A sway bar works by connecting one control arm to the other control arm on the other side of the car. As you turn one control arm compresses and the other arm de-compresses. This causes the bar to twist. The lbs per inch of twist is the numbers we always talk about when comparing bar settings. The resistance of twisting the bar is what controls the body roll.

When running a stiff bar as one side of the car compresses the arm want to compress into the the fender well, on the other side of the car the arm is de-compressing away from the fender well. Although with that stiff bar the forces from the twisting actually pick up the de-compressing wheel from the ground. I've seen pics of cars lift the wheels completly off the ground to where you could see under the wheel. Street tires only have so much grip, lifting one off the ground makes the front tires have even less grip then they already do.

Think of it as being the same way as skiing. When you want to turn you transfer weight off one foot and onto the other. The foot you took the weight off of is the way you turn. Same thing with a sway bar. Your taking weight off one side of the car and putting weight on the other side. The stiffer the swaybar the more weight your taking off that inside wheel relative to the degrees the other side of the car is compressing. This is when when you run a stiffer bar it "transitions" / "turns" faster.


The issue your having is your asking to much out of the steering wheel and the fast transiting of weight onto one side of the car causes the car to quickly compress. The other side is lifting the tire or atleast taking alot of weight off that corner is causing you to push due to less overal front grip. You need to be smooth with your transitions and not just throw the car in, it's not going to turn when doing that. You should turn in and let the car settle don't just turn in and keep turning.

I hope I helped, I've explained it the best I can while typing on my phone at 2 in the morning. Sorry if this post seems dis-orgainized or rambling. I keep adding things as I thought of them to better explain the issue that people complain about when running a stiff bar.

Their is a line between having to much bar and taking to much weight off the inside front corner which is relitive to the amount of lateral grip the front tire can create. I would guess thier is some mathmatical calc that would say "if you have tires that can pull X amount of G's then you should only run Y amount of lb/in bar." Although to come up with this number it would take ton and tons of testing to get the baseline. Basicly ideally with more grip just as hoosier you "should" run more bar and with less grip tires such as kooks you should run less bar" On kooks I would guess this number is somewhere between 850 and 1138 lb/in rate calculated at the link.

Btw ball bearing mounts take out all of the slop or delay in the time of the the bar loading up. That's is why they are awesome and worth the $280.00

 

With a stiff front bar and no rear bar the car will be very pushy. Thats why we run the miata bar.

As for lots of rebound and a stiff bar with soft springs that's becoming popular in some forms of racing. Sort of like stock class set-up.

 

that depends a lot on driving style and other setup factors. for example, with my Saner front and no rear bar, I am balanced pretty nicely, with the car being slightly tail happy in transitions and slightly pushy in real tight turnarounds, and close to neutral elsewhere. Thats why a lot of the fast guys run no rear bar.

 

Thats interesting, So what fast guys run no rear bar? the top 9 people at nationals ran a rear bar and number 10 was fast dispite his set-up not because of it. Not trying to call you out, I'm just curious as to who besides you runs that set-up? The top 9 drivers all had the mx-5 bar on. The bar on seemed to work better then the no bar cars.

Now I will agree it's a driver style thing. Driving on a stiff bar takes a different driving style then driving on a softer bar. Softer bar your off throttle during elements because your waiting on the car to transition and can only drive the element so fast. Turn arounds and tight stuff the soft bar set-up you dont have to wait for the car to settle before getting on the gas. The stiff bar driving style consist of the throttle to the floor during transitions with just steering the car through the element but on tight turn arounds you have to wait to get on the gas. It's a trade off. I like taking a set with the throttle to the floor and the car just dancing through the cones, It makes me simle.

 

Thats interesting, So what fast guys run no rear bar? the top 9 people at nationals ran a rear bar and number 10 was fast dispite his set-up not because of it. Not trying to call you out, I'm just curious as to who besides you runs that set-up? The top 9 drivers all had the mx-5 bar on. The bar on seemed to work better then the no bar cars.

Now I will agree it's a driver style thing. Driving on a stiff bar takes a different driving style then driving on a softer bar. Softer bar your off throttle during elements because your waiting on the car to transition and can only drive the element so fast. Turn arounds and tight stuff the soft bar set-up you dont have to wait for the car to settle before getting on the gas. The stiff bar driving style consist of the throttle to the floor during transitions with just steering the car through the element but on tight turn arounds you have to wait to get on the gas. It's a trade off. I like taking a set with the throttle to the floor and the car just dancing through the cones, It makes me simle.
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Now when guys run the mx-5 bar in the rear . Being specific ? What year mx-5 ? is it a factory bar or a aftermarket bar but set to miata specs? I am interseted in that theory and by running an mx-5 bar what your doing is just running a tighter smaller bar that lessens oversteer but tight enough to prevent body roll ??

 

I recall thorne not having a bar, but could be wrong. Also, Glagola runs a stock ap1 rear bar, and Annie Bauer's car has the stock CR bar. So you're a little off on your blanket statement that the top 9 all had the mx5 bar.

 

I am using the '06 MX-5 Base FSB in the back of my car.

-D

 

I def gotta try that. These sway bar tricks are something that benefit ap1 or just S2000's in general.

 

I don't have an AP2, so I cannot answer that for sure. I just know the early AP1's had a huge ass RSB and going without a RSB was not to our liking. So, we wanted a smaller bar. This was just laying around and tried it out. Amazingly, it worked like a champ.

So, if the AP2's need less bar than the stock bar, it might be an option to try. I personally have not seen this installed on one, so I'm not sure of the fitment. I just know there had to be a little modifications to make it work with my '01.

-Dave

 

Sorry for my blanket statement that the top 9 all had mx5 bars. It was 4am when I posted that. 6 or 7 of the top 9 had mx5 bars. The point I was makin is no one in the top 9 ran what he claimed "all the fast guys run". I dont want some new comer reading this thread one day thinking "all the fast guys run no bar so i have to run that and work around it" because thats defiantly not the case. Also when Dave shared with the world the mx5 bar fits he told everyone it was a 06 base bar. That doesn't mean anyone hasn't got a different mx5 bar though.

Happy motoring...