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      03-18-2014, 03:56 PM   #23
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What is everyone running for rear camber arms? I thought that the stock rear arms can only dial in -1 camber at the most? Is that correct?
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      03-18-2014, 03:57 PM   #24
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What is everyone running for rear camber arms? I thought that the stock rear arms can only dial in -1 camber at the most? Is that correct?
I'm as almost -3 rear with stock arms (car is lowered).
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      03-19-2014, 09:16 AM   #25
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I'm at -2.5 with stock arms and Eibach springs.
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      03-20-2014, 10:10 PM   #26
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-1.9 for me
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      03-21-2014, 08:53 AM   #27
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Quote:
Originally Posted by 3002 tii View Post
I'm as almost -3 rear with stock arms (car is lowered).
have you had any track time on this yet?
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      03-21-2014, 10:42 AM   #28
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Originally Posted by inTgr8r View Post
have you had any track time on this yet?
Heading down tomorrow morning! =D
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      03-21-2014, 11:02 AM   #29
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Originally Posted by 3002 tii View Post
Heading down tomorrow morning! =D
awesome!!!!
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      03-21-2014, 11:50 AM   #30
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Thanks guys. Do we have camber adjustment in the front as well on stock suspension?
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      03-21-2014, 12:43 PM   #31
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Originally Posted by R0ME0 View Post
Thanks guys. Do we have camber adjustment in the front as well on stock suspension?
minimal...
You can pull the pins on the tower to allow some adjustment at the 3 tower nuts.
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      03-22-2014, 05:15 PM   #32
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Originally Posted by inTgr8r View Post
awesome!!!!
Finished first day, car feels good but it's my first time driving on R-comps so it takes some getting used to. I definitely want to dial in more camber up front, I feel some 'resistance' on some of the faster turns. Luckily the tires grippy enough to get me through but it doesn't feel as precise. Here's how she looks with new 17" Apex

9" front et42, 9" rear et30, 255/40 R888's square

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      03-23-2014, 08:54 PM   #33
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Good stuff!
Car looks very different with more camber in the back.
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      04-20-2014, 03:50 PM   #34
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Just came back from 2nd event which was at Summit Point. Compared to NJMP, despite having a longer straight, the track is slower because of the tighter turns. My new alignment is -2.8* and 1/16 toe out in front, -3.0* and 1/8 toe in on rear (just added a tad bit more negative camber up front).

Turn in and mid-corner felt great but car was squirming under heavy braking. Also noticed the front end feels really light, think my left tire was catching air on some of the uphill turns. I actually like the soft spring rates I'm running now so I'm going to start with a stiffer front sway to see if that'll help.

Oh yea 255 R888's square... Totally ate through my front liner by the bumper attachment area lol. Stiffer springs might help a little bit with that.
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Last edited by 3002 tii; 04-21-2014 at 08:35 PM..
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      04-20-2014, 06:11 PM   #35
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Tires making some clearance

To combat the wheel life you're going to have to adjust your rebound in the rear for the shocks) if you can do that, increase spring rate, or bar. It looks like you took option 3.

The squirming can be contributed towards not enough toe.
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      04-21-2014, 03:14 AM   #36
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Quote:
Originally Posted by 3002 tii View Post
Just came back from 2nd event which was at Summit Point. Compared to NJMP, despite having a longer straight, the track is slower because of the tighter turns. My current alignment is -2.8* and 1/16 toe out in front, -3.0* and 1/8 toe in on rear. Turn in and mid-corner feel great but car is squirming under heavy braking. Also noticed the front end feels really light, think my left tire was catching air on some of the uphill turns. I actually like the soft spring rates I'm running now so I'm going to start with a stiffer front sway to see if that'll help.
Softer springs will permit more pitching onto the nose during breaking, lifting of the nose and squatting of the rear under acceleration and increased lateral body roll during cornering, therefore it's not really surprising that you are noticing squirming under braking and the front end going light.

Likewise, the static geometry settings on a car are a "best guess" compromise to account for the movement of the chassis relative to the wheels which will occur in the dynamic situation. If you can contain the movement of the chassis better by using springs of the correct stiffness, you won't need to run so much camber either and your car will handle so much better.

Increasing the stiffness of the ARBs will only reduce lateral body roll and will have no effect on the pitching and lifting you describe.
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      04-21-2014, 09:23 AM   #37
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Originally Posted by exdos View Post
Softer springs will permit more pitching onto the nose during breaking, lifting of the nose and squatting of the rear under acceleration and increased lateral body roll during cornering, therefore it's not really surprising that you are noticing squirming under braking and the front end going light.

Likewise, the static geometry settings on a car are a "best guess" compromise to account for the movement of the chassis relative to the wheels which will occur in the dynamic situation. If you can contain the movement of the chassis better by using springs of the correct stiffness, you won't need to run so much camber either and your car will handle so much better.

Increasing the stiffness of the ARBs will only reduce lateral body roll and will have no effect on the pitching and lifting you describe.
Very informative and helpful. I'm seriously wondering if its just more practical to go back to street tires next year, something sticky like RS-3's which didn't create this lifting effect on my soft suspension. The time differential between RS-3's and R888's can't be significant, maybe a second max?

Can you explain why a stiffer ARB wouldn't effectively stiffen up the springs and help alleviate the issues I described?
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      04-21-2014, 12:38 PM   #38
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Quote:
Originally Posted by 3002 tii View Post
Can you explain why a stiffer ARB wouldn't effectively stiffen up the springs and help alleviate the issues I described?
The ARBs effectively connect left and right springs on the same axle which overcomes the "independent" nature of springs and dampers working at all 4 corners. Therefore, when cornering, the ARB resists lateral body roll because the suspension on the same axles are joined by the ARB, but under acceleration and braking the front and rear springs are not joined in a similar way so pitching and lifting aren't resisted by stiffer ARBs.

You'll find that stiffer springs and dampers at the front of the Z4MC will better prevent the pitching and lifting as well as help to reduce lateral bodyroll.
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      04-21-2014, 12:45 PM   #39
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Quote:
Originally Posted by exdos View Post
The ARBs effectively connect left and right springs on the same axle which overcomes the "independent" nature of springs and dampers working at all 4 corners. Therefore, when cornering, the ARB resists lateral body roll because the suspension on the same axles are joined by the ARB, but under acceleration and braking the front and rear springs are not joined in a similar way so pitching and lifting aren't resisted by stiffer ARBs.

You'll find that stiffer springs and dampers at the front of the Z4MC will better prevent the pitching and lifting as well as help to reduce lateral bodyroll.
Thanks, last question. I'm currently running 440f/550r... I don't mind increasing the front but the next increment would be 500 and 600 for the front (front and rear springs are different lengths. If I went 600 in the front, how would handling be affected if I keep the rear at 550? Should I also be increasing the rear. I don't mind the squirmy back during braking... it's just the front end lightness on the uphills and certain transitions that I want to address the most.
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      04-21-2014, 01:07 PM   #40
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Quote:
Originally Posted by 3002 tii View Post
Thanks, last question. I'm currently running 440f/550r... I don't mind increasing the front but the next increment would be 500 and 600 for the front (front and rear springs are different lengths. If I went 600 in the front, how would handling be affected if I keep the rear at 550? Should I also be increasing the rear. I don't mind the squirmy back during braking... it's just the front end lightness on the uphills and certain transitions that I want to address the most.
Looking at the photo of your car, IMO it's far too low at the rear, so you've lost the rake angle and the underside of the car is now parallel to the road. This configuration will generate lift irrespective of the spring rates and despite the fact that you've installed a lip splitter. I'm assuming that you've got an adjustable suspension set-up, if so, before you consider changing the springs, I'd like to suggest that you raise the rear end of the car so that the cill just in front of the rear wheels is about 1" or slightly more higher than the cill just behind the front wheels on the same side. This way you will create a Venturi effect under the car which will improve the aerodynamic profile of your car which will reduce lift under acceleration and forward movement at speed. If you prevent the lifting, the front end can't drop so much under braking, therefore you will also considerably improve braking with much reduced pitching. This will cost you nothing to do.




EDIT
I've just revisited the beginning of this thread and I see that you had the car corner weighted. I really can't see how "static" corner weighting can work when in the dynamic situation it promotes aerodynamic lift, which alters the dynamic corner weights. If the front of the car is getting "light" during acceleration, then the ride height adjustments which produced the perfect static corner weighting are blown out of the window when the car is driven!

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      04-21-2014, 08:04 PM   #41
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Quote:
Originally Posted by exdos View Post
I've just revisited the beginning of this thread and I see that you had the car corner weighted. I really can't see how "static" corner weighting can work when in the dynamic situation it promotes aerodynamic lift, which alters the dynamic corner weights. If the front of the car is getting "light" during acceleration, then the ride height adjustments which produced the perfect static corner weighting are blown out of the window when the car is driven!
Why would corner balancing the car promote aerodynamic lift? Makes zero sense. All corner balancing does is make the center of mass fall on the same axis as the physical roll center. It does not affect ride height or "rake."

Does not compute.
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      04-21-2014, 08:25 PM   #42
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I know it isn't a E85/6, but I'm running 0.75" Rake on my E82 with TC Coilovers, per TC's suggestion.

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      04-21-2014, 08:37 PM   #43
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I spent the better half of the day reading some threads on BFC's racing section as well some other forums and it seems like wheel lifting isn't unusual and shouldn't be a major concern unless it affects overall handling.

I know I'm coming off a little scatterbrained in trying to summarize my observations but if I had to sum it up concisely, my primary issue is that at times the front end would compress so much that it almost wouldn't recover fast enough for the next turn. However I can't tell if this is an alignment issue or running tires that are too sticky relative to soft springs.
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      04-22-2014, 05:42 AM   #44
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Quote:
Originally Posted by The HACK View Post
Why would corner balancing the car promote aerodynamic lift? Makes zero sense. All corner balancing does is make the center of mass fall on the same axis as the physical roll center. It does not affect ride height or "rake."

Does not compute.
So how do you corner weight the car without adjusting the suspension heights at each corner? Surely this must alter the position of the body of the vehicle relative to the road which may alter the rake angle?

In the case of 3002 tii's car, how come it appears to have zero rake after corner weighting when OEM has some positive rake?
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