Are sway bars worth it?

[Ultramaroon]

I cross a nice perpendicular pavement gap in a long left-handed downhill sweeper. It limits my approach enough that I have to let up on the wheel to distribute the "event" evenly to the chassis, and then lean back into it. It's my adopted test corner.


Also maths.

[86MLR]

Originally Posted by nikitopo

Sway bars are used in our cars by the factory and they are not a band aid solution. They make handling worse only when the sizes and stiffness rates of the bars are going beyond reasonable limits. In fact they are a nice alternative if you want to have a relatively comfortable suspension on straights without much roll on corners. Good solution for a weekend fun and occasional race track car. People don't use them too much, because they want usually at same time to lower the car and in this case they don't work alone without changing the spring lengths and rates.

I realise that swaybars come standard, I was talking about aftermarket bars, where people tend to go stiffer "because" they don't actually understand what is required, generally.

Opinions may vary

[Capt Spaulding]

As others have said, sways would be my last stop on the suspension odyssey. Getting them right is not entirely straightforward. If I had managed to build a good wheel/tire/shock/spring/camber/everything else setup and the suspension(body roll) was still preventing the car from doing what I wanted (and was able to correctly ask) it to do, I'd either hit the books hard or get advice from someone who REALLY knows suspension set up.

[Icecreamtruk]

For what its worth, I think I have an experience worth sharing.

At my last time trial, a week ago, I disconnected the front sway bar to try and get rid of some unwanted understeer I had picked up after my spring rate change from last season. Funny things happened, the first interesting (and expected) thing was the car had more grip on steady stat cornering, but was a bit more sluggish changing directions, which hurt quite a bit on S type corners. The second, less expected problem was that the car was lifting the inside rear wheel during cornering. So at the moment of getting back on power I was getting a lot of wheel spin on the inside tire and losing quite a bit of time there. Even tho the data shows higher mid corner speed, the car was actually slower over the whole lap, losing quite a bit of time on corner exit (probably due to spinning a wheel).

For those curious, I was pushing quite hard, not just doing parade laps (start at 2:30 to skip the warm up lap). This is with the sway bar, best time is 1:44.1, best time with sway bar off was 1:45.6

[ame]https://www.youtube.com/watch?v=IjzuZ60W0CE&t=150s[/ame]

[wparsons]

Originally Posted by Icecreamtruk

For what its worth, I think I have an experience worth sharing.

At my last time trial, a week ago, I disconnected the front sway bar to try and get rid of some unwanted understeer I had picked up after my spring rate change from last season. Funny things happened, the first interesting (and expected) thing was the car had more grip on steady stat cornering, but was a bit more sluggish changing directions, which hurt quite a bit on S type corners. The second, less expected problem was that the car was lifting the inside rear wheel during cornering. So at the moment of getting back on power I was getting a lot of wheel spin on the inside tire and losing quite a bit of time there. Even tho the data shows higher mid corner speed, the car was actually slower over the whole lap, losing quite a bit of time on corner exit (probably due to spinning a wheel).

For those curious, I was pushing quite hard, not just doing parade laps (start at 2:30 to skip the warm up lap). This is with the sway bar, best time is 1:44.1, best time with sway bar off was 1:45.6

Lifting the inside rear isn't unexpected IMO. You softened up the front roll stiffness significantly without undoing the rear bar, so the car is rolling onto the outside front tire much harder while the rear bar keeps the inside rear tire lifted.

[Icecreamtruk]

You are right that it wasnt probably unexpected for most, but it was for me, as the car has quite the stiff spring setup and quite a bit of downforce (not into the thousands pounds, but not that far). To think that just undoing the front bar will completely lift of the ground the rear kinda did caught me by surprise. Its not a shoft wheelbase hothatch after all.

[ZDan]

Originally Posted by Icecreamtruk

At my last time trial, a week ago, I disconnected the front sway bar to try and get rid of some unwanted understeer I had picked up after my spring rate change from last season.

Never heard of anyone disconnect a sway bar at the NON-driven end of a 2wd car in an attempt to go faster at the track! Not surprised it didn't work... but good on ya for trying something absurd, sometimes worth a shot when in a bind and at least you learn something.

[Pat]

The fastest 86 I know of in my region is has (or had?) the front sway bar removed. it is a fully built car for WRL. I don't know much about the car, but anti-sway bars are just one of many variables in setup.

[Racecomp Engineering]

The answer is of course "it depends." Love that answer.

In the early Subaru USDM WRX and STI days, the choice was often presented as "soft springs and stiff bars" or "stiff springs and soft bars" for most track cars and autocrossers. The latter meant good quality coilovers so that the ride wasn't crap, which meant you needed a bigger budget. It was the better choice, but you really could just thrown on a bigger set of swaybars for 400 bucks and it was a massive difference over stock for those understeering pig cars. Of course a lot of people started going way too big and found the limits of that tuning philosophy when cars with reasonably stiff springs and reasonably stiff swaybars were faster than them.

Subaru increased the rear bar size ever so slightly on BRZs in 2017. Does this mean that bigger bars are better? No. It means that they decided that they wanted slightly more front grip than they did on the previous cars. They could have increased front grip by increasing rear spring rate (could alter ride and pitch characteristics too) or decrease front spring (also alter ride and pitch and result in more bumpstop engagement) or more front camber (much more complicated on their end than it sounds) or a variety of other things. It's not necessarily the best way to increase front grip, but for them a rear bar size increase of 1mm was an easy, cheap, and straightforward way to achieve what they wanted to achieve.

With regards to bumpstops, these cars are very bumpstop active. You're well into your bumpstops when you hit the brakes hard and turn into McDonalds and get a BigMac with a large fry and a liter of cola AND you very well could be into your bumpstops when you just sit back down in your car after your done eating. It's designed into our cars (and many other cars) stock.

Swaybars (and bumpstops) can be used in different ways by different tuners and OEMs...the important thing is that the complete package is considered when making any changes.

- Andrew

[strat61caster]

Originally Posted by Racecomp Engineering

or more front camber (much more complicated on their end than it sounds)

How so? They've sold cars with adjustable camber bolts before (definitely STI's had them), the OE struts are sized for them, it would be cake to toss a pair in and have them roll off the line with -1.2° or so...

Edit: your comment about 'stiff sways soft springs' vs 'stiff springs soft sways' is really relevant to the discussion imho, there's a middle ground and a mild upgrade from stock that's reasonable that some people will like, some won't. Good luck OP.

[Racecomp Engineering]

Originally Posted by strat61caster

How so? They've sold cars with adjustable camber bolts before (definitely STI's had them), the OE struts are sized for them, it would be cake to toss a pair in and have them roll off the line with -1.2° or so...

I think the difference is a new rear swaybar is just a new part they use in assembly, whereas camber bolts require a new part number AND some adjustment during assembly. Not much, but enough that it's an additional process.

Mitsubishi EVOs had a 2 postion camber bolt on their front struts that was either -1 or -2 degrees. All were assembled the same way in the -1 position. It was simple and effective for an OEM and man I wish Subaru did at least that for the BRZ.

Originally Posted by strat61caster

Edit: your comment about 'stiff sways soft springs' vs 'stiff springs soft sways' is really relevant to the discussion imho, there's a middle ground and a mild upgrade from stock that's reasonable that some people will like, some won't. Good luck OP.

Agreed!

- Andrew

[Ultramaroon]

Originally Posted by Racecomp Engineering

Agreed!

- Andrew

Would you ever ditch the sways in favor of higher spring rates? Is that just crazy talk?

[churchx]

Both STI & Evos are priced much higher. No wonder they include some bits that customers paying premium expect. Twins main trait is "good enough for cheap", like spiritual predecessor, AE86. It would have been nice .. but no stock camber adjustment is just one of bits, that didn't pass through budget trimming.

[Tokay444]

Worth what?