Autocross nerd thread: The Ultimate E9X A-Stock SCCA Autocross Build?

[BimmerFreakJoe]

Edit:

A-Stock Rules!

[Richbot]

You're welcome to try it.

[BimmerFreakJoe]

Originally Posted by Richbot

You're welcome to try it.

Edit:

A-Stock Rules!

[Maypo]

Originally Posted by BimmerFreakJoe

As I see it; STU is the class that makes most sense for M3 drivers that want to have the most desired mods on their street car, yet still have a somewhat competitive Solo car come race day.

I agree completely, I'm just not happy with being "somewhat competitive."

[BimmerFreakJoe]

Originally Posted by Maypo

I agree completely, I'm just not happy with being "somewhat competitive."

Edit:
A Stock Rules!

[Richbot]

Didn't you start an STU thread? Let's talk about it in there.

[BimmerFreakJoe]

Originally Posted by Richbot

Didn't you start an STU thread? Let's talk about it in there.

Are you serious?

Need a hug?

[Richbot]

So I've got a couple weeks until my next event (which will be the first event on the new MCS 2-way Stock-class dampers) and I got bored and wanted to check my math on curb weight, so I threw the Hoosiers on the car and weighed the car. I also test-fitted 315/30-18's on the front...

The car weighed 3522 with about 2-3 extra gallons of gas in it, but otherwise set up how I would compete in it with all trunk junk and spare change removed. I can autocross without any fuel starve until well below the 1/4 tank mark, the car was at about 3/8 tank. So figure conservatively there was 12 lbs of extra weight in it. This all makes sense considering I was figuring 3500 with 1/4 tank on the stock shocks and now with the ~8lb weight gain I'm at about 3510 with 1/4 tank.

The car could lose some in the wheels as my TR MT1's are not the lightest choice out there and I'm using ~1lb's worth of spacers. With some TE37SL ET22 rears, which wouldn't need spacers, and some kind of lighter 18x8.5 there might be another 5-7lbs in the wheels. There is also room to lose in the exhaust, and I'm going to try running without the M Performance muffler (just connecting pipes) to see if I can make sound. The canister weighs about 22lbs. So my less than ideal car could, in theory and with more $$$, get to ~3480 competition weight. A car without the cold weather and premium packages might be another 10-20lbs lighter, figure another 25lbs lighter for an E92 and you're probably looking at 3425 or so for a full-tilt no-compromises build, maybe even lighter if 11+ cars with manual seats are lighter (I suspect they aren't because of the auto stop/start system, but haven't seen data yet).

So on to the silliness:

One of the advantages of using the stock spring perch location is the great tire clearance, and the MCS dampers are a little smaller OD than the stock dampers so there's more room now. The 315's fit on the front with 18x9.5ET35 and 12.5mm spacers, but they stick out about 1/4" from the fenders. This *might* tuck in as the car rolls but I'm not going to find out. They also rub slightly on the back of the fender liner, but they fit, and don't rub at all in the front of the fender. So a little relieving of the fender liner with a heat gun or whatever, and more camber would probably make them fit comfortably, *without cutting the fenders ! This could be big in a more modified class as you can go pretty wide with the tires without making the car wider. You could even do this with coilovers with the right spring and perch. As long as I don't have holes rubbed in the fender liners a little "rubbin' is racin'" is legal in Stock, so it might even work in Stock class. Pretty crazy. Wonder what they would look like on 8.5" wheels? Maybe we'll find out...

[Richbot]

Event 7 with more bumper cam footage from event 6. After 3 runs, was 0.112 behind Andy Hohl in an SS Z06 on index. He pulled out another .290 seconds on his 5th run but I'm going to pretend that didn't happen

[klammer]

Originally Posted by Richbot

Event 7 with more bumper cam footage from event 6. After 3 runs, was 0.112 behind Andy Hohl in an SS Z06 on index. He pulled out another .290 seconds on his 5th run but I'm going to pretend that didn't happen

Well done sir That is some impressive driving. Like the head bob at the end

[Richbot]

Thanks! I am still trying to find a good angle to watch my hands from, I hate wind noise in videos but my camera doesn't have an external mic hookup and I'm not buying anything until this one dies. It appears from the video that much like Derek Zoolander, I can't turn left, because I'm only shuffling in right turns, and I'm closer to the cones in right turns than lefts. There was only one really tight left but still, weird. I'm still too far off the cones, I only hit 1 cone on the first run in the video (which is why I started hooning)

[schnell325]

What an awesome thread!!!!

[CSBM5]

Originally Posted by Richbot

Thanks! I am still trying to find a good angle to watch my hands from, I hate wind noise in videos but my camera doesn't have an external mic hookup and I'm not buying anything until this one dies. It appears from the video that much like Derek Zoolander, I can't turn left, because I'm only shuffling in right turns, and I'm closer to the cones in right turns than lefts. There was only one really tight left but still, weird. I'm still too far off the cones, I only hit 1 cone on the first run in the video (which is why I started hooning)

Try a piece of scotch tape over the mic hole on the camera next time and see if that helps...

[Richbot]

Did a T&T today and found out something surprising (well, surprising to me). The car seems to like 42psi in the front and 35 in the rear, with the same shock settings it was markedly better behaved and easier to place precisely, with more frontend grip everywhere in the corner. I'm going to start using these pressures in competition and see what happens, but I was ftd at the test and tune! Kindof like being HPDE national champion...

Up to about 50 runs on the tires and so far the rears look like they are about 15 runs from the cords, the fronts will have more if the shoulder doesn't give out. Flipped them at about 23 runs so I'm going to run this shoulder until it cords, it might not even cord at the shoulder, they are finally starting to get a groove of doom on the outer groove, partially because I hotlapped them a few times at the T&T today and so they got too hot to be happy

[m3kerry]

Rich, here is the link you need

http://www.motorsportreg.com/index.c...25BCC2F1125D3A

[Richbot]

Ugh. Don't remind me. I'm not sure who has been committing me to all of this other crap but it sure is taking a bite out of my motorsports schedule this year.

[Richbot]

Last regular STL event, finally corded the fronts after 72 runs. Could have made to around 90 if i had not flipped them so early but the internet told me BMWs in stock class can only get 20 runs before cording the shoulder so I flipped at 23 runs. Had a codriver for this one, comparison is in the video

New A6's are here, ready for the Blytheville Tour/Shootout!

[CSBM5]

The car looks like it's a LOT of fun to drive. What are the chances that it actually goes to F-stock? Does it stand a chance against the best Mustang platform in that class? I actually thought it might be a good challenger in A-stock?

I've been hunting non-sunroof (helmet clearance) E90s for a few months, but I guess I'm a bit too specific in what I want as I plan to use it as a daily driver too a bit (Tech, heated seats, no sunroof, 6MT, and preferably in a non-silver color). Not too happy to see what some 2010 and 2011 owners are finding with main bearing issues, noises, etc. Makes me wonder if I should hunt for an older car (2008 or 2009) actually.

[Richbot]

It's been recommended to the BOD that the car be moved to FS along with the ISF and C63 effective 1/1/2013. It would be very unusual for the BOD to go against that recommendation. My thought is that it will be capable of winning everywhere in FS, but not an overdog. The Shelby GT (4.6l car) is lower, stiffer, and about the same weight, with the same tire, and better front camber. The 2012 is essentially the same weight has more power with 19x9's and more clearance than you would ever need but is just as floppy as the M3, and it's wide. Both Mustangs have better thrust in gear at 35mph but they're both stick axle which is a handicap on corner exit if there are bumps. Based on Matt Murray's results in the 1M, the M3 is probably not competitive in AS, though it's not totally useless either. I would keep running it either way.

It is a lot of fun to drive, very predictable but you can hoon at will if you want to, and place it really close to the cones with confidence. You can see from my friend's run that it's possible to break the tires loose anytime the wheel is turned, so it requires patience on corner exit but once you get to 100% throttle it really rocks on the high end, if you load the tires smoothly it boogies from 45mph to the limiter in a hurry even with the wheel turned, you can hear it in the second half (my run) coming into the last slalom. And it can carry surprising speed through sweepers. Slaloms are where the car is least happy due to size weight and softness

A good no-sunroof car is going to be a tough get. I wish you luck. I can tell you I do not miss the tech package at all, but I would miss the heated seats, fold-down seats are a must for transporting tires, and I would miss the homelink/dimming mirrors from the premium package

[CatchM3IfYouCan181]

Originally Posted by Z K

I've been running the M3 in ST-U class since purchasing it. My previous car was a shoe-in for the class and was competitive (Mitsubishi Evo). The M3 is not so much in stock form... but I knew that from the start anyway. So far compared to my usual benchmark of regulars, I am down about 3 seconds on a 40 second course - that is a pretty big margin to gain back.

The car's power is not an issue, for me it was putting the power down without going power sliding around corners. Also, the soft suspension and lack of feedback aren't very reassuring. But I am getting used to the car now and a lot smoother than before. The car does have great turn in response though! Incredible turn in response.

Here's a video of one of my laps where I was throttle happy and go spinning.

The front stock camber is woefully inadequate even with a performance alignment. The tires are rolling onto the sidewalls in front. I'll probably start there and pick up some stickier street tires as well.

Great thing about a Street Touring class is that you run street tires which keeps the budget down and it is pretty open to a lot of mods as long as you don't change internal engine parts.

have you made any changes since this video? i just switched to STU from AS and i did fairly in AS but i'm a little nervous since the competition should be a lot tougher in STU.

[CSBM5]

Originally Posted by CatchM3IfYouCan181

have you made any changes since this video? i just switched to STU from AS and i did fairly in AS but i'm a little nervous since the competition should be a lot tougher in STU.

What mods have you done for STU? What tires are you running on?

[CatchM3IfYouCan181]

Originally Posted by CSBM5

What mods have you done for STU? What tires are you running on?

i did double adjustables for my suspension and im running 18x10s with direzzas.