wheel at the apex? How so? Doing the math, I'd have a hard time believing the car would lift a wheel under anything much more than trail braking, which any front-heavy car will do. I hope you're not still lifting or on the brakes at the apex. Perhaps I estimate the Cg to be too low- 20" or so? In a steady-state turn, the rear ought to be planted, and it ought to have plenty of weight on it as you ease on the throttle.
I've got some pics bouncing around, and a few others do too of wheel lift at apex. It's not fun because as you get on the gas the RPMs peg. Even with all our diffs they don't have enough locking factor to overcome a wheel in the air.

Another thought- if it does take a low rear spring/bar rate to keep the tire on the ground, how much weight could it possibly have on it? Is it worth sacrificing some turn-in and tossibility to put all of 50lbs on a tire?
Don't forget cross loading - I fixed my wheel lift with stiffer front springs. hell, I can bottom out those 10K springs and still not lift a rear wheel now. I've got the ripped out fender liner, and scuffs on the inner fender well to prove it.

how much have you been able to widen without getting into trouble with the fenders? 35mm offset wheels would widen the track over the more typical 48mm offset wheels, but at what expense of tire width? I tend to think that the best way to widen one's track is to simply widen your wheels and tires. I'm not sure those with 255's on 17x8.5's can push their wheels out any further without doing lots of fender work.
I wish we had the cash to play around with different offset wheels like that. We've been doing it with wheel spacers.

for the folks running 17x8.5 with 255's they need to roll the rears, but they have just enough clearance up front with using a +48, and some decent static negative camber.

My daily and track setup is the same -3* camber up front -1.5* camber in the rear. Wheels are 17x7.5 running 245/45 tires with +48. i usually run 5mm spacers in just the front.

front sway is set at 29mm, and rear is set at 22mm (both solid bars). Now, here's my problem. I really don't like the lack of rotation from the rear. for autoX it's too planted. I can bump my rear struts up two settings, and not touch the rear sway and the backend is all over the place, too loose. Ideally, what I'm thinking of doing is going up in the rear 1 notch, leave the bar alone, and pull rear neg. camber back to about -1.1 or 1.2.
 

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Turninconcepts.com said:
front sway is set at 29mm, and rear is set at 22mm (both solid bars). Now, here's my problem. I really don't like the lack of rotation from the rear. for autoX it's too planted. I can bump my rear struts up two settings, and not touch the rear sway and the backend is all over the place, too loose. Ideally, what I'm thinking of doing is going up in the rear 1 notch, leave the bar alone, and pull rear neg. camber back to about -1.1 or 1.2.
-1 or maybe even lower will be nice for autoX. If you want to get real crazy, you could run -2 or -2.5 up front and 0 to -0.5 in the rear and see what you think.
 

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Turninconcepts.com said:
I've got some pics bouncing around, and a few others do too of wheel lift at apex. It's not fun because as you get on the gas the RPMs peg. Even with all our diffs they don't have enough locking factor to overcome a wheel in the air.
I don't want to get too off track, but a couple weeks ago i went around a corner real good, and at apex it felt like the clutch slipped. Hasn't done it since. So when lifting one wheel it may do this? sad, i was on snow tires too.
 

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dailydriversti said:
I don't want to get too off track, but a couple weeks ago i went around a corner real good, and at apex it felt like the clutch slipped. Hasn't done it since. So when lifting one wheel it may do this? sad, i was on snow tires too.
it's not MAY do this. It's will. when you lift that wheel it will peg the RPMs when you feed it gas. The first time it happened to me I though i had catistrophic clutch failure. It took me a few times to figure out what was going on.
 

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I see, thanks. :tup: This next autox may be interesting for me then.
 

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Discussion Starter #17 (Edited)
javid said:
Just so I am aware, what are the stickiest tires you have run on your setup and where have you run the car (autoX or tracks?). Not trying to call you out but just want to make sure I understand what degree of weight tranfer you have experianced.
RA-1's, and autocross (on a large, fast course- but still no HPDE's).

Like I said, I'm new to the STI. I'm only exploring suspension ideas and speaking in theory. I don't claim any experience on the STi!


My helper springs allow me to run the ride height I want (roughly 14/13.5) and have 3.5" of droop up front and 2.5" of droop in the rear. This helps keep wheels on the ground and helps the diff's stay happy. If you buy Tiens or JIC with out helper spring you will not have the same droop travel I have at my ride hieght.
Your helper springs are only keeping your springs seated; if your coil springs are fully extended then there's no meaningful weight on your tire. Your shocks may have the extra droop travel, but it serves no purpose.

WRONG, a wheel will also lift if a sway bar is pulling up on it.
A sway pushing up on a spring with a force equal to the load on the spring has the same behavior as a firmer spring simply being unloaded. They dynamics here are NO different than if you were acheiving the same wheel rate with firmer springs.

TurnInConcepts said:
With the cross loading you may get the droop travel for the rear, but you have keep in mind you have the bump travel up front. With so many of the cars lowered for track work you lose some of the bump travel. That's why so much has been written about the idea ride heights of these cars.
I wonder how important cross-loading is to lifting a rear wheel. It definately effects it, but only if there is braking going on in addition to cornering. And, if you're braking, then it doesn't really matter if a rear wheel is airborn. It only needs to be planted come time for throttle.
 

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This is pretty good info.

But you are forgetting tires. And its being mentioned now about tires. People forget that 65-75% of the car handling is TIRES!

- Get crappy tires - off to the grass while braking
- Get good tires - good handling but not there yet
- Super Glue Tires - so good that the car wants to go off the track while the tires turns, ie. creating the lift effect.


Example.
At a autoX or Track day. You can have the car #1 with least amount of HP/TQ against a car #2 with massive HP/TQ. But what happens is that Car #1 is ahead all times because his suspension set up is perfect. While Car #2 is all over the place, because it cannot handle the loads of the car.


Where I am going with this is, basically the inner wheel lift, oversteer, understeer etc is all caused by tires 1st then the suspension geometry.

Like I said on one of the threads before, when I used to race RC - I could have the car setup perfect change the tires only and the car would be totally different. Like going from harder compound to soft or vice versa.
 

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Discussion Starter #19
Yeah, that's what Javid was touching on. Tire lift becomes a bigger issue with more aggressive tires because cornering forces go up, increasing weight transfer.
 

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stretch said:
Like I've said, the only way to reduce wheel lift without altering your roll resistance is to lower your center of gravity or widen your track. Doing it with a change of spring (or bar) rate changes your roll resistance and really addresses the wrong problem.
As several people have already said, ARBs create jacking on the inside so it's not just the WT taking the wheel off the ground. Still, this is a minor issue compared to what you say in your post above.

There are 3 kinds of weight transfer on any car: elastic, geometric, and unsprung, which is minor to the point of insignificance on road cars. So really we have to ways to put weight on the outside wheel: through the springs and ARB (elastic), or through the suspension links themselves (geometric).

If you want less spring/ARB deflection for a given lateral acceleration, you can just increase the proportion of geometric WT to elastic. I say it like it's easy (it's not), but your statement that you can only fix wheel lift by changing the CG or track isn't 100% true.

In the real world, I think it's better to have more roll resistance from springs than an ARB so the amount of jacking is reduced.
 
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