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      06-03-2011, 02:11 PM   #1
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Are you excited? Post your autocross setups!



Does this make anyone else excited!?!?!?

I know it does for me because I have had this car for less than a week!!! And for a car that will see track duty this is the first time I can really push it. Yes autocross is different than the track but I don't have my carbon race brakes, 600 fluid, track wheels and tires yet, so this is as good as it gets right now!!!

Setup:
BONESTOCK M3 (although I did just get the windows done!)
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Stock PS2 245/40/18 and 265/40/18 - TPMS don't think it will help
Tire pressures 36/36, will test with chalk on the sidewall
stock camber - will remove the pins for next event
M settings - DSC OFF, EDC sport, sport steering, only thing I am wondering about is throttle "power button" I think I will start with it on sport and remove it if I'm unable to control the throttle enough

I am going to be so amped/jittery after I put on all my racing gear and line it up. KID IN A CANDY STORE!!! FAT KID IN A STEAKHOUSE HAHA!!! Any advice conserning tire pressure on stock PS2 & 18s appreciated or "power" settings. No autocross for beginners tips please unless they are M3 specific!!! Thanks I am so excited to do anything with this car!!! Oh yeah and its "American AutoX" so the courses are wider and designed for Corvettes, so I get to use the V8 a little.
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      06-03-2011, 03:08 PM   #2
arter
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I would set your tire pressures higher as autocross won't heat the tires ( and increase the pressure much).

With the soft sidewalls on PS2's I suggest 40-41....... especially if you don't have negative chamber yet.....


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      06-03-2011, 07:03 PM   #3
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M3 with new wheels and tires by dcstep, on Flickr

18x10" 19-lb Apex ARC-8 wheels with 25 offset, 275-35/18 Dunlop Direzza Star Spec tires (square set up) 4.10 final drive, Dinan springs and camber plates with -1.8-degree camber up front and 1.5-degrees in back. Tire pressures, 27 cold in the back and 34 in front.

About tire pressures, AX is more about traction under acceleration and manhandling the car through corners by trail-braking the car on its nose. Low
TP in the back (combined with appropriately wide wheels) give better acceleration than high TP. Low pressure in back also helps the car to rotate in tight corners. You want enough TP in front so that you don't roll the tires, but that'll depend more on camber and wheel width, than temp and pressure. Usually, if you do find a big sweeper on an AX, it'll be midway through and your tires will have gained several pounds. I used to run the stock 19" Michelin setup with TPs very close to what I use with this wider setup and it worked great. 40-pounds will reduce acceleration and reduce tire effectiveness, IME.

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      06-03-2011, 09:24 PM   #4
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Quote:
Originally Posted by dcstep View Post

18x10" 19-lb Apex ARC-8 wheels with 25 offset, 275-35/18 Dunlop Direzza Star Spec tires (square set up) 4.10 final drive, Dinan springs and camber plates with -1.8-degree camber up front and 1.5-degrees in back. Tire pressures, 27 cold in the back and 34 in front.

About tire pressures, AX is more about traction under acceleration and manhandling the car through corners by trail-braking the car on its nose. Low
TP in the back (combined with appropriately wide wheels) give better acceleration than high TP. Low pressure in back also helps the car to rotate in tight corners. You want enough TP in front so that you don't roll the tires, but that'll depend more on camber and wheel width, than temp and pressure. Usually, if you do find a big sweeper on an AX, it'll be midway through and your tires will have gained several pounds. I used to run the stock 19" Michelin setup with TPs very close to what I use with this wider setup and it worked great. 40-pounds will reduce acceleration and reduce tire effectiveness, IME.

Dave
Quote:
Originally Posted by arter View Post
I would set your tire pressures higher as autocross won't heat the tires ( and increase the pressure much).

With the soft sidewalls on PS2's I suggest 40-41....... especially if you don't have negative chamber yet.....

Both sides of the spectrum and I'm right in the middle. Luckily with a 2 day AutoX I will have time to tune my setup. I think the real test will be chalking the tires and seeing how much is used. If 27 is too low and PS2 sidewalks are too soft then I can see how much sidewalk was used and add pressure. But what would be the indicator of too high tire pressures?

Normally I aim for 42 hot at Laguna Seca and have had success with that. With AX I go just a few higher than stock, hence 36/36. I will just have to test it tomorrow. But I do feel you on the lower pressures in the rear, maybe I'll do 36F/30R cold and see what the chalk says! Thanks guys!
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      06-04-2011, 03:05 PM   #5
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My setup... oh wait is this not what you meant?



I usually drive the E90 in autox when my tires are almost corded on the E36 and I then swap the wheels over to the E90. I run 18x10s on the E36, so they fit nicely on the E90 as well. The E90 will easily finish off the tires in one event.

The E90 is fun to autox and surprisingly capable, but my E36 is 1000lbs lighter and the "slight" modifications I've done to it make it an absolute blast to drive.
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      06-04-2011, 03:08 PM   #6
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Quote:
Originally Posted by attbimmer View Post
My setup... oh wait is this not what you meant?

I usually drive the E90 in autox when my tires are almost corded on the E36 and I then swap the wheels over to the E90. I run 18x10s on the E36, so they fit nicely on the E90 as well. The E90 will easily finish off the tires in one event.

The E90 is fun to autox and surprisingly capable, but my E36 is 1000lbs lighter and the "slight" modifications I've done to it make it an absolute blast to drive.
Yeah I'll take the 1000 pound weight mod anyway, NICE!!!

What tire pressures do you run on both?
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      06-04-2011, 03:17 PM   #7
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So tire pressures of 36 front / 34 rear (cold) were too low, the sidewalks flexed over a few times especially under hard cornering or any sideways action. The only thing to consider is that it was very wet today so traction limit came faster than normal. Even with that I am going to amp the pressures up a little to at least 38 / 38. I think with higher pressures in the back I will be able to initiate tire spin a little easier to help with rotation. I will chalk the tires again and see how it goes tomorrow.
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      06-04-2011, 04:35 PM   #8
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Quote:
Originally Posted by Merked M3 View Post
So tire pressures of 36 front / 34 rear (cold) were too low, the sidewalks flexed over a few times especially under hard cornering or any sideways action. The only thing to consider is that it was very wet today so traction limit came faster than normal. Even with that I am going to amp the pressures up a little to at least 38 / 38. I think with higher pressures in the back I will be able to initiate tire spin a little easier to help with rotation. I will chalk the tires again and see how it goes tomorrow.
You want your rotation under braking, not under acceleration. It'll lose you speed on exit if the car rotates.

Trail-brake into the corner and the back should ideally get light and rotate you toward the apex. When your lined up in the direction that you want to go, apply the throttle smoothly to stop the rotatation and the progressively add throttle at the limit of adhesion. If you lose grip at the rear under acceleration then you're losing time. Midcorner rotation while scrubbing off speed and turning is "free" but rotation under accelleration is eating time.

Run less pressure in the back. Since you don't have any extra camber and stock wheel widths, you made need 38 in the front, particularly while you're learning, but I'd stick with 34 in the back.

Dave
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      06-05-2011, 11:51 AM   #9
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Quote:
Originally Posted by dcstep View Post
You want your rotation under braking, not under acceleration. It'll lose you speed on exit if the car rotates.

Trail-brake into the corner and the back should ideally get light and rotate you toward the apex. When your lined up in the direction that you want to go, apply the throttle smoothly to stop the rotatation and the progressively add throttle at the limit of adhesion. If you lose grip at the rear under acceleration then you're losing time. Midcorner rotation while scrubbing off speed and turning is "free" but rotation under accelleration is eating time.

Run less pressure in the back. Since you don't have any extra camber and stock wheel widths, you made need 38 in the front, particularly while you're learning, but I'd stick with 34 in the back.

Dave
THANK YOU, AMAZING!!!!

I have been using my track fundamentals for autocross, so I definitely have to change that up. I have been reading up on trail braking and I really like your analogies, thanks!!! So I will attempt trail braking today by turning and braking up to the apex to rotate the car more then normal, and then modulate the throttle out of the corner for maximum acceleration. That way I'm not using acceleration to turn at all and losing that speed.

And it's sunny/dry today so I will really be able to see what this beast is made of!
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      06-05-2011, 12:30 PM   #10
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Quote:
Originally Posted by Merked M3 View Post
THANK YOU, AMAZING!!!!

I have been using my track fundamentals for autocross, so I definitely have to change that up. I have been reading up on trail braking and I really like your analogies, thanks!!! So I will attempt trail braking today by turning and braking up to the apex to rotate the car more then normal, and then modulate the throttle out of the corner for maximum acceleration. That way I'm not using acceleration to turn at all and losing that speed.

And it's sunny/dry today so I will really be able to see what this beast is made of!
You're welcome.

Trail-braking requires some practice to achieve the optimal combination of braking and turn in. The turn-in is the easiest part because you're braking hard and the car will respond to lots of steering input; however, as you start easing off the brakes, then the steering input will need to be reduced in a correlated manner. When you get really good at it you'll be able to carry the braking all the way to the apex. While learning, you'll most likely brake too early and then coast a bit to the apex.

Trail-braking allows you to brake later and carry more speed into the corner, generating more cornering force because of the weighting on the front tires. The extra speed tends to allow the car's inertia to transition to rotation near the apex, saving the front tires and giving you a "free" extra few degrees of turning without scrubbing off as much speed as if you'd done it with steering angle.

Those coming from road courses need to realize that the transitions still need to be smooth, BUT you can take a lot more risk particularly when entering the very common U-turns of AX. Braking while turning, all the way to the apex, is a key to being fast in AX. If you're a little too late braking, then don't worry about missing an apex and running out to an exit pylon, just adjust the next time around and be thankful there are no guard rails, trees or fences to hit.

Let us know how it goes.

Dave
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      06-11-2011, 09:56 AM   #11
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Quote:
Originally Posted by Merked M3 View Post
Yeah I'll take the 1000 pound weight mod anyway, NICE!!!

What tire pressures do you run on both?
I'm running either A6 or V710 in 285/30/18 at all 4 corners. Hot tire pressures on the E36 are about 28 f 26 r. On the E90 they were about 32 front and rear.
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      06-14-2011, 04:16 PM   #12
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Dave, thank you so much for your help on trail braking again. I will be removing the alignment pins tommorrow and have a shop max out the camber for an added edge. I am running again with UFO on father's day.

Arter, Dcstep, and Attbimmer; thank you so much for the pressure inputs, here are the results after chalking and running 5 times at the autocross:

(cold pressures - 38F / 34R)


Passenger Rear



Passenger Front



Drivers Front



Drivers Rear

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      06-14-2011, 05:00 PM   #13
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Tires look fine.

Try taking the rears down to 30.
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      06-16-2011, 12:43 PM   #14
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I pulled the front aligment pins and maxed out front camber (feels great in corners!!!) and am now running:

Front left -1.75 camber, 1/32 toe
Front right -1.4 camber, 1/16 toe
Rear left -1.57 camber, 1/16 toe
Rear right -1.31 camber, 1/16 toe

I believe the rears are still within BMW specs, but since I have made the fronts more negative, I am assuming I can drop pressures in the front. There is less of a need for a stiff sidewall as the tires and wheels are more properly angled for corners?

So I am thinking pressures for the Norcal UFO autocross this Sunday: 36 F (down 2 due to increased negative camber) and 32/34 in the rear.
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      06-27-2011, 12:48 PM   #15
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I've now got 26 AX laps on my new tire/wheel setup. Since I first wrote in this thread, I've increased negative camber up front to -1.9-degrees and -1.8 in back. The square setup with 275/35-18 Direzza Star Spec tires on APEX ARC-8 18"x10" wheels is working very well. The bigger tire up front is allowing much more aggressive trail-braking into corners, yielding longer straights, faster cornering and nice controllable rotation at the apex.

My car is an E92 M3 up against turbocharged E46 M3 and we were racing at 6000-ft above sea level yesterday. Most of the E46 cars are prepared, with racing seats, back seat out and various suspension modes from camber plates up to coil-overs. The new tire/wheel package brought me into balance with those cars, despite several hundred extra pounds and hp loss due to high altitudes. I got a class win yesterday, but one or two of the better E46 drivers weren't there.

I'm meeting lots and lots of people that are saying that the tire pressure for E46 and E92 M3s is 35-lbs all around, assuming you've got decent negative camber. I'm now running cold pressures of 34-front and 28-rear and find that the traction under acceleration is much improved vs. 35-lbs in back. One of my turboed E46 competitors was complaining about lack of rear traction and he followed my suggestion and picked up almost a full second the first lap that he tried it.

If I didn't have 10-inch wide wheels and almost 2-degrees of negative camber, I'd run three or more additional pounds up front and probably around 32 to 34 in back, cold pressures.

Anyway, I love this square setup for street and AX.

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      12-17-2013, 04:18 PM   #16
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Quote:
Originally Posted by Merked M3 View Post
I pulled the front aligment pins and maxed out front camber (feels great in corners!!!) and am now running:

Front left -1.75 camber, 1/32 toe
Front right -1.4 camber, 1/16 toe
Rear left -1.57 camber, 1/16 toe
Rear right -1.31 camber, 1/16 toe

I believe the rears are still within BMW specs, but since I have made the fronts more negative, I am assuming I can drop pressures in the front. There is less of a need for a stiff sidewall as the tires and wheels are more properly angled for corners?

So I am thinking pressures for the Norcal UFO autocross this Sunday: 36 F (down 2 due to increased negative camber) and 32/34 in the rear.
I know this is an old-ish thread, but are you still autoxing with norcal UFO? I used to run with them a lot in my old Cooper S. I just bought a used M3 and plan to go out next year. It would be cool to meet up and pick your brain on autoxing the E9x m3.
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      12-18-2013, 02:26 AM   #17
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I know this is an old-ish thread, but are you still autoxing with norcal UFO? I used to run with them a lot in my old Cooper S. I just bought a used M3 and plan to go out next year. It would be cool to meet up and pick your brain on autoxing the E9x m3.
Hey whats up. Yeah I won AS this year with NorCal UFO!! I go to like every event. I ran full slicks last year and it was amazing! I know everyone there.
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      12-18-2013, 11:43 AM   #18
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Quote:
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Quote:
Originally Posted by fjork_duf View Post
I know this is an old-ish thread, but are you still autoxing with norcal UFO? I used to run with them a lot in my old Cooper S. I just bought a used M3 and plan to go out next year. It would be cool to meet up and pick your brain on autoxing the E9x m3.
Hey whats up. Yeah I won AS this year with NorCal UFO!! I go to like every event. I ran full slicks last year and it was amazing! I know everyone there.
Congrats on the win. The M is in AS? The SCCA rules say FStock. Although UFO runs one year behind the scca rules I guess.

I won 2008 GStock in my mini. It was basically a participation prize though since there were no other regulars for GS. ;-)

I see the first event is in feb. I am going to try and make it. I will most likely be on the michelins. You will easily destroy me.

If I do go I will come find you.
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      12-18-2013, 12:25 PM   #19
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I am running in STU class.. running KW V3 coilovers with Michelin PSS tires. When the Michelins wear out, I am probably going to Yokohama AD08R. I want more grip from my street tires and stiffer sidewalls. Alignment is set with -1.5 camber in front and -2 camber in back... The fronts are maxed out as far as it'll go with adjustment from pulling the pins.

The car is not really set up for just autocross as I also track and daily drive the car so there are some compromises in a "do everything" car. I've been autocrossing for 15+ years... the M3 is not very competitive in STU against modded Evos, STIs and E36 M3s which dominate the class.
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      12-18-2013, 01:54 PM   #20
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I am running in STU class.. running KW V3 coilovers with Michelin PSS tires. When the Michelins wear out, I am probably going to Yokohama AD08R. I want more grip from my street tires and stiffer sidewalls. Alignment is set with -1.5 camber in front and -2 camber in back... The fronts are maxed out as far as it'll go with adjustment from pulling the pins.

The car is not really set up for just autocross as I also track and daily drive the car so there are some compromises in a "do everything" car. I've been autocrossing for 15+ years... the M3 is not very competitive in STU against modded Evos, STIs and E36 M3s which dominate the class.
Yeah I usually get competitive with my times but in reality I know the M3 isn't the best for autox. My primary goal is going to run with DSC off to understand how to better manage RWD. (And have fun)

I come from lots of FWD and AWD cars so I don't feel like I have enough experience with RWD.

Like you I also plan on doing at least 2 track days a year. More time permitting.
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      12-19-2013, 02:35 PM   #21
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I've got a year and a half now autocrossing in this car. It's a stock ZCP coupe (DCT) with AD08's (highly underrated tire) and I can say for a stock car, it's been great.

I had an E46 M3 with a full suspension that I ran in STU before for a number of years and although that handled better, and was smaller and lighter (and faster), it did not have the grunt the E9x's V8's do. With the RTR class and the car in FS, I was paxing higher than I was in the E46 even though I'm around 1.5-2 sec's slower.

I run without traction control and after the first run and it's reasonably warm (60+), on the stiffest EDC setting. I have not gotten an alignment but did pull the pins which produced a noticeable, albeit small, difference in handling. I feel like you can overcome any understeer with the throttle and I find the car is very manageable when things start to get hectic. I was recently in close to a 90 degree drift at an autox, not on purpose, and was able to bring it back under control moving at close to 50mph. I took a passenger that run and he was laughing the whole time. He used to own an E90 M3 and says he misses it every time he rides with me. He now drives a full on ASP 997 GT3 on slicks, so it's nice to hear he's still impressed with the M3.
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