THE LARGEST BMW 2-SERIES FORUM ON THE PLANET
2Addicts
2Addicts
BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read
2Addicts | BMW 2-Series forum Technical Topics Tracking / Autocrossing My track M240i(R?) build

Post Reply
 
Thread Tools Search this Thread
      03-23-2020, 12:23 AM   #1
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

My track M240i(R?) build

A little bored cooped up at home, figured I'd start a thread to describe the process I went through with my track car. I don't know of too many B58-based cup car conversions (other than capt_and's), so figured it might be interesting.

I don't want to just put down a parts list, but describe my reasoning at each step, so I'll just post the different "stages" one by one. When I first got the car, I'd never stepped on a track -- it never even crossed my mind that there's an amateur level at motorsports. Having a bit more experience now, I'd definitely do many things differently (and probably not start with the F22 platform). But all in good time.

Anyway, here's what the car looks like now. The chassis and the engine have about 110-120 on-track hours on them. Current goals for it are mostly fun HPDE / occasional time trial. I don't plan to take it wheel-to-wheel racing, mostly because of the pretty high running / repair costs.





Stage 1: stock(-ish)
Stage 2: spin city
Stage 3: track car now?
Stage 4: track car now!
Stage 5: M240iR
Stage X: In progress
Stage 6: COVID

Last edited by msendit; 03-09-2021 at 09:10 AM..
Appreciate 13
Maynard2219.00
Dylan861301.00
dradernh1702.00
230iZTR186.00
ifobd23.00
K8_M235i386.00
519.E82228.00
JD11937118.00
      03-24-2020, 10:50 AM   #2
Dylan86
Colonel
Dylan86's Avatar
Canada
1301
Rep
2,219
Posts

Drives: F15d msport, F22 m235i
Join Date: Jan 2016
Location: GTA

iTrader: (0)

More pics of the body panels/fitment if you could! This is a long term goal for me on the bodywork/cage side. Well done, sir

D
__________________
Appreciate 0
      03-24-2020, 12:19 PM   #3
dradernh
Colonel
dradernh's Avatar
1702
Rep
2,728
Posts

Drives: 2017 M240i
Join Date: Aug 2013
Location: Ohio

iTrader: (0)

Quote:
Originally Posted by msendit View Post
Anyway, here's what the car looks like now.
The car looks good!

Do you know its on-track weight with you in it; if so, how many gallons of fuel are in the tank at that weight?
__________________
2017 M240i: 14.0K, 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; Dinan Elite V2 & CAI; Rogue SSK; MPerf BBK; Schroth Quick Fit Pro;
GTechniq Crystal Serum Ultra Ceramic; Suntek PPF
Appreciate 0
      03-24-2020, 02:01 PM   #4
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Quote:
Originally Posted by Dylan86 View Post
More pics of the body panels/fitment if you could!
I'll grab some closeups later. Generally speaking it's OK, some imperfections here and there. I fully expect the panels to get bent / cracked / replaced #becauseracecar, so haven't been obsessing too much with fitment.

Quote:
Originally Posted by dradernh View Post
Do you know its on-track weight with you in it; if so, how many gallons of fuel are in the tank at that weight?
Not on this latest config. I need to get it corner balanced after the next time out, but it's a bit unclear when that will be.

Last weigh in I did was 3715 lbs with me (140) and a full tank (~12 gal). This was before the bodykit -- panels, wider tires, bigger brakes will probably add some, but I also had to remove some pretty heavy bracing to make space, so ... maybe 40-50 lbs more now.
Note I haven't done much in terms of weight reduction (yet?) -- all the interior panels / sound deadening are still there, massive OEM battery, A/C, etc. Oh, and the frigging sunroof!

Last edited by msendit; 03-24-2020 at 02:05 PM.. Reason: sunroof!
Appreciate 2
dradernh1702.00
Dylan861301.00
      03-24-2020, 05:32 PM   #5
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Stage 1: stock(-ish)

End track-hours: 15-20
End Laguna Seca time: 1:56-high

End parts/specs:
KW V3 coilovers
Ground control camber plates
Turner thrust arms with monoballs
Apex studs
RBF660 fluid
-2.2 F -2.2 R camber; ?? toe
MPSS/MP4S tires: 225/40/18, 245/35/18
Stock BMW rims: 7.5x18 ET45 F, 8.5x18 ET52
"compulsory" exterior bits: black grilles, black mirror caps, painted front reflectors

As I mentioned, I didn't get this car with tracking in mind -- I'd actually never been to a track before. I don't need a car for work, so it was mostly something for weekends / roadtrip adventures. The day after I grabbed it from the dealer, I took care of the engine break-in with a 2000-mi trip from San Francisco to Denver and back the scenic route, dealer plates and all (CO police was *not* happy about that!). I'd been reading the forums here, so I swapped the "compulsory" exterior bits literally on the side of the road somewhere in Nevada on the way.



I did a few other longer trips and was pretty happy with how the B58 pulled for overtaking. Plus, the usual other things -- some "spirited" runs on local twisties, some onramp kicks -- none of which were really pushing the car anywhere near its limits, but I was definitely enjoying it. Around that time, a coworker mentioned some "racing school" they've done on a local track, and the gears in my head started turning. I've been watching motorsports pretty much my entire life, but never really connected the dots that you can take a "normal" car on the track between the real races. Having a fast car, it was a no-brainer to try it.

First HPDE with the car (and for me) was pretty typical -- some nerves, big sensory overload, tiptoeing around, learning the line. Honestly I wasn't too impressed until I took a ride with my instructor (in some M4 IIRC) for a couple of hot laps. That was the holy cow moment when things clicked! I realized: (i) why the line was what it was, car just goes there anyway; (ii) how far away I was from any reasonable limit. These two laps were better than any crack that instructor might have given me... Now that I occasionally instruct myself, I always encourage my students to come along for rides.

Anyway, at that point, the car was bone stock. I did a couple more events in the next few weeks, learning to pick up the pace a bit. I destroyed my first set of front tire shoulders between two consecutive days, and put on whatever terrible all-season fronts the local Les Schwab in Yolo county had for the second day. This would pretty much set the tone for the next quite a while -- I'm pretty aware I'm the limiting factor for the car -- so I don't need a perfect setup to learn something new. Bonus points, I'd learn how to adapt to different setup changes.



I was reading the forums for camber solutions and it seemed like the M2 LCA thing was more or less half-assing it, but camber plates didn't work great with the stock suspension. So, decided to focus on the long term and invest in good coilovers and camber plates. I talked to a local performance shop, and they spent a while convincing me that the KW clubsport I had my eyes on didn't work with the new M240, only with the M235. In hindsight, total bollocks, but I ended up with KW V3s, Ground control plates, some camber, a fairly slammed ride height, and better brake fluid. Note to self, a pretty instagram page with shiny cars in front of the shop doesn't guarantee solid track knowledge.

With the KWs the car was leaning less in corners, and the front tires had a higher chance of surviving. Went through some more MP4s tires, stock pads (yay warranty), cracked the front bumper in my first off track excursion (it's still that way despite bondoing it like 5 times), moved to slightly more aggressive alignment settings each time, and put in thrust arms with monoballs mostly on a whim (and really appreciated the improved steering feel).

At this point, I'd learned how to push this setup hard enough that the MP4s were starting to chunk. Plus, I'd corded my tires a couple of times in the middle of nowhere, with very few replacment options. Sounded like the right time to jump to dedicated track wheels / tires. I put on some Apex studs to prepare for that.


Last edited by msendit; 03-29-2020 at 07:34 PM..
Appreciate 6
ifobd23.00
Maynard2219.00
MassNerd146.00
519.E82228.00
JD11937118.00
      03-26-2020, 05:11 PM   #6
kthor703
Private First Class
23
Rep
120
Posts

Drives: 2021 M2 Competition
Join Date: Nov 2017
Location: SE Michigan

iTrader: (0)

Sub'd for more. Fun read and enjoy seeing what other people are doing. I'm tracking on a mostly "stock +" set up now (GC Camber plates, 8.5" square with 235s, Hawk DTC 60s). Have a downpipe and just recently an intercooler, but run the stock map on the track, as it is plenty of power and keeps the consumables in check.
Appreciate 1
msendit291.50
      03-26-2020, 09:27 PM   #7
K8_M235i
Lieutenant
K8_M235i's Avatar
United_States
386
Rep
574
Posts

Drives: 2016 M235i 6MT
Join Date: Jan 2018
Location: Boston, Ma

iTrader: (0)

That's awesome. I went through a similar process as you described, but decided to buy an e36 track car.

This season (if it happens) will be its first as a legal race car.

Someday my m235 will be a race car as well, but I want to get some more time out of it on the street.
__________________
2016 F22 M235i 6MT, LSD, Slicktop
2015 F80 M3 DCT, Carbon Roof
1998 S54 E36 M3 Clubracer Build
2005 E53 X5 3.0 AT
Appreciate 1
msendit291.50
      03-26-2020, 09:46 PM   #8
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Quote:
Originally Posted by K8_M235i View Post
That's awesome. I went through a similar process as you described, but decided to buy an e36 track car.

This season (if it happens) will be its first as a legal race car.

Someday my m235 will be a race car as well, but I want to get some more time out of it on the street.
Awesome. Yeah, that's the reason I'm keeping this one just for time trials / HPDE. It chews through consumables like candy and the dings you get in a real race won't be fun to pay either.

My "real racecar" is a '92 MR2. Sitting without an engine at the moment, but should be good to go once things come back to normal.
Appreciate 0
      03-26-2020, 09:51 PM   #9
K8_M235i
Lieutenant
K8_M235i's Avatar
United_States
386
Rep
574
Posts

Drives: 2016 M235i 6MT
Join Date: Jan 2018
Location: Boston, Ma

iTrader: (0)

Quote:
Originally Posted by msendit View Post
Quote:
Originally Posted by K8_M235i View Post
That's awesome. I went through a similar process as you described, but decided to buy an e36 track car.

This season (if it happens) will be its first as a legal race car.

Someday my m235 will be a race car as well, but I want to get some more time out of it on the street.
Awesome. Yeah, that's the reason I'm keeping this one just for time trials / HPDE. It chews through consumables like candy and the dings you get in a real race won't be fun to pay either.

My "real racecar" is a '92 MR2. Sitting without an engine at the moment, but should be good to go once things come back to normal.
My e36 is the same way right now. I'm currently re wiring the whole car and adding all necessary safety items like a battery cut off and fire suppression.

After this, I'll pull the drivetrain for a refresh.

At least we have time to work on them now!
__________________
2016 F22 M235i 6MT, LSD, Slicktop
2015 F80 M3 DCT, Carbon Roof
1998 S54 E36 M3 Clubracer Build
2005 E53 X5 3.0 AT
Appreciate 0
      03-29-2020, 07:33 PM   #10
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Stage 2: spin city

End track-hours: 30-something
End Laguna Seca time: 1:50

End parts/specs:
Pagid RS29 brake pads
-2.2 F camber, -2.2 R camber
RE71-r tires: 235/40/18 F, 265/35/18 R
Forgestar F14 rims: 8.5x18 ET40, 9x18 ET40-high
Eventuri intake
lots of front rebound dampening

So, into the summer of 2018, I was pushing the MP4s tires a bit too much and it was time for a dedicated track set. I was still going to the shop that did the KW suspension, and they recommended Bridgestone RE-71r, which have been kind to me since(*). As people here know very well, our cars need deep-offset wheels and finding these isn't particularly easy. After some searching around, I found Forgestar, who make flow-formed wheels with custom offsets at a pretty reasonable price. 265 tires at the back seemed to be the max people here had done, so eventually settled on 235/40 and 265/35. The distributor I talked to convinced me to do 9" at the back instead of 9.5" and that "the experts at Forgestar will take care of the offsets". Fine.

(*) I've gone through many (20?) sets of RE-71rs on this car. Pretty much everything about them has been said already, but let me recap in short: awesome levels of dry grip; gets maximum grip very fast (2-3 corners); gets greasy / overheated fast too (2-3 laps); max grip on our cars seems to be ~34-35 psi hot; when new, tolerable in the wet. Also, stay away from the 285/30/18 size on our hefty cars (see "stage kaboom" later)!

Sticky tires without better brakes didn't sound fun, so I also grabbed myself a set of Pagid RS29 pads. They seemed to be the default track pad for our cars (and the F8X). In hindsight, after going through a few sets, pretty happy with them overall. The fronts tended to last about 6-7 track days, as long as you don't overheat them too much. The release characteristics are the best I've seen in a pad, great for trailbraking. They didn't handle overheating well though -- the edges tended to crumble a lot and the pad could crack through the middle. Oh, and as any track pad, they sound as subtle as a freight train when cold.



The day after I got the wheels and pads, I tried them out at Thunderhill. Stayed with this setup through the summer for another 8-9 days (~15 hours).
To state the obvious, there was lots more grip and times were getting down. But It was a little... sketchy... Quite a few times losing the rear, a few spins, some tank slappers, the whole nine yards. The scariest one was probably losing it going thourgh Riverside at Buttonwillow (in reverse) at 90+ mph. Fun times. Good thing I was only going to tracks with ample runoff at that point, where you have to really try hard to hit a solid object. The worst of it was caking the interior with dust and collecting sand / small stones in various nooks of the undertray or the suspension. And soiled pants, allegedly.

My track friends were of course, giving me a hard time, talking about fidget spinners and things. The consensus was my issues were because of tracking a car with an open diff and soft bushings. The usual: all power to one wheel, plus bushing deflection makes things rather unpredictable. There was probably some of that, but honestly, I just wasn't that good at catching the rear and anticipating slides. It probably didn't help that these were my first few times with sticky tires -- which generally give you way less warning than street tires, and lose grip more suddenly.

There was another thing too. I hadn't had adjustable coilovers for too long and I was still experimenting with the various dampening options. Which mostly meant setting the front rebound higher and higher, because (i) it's the easiest to feel and (ii) hadrer's more racecar, amirite?! I actually wouldn't figure out that I'd set the rear up too loose and snappy until way later -- once I'd forgotten to restore the softer shock settings from a wet day, and the car felt way easier to slide around on the dry too.

Anyway, it would take me a while to figure that out (and a lot more time in iRacing to get better at catching slides), so I went with the most obvious thing and started thinking about a limited-slip diff and solid bushings.



Oh, also around the end of that period, I put on an Eventuri intake. Because you can't go wrong with carbon fiber! This was a bit against my philosophy to keep the engine completely stock[*]. But I'd just spent a few weeks on a death march at work, nights and weekends at the office, so I wanted something nice and blingy dammit! Reason be damned...
[*] It's pretty clear the car isn't exactly lacking power from the factory, and I'd much rather have reliability and lots of track time to improve the nut behind the wheel. This B58 so far has made it to ~120 hours on track with only consumable changes, which still continues to baffle me. Some (very small) problems are just starting to show, so maybe time to refresh it soon...

Last edited by msendit; 03-30-2020 at 01:35 AM..
Appreciate 3
Maynard2219.00
519.E82228.00
      03-30-2020, 07:17 AM   #11
dradernh
Colonel
dradernh's Avatar
1702
Rep
2,728
Posts

Drives: 2017 M240i
Join Date: Aug 2013
Location: Ohio

iTrader: (0)

Quote:
Originally Posted by msendit View Post
RE-71rs...let me recap in short: awesome levels of dry grip; gets maximum grip very fast (2-3 corners); gets greasy / overheated fast too (2-3 laps)
Autocross tires behave this way. I've heard reports on the RE-71R like yours before and understand this is why the tire is so popular with autocrossers. I suppose it's possible they don't overheat as quickly when run on lighter, less powerful cars.

I ran A7s and R-1 S' in time trials on a 318 RWHP 2,708# E36 M3, and they could get greasy pretty quickly in temps >80 F. They're also softer than the RE-71R. Due to the TT clubs' formats, I never ran them for more than four laps at a time.
__________________
2017 M240i: 14.0K, 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; Dinan Elite V2 & CAI; Rogue SSK; MPerf BBK; Schroth Quick Fit Pro;
GTechniq Crystal Serum Ultra Ceramic; Suntek PPF

Last edited by dradernh; 03-30-2020 at 01:31 PM..
Appreciate 0
      03-30-2020, 11:10 AM   #12
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Quote:
Originally Posted by dradernh View Post
RE71-r: I suppose it's possible they don't overheat as quickly when run on lighter, less powerful cars.
Yes, I know a few folks that run them on miatas and S2000s. Their impressions are quite different. For one, they usually complain about heatcycling them away, and not wearing the thread at all. Which is pretty much the exact opposite of our cars.
Appreciate 0
      04-01-2020, 03:14 PM   #13
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Stage 3: track car now?

End track-hours: ~60
End Laguna Seca time: 1:46-high

End parts/specs:
Diffsonline 3-clutch LSD
Derlin subframe & diff bushings
Hotchkis swaybars -- 32 mm F, 19 mm R
Front tires: RE71r 245/40/18 on 8.5x18 ET35 Apex SM-10 wheels
Rear tires: <same as before> + 3mm spacer
Stoptech 340x30mm slotted front rotors
-3.0 camber F, -2.2 camber R, a bit of toe-in

So, I wanted to tame the rear axle a bit, and a diff and solid subframe bushings sounded like the natural next step to get things a little more planted and predictable. This was probably the last time I had some concerns about "streetability" , especially around the rough ride from the bushings (joke's on me -- the diff I ended up with is way less streetable). At the end of the day, I realized I was already pretty obsessed with the whole racing thing, so decided to stop worrying and sacrifice the car to the track gods (and maybe one day sell it as a racecar, with the appropriate expectations).



For the diff, I talked to Dan at Diffsonline (his work came highly regarded everywhere) and we settled on a 3-clutch unit with the 30% lockup and 45/45 angles. Dan discouraged me from changing the gear ratio (from 2.81 on the AT to 3.06) saying that for other customers, the transmission ECU didn't like changes more than ~8%. In hindsight, probably a better idea anyway -- the B58 has heaps of torque all around the rev range.

The "while I'm there" thinking (dropping the subframe and the diff anyway) also led me to change the diff bushings to derlin. And look for a beefier rear swaybar. But then only a monster would change the rear bar and leave the front one stock (especially trying to cure oversteer)... Sigh... I'd promised myself no more speculative modding... That led me to a fairly beefy front bar for our chassis (Hotchkis, 32mm) and their corresponding rear bar (19mm). The endlinks I ended up with to get rid of preload at this height were 12.5" front and 6" rear (measured at the shortest length, ball joint to ball joint).



I tracked this config for a while without any major changes. With the massive swaybars, things were quite more planted through corners. I could feel the diff doing its magic coming out of the hole and rolling on the throttle. Oh, I could also hear the diff -- like, a lot. I am running the stock exhaust and from inside the car the diff whine is still a fair bit louder than the engine.

The off-track excursions decreased somewhat, but would still happen every once in a while. The car was still reasonably snappy, especially around mid-corner, transitioning from understeer to oversteer. As I mentioned, it would take me an accidental wet day setup (less rebound damping, less front swaybar) to get it better sorted when sliding.



Speaking of understeer, this tire combination (235, 265) was pushing a fair bit on entry. I learned how to trailbrake fairly deeply to get the car rotated. That, plus leaning more heavily on the brakes in general, was starting to overheat the brakes on occasion (that issue would only get worse the more I learned to push). I noticed there was space for a little more tire upfront, plus the Forgestar wheels turned out to bend fairly easily, so I got some extra Apex wheels (18x8.5, ET35) and put 245/40 tires on them. They fit witout problem, but didn't leave much space for anything else. Honestly, I couldn't feel a significant change.



At this point, I'd already put a lot of track time (maybe 60 hours or so) on this car and more things were starting to show as consumables. Some definitely expected (like brake rotors, went with slotted 340x30 Stoptech, pretty good brake feel with them), some not so much. Especially studs. I was changing wheels frequently -- drive to the track on street tires, change there, then change back at the end of the day -- and had my first couple of stud failures around this time. Luckily, they happened when torquing wheels, and not on track (this time), so the only drama was drilling out the broken bits from the hubs. That still took a while -- I'd used heaps of red locktite when putting them on in the first time, and it didn't give out without a fight. Other than that, it was mostly going through more and more tires, brakes, fluids, windshields and learning how to push the car harder.
Appreciate 3
Maynard2219.00
519.E82228.00
      04-02-2020, 08:35 AM   #14
Maynard
Colonel
United_States
2219
Rep
2,442
Posts

Drives: 228iX & M2C
Join Date: Mar 2016
Location: Upstate NY

iTrader: (1)

Windshields? And how did you bend the Forgestars (off-tracking, or just from hitting rumble strips)?
Appreciate 0
      04-02-2020, 09:59 AM   #15
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Quote:
Originally Posted by Maynard View Post
Windshields? And how did you bend the Forgestars (off-tracking, or just from hitting rumble strips)?
Windshields: just following other cars closely, stone gets picked up by their rears (especially on something with massive rears, like a GT3 RS), and ends up in my windshield. On #3 right now, waiting for another spider crack on it before swapping it.

Forgestars: I bent one on the red kerbs on the inside of the apexes at Laguna Seca. They're just on the inside of the rumble strips, designed to hurt you and make sure you don't cut the corner. On the other one, the lip cracked one day -- not an isolated incident, just the ususal kerb hopping.

Last edited by msendit; 04-02-2020 at 10:31 AM..
Appreciate 1
Maynard2219.00
      04-03-2020, 12:38 PM   #16
POMFKIMOCHI
Private First Class
POMFKIMOCHI's Avatar
Canada
36
Rep
175
Posts

Drives: 2017 M240i 6MT/RWD EBII
Join Date: May 2019
Location: Richmond Hill, Ontario

iTrader: (1)

I got a pretty bad spider crack on my windshield from the highway, what were your choices for replacements?
Appreciate 0
      04-03-2020, 01:25 PM   #17
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Quote:
Originally Posted by POMFKIMOCHI View Post
I got a pretty bad spider crack on my windshield from the highway, what were your choices for replacements?
I haven't tried anything but OEM, so can't help much. Mostly because of all the sensors in there, but haven't really looked too much.
Appreciate 0
      04-06-2020, 03:15 PM   #18
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Stage 4: track car now!

End track-hours: ~90
End Laguna Seca time: <didn't go these few months>

End parts/specs:
TC Design roll bar
Schroth Enduro 6-point harnesses
Seats: OMP HTE-R (driver), Sparco QRT-R (passenger)
Aim Solo 2 DL lap timer
-3.2 camber F, 0 toe F, -2.2 camber R
Bimmerworld race studs

At this point, I was getting a bit tired of being flung around in the stock seats. I'd use my left foot to kinda brace myself against the dead pedal, and would also death grip the steering wheel for support. Neither was too much fun. Plus, I was already spending a lot of time on track and proper safety was probably a bit overdue. Of course, race seats and 3-point belts don't match, so it was time for harnesses and a roll bar to attach them to.

Spending a bit more time at the track, you start noticing which of the local shops are there frequently and which ones are mostly in the business of slapping on downpipes (but have "race" in the name somewhere). So I went to Tony and Joe at TC Design for all the safety bits. I'd gotten rid of the rear seat a while back (a whopping ~40 lbs) and used the space to lug my tools and a full set of wheels to the track. I wanted to still be able to do that, so we settled on a rollbar design that doesn't block the opening from the trunk to the cabin. (This idea mostly worked out -- I could still load wheels through the trunk, but lost a couple of inches because of the main hoop and could only fit 3 wheels in the back. I'd just end up putting the 4th on the passenger seat.)

Nothing particularly special about the seats -- just went to the local racing store and tried a few that seemed to match my body shape -- I'm on the smaller / shorter side, so the biggest issue was the holes for the belt being a little too high above my shoulders. Same for the belts -- seems like the racing crowd was migrating to 2" 6-point, so I went with that.



I tracked this config for quite a while without any other changes (except for alignment/setup and loooots of consumables). At this point I was already capturing telemetry and didn't see a big difference from any weight savings -- they were probably minial anyway, the seats shaved off a fair bit, but the rollbar added a lot too. There was a massive difference in my feel of what the car was doing though! Getting rid of the cushy stock seats, my butt could actually feel the rear giving away much earlier and I started catching slides way better.

Of course, nothing comes for free -- driving to the track and back became way less comfortable. For one, some of the "local" tracks are ~300 mi away and that same butt really didn't appreciate the trip in a bucket seat, especially after hard running workouts. Visibility wasn't great too. Most people seem to have visibility trouble with seat headbolsters, which was actually fine for me. My bigger issue was the lower seating position. But oh well, I'd already chosen to optimize this car for the track, so no point in dwelling more.

At this point, I was getting very comfortable with the car. I could toss it around a lot and really appreciated the predictability, no more sudden snapping. With enough trailbraking, I could get the front to rotate pretty well too. Sudden changes of direction were quite good too -- the T3-T4 right-left sequence at Thunderhill is a great test for that. The only major problem was brakes.



Once I'd learned how to drive a bit closer to the limit, it was very obvious how massively underprovisioned the brakes were for my use. The Pagid enduro pads I was using would overheat signficiantly. There was barely a day without some sort of brake overheating drama, and that was even without going to Laguna Seca, which is way harder on the brakes than the other local tracks. I tried some Hawks too, but all they did was transfer the extra heat to the fluid instead and boiled it in the span of a few laps.

Annoyingly, our chassis has some brake ducting, but it's pretty much usesless, especially so once you put wider tires than the stock 225s. The duct just ends up blowing directly into the tire surface, not anywhere near the rotor. And because of the really narrow wheel wells, you can't easily run a hose from the stock ducts to the rotors. I started mocking up some ducting, but would end up scraping it because things escalated a bit.



I'd mentioned having a couple of studs snap while changing wheels a few months back. I replaced all 4 corners with a fresh set of Apex studs after that. Then one day, at Big Willow, I had all 5 on my FL snap on track, while going 90mph through T9 (post). I was actually pretty lucky that the wheel detached after most of the rotation was done and the car didn't flip or anything drastic like that -- just dragged along a bit. I got away with damaging a couple of wheels (the one that detached, plus the spare I used to hobble 300 mi back on a bent hub), the wheel hub, and ball joints. The tie rods and control arms looked straight, but I still replaced them out of caution.

Oh, and more importantly, the FL fender lip was roughed up from that accident. I'd actually roughed up the FR lip as well a couple of months earlier (still unclear how exactly, but some debris got stuck in the little space between the tire and the lip and ended up bending it), so both sides looked like they had a very ghetto roll done.

The bulk of the fenders were completely fine, and the messed up bits were exactly what you'd cut out putting on fender flares. I'd talked about doing a widebody on this car with my friends for a while now, but it was mostly just joking around that I'd turn a 3700 lbs boat into Project Momentum, nothing really serious. But now I actually started thinking seriously about it -- it was a choice between replacing & repainting fenders just to end up with a config that still had a big brake problem, or "doing things right" and escalating things to make sure there's both enough tires and brakes for the car's hefty weight. Needless to say, in racecar math, the second option was clearly the way to go.

Last edited by msendit; 04-06-2020 at 04:39 PM..
Appreciate 2
519.E82228.00
ngl93.50
      04-08-2020, 09:39 AM   #19
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Stage 5: M240iR

End track-hours: ~120
End Laguna Seca time: 1:44.0

End parts/specs:
M235iR fender flares from Flossman
Calipers: Brembo Club Race F, Brembo GT R
Rotors: 355x35 mm F, 345x28 mm R
Pads: RaceTechnologies RE10
Wheels: Apex FL-5 / SM-10 18x10" ET25
12 -> 15 -> 20 mm spacer front
Tires: RE71-r 285/30/18 square
occasional "drift setup": Hankook RS4 285/35 R only
Springs: 90 N/m 200 mm F, 150 N/m 200mm R
-3 camber, 1/16 toe out F, -2.2 camber 2/16 toe in R
many alignment variations between (-3;-3.5) F, (-2; -2.5) R

All the braking issues I described earlier made me realize the difference between a car that can do a few "hero" laps on track, and a sorted racecar with consistent performance every day. There's a massive step in between and the F22 weight isn't exactly helping it. Add in all the issues from damaging the bodywork and it seemed like the right time to try and step in the latter category. This would mean at the very least bumping up tires and brakes to match the car's weight.

Like many folks here, I'd salivated over the few bodykits for our chassis. I was leaning toward Manhart, but then I saw a set of cup car flares from a shop in Germany for what looked like a good price, so I jumped in. In hindsight, it was definitely not worth the trouble -- after taxes, duties, freight shipping, and a customs broker fee the cost was pretty much the same as getting them from Bimmerworld. Oh well, now I know...

I knew that the cup cars run 265/660 slicks at VLN. In the DOT sizes we're used to, that's about 285/35. There aren't that many sticky tires in 285/35/18, so I was choosing between 275/35 (very popular, many compounds) and the rare 285/30 (pretty much just RE71-r and Hoosiers). Decided to go for the 285/30 so I can still use the RE71-rs I was used to (I'd later find out that 275/35 actually needs a fair bit more work to fit in the well). A 10" wheel seems about right for that, with as low offset as possible -- there should be plenty of room to push them out with the flares and I was expecting the biggest problem would be clearing the suspension at the front.

I was already overwhelming the brakes with 245 tires -- adding this much more grip without better brakes wouldn't be smart. At that point I was thinking a Stoptech BBK with some ducting, similar to what I've been mocking out at home. Also, a big bump in grip under braking would probably need stiffer springs too -- my previous setup was already diving a lot in braking zones. Problem is, I had no idea what the effective rate of the progressive spring in my KW V3 was. I cursed the shop that sold me the V3 again for good measure (not that I'm holding a grudge or anything), and figured 90 N/m might be a good starting point (based on the Clubsport rates).

With that, I felt like I'd done enough of my homework to start talking to the race shop that was actually doing the work. The plan changed a bit after talking to them -- they'd spec out a brake kit with Brembo (Club Race calipers front and GT calipers rear) and ditch the brake ducts (unless we really need them). I still don't trailer the car and drive it to the track and back -- brake ducts would probably get destroyed in that process. Plus, they had had very good experience competing with the Brembo brakes (including in the 25 hours of Thunderhill), so it was a known solid piece of kit to go with. There isn't that much choice in race pads for this caliper shape -- I'd rather not use a sprint compound on a car that still sees the street, which left us with the enduro RE10. On some other (admittedly much lighter) cars, they'd lasted more than half-distance in the 25-hours, which sounded pretty promising.



Fitting the fender flares went without much trouble. Of course, we needed to trim the original fender lips -- that's the whole purpose of doing this. The front flares have a convenient lip on the inside with mounting holes, so we could just bolt them in. The big rear panels actually had bolts laid into the fiber and sticking out, but we ended up not using them -- that would've required taking out all the interior panels (that was probably a mistake -- I should've just gutted the interior and stopped pretending this is a street car any more). Instead we riveted them. Also riveted the front bumper extensions. The point was never to optimize for looks, so rivets didn't bother me -- plus a livery would mostly cover them anyway. For the most part the new panels fit ok -- the front bumper extensions needed a tiny trim to clear my air dam, and the driver-side rear panel had a bit of a kink near the tail light, but really nothing major. Here's a few closeups on fitment (for Dylan86 ).

No problems with fitting the wheels and tires at the rear, there's plenty of space there -- if I had to guess probably enough even to fit a 305 tire on a 11" wheel. The front, on the other hand... much more painful. To clear the suspension, we started with a 12mm spacer. It was still a pretty tight fit -- maybe 2-3 mm clearance from the spring perch. The low-profile 285/30 tires barely brushed the fender liners (which we kept, because why not) once you add a lot of steering lock -- both at the front and at the back of the wheel well. Not enough to cause trouble yet, but it meant that pushing the wheel out even more would start rubbing harder (and at less steering lock). It would also mean running /35 tires would be much harder without more drastic changes.



All that said and done, it was time to start testing. First, the good. The increase in front-end grip is pretty drastic. The car actually wants to rotate on entry now instead of only pushing, so I had to unlearn some of my deep trailbraking habits. Also, braking distances are way shorter now. In fact, the first thing anyone notices riding along on track is "Holy cow, these brakes!". Even after ~30 hours with this config, I'm still not completely used to it and tend to overbrake into corners. They seem to cool adequately without brake ducts too -- for now at least, I'd be curious to see if that's still the case during the summer. The spring rates we ended up with actually turned out OK too -- I was worried they might bring back some snappy behaviors, but slides are still very predictable.

The bad -- these 285/30 tires. First test day out with this setup, the inside sidewall of the loaded tire caught the suspension and tore. I didn't think too much of it -- there was barely 2-3 mm clearance, the tires expand a bit when you push them, plus the sidewall can flex a little. So, I just swapped the 12mm spacers with 15mm and decided to live with a little more fender liner rubbing for the time being.

A couple of days later, similar story. Inside sidewall of the loaded tire caught the suspension again and tore. More worried now, but went to a 20mm spacer with heaps of suspension clearance (and a pretty bad rub in the frame once you add steering lock). More testing (and more failed tires) revealed the root cause of the issue -- the sidewall was failing and buldging out and only then catching the suspension (example). Kinda like runflats against potholes -- but I wouldn't expect that from stiff sidewall tires like the RE71-r. Over the next few test days, I tried out many theories about what could be causing this -- too much camber, too much toe out, pushing too hard on cold tires, etc. None of them seemed to pan out. After 7 tires failing this way (as if the running costs of this car weren't already absurd) and trying to make the /30 tire work, I decided I've had enough and the simplest explanation was probably enough -- just too little sidewall to support the car's (massive) weight when leaning in a corner. Which would mean making even more changes to try and fit a /35-profile tire.


Last edited by msendit; 04-16-2020 at 09:46 AM..
Appreciate 3
ifobd23.00
519.E82228.00
ngl93.50
      04-09-2020, 02:00 AM   #20
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Stage X: (in progress)

End parts/specs:
SPL rear suspension links
Tires: RE71-r 275/35/18 square
12 mm spacer front
Front spring: 90 N/m 170 mm

This is where things are now, a few big bits still largely untested. I'll keep updating this thread if / when there's other major "stages".

As I mentioned, the biggest issue with the previous config was that 285/30 tires didn't have enough sidewall strength and kept failing on track, and 275/35 (which presumably have enough sidewall) didn't fit in the wheel wells in the front. I swapped the front spring with a 30mm shorter one to get a bit more suspension clearance. Also, /35 tires had the worst clearance problem at the back of the wheel well -- not just a light rub, but full on jacking. Turns out the actual contact point is not in the frame itself, but in a stiffening brace that's bolted to the frame. The black bit here. Even better, my shop had a new M2 in for cage work and they noticed it didn't have that brace at all! (The M240 vert doesn't have it either.) So I just took it out -- like this -- which gained a good 2-3 cm of clearance. Also, it was a pretty hefty piece -- about 15 lbs on each side. I then trimmed the plastic fender liner at the front of the wheel well just a bit.

So, now 275/35 fits easily with a 12mm spacer. Haven't tested this out on track yet -- if the chassis ends up flexing too much (doubt it), we can come up with a much more discrete brace.
This actually ended up much easier than expected. Before we realized the clearance problems were due to a removable bit, the thinking was to add an adjustable thrust arm and way more caster to pull the wheel 10-20 mm to the front, then trim whatever's in the way upfront. Seems like we can get away without that.

The other largely untested bit right now is at the back of the car. Late January, I noticed that my rear suspension was starting to wander. Over a few days, I'd see pretty uneven tire wear especially on RL. Grip in right-handers was somewhat unpredictable too. Once back from the track, we'd put the car on the alignment rack and everything would look fine. This smelled like busted bushings on the rear suspension -- I was still running the OEM rubber bushings, now with more than 100 hours of track time on them. So we took them out and replaced the 4 links with SPL adjustable parts with solid ends. The old bushings looked worn but not outrageous. So far, I've only taken the car out once with this rear and it felt fine -- needs more testing to see if that was the real issue.


Last edited by msendit; 04-09-2020 at 04:29 PM..
Appreciate 3
519.E82228.00
ngl93.50
      04-09-2020, 12:17 PM   #21
dradernh
Colonel
dradernh's Avatar
1702
Rep
2,728
Posts

Drives: 2017 M240i
Join Date: Aug 2013
Location: Ohio

iTrader: (0)

Quote:
Originally Posted by msendit View Post
The other largely untested bit right now is at the back of the car. Late January, I noticed that my rear suspension was starting to wander. Over a few days, I'd see pretty uneven tire wear especially on RL. Grip in right-handers was somewhat unpredictable too. Once back from the track, we'd put the car on the alignment rack and everything would look fine. This smelled like busted bushings on the rear suspension -- I was still running the OEM rubber bushings, now with more than 100 hours of track time on them. So we took them out and replaced the 4 links with SPL adjustable parts with solid ends. The old bushings looked worn but not outrageous. So far, I've only taken the car out once with this rear and it felt fine -- needs more testing to see if that was the real issue.
This sounds like the variable toe that can occur with worn suspension bushings and with worn rod ends. One nice thing about rod ends is that you can tell when they're worn by doing a push-pull along the length of the arm they're attached to. If you feel any movement or hear a 'click', it's time to change them out.
__________________
2017 M240i: 14.0K, 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; Dinan Elite V2 & CAI; Rogue SSK; MPerf BBK; Schroth Quick Fit Pro;
GTechniq Crystal Serum Ultra Ceramic; Suntek PPF
Appreciate 0
      04-09-2020, 12:51 PM   #22
msendit
Second Lieutenant
msendit's Avatar
292
Rep
265
Posts

Drives: M240i
Join Date: May 2018
Location: San Francisco, CA

iTrader: (0)

Quote:
Originally Posted by dradernh View Post
One nice thing about rod ends is that you can tell when they're worn by doing a push-pull along the length of the arm they're attached to. If you feel any movement or hear a 'click', it's time to change them out.
Yeah, the SPL arms I ended up with have rod ends -- it should be easy to check like this in the future.

The one thing that did slip my mind though was to replace the bushings on the 5th link -- the spring carrier. It has two fairly meaty rubber bushes. Hopefully they weren't the busted ones.
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 04:15 PM.




2addicts
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST