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      05-29-2023, 06:35 PM   #1
rhop101
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Autocrossing my M235i

Hi 2Addicts,

A momentous occasion has occurred. I've paid off my car!

A 2015 M235i 8-spd ZF RWD Model

Now to start planning modifications

Just kidding. First it's time for attending more Autocross events and getting a real feel for the car.

I've been autocrossing the car on and off since I got it along with my CS-lite prepped S2000, but recently I moved to NYC and that is just not an environment I want to bring an S2000 into plus I would have to pay to park the 2nd car. So I'm likely going to sell the S2000 and "for fun" build an STU-lite M235i. I know its not going to win NATs when E9X Ms can mount 10.5" wheels and 285 tires, but I've seen very few M235i get prepped for STU. I've seen a few 135i get prepped as well and with both cars now being ~$20k cars I figure others maybe looking to mod up their M235i for Autocross so why not start a build thread about it.

I already have a bit of a start. Current Mods are:
  • Vorshlag Camber Plates
  • Alignment: 0 toe up front dialed to 2.4deg Camber for the Street/AX compromise. Just a little toe in at the back with 2.1deg Camber
  • BootMod Stage1 93 tune
  • CSF Intercooler
  • Evolution Racewerks Charge Pipe
  • 225/40/18 RE71RS 200tw tires on Stock Rims

For Next Year's Season going to looking at some upgrades. A lot of research still to do here. For this year I'm really trying to focus on the driving and figuring out what the car needs the most. The above is the order I'll likely make additional improvements to the car in. Ideally I'd do the upgrades all at once, but if not still something to be said for making tweaks gradually and seeing how that changes what the car needs tweaked to keep it balanced.

In approximate order:
  • LSD - Probably M-Performance, but I may give Bimmerworld or DiffsOnline a call regarding that though
  • Coilovers - maybe Ohlin Road and Track, seen good reviews on the F3X forums about them
  • Hotchkiss Front Swaybar
  • 17x9 or 18x9 Wheels - Going to be a bit tricky, shooting to get 255 square on the car

Anyway on with the Autocrosses!

Despite not being an M2 the car is quite fun to autocross and I recommend anyone take their M235i and give it a try. The short wheelbase and good torque delivery really make the car pretty nimble for a luxury barge and real fast in more open sections. With stock wheels it is an exercise in patience in the turns, but coming from an S2000 getting on the gas and launching it down the more open straight areas of the course feels amazing. The 200tw tires definitely help with grip levels given the open diff. Here's an event I did recently with Philadelphia SCCA.



I went in the first group so I didn't get much chance to observe other drivers' lines. Between the 1st Turn-around and the 2nd I saw some drivers take a slightly wider entry up the hill just scrapping one of the walls on their way up the hill. That line would have extended the straight a few tenths more. Comparing my 5th run to my 6th I found giving up just 1mph more speed really allowed the car to turn-in slightly earlier and begin the exit onto the straightaway up the hill toward the 2nd turn-around earlier. Definitely feel the car struggling a bit with inside tire grip due to the lot being a bit of an inverse bowl, but using 3rd gear keeps this mostly under control.
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      05-29-2023, 07:19 PM   #2
jb-slow
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You could switch to staggered wheels, you can get a lot more tire under there. Also should look into a oil pan baffle or m2 oil pump setup before its too late.
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      05-29-2023, 08:05 PM   #3
rhop101
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Thanks for the reminder about the oil pump jb-slow should have this on my radar... I have looked at that in the past and didn't see any non-welded baffle options at the time, but it looks like Turner has come out with one!

https://www.turnermotorsport.com/p-4...ed-sump-plate/

Anyone installed this yet? only $444 cheap by comparison to the M2 Pump Upgrade.

I needed to do an oil pan gasket anyway this winter. So it would be a good opportunity to install this baffle and put the front sway bar in.

If anyone else wants to weigh in on Staggered vs Square I'm all ears. In theory staggered would maximize the grip potential of all 4 corners. Not like I'm used to rotating wheels anyways with either of my cars And since I'm tweaking things in the suspension I can always adjust things and add a larger rear bar if needed.
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      05-29-2023, 10:22 PM   #4
dradernh
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Quote:
Originally Posted by rhop101 View Post
If anyone else wants to weigh in on Staggered vs Square I'm all ears. In theory staggered would maximize the grip potential of all 4 corners. Not like I'm used to rotating wheels anyways with either of my cars And since I'm tweaking things in the suspension I can always adjust things and add a larger rear bar if needed.
I can't advise you on what's likely to work best for you, but this is what I did to get almost-square tread widths in the tire I wanted to run on the track.

I ran Apex 17X9 ET42 in front and 18X9 ET58 in the rear. The latter had 5mm spacers. The tires were R888Rs, 255/40 in front and 255/35 in the rear.

The street/track alignment was Front: -2.6 L&R camber, -0.15 LF/-0.06 RF toe; Rear: -2.3 LR/-2.1 RR camber, -0.11 LR/-0.21 RR toe.

The car had Koni-based coilovers. My understanding is that the wheel and tire combination in front fit not only because of the negative camber and a slight fender roll, but also because the Konis (and some other coilovers, according to one of the vendors here (can't recall which)) take up less space and leave more room for the front tires than do some other coilovers. I had no rubbing under any circumstances.
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TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9 ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro;
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      05-30-2023, 10:25 PM   #5
rhop101
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Yeaaaa I think Apex has a list and it figures when I just checked it the Olhin Road and Track is on the list 🫠. Well guess I need to add updating the camber plates to the mod list 😂. Means MCS, JRZ, Koni coilovers

Good to know about the staggered setup and that it worked. Guess once you go staggered whatever works 😅. Interesting you went with the 17 wheels up front and 18s in the back. Ill be looking for 200tw so I assume that would be similar in tread width to the R888s. Id probably try to squeeze 265 on, but Ill have to ask Bimmerworld how they go about doing that. They mention it on their site.
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      05-30-2023, 11:02 PM   #6
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Quote:
Originally Posted by rhop101 View Post
I assume...
A good friend I went to high school with who for many decades owned and operated a very successful four-bay shop in San Francisco had a big sign on the wall behind his desk. It said "Assume Nothing".

That message was for his mechanics, back when cars were still worked-on by mechanics.
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2017 M240i: 23.6K, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9 ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro;
GTechniq Crystal Serum Ultra Ceramic; Suntek PPF
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      05-31-2023, 11:45 AM   #7
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Quote:
Originally Posted by rhop101 View Post
Thanks for the reminder about the oil pump jb-slow should have this on my radar... I have looked at that in the past and didn't see any non-welded baffle options at the time, but it looks like Turner has come out with one!

https://www.turnermotorsport.com/p-4...ed-sump-plate/

Anyone installed this yet? only $444 cheap by comparison to the M2 Pump Upgrade.

I needed to do an oil pan gasket anyway this winter. So it would be a good opportunity to install this baffle and put the front sway bar in.
I put that baffle in mine, the car hasn't exploded yet so i guess it's working.
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      05-31-2023, 07:30 PM   #8
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Quote:
Originally Posted by dradernh View Post
I can't advise you on what's likely to work best for you, but this is what I did to get almost-square tread widths in the tire I wanted to run on the track.

I ran Apex 17X9 ET42 in front and 18X9 ET58 in the rear. The latter had 5mm spacers. The tires were R888Rs, 255/40 in front and 255/35 in the rear.

The street/track alignment was Front: -2.6 L&R camber, -0.15 LF/-0.06 RF toe; Rear: -2.3 LR/-2.1 RR camber, -0.11 LR/-0.21 RR toe.
Hi, what's with the asymmetrical toe front and rear? Was that intentional?
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      05-31-2023, 10:33 PM   #9
dradernh
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Quote:
Originally Posted by Aspen235 View Post
Hi, what's with the asymmetrical toe front and rear? Was that intentional?
I don't know.

I asked for a street/track alignment at 2K, drove the car for 10K or so on the street, and then had the alignment checked. The latter provided the data I listed; I'm not sure whether or not I have the original alignment data to compare it to.

The shop that checked the alignment is very sharp. I watched while the owner did the work, and he had no comment on the result. He certainly would have spoken up if he thought something was amiss.

I pretty much just drive the car.
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2017 M240i: 23.6K, MT, Sunroof Delete, 3,432#, EB, Leather, Driving Assistance Package, Heated Front Seats | Sold: E12 530i, E24 M635CSi, E39 520i, E30 325is, E36 M3 (2)
TC Kline Coilovers; H&R Front Bar; Wavetrac; Al Subframe Bushings; 18X9/9 ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro;
GTechniq Crystal Serum Ultra Ceramic; Suntek PPF
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      06-01-2023, 11:09 AM   #10
rhop101
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Quote:
Originally Posted by dradernh View Post
A good friend I went to high school with who for many decades owned and operated a very successful four-bay shop in San Francisco had a big sign on the wall behind his desk. It said "Assume Nothing".

That message was for his mechanics, back when cars were still worked-on by mechanics.
Well guess Im making a table lol. I looked at 265 RE71RS and its treadwidth was like ~9.5 and 255 R888 is like 10.1 😂. To include in the table Tread Width, Section Width, Tire Diameter

Last edited by rhop101; 06-01-2023 at 12:11 PM..
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