Sway bars questions and adjustment

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  1. In most sites I read that stiffening the front sway bar increases understeer and stiffening the rear one increases oversteer. On this site though towards the end of the article there is a table that states that for cars with a soft suspension setup and excessive roll the opposite is true. Is this the case? And what would be considered excessive roll? I guess most road cars, even sports cars, have much more roll compared to racing vehicles.
  2. What would be the downside of having both sway bars too stiff? (I'm talking about a case in which the understeer - oversteer balance has been set up fine.)
  3. Which is the best method for adjusting adjustable sway bars? Should the setup get tested in all types of corners tight, open etc. or is it safe to judge the car's behavior just from one test course?
  4. Does stiffening a sway bar also improves cornering speed or just the car's behavior? In this video I see almost the same cornering speed before and after a rear sway bar upgrade, so are there any real gains speed wise?
Thanks in advance for any answers!
 
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In most sites I read that stiffening the front sway bar increases understeer and stiffening the rear one increases oversteer. On this site though towards the end of the article there is a table that states that for cars with a soft suspension setup and excessive roll the opposite is true. Is this the case?

I'll pass on reading that article, but I agree, the (too) often repeated general rule isn't true.
There are way too many exceptions. If at all, as a 'general rule', I'd recommend to retain the
stock 'sway bar balance', which effectively means to alter both sway bars in the same manner.


And what would be considered excessive roll? I guess most road cars, even sports cars, have much more roll compared to racing vehicles.

Definitely. A typical sedan has much more roll than a sportscar and five to ten times more roll
compared to a race car (given the same conering speed/g-force). What's excessive/inacceptable
for a sportscar could still be ok for a luxury sedan.


What would be the downside of having both sway bars too stiff? (I'm talking about a case in which the understeer - oversteer balance has been set up fine.)

- would feel stiff on poor roads
- could cause loss of traction on extremely rough roads
- would 'copy' alternatingly left/right skewed surfaces (more noticeable in SUVs)
- overly stiff springs behave similarly


Which is the best method for adjusting adjustable sway bars? Should the setup get tested in all types of corners tight, open etc. or is it safe to judge the car's behavior just from one test course?

For a road car, adjust accordingly to your tastes. Commonly there's no requirement
to fit stiffer sway bars, you buy them because you like to reduce body roll. Watch how
it feels over several days on varying roads for best judgement. If you alter both sway
bars in a similar manner you'll retain a safe balance. I bet it'll feel great on smoother
roads and perhaps not that great in particular if the sway bars are (or are set) overly
stiff.


Does stiffening a sway bar also improves cornering speed or just the car's behavior? In this video I see almost the same cornering speed before and after a rear sway bar upgrade, so are there any real gains speed wise?

It depends on the stock roll and the camber curves. Some double-wishbone suspension
accordingly increase camber with bump-in/body roll, common McPherson struts do not.
As a result, very most passenger car suspension benefit from reducing roll to retain the
best tire contact patch. Better (more even) contact patch results in increased grip (on a
smooth surface at least). The inadequate camber curve is one reason why many smaller
cars (in particular FWD with a 60/40 weight distribution) don't follow the popular rule
you mentioned at the beginning. Positive instead of negative camber as a result of both
excessive roll and poor front suspension kinematics (camber curve) makes for excessive
understeer. Making the rear weaker (with a stiff rear sway bar only) can add some over-
steer, but that isn't making the car actually corner quicker.
.
 

inquirer

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I'd recommend to retain the
stock 'sway bar balance', which effectively means to alter both sway bars in the same manner.

First of all, thanks for the detailed answer. Driving a FWD I think I wouldn't mind with a little less understeer. If we are talking about adjustable aftermarket bars maybe changing only one is fine if it has an adequate range.
 
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Changing one only is rarely ideal. One exception being a base model
came with just one, while upper versions have two sway bars. What car
are we talking about? Is there a possibility to alter negative camber on
front? What tires are you running and what tire pressures?
.
 

inquirer

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Changing one only is rarely ideal. One exception being a base model
came with just one, while upper versions have two sway bars. What car
are we talking about? Is there a possibility to alter negative camber on
front? What tires are you running and what tire pressures?
.

The car is a Lancer of 2010, 1.5L.
Only the rear is available by Whiteline. The front one is not compatible with models with electric power steering, as the 1.5L version of the Lancer.
Tire pressure is 32 psi all around.
I have installed Koni Sport shock absorbers which have greatly improved handling, but I would like to tune the suspension further.
 

TiGeo

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  1. In most sites I read that stiffening the front sway bar increases understeer and stiffening the rear one increases oversteer. On I this site though towards the end of the article there is a table that states that for cars with a soft suspension setup and excessive roll the opposite is true. Is this the case? And what would be considered excessive roll? I guess most road cars, even sports cars, have much more roll compared to racing vehicles.
  2. What would be the downside of having both sway bars too stiff? (I'm talking about a case in which the understeer - oversteer balance has been set up fine.)
  3. Which is the best method for adjusting adjustable sway bars? Should the setup get tested in all types of corners tight, open etc. or is it safe to judge the car's behavior just from one test course?
  4. Does stiffening a sway bar also improves cornering speed or just the car's behavior? In this video I see almost the same cornering speed before and after a rear sway bar upgrade, so are there any real gains speed wise?
Thanks in advance for any answers!
On my awd Golf Sportwagen, and all the MQB chasis Golfs, the preference is larger RSB/leave the front alone to combat understeer. I run a 25mm RSB only and find it handles well across the board and certainly doesn't oversteer at all. Body roll is reduced.

I am now getting a larger (27mm) FSB installed during some chasis work b/c the front subframe will be out and am curious as well does this actually negate the improvements made by throwing the balance off with just a larger RSB. Many that have done just that (FSB+RSB) have not indicated so and note that the body roll is further reduced and handling is further improved.

I think that many people relate lowering body roll to improving handling but it's not necessarily the case.
 
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inquirer

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I am now getting a larger (27mm) FSB installed during some chasis work b/c the front subframe will be out and am curious as well does this actually negate the improvements made by throwing the balance off with just a larger RSB. Many that have done just that (FSB+RSB) have not indicated so and note that the body roll is further reduced and handling is further improved.

Probably stiffening the front bar will increase understeer, but if in the case of your car will also improve cornering speed then reaching that point where understeer happens it obviously takes pushing the car harder to reach its limit.

If the aftermarket bars are adjustable then after a trial and error procedure you can find out which setup suits you better.
 
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The car is a Lancer of 2010, 1.5L.
Only the rear is available by Whiteline. The front one is not compatible with models with
electric power steering, as the 1.5L version of the Lancer.
Tire pressure is 32 psi all around.
I have installed Koni Sport shock absorbers which have greatly improved handling, but I
would like to tune the suspension further.

I'd stay away from Whiteline's ARBs. I had them in my hands some years ago
(provided by Whiteline for testing). I wasn't impressed. Quite poor/rural build
quality, made in North Korea (yes, actually!), the centering rings being a joke,
which will likely let to issues longer term.
Best build quality is H&R (except specialty stuff like Tarett), 2nd best is Eibach.
If they don't make a front sway bar you could fit a rear one and set it to its soft
setting, but don't expect too much of a gain. I'd also do some research if Evo
ARBs do fit your Lancer.
Koni Yellows are still a great choice. I'd suggest to stiffen them just a tiny bit
to compensate for the increased total spring rate after fitting a (set of) bigger
sway bar(s). Are you on 16" or 17" tires? If you haven't yet a set of good UHP
tires would be your next worthwhile step. It perhaps doesn't make much sense
going beyond that on this car.


On my awd Golf Sportwagen, and all the MQB chasis Golfs, the preference is larger
RSB/leave the front alone to combat understeer.

Who's preference? The honest answer is forum talk. I tried virtually every imaginable
combination on both the PQ35 and MQB platforms and the above approach proved
inefficient. As a matter of fact virtually all people who promote the 'rear only' strategy
(or hype) have never ever tried stronger ARBs on both axles. That should tell you a lot.
If in doubt ask them. How many people have fitted bigger sway bars and removed the
front one? Guess nobody did that.
Please forgive me when I sound a bit rough, I don't intent to argue with you at all mate.
Maybe I have heard certain popular whisdom too often.


I run a 25mm RSB only and find it handles well across the board and certainly doesn't
oversteer at all. Body roll is reduced.

Marginally. You'd be impressed the day you have fitted a thicker sway bar on front. If
you find you car understeers too much solve the cause which is insufficient camber on
front. There's no way around that. Just remember rear camber commonly ranges from
-1°30' to -2°00' while front camber is less than -1°00', obviously resulting in understeer
(which isn't even necessarily a bad thing if not excessive). For the sake of simplification
I won't talk about the effects of toe (which is less in steady-state cornering anyway).
Because your Golf is a Sportwagen and AWD it's much more rear heavy compared to a
GTI or GLI, making the effect of a RSB likely more noticeable in a positive way.


I am now getting a larger (27mm) FSB installed during some chasis work b/c the front subframe will be out and am curious as well does this actually negate the improvements made by throwing the balance off with just a larger RSB. Many that have done just that (FSB+RSB) have not indicated so and note that the body roll is further reduced and handling is further improved.

It'll be immidiately noticeable and I'd bet you'll be pleased. Your steering will feel quicker.


I think that many people relate lowering body roll to improving handling but it's not necessarily the case.

Not necessarily, I agree. However it should be beneficial in both your case as well as in case
of inquirer's Lancer.
.
 

inquirer

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I'd stay away from Whiteline's ARBs. I had them in my hands some years ago
(provided by Whiteline for testing). I wasn't impressed. Quite poor/rural build
quality, made in North Korea (yes, actually!), the centering rings being a joke,
which will likely let to issues longer term.
Best build quality is H&R (except specialty stuff like Tarett), 2nd best is Eibach.
If they don't make a front sway bar you could fit a rear one and set it to its soft
setting, but don't expect too much of a gain. I'd also do some research if Evo
ARBs do fit your Lancer.
Koni Yellows are still a great choice. I'd suggest to stiffen them just a tiny bit
to compensate for the increased total spring rate after fitting a (set of) bigger
sway bar(s). Are you on 16" or 17" tires? If you haven't yet a set of good UHP
tires would be your next worthwhile step. It perhaps doesn't make much sense
going beyond that on this car.

Well, H&R offers only lowering springs and wheel spacers for the CY0 lancer. It's the same for Eibach. (They also offer splash guards, but obviously that's not what I'm looking for.)

I have also in mind the Evo's option. I'm not sure if the bars fit. If the models with electric power steering have an incompatible sway bar as Whiteline states, then I guess the front will certainly not fit. In that case even if the rear fits it may unbalance the car as it may be way to stiff to be used with the standard front one. That's why I would prefer an adjustable rear bar.

I have 16" rims with 205/60R16 Hankook Ventus Prime 3 tires. I don't know if switching to wider rims, 18" for example with 215/45R18 tires (always maintaining the same wheel diameter), would offer better handling because of the lower sidewall.
 

TiGeo

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Who's preference? The honest answer is forum talk. I tried virtually every imaginable
combination on both the PQ35 and MQB platforms and the above approach proved
inefficient. As a matter of fact virtually all people who promote the 'rear only' strategy
(or hype) have never ever tried stronger ARBs on both axles. That should tell you a lot.
If in doubt ask them. How many people have fitted bigger sway bars and removed the
front one? Guess nobody did that.
Please forgive me when I sound a bit rough, I don't intent to argue with you at all mate.
Maybe I have heard certain popular whisdom too often.
I am in agreement with you - simply passing out what I've read and folks have told me (that track their cars) w/r to doing a RSB only on a fwd car. But you are 100% spot-on - it's only b/c the front is a pain in the *** so nobody does it!
 
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Well, H&R offers only lowering springs and wheel spacers for the CY0 lancer. It's the same for Eibach. (They also offer splash guards, but obviously that's not what I'm looking for.)

Sad to hear that. What's the diameter of your stock sway bars? I assume
you don't have any sway bar rates available.


I have also in mind the Evo's option. I'm not sure if the bars fit. If the models with electric power steering have an incompatible sway bar as Whiteline states, then I guess the front will certainly not fit. In that case even if the rear fits it may unbalance the car as it may be way to stiff to be used with the standard front one. That's why I would prefer an adjustable rear bar.

I can't say if another stock FSB would fit, but if another stock RSB does, I'd
first see what's its diameter (or even rate). It might be similar in stiffness/rate
as an aftermarket one in its softest setting. So why would it cause more of an
unbalance than the aftermarket one?


I have 16" rims with 205/60R16 Hankook Ventus Prime 3 tires. I don't know if switching to wider rims, 18" for example with 215/45R18 tires (always maintaining the same wheel diameter), would offer better handling because of the lower sidewall.

Hankook's Ventus Prime 3 is a nice touring tire, but it's soft. By going for
215/45 R18 you not only gain grip and precision due to the lower sidewall
but more so due to being true UHP tires being available in that size though
a couple of decent tires are even available in Europe in your current size:

Hankook Ventus S1 Evo 2 K117 205/60 R16 92W
Bridgestone Turanza T-005 205/60 R16 96W
Michelin Primacy 4 205/60 R16 96W

Both Primacy 4 and Turanza T-005 are no true UHP tires, however they do
yield pretty excellent results in virtually any review. I'd bet they're at least
close to the Hankook Ventus S1 Evo 2. Regardless, reasonably bigger is
actually better. I wouldn't go that far and recommend going 215/45 R18.
If going bigger I'd consider 215/50 R17.


I am in agreement with you - simply passing out what I've read and folks have
told me (that track their cars) w/r to doing a RSB only on a fwd car. But you are
100% spot-on - it's only b/c the front is a pain in the *** so nobody does it!

Yeah, I forgot to mention that point. It IS a **** to swap the FSB on our MQB
cars (like it is on most) and that makes FSBs quite hard to sell. All the vendors
are aware of that fact, promoting mainly RSBs as a logical result.
.
 
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inquirer

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Sad to hear that. What's the diameter of your stock sway bars? I assume
you don't have any sway bar rates available.

I have no idea. I guess I can measure the diameter, but I'm not sure when I can find the rate.


I can't say if another stock FSB would fit, but if another stock RSB does, I'd
first see what's its diameter (or even rate). It might be similar in stiffness/rate
as an aftermarket one in its softest setting. So why would it cause more of an
unbalance than the aftermarket one?

Evo's RSB being similar with the softest setting of an aftermarket bar is surely one possibility. My assumption that it will be stiffer arises from the fact that is already matched with a thicker FSB on the EVO. Anyway, that's just an assumption.


Hankook's Ventus Prime 3 is a nice touring tire, but it's soft. By going for
215/45 R18 you not only gain grip and precision due to the lower sidewall
but more so due to being true UHP tires being available in that size though
a couple of decent tires are even available in Europe in your current size:

Hankook Ventus S1 Evo 2 K117 205/60 R16 92W
Bridgestone Turanza T-005 205/60 R16 96W
Michelin Primacy 4 205/60 R16 96W

Both Primacy 4 and Turanza T-005 are no true UHP tires, however they do
yield pretty excellent results in virtually any review. I'd bet they're at least
close to the Hankook Ventus S1 Evo 2. Regardless, reasonably bigger is
actually better.

I have used Dunlop Sport MaxxRT and Goodyear Eagle F1 Asymmetric 2 at 225/55R16 in the past (to keep wheel diameter exactly the same) and I can't recall a big difference on dry roads. There is a difference on wet. Of course maybe my comparison isn't that fair because I have in mind the performance during the end of the life of the previous tires which is obviously reduced. By the way, the Asymetrics dry rotted way too soon and their performance dropped substantially and prematurely.


Regardless, reasonably bigger is
actually better. I wouldn't go that far and recommend going 215/45 R18.
If going bigger I'd consider 215/50 R17.

Going to 215/45R18 is the option that keeps the diameter essentially the same (-0.26%), but your option too is pretty close (-0.86%).
 

TiGeo

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Sad to hear that. What's the diameter of your stock sway bars? I assume
you don't have any sway bar rates available.




I can't say if another stock FSB would fit, but if another stock RSB does, I'd
first see what's its diameter (or even rate). It might be similar in stiffness/rate
as an aftermarket one in its softest setting. So why would it cause more of an
unbalance than the aftermarket one?




Hankook's Ventus Prime 3 is a nice touring tire, but it's soft. By going for
215/45 R18 you not only gain grip and precision due to the lower sidewall
but more so due to being true UHP tires being available in that size though
a couple of decent tires are even available in Europe in your current size:

Hankook Ventus S1 Evo 2 K117 205/60 R16 92W
Bridgestone Turanza T-005 205/60 R16 96W
Michelin Primacy 4 205/60 R16 96W

Both Primacy 4 and Turanza T-005 are no true UHP tires, however they do
yield pretty excellent results in virtually any review. I'd bet they're at least
close to the Hankook Ventus S1 Evo 2. Regardless, reasonably bigger is
actually better. I wouldn't go that far and recommend going 215/45 R18.
If going bigger I'd consider 215/50 R17.




Yeah, I forgot to mention that point. It IS a **** to swap the FSB on our MQB
cars (like it is on most) and that makes FSBs much hard to sell. All the vendors
are aware of that fact, promoting mainly RSBs as a logical result.
.
I'm about to do the Superpro Al lower control arms and with a DSG, the subframe has to be dropped to do it so....FSB...deadset kit....yadda yadda b/c "you're already in there"..ahahaha
 
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I'm not surprised you'll do the job properly. (y)

@inquirer: I use to make my tire size choices with availability in mind.
Even when it comes to the very popular 225/45 R17 and 225/40 R18
sizes there are decisive differences. For example I went for 225/40 R18
on my GTI and 205/45 R17 on my Cooper not for looks, but mainly to
run Michelin PSS (and now PS4S in case of the GTI). I have sympathy
for running 17" and 16" respectively on these cars* and there are clear
advantages when it comes to less than ideal real-world roads. Some-
times I even need to slow down just because I feel with the car and I
certainly wouldn't need to do that on 15" or 16" wheels - a concern
not present on a perfectly smooth race track.

* which is what I run during winter
.
 
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  1. In most sites I read that stiffening the front sway bar increases understeer and stiffening the rear one increases oversteer. On this site though towards the end of the article there is a table that states that for cars with a soft suspension setup and excessive roll the opposite is true. Is this the case? And what would be considered excessive roll? I guess most road cars, even sports cars, have much more roll compared to racing vehicles.
  2. What would be the downside of having both sway bars too stiff? (I'm talking about a case in which the understeer - oversteer balance has been set up fine.)
  3. Which is the best method for adjusting adjustable sway bars? Should the setup get tested in all types of corners tight, open etc. or is it safe to judge the car's behavior just from one test course?
  4. Does stiffening a sway bar also improves cornering speed or just the car's behavior? In this video I see almost the same cornering speed before and after a rear sway bar upgrade, so are there any real gains speed wise?
Thanks in advance for any answers!

1) yes it is the case if the roll results in a lot of positive camber. The camber thrust when it's positive pushes you to understeer. When that becomes an issue depends on the tyres fitted, they all produce different amounts of camber thrust.

2) there's no issue if the understeer/oversteer balance is correct, except on rough roads, the car will react more violently than needed to bumps mid corner.

3) you'd need a low grip and high grip setup, say wet & dry.

4) they can increase cornering sped, or decrease it. But you're looking at 15% grip change either way (best case) which will result in 4% or so higher or lower cornering speeds.
 

inquirer

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