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      06-19-2020, 01:36 PM   #243
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Quote:
Originally Posted by BeastieBombRacing View Post
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Originally Posted by PLF69 View Post
If I recall you have M4 specific swift springs or your car, how much did it lower the car ?

I frequently hit 210kmh on a straight in one of our local track and don't feel any weird behavior, what it your alignment at ?
It’s going over the hill, I think, that’s the problem.

Currently on Factory alignment.
I felt a considerable difference in high speed stability in stock form vs lower aftermarket suspension.
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      06-19-2020, 01:47 PM   #244
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Originally Posted by PLF69 View Post
I felt a considerable difference in high speed stability in stock form vs lower aftermarket suspension.
I really hadnt even considered damping as a factor, but you may well be on to something.
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      06-19-2020, 03:19 PM   #245
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Originally Posted by BeastieBombRacing View Post
It’s going over the hill, I think, that’s the problem.

Currently on Factory alignment.
How fast are you going over the hill, and is it a steep crest, or a jump?

I take the kink/hill just past the bridge of the 'Ring at over 150mph, flat on throttle and feel ok with stock setup. The jump before the small carousel doesn't upset the car either.

Also a lip spoiler and a wing on the back is cool as long as you have matching downforce on the front. Because Racecar!
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      06-19-2020, 03:28 PM   #246
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Originally Posted by 5.M0NSTER View Post
How fast are you going over the hill, and is it a steep crest, or a jump?

I take the kink/hill just past the bridge of the 'Ring at over 150mph, flat on throttle and feel ok with stock setup. The jump before the small carousel doesn't upset the car either.

Also a lip spoiler and a wing on the back is cool as long as you have matching downforce on the front. Because Racecar!
Excuse the horrible driving. Hill is right at the start of the video. I'm at about 122 on the speedo when I lift at the start of it. By the time I crest it, I can feel the rear end get very light and loose.

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      06-19-2020, 04:29 PM   #247
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Hm, that loops pretty gentle in the video. Which means less gentle in real life. But there seems to be no major drop on the other side. SO I think PLF69 might have a good point. Rebound may be too slow on the dampers, so the wheels stay tucked after the initial compression of the uphill section.
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      06-19-2020, 11:35 PM   #248
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Quote:
Originally Posted by BeastieBombRacing View Post
Excuse the horrible driving. Hill is right at the start of the video. I'm at about 122 on the speedo when I lift at the start of it. By the time I crest it, I can feel the rear end get very light and loose.
Are you lifting to 0% throttle, or just to a neutral throttle position where you’re neither accelerating or decelerating?

Asking because if this is an abrupt lift, maybe you’re destabilizing the car enough to decrease rear end traction. Hard to tell from the video, but it does look like you’re dropping speed as you crest the hill.

Re: buffeting with windows down. I’d love to find a fix. I removed the rear seat and it got noticeably worse. Fortunately, my local tracks only have one straight each that is fast enough to be a real problem.
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      06-19-2020, 11:53 PM   #249
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Originally Posted by bentom2 View Post
Are you lifting to 0% throttle, or just to a neutral throttle position where you’re neither accelerating or decelerating?

Asking because if this is an abrupt lift, maybe you’re destabilizing the car enough to decrease rear end traction. Hard to tell from the video, but it does look like you’re dropping speed as you crest the hill.

Re: buffeting with windows down. I’d love to find a fix. I removed the rear seat and it got noticeably worse. Fortunately, my local tracks only have one straight each that is fast enough to be a real problem.
Here’s the throttle data from M Laptimer for this lap:



I can also confirm this is MUCH worse after removing the rear seat.
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      06-21-2020, 06:48 PM   #250
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I've taken my stock M2C to about 10 autocross events so far. I feel that I've improved quite a bit as a driver (there's always more room to go), but I'm now looking to tweak the car. Without regard for classing, what is the best first modification to improve my times?
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      06-21-2020, 06:50 PM   #251
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BeastieBombRacing -There’s a somewhat similar crest at one of my local tracks, and while I can get through at WOT when running staggered tires, when I switched to square, I started lifting a bit for the crest or the rear gets unstable, but as you can see, it’s a partial lift, and fairly gradual so I don’t upset the balance of the car. The right throttle position to keep the chassis stable on your track is probably different, but you the the idea.

Here’s a video of the track for reference. The crest is at roughly 1:19 into the video and then every 2:10-2:15 after that.

https://youtu.be/9V0w9GlupEg

I could be way off on the root cause, but these cars are very responsive to throttle position changes. Can be a useful tool, or your worst enemy, depending on the situation.
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      06-22-2020, 12:22 PM   #252
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Guys with the M app. Is it worth it? Thinking of going back to apple as BMW supports them much more.
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      06-22-2020, 12:28 PM   #253
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Quote:
Originally Posted by Blue2 View Post
I've taken my stock M2C to about 10 autocross events so far. I feel that I've improved quite a bit as a driver (there's always more room to go), but I'm now looking to tweak the car. Without regard for classing, what is the best first modification to improve my times?
Tires.
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      06-22-2020, 06:06 PM   #254
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Tires.
I would add camber plates as well. They will pay for themselves in tire wear very quickly.
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      06-22-2020, 11:34 PM   #255
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I would add camber plates as well. They will pay for themselves in tire wear very quickly.
Oooo yea, definitely! Good call.
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      07-04-2020, 09:12 PM   #256
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Anyone have shoulder wear even with camber plates? Running -2 degrees of camber with Vorshlag camber plates and still facing uneven shoulder wear. Using RE71R tires starting at 25 PSI cold and running between 32-34PSI hot. Other mods consistent of Ohlins R&T.


All on Watkins Glen so a predominantly right handed track but my driver front tire got way more outside wear than expected. I will note that drive front was set to full soft while rest of car was full stiff.
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      07-04-2020, 09:28 PM   #257
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Quote:
Originally Posted by moveswiftly View Post
Anyone have shoulder wear even with camber plates? Running -2 degrees of camber with Vorshlag camber plates and still facing uneven shoulder wear. Using RE71R tires starting at 25 PSI cold and running between 32-34PSI hot. Other mods consistent of Ohlins R&T.


All on Watkins Glen so a predominantly right handed track but my driver front tire got way more outside wear than expected. I will note that drive front was set to full soft while rest of car was full stiff.
I ran 2.8 on otherwise stock suspension and still had some shoulder wear. Currently at 3.2, but also Ohlins went on at the same time and wear appeared to even out as I used up the last set. 3.2 might be a tad too much, but I’m giving it another day so I can read the tire wear. I’m running Hankook RS4 and they last forever, so it takes a while to show a wear pattern. Might go to 3.0 next.

In both cases, not a particularly relaxing highway drive with the car following ruts and camber changes quite aggressively, so you’ll have to decide how much of a trade off you’ll want to make in either direction.
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      07-04-2020, 10:06 PM   #258
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I run -2.7 on stock suspension and the outside shoulders are still wearing faster on RS4s (and RE71Rs before). I'm fairly happy with -2.7 though, I can have the tires remounted to flip inside/outside and that gets me a few extra days.

At -2 you've not got enough camber to stop the uneven wear, you'll have to add more. I think most people who daily + track go for -2.5 - -2.7.
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      07-05-2020, 07:39 AM   #259
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Thanks all. I'll bump it to -3 and see how the wear improves.
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      07-05-2020, 10:28 AM   #260
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Quote:
Originally Posted by moveswiftly View Post
Thanks all. I'll bump it to -3 and see how the wear improves.
Even after you get your alignment settings dialed in, one other thing to think about to maximize life of your tires, if all your local tracks run in the same direction, is to get your tires flipped on the wheels when the outside tires are around 50% worn. That’ll allow you to swap them left to right, and the outside shoulder will become the inner shoulder.

All my local tracks run counter-clockwise, so I have the opposite problem and have had good success with this.

Looks like there’s a ton of life in that right side tire, so could extend your tire’s usable life by a couple days or more.
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      07-05-2020, 04:22 PM   #261
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Quote:
Originally Posted by moveswiftly View Post
Anyone have shoulder wear even with camber plates? Running -2 degrees of camber with Vorshlag camber plates and still facing uneven shoulder wear. Using RE71R tires starting at 25 PSI cold and running between 32-34PSI hot. Other mods consistent of Ohlins R&T.


All on Watkins Glen so a predominantly right handed track but my driver front tire got way more outside wear than expected. I will note that drive front was set to full soft while rest of car was full stiff.
Needs more camber! Time to flip them as well. Love WGI such a quality track, will be taking my M2C there for the first time in August. Was meant to be there in May but COVID ruined that. First time this year will be summit point next week, it's been a very long wait!
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      07-05-2020, 08:33 PM   #262
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Originally Posted by Montaver View Post
Needs more camber! Time to flip them as well. Love WGI such a quality track, will be taking my M2C there for the first time in August. Was meant to be there in May but COVID ruined that. First time this year will be summit point next week, it's been a very long wait!
I have been running 3.2 with Ground Control and MCS with very even wear...I do flip at least every 2 track days.
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      07-05-2020, 10:38 PM   #263
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Quote:
Originally Posted by Montaver View Post
Quote:
Originally Posted by moveswiftly View Post
Anyone have shoulder wear even with camber plates? Running -2 degrees of camber with Vorshlag camber plates and still facing uneven shoulder wear. Using RE71R tires starting at 25 PSI cold and running between 32-34PSI hot. Other mods consistent of Ohlins R&T.


All on Watkins Glen so a predominantly right handed track but my driver front tire got way more outside wear than expected. I will note that drive front was set to full soft while rest of car was full stiff.
Needs more camber! Time to flip them as well. Love WGI such a quality track, will be taking my M2C there for the first time in August. Was meant to be there in May but COVID ruined that. First time this year will be summit point next week, it's been a very long wait!
Which organization are you going with? I've been to WGI dozens of times. My favorite track. First time with my M2C - hit a 2:13.08 although the car has a good 5-6 seconds left on it.
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      07-06-2020, 06:29 AM   #264
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Quote:
Originally Posted by moveswiftly View Post
Quote:
Originally Posted by Montaver View Post
Quote:
Originally Posted by moveswiftly View Post
Anyone have shoulder wear even with camber plates? Running -2 degrees of camber with Vorshlag camber plates and still facing uneven shoulder wear. Using RE71R tires starting at 25 PSI cold and running between 32-34PSI hot. Other mods consistent of Ohlins R&T.


All on Watkins Glen so a predominantly right handed track but my driver front tire got way more outside wear than expected. I will note that drive front was set to full soft while rest of car was full stiff.
Needs more camber! Time to flip them as well. Love WGI such a quality track, will be taking my M2C there for the first time in August. Was meant to be there in May but COVID ruined that. First time this year will be summit point next week, it's been a very long wait!
Which organization are you going with? I've been to WGI dozens of times. My favorite track. First time with my M2C - hit a 2:13.08 although the car has a good 5-6 seconds left on it.
I'll be at Summit this weekend with a PCA, at WGI end of August with NASA. Might try and fit another event somewhere in between as well.

Solid time, what suspension / tires?
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