[Mboi235i]

Hey yall, just joined the forums - I had a major hard on for BMWs for a while and I'm glad to be an owner of an M235i. Prolly got the hardon from the BMW S1KRR motorcycle.

I just wanted to know if there was a detailed write up on making a light-ish track build for the m235i or if you could do a quick review on what I am thinking of right now. I didnt understand the few write ups that I did find and they were either not enough or too much.

A bit of background - I used to race motorcycles and was pushing times rivaling bikes that had 3 to 5 times more horsepower than mine on the track. Got into a major accident, amnesia, severe muscle trauma, broken bones. Lost my drive to ride after that - but I still feel the need for speed so I decided to jump into the car scene. Pulled the trigger on a M235i just today.

My use case for this vehicle is to drive on street, light hooning, and trackdays! I mainly use pubic transport so its mainly going to be a weekend toy with grocery hauls every now and then.
Now I realise the M2 is a better fit for my use case, but I do not have the budget to buy an M2. I don't know the operating costs, but I would guess the M2 has a higher cost of ownership than the M235i as well. I dont think any amount of mods I do will put it up to the level of an M2 but I dont think I need a weapon, I just need something I can feel good in.

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So finally approaching the point of this thread.
A F87 M2 costs over 50,000NZD (30,000USD) and my M235i costed me 25,000NZD (15,000USD). So I want to keep my mods well under the the difference.

I think the main mods I want to put onto the M235i are suspension and brake upgrades. I dont really care much about engine power but I do care about loose handling. So this is what I have found out until now. Hoping some kind samaritan could do a review of this.

Preventative maintenance
Charge pipe $220NZD (132USD)

Wheels and Tires
245/35/18 with 18x8.5 ET 35-40
Camber: Front -1.5 | Rear -1.8 minimum
Will require camber plates
Wheels: Around 2500NZD (1500USD)

Camber plates: Vorshlag seems to have the best reputation so I will get these.
US$685

Coilovers: KW is the most thrown around name and there seems to be V1, V2, V3 but I don't know what exactly I need. QUick research and I think V2 might be appropriate? But I dont really want to spend money again buying a V3 if I find that V2 is lacklustre.
V2: 2500USD

Struts and bracing: I actually have no idea about any of this. I do know that I want to do something to it. I seem to have two struts installed already by the previous owner.

Steel brake lines: FCP Euro sells brake lines at around US$65 - Not too sure if this is the real deal
https://www.fcpeuro.com/products/bmw...tech-950-34032
OTherwise not too sure what to do for the brakes, does it need to be upgraded?

Do any of the cooling units need an upgrade?

Finally, an ECU flash NZ$1000 ($US600)

So at the moment the list of things to do is around US$5477 without labor. Not too bad. What do you guys think?

Hope my issue was communicated clearly.

[dradernh]

My first thought is that you'll have a greater chance of achieving your goal while minimizing your overall expense if you engage with a specialist shop that is quite familiar with these issues regarding BMWs. Even better is if they've previously built-up a 2 Series (or a 1 Series).

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tldr; get an LSD, choose coilovers that give the greatest flexibility for fitting wider front wheels and tires, and note that track duty requires that you be prepared to deal with unavoidably excessive heat build-up within the braking system.

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To me, there are two principal issues with building a 2 Series street/track car: the lack of a limited slip differential, and the minimal space available to fit wider rubber in front.

The LSD is generally considered to be the first performance upgrade, even if you're not going to the track. Regarding larger wheels and tires in front, the choice of coilover brand can make a difference. If I recall, KW is not on the 'good' list, but don't quote me on that. Harold at HP Autosport (HP Autosport) once posted a list of the coilover brands in terms of how much space they do or don't leave in front. I strongly recommend contacting him for coilover advice in general. As an example, I came across a post of his while looking for his good/bad coilover front space list, and he stated that KW V2 is strictly for the street.

Tires

The first question is which performance level of tires you plan to put on the car. If you're going to run street tires both on the street and at the track, and you don't want to run Extreme Performance tires, and you can get them, and they will fit in front, I recommend the Michelin Pilot Super Sport in 245/35-18. The reason for that is their tread width of 9.2", which is greater than most tires specificed as 255/35-18. Plus, it's a tire specified by BMW for our cars (i.e., it's a "Star BMW" tire). More here: https://www.tirerack.com/tires/tires...XLV2&tab=Sizes The tread is a little wide for an 8.5" wheel, but they'll work.

Note that many owners have destroyed a set of street tires at the track due to a lack of negative camber. That factor is all-important if you want your street tires to last at the track; not even the Michelin PSS was built for track duty.

Coilovers

Given all the choices out there, I again recommend contacting Harold for professional advice. He knows this subject, his advice (in my estimation) has always been spot-on, and his firm supports our site.

Struts and Bracing

The race shop that built-up my car recommended an H&R front sway bar if I wanted greater front roll resistance and turn-in capability. They never mentioned strut bracing, and they would have if they thought it was appropriate for a street/track build. In the event you haven't seen it already, more on my experience of that here: https://www.2addicts.com/forums/show....php?t=1532418

Brakes

Get SS brake lines front and rear. Get race pads for the track. Don't be misled by the terms "street-race pads" or "street-track pads". For cars weighing the better part of two tons while being pushed by north of ~300 HP, those pad are, effectively, street pads.

If the lack of an LSD and room for wider front wheels and tires are the car's most obvious shortcomings, the lack of braking capacity at the track is an unavoidable performance and safety issue. Without spending a lot of money, the way it's dealt with is via pads that can tolerate significantly more heat and brake fluid that can do the same.

Generally, the more practical approach is to change to race pads for track days and change back to street pads for the rest of the time. This thread will show you some of the efforts I went to to try to minimize heat buildup within the braking system: https://www.2addicts.com/forums/show....php?t=1670372 More here from another member: https://www.2addicts.com/forums/show....php?t=1693335 I chose to run race pads year-round (yes, even in the winter); but, like you, I'm a former bike racer.

[XutvJet]

For your purposes, a 2016-2018 M2 is a far better fit. Running costs will not be more expensive has it's just a tuned N55 with a highly desirable oiling system which is far better suited to track driving than what comes in the M235. You'll spend nearly the same money to get a modded M235 to perform like a stock M2 on the track and even then, the M2 will be more composed, connected, and consistent plus you have options to make the M2 even better with wider rubber with no clearance concerns. The M2 has a far better LSD than the ones available to the M235 and the M2 has the M3/M4 front and rear subframes which are better in every way from a performance and dynamics perspective. So either save up for the M2 or dump money into the M235 and just accept the fact that it will never be quite like an M2 when it comes to track driving.

[Mboi235i]

I will update the OP after I do more research and budget my options. Cars are so much more complicated than motorcycles rofl.

The objective is not to make an M2. Its to have some fun modding my car while trying to achieve M2 performance levels. Im not going to race competitively any time soon so I don't mind 'never being an m2', and when I arrive at the point where I am able to race competitively with finances to back it up, I'll pick up something better than the M235i.

And tyvm dradernh for your post. I was thinking wheels as first mod. But that requires camber plates or coilovers with adjustable cambers. Puts a bigger price tag on everything.

[XutvJet]

Originally Posted by Mboi235i

I will update the OP after I do more research and budget my options. Cars are so much more complicated than motorcycles rofl.

The objective is not to make an M2. Its to have some fun modding my car while trying to achieve M2 performance levels. Im not going to race competitively any time soon so I don't mind 'never being an m2', and when I arrive at the point where I am able to race competitively with finances to back it up, I'll pick up something better than the M235i.

And tyvm dradernh for your post. I was thinking wheels as first mod. But that requires camber plates or coilovers with adjustable cambers. Puts a bigger price tag on everything.

I'm running 245/35R18s all around with 18x8et43 wheels and no camber or spacer mods. The M235 is seriously hampered by the narrow 225/40R18s in the front. Putting 245s on the front axle makes a huge difference in front end grip.

My setup is as follows:

1) 245/35R18 square PS4s with 18x8et43

2) Dinan springs in the front with stock shocks. This gives about a 3/4" drop. I tried Bilstein Damptronics shocks in the front but they raised the front by 1/2", were very harsh, and clunked. All well known common issues.

3) Eibach springs in the back with Bilstein Damptronic shocks. This setup gives a 1/2" rear drop. I had Dinans in the back with their lift spacer and it was still too low (nearly 1"). The Eibachs are stiffer and teamed with the Bilsteins (which are great) gives more roll stiffness in the rear. The stance of the car is perfect.

4) M Performance LSD

For a street car, I think the setup is excellent and has no compromises. It's quiet, rides excellent, and handles far better than stock. I don't track the car, but I do hustle it on back roads. If I could change one thing, it would be a little more roll stiffness in the front. The car has lots of grip, but I'd like it just a little flatter. I think my 2011 Cayman has influenced this feeling a bit. I'd add a front sway bar, but I'm not doing anymore mods as I'm likely replacing it in 6 months or so. If it was an automatic, I'd probably keep it. My Cayman is a 6MT and far better sorted and enjoyable than the 6MT in the M235.

[freakystyly]

Sway bars aka. anti roll bars are difficult on this chassis but doable. They're above the subframe so you have to drop it to access. You be the judge if it's worth it or not.

Control arm bushings to monoballs and solid or stiffer subframe/differential bushings if you want to go there.

The largest hold back is tire size as mentioned of course.