bimmer635csi's Autocrosses

[bimmer635csi]

Pushing Hard enough to Kill Cone!

Nice. Sounds like a good day indeed.

Yep, yesterday and today were really decent. I had very consistent fast times, which makes it easy to fine tune things.

I'm waiting for the final official times before I publish the videos, but as a teaser update, I ended up faster today (because I found a cone yesterday), but the 325i competition found nearly 1 second on the track, so he smoked me today. I still wound up in 2nd today though, so I can't complain.

But to show how hard I was pushing yesterday, watch this...



The "best run" videos will come after I get the official times. I'm starting to add info to the videos and need the times to make the videos complete.

 

[Brendon]

Nice. Looking forward to seeing your best run and official results.

 

[bimmer635csi]

Ax2 & Ax3: Furrin Group Autocross at WMAA

Finally able to get to some of the videos and get them up to YouTube. Also figured out how to make the videos a little more fancy with subtitles. I'm no Ron Howard, but it is a more entertaining way of showing what I'm thinking while watching the videos.

Anyway, here's the best runs from each day.

Day 1 for Ax2:

Day 2 for Ax3:

I know the run labeled "Best" looks wonky. All I can figure is the GPS in my phone is showing its true capability because the line was pretty tight (as seen in the video above).

From the outside looking in (courtesy of the wife):

Look at that mad lean and gravel spraying from under the Direzza ZII's

This is in the last left-hander before the finish.

 

[RacingManiac]

Dusty lot...wow...also, way less boring than my videos...lol

 

[bimmer635csi]

Dusty lot...wow...also, way less boring than my videos...lol

Yeah, for as small of a parking lot as that was, it flowed really well and you never had time to take your eyes off the line. And if you got out of the main groove, you may as well have been driving on ice because the sand and gravel was slicker than greased owl poop on a marble floor (as one of my profs used to say).

But in your defense, no car racing video is boring.

 

[RacingManiac]

Random question, is that the perspective of those cameras or do you actually have that much front camber?

 

[bimmer635csi]

Random question, is that the perspective of those cameras or do you actually have that much front camber?

Not sure which one you are talking about (the photo or the videos), but it must be the camera. Here's the alignment according to the dealer:

It is fairly balanced very close to 1 degree negative on both sides.

I did find that I need a little more rear camber though because the inner shoulder of the tires are about 3 degrees C cooler after a run. I could probably use a little more front also, but I don't know how to get it legally.

I have a suspicion that the Direzza ZII's are too low of a load rating for this car under these conditions. I was running 49 psi on the fronts and the center temperature was about 1.5 degrees higher than either shoulder but the chalk on the shoulders was still rubbing off more than I'd like. The next tires are probably going to need to be 92Ys instead of these 88Ys.

 

[RacingManiac]

They look more negative from the side view camera, like I said its probably the perspective of the lens.

How much pressure do you run at the rear if you run 49 front? TBH I've never had enough runs to really play with the pressure that much. Last 2 years the car being completely stock I've been just jacking the rear up to 50 and keep the front at 35-38 to get more rotation into the car. I still have yet to done a proper dry autoX so I can't say what the RSB will do for me on that front...the Evo school probably will paint a better picture...

 

[bimmer635csi]

They look more negative from the side view camera, like I said its probably the perspective of the lens.

How much pressure do you run at the rear if you run 49 front? TBH I've never had enough runs to really play with the pressure that much. Last 2 years the car being completely stock I've been just jacking the rear up to 50 and keep the front at 35-38 to get more rotation into the car. I still have yet to done a proper dry autoX so I can't say what the RSB will do for me on that front...the Evo school probably will paint a better picture...

I check for shoulder roll every run, temperature every other run, and adjust pressure as needed based on the above data and feel after every run. I was tuning by 0.5 psi in the BMW last year and it may have been placebo effect, but it sure felt different (and on occasion I adjusted the wrong way and the car was absolute crap after that ... whooops).

Anyway, to answer your question, I ran 49 psi Fronts and 39 psi Rears. But if I remember, you have a lot more tire under your car than I do, so you can get away with lower pressure if that is true.

 

[RacingManiac]

Are you not running 245s? Going wider definite had a noticeable effect on pressure variation. For DCSCC I typically do 2 runs consecutively then check pressure and then do the rest of the runs. The pressure change when I check is a lot less than when I was on stock A/S tires.

 

[bimmer635csi]

Are you not running 245s? Going wider definite had a noticeable effect on pressure variation. For DCSCC I typically do 2 runs consecutively then check pressure and then do the rest of the runs. The pressure change when I check is a lot less than when I was on stock A/S tires.

Yeah, I'm running 7.5" wide wheels, so I think 245 is just too much. I might be able to get a narrow-ish 235 on there, but I'm also thinking a RE-01 with the 92 load rating will help also.

I'm going to get some help from the resident tire guy, if I can. ** Paging Sonny **

 

[RacingManiac]

The other GTI running around here that I mentioned before is running 245 RS3 on the 18x7.5 RPF1s I believe. So its definitely doable...

 

[bimmer635csi]

I already have a rub somewhere (not sure where yet) ... so I'm hesitant to go drop 700 bucks only to find it is rubbing even worse. I need to do some deep investigation into this, including figuring out where I'm rubbing.

 

[RacingManiac]

Yeah I saw that on the video. Do the Ohlins do anything to the rideheight? Or maybe pushing the offset out 6mm is really making that much of a difference?

 

[Sonny@TireRack.com]

Yeah, I'm running 7.5" wide wheels, so I think 245 is just too much. I might be able to get a narrow-ish 235 on there, but I'm also thinking a RE-01 with the 92 load rating will help also.

I'm going to get some help from the resident tire guy, if I can. ** Paging Sonny **

I will be giving you a call shortly.