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      07-16-2019, 03:54 PM   #1
Kreester
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Swaybar setup for autocross

Ive recently fitted KW V3s on my 135i E82. Also have H&R 28 mm front sway and H&R 20 mm rear sway. In the front M3 control arms and Dinan fixed camberplate. Running square 245/40/17 Advan neova AD08R.

In my opinion the car feels neutral/ a bit understeer specially in high speed bends (on big tracks)and in tight corners (autocross).

I want to have the car a bit more tailhappy with more front end grip.

Anyone here that have tried with OEM front sway to gain more oversteer?

Any other solutions?
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      07-16-2019, 04:26 PM   #2
lowside67
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How much camber do you have? My estimate is you have less than -3 degrees based on Dinan plates plus M3 arms.

If I'm correct, the first thing you should do is add proper camber plates which will allow you to achieve more like -3.5 degrees. In my car, going from -2.8 to -3.6 was a HUGE improvement.

The second thing to consider is the spring rates in the KW V3s are very soft. The answer is probably not to go to a smaller front bar, but rather more rear spring.

-Mark
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      07-16-2019, 06:31 PM   #3
Ginger_Extract
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People get so triggered by this, but running the car with no sway bars, at all, made my car perfectly neutral, and it was actually faster in terms of lap times.
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      07-16-2019, 08:30 PM   #4
Mark Aubele
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Quote:
Originally Posted by Ginger_Extract View Post
People get so triggered by this, but running the car with no sway bars, at all, made my car perfectly neutral, and it was actually faster in terms of lap times.
People get triggered by it because it is absolutely ridiculous. If your 2010 Civic is running similar lap times to your heavily modified 135i, that might be a place I would start. If it worked, fast guys would be doing it, and NONE are (maybe in the wet, but that is another conversation entirely).
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      07-17-2019, 10:55 AM   #5
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The first thing to play with is tire pressures. Try going up a couple pounds in the rear and see if the balance changes. If you're only trying to dial out mild understeer in some conditions, it's reasonable to expect that you may be able to do it this way. If you can't get enough change out of it, then the question becomes one of either adding stiffness in the rear or taking it out of the front (or both). Personally, I don't like so much roll stiffness that you can't feel the weight transfer, so I'd opt for dialing back the front a little bit. It would probably be better to do it with spring adjustment rather than bars, but that's far less practical for a street car.
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      07-17-2019, 01:47 PM   #6
The Wind Breezes
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So since you're asking this you already have massive neg camber in front and reduced in rear right? And not too much toe in.
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      07-17-2019, 03:53 PM   #7
lowside67
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Quote:
Originally Posted by Ginger_Extract View Post
People get so triggered by this, but running the car with no sway bars, at all, made my car perfectly neutral, and it was actually faster in terms of lap times.
Without posting your spring rates and the car weight, this is pretty useless feedback as the addition of stiffer sway bars to a car with stock springs is complete different than a car running 800/1200 springs.

I'm open to being proved wrong, but I somewhat doubt that you have back to back tested your car with equivalently softer springs + sway bars versus your current springs and no sway bars to prove your thesis.

In general - "feel" is a terrible indicator of performance potential and unless you are running data logging and are a relatively accomplished driver, most people have far more variation in lap times resulting from driver than they think.

Again - not "triggered" and not bent out of shape, but would caution anybody from taking your post and assuming it is absolute truth. And if it was truly the case always, you wouldn't see virtually every street and race car using a combination of spring and sway bar.

-Mark
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      07-17-2019, 04:11 PM   #8
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To echo 02pilot, I would start with tire pressures.

Another easy thing to try is to increase your damper stiffness a touch in the rear.
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      07-18-2019, 10:27 AM   #9
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Quote:
Originally Posted by The Wind Breezes View Post
So since you're asking this you already have massive neg camber in front and reduced in rear right? And not too much toe in.
Front: -2,4
Rear: -1,5
toe in close to 0
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      07-18-2019, 01:35 PM   #10
lowside67
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Quote:
Originally Posted by Kreester View Post
Front: -2,4
Rear: -1,5
toe in close to 0
Please, before any other mods, increase camber both front and rear. You should be able to achieve around -3.5 with adjustable camber plates in front and this will change the car positively. You will also want to maximize rear camber with stock arms while not compromising toe in. This is usually around -2.1 to -2.3 depending on desired rear toe setting.

Your car will be faster and your tires will wear better.

I run street tire autocross in my highly prepared BMW 128i and to give you an idea, my codriver and I were the fastest of 21 cars in a close field at the SCCA National Tour in Packwood on day 2 this weekend. Our experience with this car is likely highly applicable to what you are doing.

-Mark
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