Better handling by removing/reducing swaybars?

[Chad_W]

I'm wondering with our lower center of gravity and huge choice of stiffer springs and dampeners, can we benefit from reducing anti-roll stiffness?

Ideally the ideal suspension is about the correct spring rates and appropriate dampening. The roll bars should just be used to dial in understeer/oversteer

Has anyone played with this idea? I'm thinking primarily from a street car perspective, where improved ride quality is appreciate and more independent wheel movement can provide more overall grip.

As an example, the new Miata has a bit of body roll, but an tremendous amount of grip and reasonable compliant suspension.

[Calum]

Let's just get this out of the way quickly.

Your car will be unpredictable and thus unsafe without the sway bars.

That other guy ran without them and didn't kill himself.

Nobody cares about that other guy.

Well, OK, some think he's an innovator.

There we go, now this thread can carry on without interruption about that guy and his research.

[GSpeed]

Originally Posted by Chad_W

I'm wondering with our lower center of gravity and huge choice of stiffer springs and dampeners, can we benefit from reducing anti-roll stiffness?

Ideally the ideal suspension is about the correct spring rates and appropriate dampening. The roll bars should just be used to dial in understeer/oversteer

Has anyone played with this idea? I'm thinking primarily from a street car perspective, where improved ride quality is appreciate and more independent wheel movement can provide more overall grip.

As an example, the new Miata has a bit of body roll, but an tremendous amount of grip and reasonable compliant suspension.

It's all a balance. If you were to take the sway bars off the car, you'd have waaaay too much body roll. We can all agree on that. But let's say you increase your ride frequency to something super high like 6-7 Hz to make up for the lack of roll bars. Something sufficiently high to get your roll rate back down to the 1-2-1.5°/G level that's a good non-downforce racecar level. Now you've put some massive, massive springs on the car, so stiff that your car is upset at the slightest bump and you're skating all over the track.

So why not just have a higher roll rate? Weight transfer. It'll take forever for the car to take a set from one corner to another.

If you want to make your car roll like a Coupe DeVille, then yes, take off the sway bars. But you'd be messing up all kinds of analysis that's been done on matching ride and roll frequencies to the environments these cars will see.

[Sammakko]

i'd leave the front swaybar in place, and try deleting the rear (you don't have to remove it to do your testing, just disconnect one of the link arms). MR2Spyder guys go FASTER without a rear swaybar. allowing the back of the car to "roll" while keeping pressure on the outside front tire, can help with oversteer, which the ft86 is extremely prone to, especially with helical diff..

[wparsons]

Originally Posted by Sammakko

i'd leave the front swaybar in place, and try deleting the rear (you don't have to remove it to do your testing, just disconnect one of the link arms). MR2Spyder guys go FASTER without a rear swaybar. allowing the back of the car to "roll" while keeping pressure on the outside front tire, can help with oversteer, which the ft86 is extremely prone to, especially with helical diff..

I would be extremely shocked if lap times improved by just removing the stock rear bar. I also wouldn't call it extremely prone to oversteer.

Even on the stock tires, the FRS (loosest rear of all FT86 models) is still understeer biased in steady state cornering. They're easy to get sliding on the stock tires, but that's power oversteer and not too much rear bias.

With sticky tires, that bias is more obvious. Can you make it oversteer, sure, but it's also very easy to make it understeer. I've got A LOT of track kms on mine, and I don't find it overly tail happy at all, even with an alignment designed to give it more rotation.

Beyond that, they're VERY east to catch if the tail does step out.

Drive an AP1 S2000 and an FRS back to back and you'll understand

[Sammakko]

Originally Posted by wparsons

Drive an AP1 S2000 and an FRS back to back and you'll understand

haha, point taken!

[Kostamojen]

Some base model Imprezas, which have the exact same rear suspension as this car, come from the factory without swaybars...

They also handle like crap.

[Hoosier Daddy]

You'd need to figure out how much extra front spring stiffness would be needed to compensate for unhooking the front FARB, or maybe not if the OEM FARB doesn't contribute much to roll stiffness. But you would be sacrificing ride comfort due to the stiffer corner springs to have optimal roll stiffness distribution (whatever you think that is).

Otherwise, it's not a huge deal. Generally, though just like OEM springs, the OEM ARBs are puny, and are increased in size when converting over to a race car. Also, there is a reason ARBs are unhooked in sessions with rain and plenty of different racing cars run with bars unhooked, albeit in the rear most of the time.

[Chad_W]

In the spirit of spit balling....

Let's say you already decided you want to lower your car about an 1 inch, you add some springs that are about 30% stiffer and Bilsteins.

At the same time you replaced the OEM sway bars with ones 2-3mm less in diameter... Would you retain some ride comfort here, while shifting some of the anti roll responsibility to your now stiffer strut/spring combo?

I'm really only thinking about this for a street application. The desired result would be to not sacrifice too much compliance, while going to a slightly more aggressive spring/strut combo

[GSpeed]

Here's a plot showing roll gradient (°/G) over three laps.

Green- Stock springs, stock bars
Red- 400 lb springs, stock bars
Blue- 400 lb springs, Whiteline Bars (3X & 2X stiffer than OEM)

This shows the effectiveness of springs and bars fairly well. Increasing spring rate by a factor of 2.5 or so dropped the roll gradient by what, 30%? If your springs were only 30% stiffer, your roll gradient would hardly be affected.

Considering you're looking at this from a street perspective, I think you're going about it backwards. Bars will allow you to corner flat while maintaining compliance over bumps, whereas stiffer springs all around will handle everything like a skateboard.

[venturaII]

If your combination of aftermarket springs and sway bars equaled the same total amount of roll resistance as a stock combo provided at a given amount of input, then the total amount of lean wouldn't be any different. However, given that you'd need to calculate the curve for two different contributing components to the total amount of roll resistance and compare how their overlap plotted out compared to oem, I don't think you'd ever come up with the same overall curve using a different combination of rates. If you used lighter bars, then you'd need correspondingly stiffer strings to compensate, which would pretty much ruin your ride quality in a straight line. The oem setup is pretty generous with stroke right out of the box, and is a pretty good blend of compliance and camber control, as is, for a strut front end. If anything, lighter springs/shocks and heavier bars would offer a more compliant ride while keeping overall balance/geometry roughly the same. There'd still be sacrifices in other areas though.

[Hoosier Daddy]

Originally Posted by PST

Here's a plot showing roll gradient (°/G) over three laps.

Green- Stock springs, stock bars
Red- 400 lb springs, stock bars
Blue- 400 lb springs, Whiteline Bars (3X & 2X stiffer than OEM)

This shows the effectiveness of springs and bars fairly well. Increasing spring rate by a factor of 2.5 or so dropped the roll gradient by what, 30%? If your springs were only 30% stiffer, your roll gradient would hardly be affected.

Considering you're looking at this from a street perspective, I think you're going about it backwards. Bars will allow you to corner flat while maintaining compliance over bumps, whereas stiffer springs all around will handle everything like a skateboard.

Unfortunately, all your plots show is less body roll with stiffer springs and then even less with stiffer springs and stiffer bars. That doesn't say anything about actual handling. If body roll is really bad then even stiffer springs/bars is better... Although, your last point is more than valid, mirroring my own comment.

[wparsons]

Originally Posted by Kostamojen

Some base model Imprezas, which have the exact same rear suspension as this car, come from the factory without swaybars...

They also handle like crap.

They don't have the exact same rear suspension... they use the same control arms, that's it. They sit at a different geometry at stock height, use very different shock and spring rates, and the weight distribution is way different.

[Captain Snooze]

I have driven my car without swaybars with 6k/6k springs and am now driving without swaybars on 9k/10k springs. There is no way I am going back with sways.

(For what ever reason I can't quote PST)

"Bars will allow you to corner flat while maintaining compliance over bumps [1], whereas stiffer springs all around will handle everything like a skateboard.[2]"
1/ There is no free lunch. Anti roll bars tie the suspension together at each end. If the anti roll bars make up a high percentage of total roll stiffness there will be a reduction of independance.
2/ You have stated a either/or argument but there are many different rates of spring that are stiffer. 20% stiffer or 400% stiffer?

"If you were to take the sway bars off the car, you'd have waaaay too much body roll.[3]"
3/ I have not driven my car without swaybars on stock springs but I am hypothesizing that given how small the standard anti-roll bars are their removal wouldn't turn the car into a rolling monster.

Because compromise.