Front Sway Bar Disconnection for Autox - A Discussion

[kivnul]

I am trying out new stuff in order to improve my AutoX experience. Currently I can carry plenty of speed thru quick slaloms but I cannot apply any throttle on turns until the car has leveled out: the inside front tire just has no grip with the increased HP. There is a older Civic in my class who disconnects his front sway bar for good effect. I am pretty new to suspension changes but from what I understand:

More front sway = quicker turn response
Less front sway = better inside tire downforce at end of turn

I am running stiffer springs from the MeisterR coilovers: I have heard its possible to bottom out a suspension without a sway bar and I am hoping the stiffer springs prevent that.

Anyone have some thoughts on this?

 

[RubenZZZ]

No front sway bar and a rear bar was the hot ticket for civic handling. This allowed the car to rotate a bit more versus always having understeer.



Sent from my LGLS992 using Tapatalk

 

[theblue]

In the scenario you describe the real answer is a limited slip. The next best thing after that is getting more weigh down on the inside tire. Trail braking will help, anything to get the nose down. With front wheel drive, one you've over-driven the car into a turn on entry its tough to recover until you scrub speed or remove steering angle really. Once you're past the apex and are able to start to unwind you'll notice you can get some grip again and pull out of the turn. You can induce rear lift off oversteer by violently pulling your foot off the gas in these cars which really brings the back around nicely I find.

None of this stuff is a single answer fix. changing one thing impacts others and there is so much you can try which comes with experience. even changing tire pressures can help.

 

[jeffreylyon]

More front anti-sway == grip balance to the rear (tending towards understeer)
More rear anti-sway == grip balance to the front (tending toward oversteer)

Decreasing front anti-sway by disconnecting the front (anti-) sway bar will increase front grip by allowing more weight to transfer to the outside tire..., and less on the inside tire. That may exacerbate your roll-on problem. You're exiting the turn so it's too late for trail braking and it's unlikely that a dab of break to transfer weight to the front is the right thing, either; you're rolling on the throttle so you're ready to open your line, not tighten it.

I did an a/c class with a Pro driver that raced in the SCCA Spec-B series. His advice was to, in some cases, enter at a slower speed to give yourself enough margin to accelerate through the turn, pushing the balance towards the rear and holding it there through the turn for a faster exit speed. You could also try a later apex to straighten your exit - here's where trail braking and pushing the car to rotate will help you get to the exit more quickly.

And, yes, this is the best use-case for an LSD, but improving your car isn't anywhere near as satisfying as improving yourself.

 

[kevinatfms]

How much camber do you have dialed in? Are you class legal to add camber bolts or do the Meister R coilovers have camber plates up top?

 

[jeffreylyon]

How much camber do you have dialed in? Are you class legal to add camber bolts or do the Meister R coilovers have camber plates up top?

He's trying to increase traction on the inside wheel; more negative camber will make it worse, although it might allow him to apex later and roll on sooner.

 

[kevinatfms]

He's trying to increase traction on the inside wheel; more negative camber will make it worse, although it might allow him to apex later and roll on sooner.

I would want to get the car to rotate as much as possible as early as possible, so your corner exit is a straighter shot which reduces wheel spin in whole. As he already has the car good through the slaloms(he has good balance F/R). If he removes the front bar he is going to upset the balance during the slaloms. Adding a little bit of camber will allow him to plant that front outer wheel earlier without upsetting the balance of the car through the other portions of the course.

Also, older Civics are significantly lighter than a Fiesta ST and can run crazy high spring rates with no front bar. I dont see it being any benefit on a Fiesta but try it out and report back. I would think that with no rear bar and no front bar the car will wallow through the slaloms.

Test it out and see. Report back so we all know how it reacts.

 

[kevinatfms]

On another note, i know some were trying a bigger front bar. I could see this working in theory as it would keep the tires planted more but it would add more understeer. Has anyone run a bigger front bar and seen any increase in contact patch/understeer?

Since OP has coilovers, go with a high rate rear spring(550-700ish), larger front bar(to maximize front contact patch) and regular(350ish) rate front springs?

One more thing to consider, is the front bar preloaded by the OP's lowering? Could reducing front bar preload allow more traction on corner entry/exit while still allowing the roll rate of the bar to come into play?

 

[Scotman2]

You don't mention what class you are in....

That dictates what you can do that is acceptable within the rules structure for the club. All that aside. I like to take a more holistic approach to the problem. And that approach is weight management. Not just how much but where can it be removed or at least moved to a more advantages position. Do you drain the washer fluid? A full reservoir is 12 lbs. The battery, is it possible to get a lighter one? (I have tried and used a garden tractor battery! It will work, but not if you are using a/c, radio and running a 12v inflator.) Spare tire and tools? Lose em'. Battery relocation to the right rear most corner will help you offset the mass of the meat bag behind the wheel. A true limited slip differential is an effective addition. I found that adjustable front asb links will become a very effective addition if several of the above changes are done. The best effect will be had if you can set the car on some scales with slip plates under the front tires. And then make the bar adjustment to better distribute the weight, including some mass simulation of the driver in that position. I never see any discussion of these points here.

 

[jeffreylyon]

I would want to get the car to rotate as much as possible as early as possible, so your corner exit is a straighter shot which reduces wheel spin in whole. As he already has the car good through the slaloms(he has good balance F/R). If he removes the front bar he is going to upset the balance during the slaloms. Adding a little bit of camber will allow him to plant that front outer wheel earlier without upsetting the balance of the car through the other portions of the course.

Also, older Civics are significantly lighter than a Fiesta ST and can run crazy high spring rates with no front bar. I dont see it being any benefit on a Fiesta but try it out and report back. I would think that with no rear bar and no front bar the car will wallow through the slaloms.

Test it out and see. Report back so we all know how it reacts.

That's what I mean by late apex-ing. Rotate more in the entry of the turn to straighten out the exit, allowing him to roll-on sooner.

 

[jeffreylyon]

One more thing to consider, is the front bar preloaded by the OP's lowering?

Not as long as both sides are lowered equally. That's the difference between an anti-sway bar (roll stiffness) and stiffer suspension springs (corner stiffness).

 

[kivnul]

Thanks for the discussion fellas. Currently in Street Modified Front (SMF) class. The Coilovers do allow some camber adjustment. Currently at about -1 and I am wearing out the outside of tires quickly so I will probably dial in about -2 for next season. The rear has been stiffened up a bit with a Pierce Torsion bar stiffener.

One point I would like to get clarification on: a sway bar effectively lifts up an inside tire; it is using the inside tires spring in order to stiffen up the outside spring to prevent roll. My premise was that by removing this link the inside tire can fully extend to the roadway = more pressure = more traction. One of the above posts made it sound like the exact opposite. As I am not an expert at this my premise could be what is in error.

As to a LSD, it is a pipe dream. I do not know of any local(ish) shops that I would trust to do the work. Add that to the price (about $2k installed) and I am wanting to try my luck at adjusting what I currently have to see if I can get a little more grip late in a turn. A LSD is the one item I am scared to do myself (Ive done everything else).

If disconnecting the sway bar does nothing (or makes things worse) I will probably pick up adjustable links so that I can corner balance the car better (I do have a good alignment shop nearby)

 

[theblue]

lets back up a little.

A sway bar is a spring. It connects one side of the loaded suspension to the other side. So if you're turning right, the driver's side strut compresses, the sway bar translates tension to the passenger's side raising the inside wheel also.

If you think about it like that, you can picture what happens with more sway, less sway, no sway, stiffer or softer springs in each scenario. You also have to think about what it happen on the other two contact patches at the back. everything is impacted by every change.

this explains it better: https://auto.howstuffworks.com/question432.htm

 

[kivnul]

Quoting from the above link is this "What you would like is for the body of the car to remain flat through a turn so that the weight stays distributed evenly on all four tires." This is suggesting that FLAT = EVEN WEIGHT per tire. This is opposite of how I understand a sway bar to work. It does indeed help keep the car flatter at the expense of less weight pressing down on an inside tire.

 

[jeffreylyon]

https://auto.howstuffworks.com/question432.htm

That article is absolutely incorrect. "Roll is bad. It tends to put more weight on the outside tires and less weigh on the inside tires, reducing traction." Wrong, wrong, wrong. An anti-sway bar *decreases* roll, which *decreases* weight transfer, which *decreases* traction. We often like to add an anti-sway bar or torsion bar stiffener to the *rear* of our FiSTs to decrease rear traction and help rotation. In general, increasing anti-sway moves balance to the opposite axle, to a point, of course - removing the front anti-sway may decrease front traction by throwing way too much positive camber to the outside tire or even by bottoming the suspension.

At slow tracks where they can't generate meaningful downforce, F1 guys *decrease* anti-sway (*increasing* roll) to aid in traction - think Monaco. At high-speed tracks where there's lots of downforce, they increase anti-sway to decrease weight transfer to avoid blistering the tires.

 

[theblue]

It's not wrong, it's just simplistic. If you take Monaco where you would reduce anti-sway I would expect they at the same time increase spring rate to reduce roll (the goal being stay flat, compliant, but don't transfer left to right)

 

[jeffreylyon]

It's not wrong, it's just simplistic. If you take Monaco where you would reduce anti-sway I would expect they at the same time increase spring rate to reduce roll (the goal being stay flat, compliant, but don't transfer left to right)

It's not simplistic, the statement is flag wrong. Weight transfer *increases* grip. More anti-sway == less weight transfer == less relative traction across that axle. Lift-throttle or trail-brake oversteer an another example of transferring traction with weight transfer.

Re. F1 - they want roll and weight transfer to aid in mechanical grip *and* want more corner compliance in bumpy street circuits. They decrease anti-sway for more weight transfer and decrease corner rate for more compliance and because they don't have to offset tons of downforce (although most high-spec race cars use a combination of springs to provide different rates depending upon travel, so it's not as simple as just reducing or increasing a single rate).