09-22-2021, 10:46 AM | #45 | |
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This chassis tends to be limited by clearance in the front wheel well. I'd set the front as low as it goes without causing problems at full compression (put the wheel on and stick a jack under it to test). Then set the rear a few mm higher. Once you've driven a few times on track, adjust the rear to taste to dial the balance. It was bundled with a few other big changes -- shocks, springs, weight. The combo was definitely noticeable. |
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09-22-2021, 02:00 PM | #46 |
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Terrific information. Thanks for the reply.
I'm running b14 Bilsteins with 18x9 255 square. Interesting that you say low as possible, as that will change suspension geometry. I think my front sway is 25mm, rear I'm not sure. |
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09-22-2021, 04:41 PM | #47 |
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Yeah, I've never particularly felt the need for roll-center correction on this car, after lowering. No idea the actual reason -- maybe long control arms, or just there's not that much opportunity to lower it before running out of fender clearance. For comparison, my other strut-based car gets pretty diabolical without bumpsteer correction. Shrug, if it ain't broke...
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09-22-2021, 07:06 PM | #48 |
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That is interesting. Yes, the change in geometry should make it twitchy on rough surfaces.
Control arm angle is important. You are saying it did not become jerky on the bumps. A stiffer rear sway should give it less under steer. Wow are the bars a big deal to replace. |
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11-03-2021, 09:00 AM | #49 | |
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11-03-2021, 09:31 AM | #50 |
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For just a fun track day car in a similar price range -- probably a Supra. Pretty much every parameter that matters is better than the F22 from the factory -- tire space, weight, power, brakes, track width, etc. Not to mention aftermarket support.
For racing, very different story, depending on rulebook / which class. I actually did decide to bite the bullet and race the M240 in NASA ST4 next season, so pretty excited about that. But the easy choice in that class seems to be either a E36 or E46. |
11-03-2021, 06:35 PM | #51 | |
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As F22 owners, I think that in the context of going faster on the track the answer is always going to be: a (much) lighter car with a more capable braking system.
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As nice as our cars are when classed as street/track cars, when they're pure track/race cars my take is that it's an entirely different ball game. Turning heavy cars at racing speeds is a severe limitation, and our cars are heavy. I look forward with great anticipation to your experiences and, hopefully, great results in ST4 next year; if you do share those with us, please include videos! I would also find it interesting to see the absolute # and HP values of your car and those of any of your competitors. I just took a quick glance at NASA's ST4 calculator and am wondering: is your car close to the #/HP limit for the class?
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2017 M240i: 25.9K, 28.9 mpg, 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; 18X9/9½ ARC-8s; 255/35-18 PS4S (4); Dinan Elite V2 & CAI; MPerf Orange BBK; Schroth Quick Fit Pro; Full PPF |
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11-03-2021, 08:24 PM | #52 |
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Thanks dradernh and msendit for the feedback.
Thanks both and great builds. Please reply either of you provide me with a reply in this thread for a different yet follow-up to my inquiry here? https://www.2addicts.com/forums/show....php?t=1871541
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11-03-2021, 10:31 PM | #53 | |
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As for P/W numbers, the NASA database is public here -- you can browse the competition all day. At least in NorCal, 2700-2800 lbs is a pretty typical min weight. The rulebook also has a nice bump in allowed tire width at 3000 lbs and some cars in other regions have done well just a bit above that weight. Before the offseason, my car sits at 3400 min weight and 315 avg whp. With some (not competitive) tires, that's enough to barely skate in ST4. I've been testing lots of more aggressive tires lately (and really not doing serious competition with it), so I just ran it one class above in TT3. In broad strokes, the offseason plan is simple: lose some weight without going too crazy, detune to keep it in class with Hoosiers / Hankook DOT tires, max out the allowed aero, and see where that gets us. Will be interesting for sure. |
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12-14-2021, 11:25 PM | #54 | |
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Looking forward to seeing how light you can get that chassis. You'll definitely have the most modern suspension design compared to the rest of the field! |
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12-15-2021, 10:01 AM | #55 | |
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About tuning platform, not sure. Randy at Epic is doing that. They have their own interface for the older cars, but not sure what his plans are for something newer. And speaking of "modern XXX design", I'm not very happy about the 2022 rule changes. The new transmission and throttle body rules will cost me an extra 0.5... See, I'm already piling up the excuses 3 months before the seasons start! |
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12-15-2021, 10:57 AM | #56 | |
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The throttle body change is an interesting one; you'd think that effect would be captured by sampling multiple datapoints on the power curve. On the plus side, most of the cars in our region already have electronic throttle so you won't be an outlier there. The automatic hit is a bit high. Yes an automatic or DCT is an advantage over a manual on a turbo car, since it does a better job of keeping the turbo spooled on shifts. But shift times with an S54 and a manual ZF 5 speed are very fast; it's not much of an advantage there to have an auto. So really, having an auto/DCT on a turbo car is just making a turbo engine have similar performance to an N/A motor. |
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03-01-2022, 11:32 AM | #57 | |
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I'm hoping to make the March Sonoma race. |
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03-01-2022, 12:44 PM | #58 | |
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My current plan is to make the March race with the M240 as well. Certainly looks like the class pace has picked up, should be fun to try and chase. |
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03-23-2022, 11:24 AM | #60 | |
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Hopefully you want to help a brother out a bit. I own a BMW F21 M135i, which is built for trackdays just like yours. I just received my M240iR carbon widebody a few days ago, and i want to ask if you want to take some pictures for me, mostly of your rear wheel arches. The reason for this, is i cant somehow figure out what to do with the existing wheels arch, i know it needs to be cut, but i cant figure out how much should be taken away, also, did you managed to fit bolts into the rear panels, in the arch lining? I see there is like 4 5mm nuts molded into the panels. I appreciate what ever help you can provide to me. Thanks mate. regards Lars Denmark/EU |
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03-23-2022, 08:36 PM | #61 | |
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Interesting your panels have nuts molded in -- mine were the same, but with bolts. We ended up just cutting the bolts out and riveting the panels to the OEM bodywork. At the time I still had rear interior and taking that apart just to bolt on the fenders seemed like a hassle. Last edited by msendit; 03-23-2022 at 11:37 PM.. |
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03-24-2022, 12:48 AM | #62 |
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Thank you!
I've attached Photos of my current state of my project with the arches. Mines bought directly from BMW dealer. Well, as you said, yours came with bolts, mine also did that, in the top of the panels. Down in the wheel arch they molded in nuts, and somehow a bolt should come through a panel there or something. Maybe i can tell what to do, when i see some pictures of yours |
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04-24-2022, 10:55 PM | #65 |
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True, and thank you.
I see you dont have the carbon inner fenders/Wheel barrels glued into the bodywork itself. I am actually going to the Nürburgring on Friday to meet some local racing companies who is used to work with the M235iR cars, curious to see how much things will set me back. But I do expect it wont be cheap nonetheless. |
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12-08-2022, 12:51 AM | #66 |
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Haven't updated this thread in a while.
But the fine folks at NASA Speed News just wrote an article about my car that covers its 2022 woes pretty well. I'm a bit biased, but I think it's a good read: https://nasaspeed.news/cool-rides/bl...a-bmw-chassis/
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Last edited by msendit; 12-08-2022 at 01:10 AM.. |
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