[Cloud9blue]

Just finished my first autocross school with the local BMWCCA chapter. Never thought it can be this much fun with just an empty parking lot and a few cones. Definitely considering doing this more often in the future.

I made a few changes to the suspension last month, and it really makes a difference on the track, comparing to the other non-M e9X and e8X. With my setup there is only a minimal understeering once you have the correct technique for trail braking. Still think the BMW performance suspension (version 2, with the yellow spring and thicker front sway bar) is a decent compromise for relatively low cost 80%/20% street/autocross setup. There is still some roll in the chassis, but on par with the e9X M3 on the stock M suspension (see pictures below). You have to remember that these are still OEM sourced dampers, not some $3-4k GC/AST/Ohlins suspension that was on the heavily modified M cars that some of the instructors were driving.

Still waiting for my wavetrac LSD to get installed in 2 weeks and feel like it would be a noticeable difference in some of tight turns, where I can use the throttle to rotate the car in a more controlled manner. Not sure if a stiffer front sway would leave to a crisper turn in or not, so any comment is welcomed on this subject.

Conti DW (235/35 19 front; 265/35 19 rear) also performed quite good. I have the cambers set at -2.0 for all four corners, and ran 38 front and 40 rear. The tires grip quite nicely in acceleration. And they don't have any excessive roll-over and/or corner wear on the shoulders with my setup running at -2.0 for all four corners, and 38/40 psi front/rear . However, I feel the braking and mid-corner grip can be further enhanced with wider front tires (currently running skinny 235/35 at the front). It is also interesting to notice that the 265/35 tires offer much better traction off the line than 265/30 tires that I ran previously.

Thinking of switching to Apex 18" wheels running 255/35 and 275/35 front and back later in the year, just wondering what are of the good street tires that are decent for autocross as well.

All in all, I guess the biggest takeaway I got from the day is that for cars with relatively soft suspension and street tires, it is much more important to have a smooth flow around the track than try to push your car hard in and out of the corners. Btw, the whole event wasn't timed since this was targeted toward beginner.

[spencers]

Michelin Pilot Super Sports are great street tires that are excellent for autocross. Really wish I had put those on my E90 rather than the AS3 (still a great tire).

[Cloud9blue]

Originally Posted by spencers

Michelin Pilot Super Sports are great street tires that are excellent for autocross. Really wish I had put those on my E90 rather than the AS3 (still a great tire).

How about Bridgestone Potenza re 11? Heard they wear much quicker than PSS, but I only do an average 6000 miles a year. Will re11 last me for a year or two at least if I do 4-5 autoX and maybe one or two track days a year?

[JC335xi]

Originally Posted by Cloud9blue

How about Bridgestone Potenza re 11? Heard they wear much quicker than PSS, but I only do an average 6000 miles a year. Will re11 last me for a year or two at least if I do 4-5 autoX and maybe one or two track days a year?

Ask me at the end of the summer. I just got a set of RE-11As about a month ago. Only 1 auto-x on them so far but I should have 6 to 8 under my belt by the end of the season. I would expect with the much lower treadwear rating (200 vs 300) that they will not last nearly as long as the PSS.

[Cloud9blue]

Originally Posted by JC335xi

Ask me at the end of the summer. I just got a set of RE-11As about a month ago. Only 1 auto-x on them so far but I should have 6 to 8 under my belt by the end of the season. I would expect with the much lower treadwear rating (200 vs 300) that they will not last nearly as long as the PSS.

How much do you drive per year? If they still have more than 60% tread left after a season of autoX, I might just pull the trigger. If not, I might just switch to PSS and then get a set of dedicated track tires after a year or two of this.

[JC335xi]

Originally Posted by Cloud9blue

How much do you drive per year? If they still have more than 60% tread left after a season of autoX, I might just pull the trigger. If not, I might just switch to PSS and then get a set of dedicated track tires after a year or two of this.

I average about 10k miles a year so it will probably be around 5k miles on these before the snow tires go back on. If I can get two seasons out of these I will be happy. I still have my old set of rims (cheap'o 18x8 with 225 summers) so I am going to keep an eye on the wear and maybe start swapping them between events if it looks like they won't last me that long.

[Cloud9blue]

Just finished first day of Tirerack autocross challenge. Here is a video of one of my better runs. The time was 59.4 something, not bad comparing to another 335i with stock suspension running on Michelin PSS, which was running around 64 seconds. Pretty sure I can shave off at least another second or two if I can get my lines right tomorrow.

Think I need to brake more and turn earlier for some of tighter corners, especially with the these Conti DW... Luckily, a set of APEX 18" and Bridgestone RE-11 should be ready at the end of this month.

- Power steering fluid start to boil / spilling out of the little bleed hole after the 3rd runs in each session. Looks like a common problem, some put socks around it to sock up the oil. Thinking about replacing the fluid with Red Line 30404 Power Steering Fluid instead of the Pentosin CHF11S. Anyone used this with good success?

- Stock non-M steering ratio is way to slow for autocross. Too bad, there is no easy fix other than fitting a M3 steering rack.

- Oil temp went up to 260F after two runs, and it wasn't even 80C. Oil cooler upgrade should probably be done if I want to keep on doing this, a transmission cooler wouldn't hurt either. Intercooler too, might as well as we are at it.

- Wavetrac, awesome. 180 turn can be done much quicker than before.

- Will probably max out my front camber from the current -2.1 to around -2.8 later this summer to further eliminate the understeering.