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      09-07-2016, 03:31 PM   #1
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Square setup caveat (more specific for the Ridge) and suggestions to "fix" it

Car - 1M with camber plates, square 265/35R18 Michelin PSS on 18x9.5 +22 ARC8
Track - http://ridgemotorsportspark.com/track-info/track-map/
Alignment = -2.8 / -1.9 F/R, 0.05 / 0.1 F/R Toe-in squared compared to -2.2 / -1.8 F/R, 0.07 / 0.06 F/R Toe-in for stock staggered

I ran the Ridge last year with less camber differences (rear is pretty much non-adjustable at -1.8 to -1.9, just between extra .5 to 1.0 difference up front) on stock staggered Michelin PSS, only MDM but didn't use Sports mode, and I did fine (only went off track twice due to aggressive late braking, straight into the run offs). Both times it was dry

Yesterday was "scary" in a sense - damp and misty rain in the morning, and I figure since I will be conservative I might as well learn how to drive the 1M without traction control. Ended up with 2 snap over-steers and one that really scratched up my driver side rims and left rock scratches on front bumpers. The first one was damp surface over the crest at Turn 3 that caused an unintentional lift - that one I ended up choosing a different line and more conservative speed. The second one (which I consider a major off) was on dry surface over the crest at Turn 10 where I backed off on the wrong place and turned, sending me straight to the gravel

Obviously I need to adjust to this setup, but I like the turn in aspect on the flatter sections of the track, and the ability to rotate tires to maximize tread life (I don't intend to have dedicated track tires so I just run normal summers). But this snap over-steer means I have no margin for error and I don't think I want to go back to staggered.

These were the suggestions to me: less negative camber up front, stiffer and lowered spring up front, stiffer sway bar in front, and spacers (+15mm) in the rears. I don't think I would ever go full coil over on this car, and I doubt the spacers will address the situation that should be addressed by springs and/or the sway bar up front.

Question is: if I were to do only one mod, would the front springs makes the most sense to solve this? Or will it bring enough under-steer that the advantages of a square setup is lost? I haven't tracked at other places yet and this is most likely my home track that I go twice a year.

Last edited by CP 1///M; 09-08-2016 at 01:59 AM.. Reason: Added alignment
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      06-23-2017, 11:35 AM   #2
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Just to bump this and augment my changes:

For this past track day I ran some 12mm spacers in the rear (effectively making them ET +10), and run 5psi more in front (45 hot) than rear (40 hot). I would say it seems to be doable but wondering if I ran out of adjustments as I probably can't go any wider in the rear (I might have tried 15mm but choosing 25mm to start was a mistake, nor milling those down 22mm help remove the rubbing)

I think with just the 12mm spacers and alignment unchanged I have increased enough rear grip to make car less snappy, and from the videos I would conclude that I'm relearning to drive without assists (TC off entirely) with more front grip than staggered and I should be able to have steering on more turns
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      07-04-2017, 02:16 AM   #3
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Quote:
Originally Posted by CP 1///M View Post
Just to bump this and augment my changes:

For this past track day I ran some 12mm spacers in the rear (effectively making them ET +10), and run 5psi more in front (45 hot) than rear (40 hot). I would say it seems to be doable but wondering if I ran out of adjustments as I probably can't go any wider in the rear (I might have tried 15mm but choosing 25mm to start was a mistake, nor milling those down 22mm help remove the rubbing)

I think with just the 12mm spacers and alignment unchanged I have increased enough rear grip to make car less snappy, and from the videos I would conclude that I'm relearning to drive without assists (TC off entirely) with more front grip than staggered and I should be able to have steering on more turns
Oh my wow.

I think your first mistake is the rear wheel choice. Stock is 10" wide and yet you went narrower at the rear to a 9.5 " wide wheel and then at the same time you went to a .5 inch wider wheel than stock order to match the front as a squared setup ?

At the same time you also increased the front tire width by 20 mm as well ?

You have effectively reduced the rear grip of the car ( in proportion to the front ) with all three of these adjustments. This is what is causing your enhanced snap oversteer. The 1M already has a propensity for the rear end to step out and you have exacerbated this greatly by increasing your contact patch at the front and reducing it at the rear.

Adding the 12 mm spacers at the rear is actually pushing the rear wheels and tires back outward to where they should be originally, which does indeed help your situation, but it's a bandaid to fix the initial issue.

I am absolutely in favor of a square setup for many reasons .. most of which don't involve a stop watch. If you are racing , go as big as you can on both ends of the car although don't get crazy with the rear stagger.

For lapping day and HPDE work, the same is true.. put as much tire on the car as you can afford to ...... for me that generally means 275/30/18 " R " Tires on an 18X 10 square setup so I can put any tire on any corner for the best ability to maximize wear not only for each course but also within the weekend.

If you want to rid the car of some of the tail happiness at the rear ... add more tire to the rear of the car... if you intend to turn.. add more wheel and tire up front as well! I found that when I went with a 285/30 front and 315/30 rear on staggered 18 x 10 front and 18x 10.5 rear wheels.. the car puts down the power best but it does feel a bit more point and shoot however ... and those rear tires get $pendy.

Back to your setup... I think you've actually managed to make all the adjustments possible for the wheels that you have. You've added back some rear track. I wouldn't go with a wider spacer as that simply distorts the front to rear widths further. You've been adjusting tire pressures as well and those are really a fine tuning adjustment.

I really am not a fan of 9.5 inch wide wheels at all on this car. Indeed They are better than stock up front for grip. But you can also fit a 10 up front .. so why not ?! if you are tracking the car then let's actually make it perform.

Finally.. when on track, if you are committed to the corner in any car.. but especially the 1M... don't lift .. if you do.. you better have really quick hands. I wasn't quick enough once, and I went for a bronco ride of a tank slapper and an OTE. Nothing but hurt pride , a lot of grass in a wheel, and video taken by a friend following
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      07-04-2017, 11:12 AM   #4
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My primary reason for considering a square setup is for tire wear, both for the street and for autocross/track.

Last year: I found that -2.8 front and -1.8 rear camber resulted in near perfect handling balance for autocross on stock wheels, running Bridgestone RE71r 255 front / 275 rear. I was also on stock suspension. Unfortunately, as the car is also a summer daily driver, I corded the fronts on the INNER tread when there was still at least 1-2mm above the wear bars in the outer tread, likely due to daily driving.

Fast forward to this year . . . same wheel and tire setup, lowered with Ohlins, adjusted camber to -2.4 front and -1.6 rear. The car is faster and handles better, but I am definitely giving up overall grip with that alignment. There is slightly more push at the limit. With the staggered setup, the car really likes 1 degree more camber up front, and would probably wear tires evenly if only used for autocross and track.

My planned cure:
I am going to get a set of Apex SM-10 18x10 ET25 and use dedicated autocross/track tires either 275/35 or 285/30. I plan to set the camber to -2.4 front and -2.0 rear with a square setup. That *should* retain some neutrality on a square autocross/track wheel tire set and will let me use a longer lasting and more comfortable street tire.
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      07-06-2017, 04:52 PM   #5
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Went to square for tire wear management - with stock staggered setup it's actually easier to drive, but the difference in tire wear means I literally throw away the fronts when the rears need to be replaced

I originally get 9.5" wheels to skim a set - we actually have a winter here, and the 19" stock rims is expensive to get winter tires for. What ended up happening right now is that I have shelved the 19s, swapping between 245/40R18 all seasons and 265/35R18 PSS for summer + track. Original setup I could have keep the 19" for summer non track use, 18" for track use, and swap between winter and summer on the 18". Needless to say, that plan never materialized

Maybe I should have cut my losses with the 18x9.5", sell them scratched as they are for cheap (doubly hard in Canada), and get some 18x10 and just run 285/30R18 for summer and get some all seasons for the stock 19". I don't know yet - right now I can get a handle with this spacer setup even though I had less grip in rear and more grip in front... maybe I can make this work for the next while (like 2 events per year for next 2 years) and then go for 18x10. Storage space for my tires / wheels are also issue
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