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      09-13-2012, 11:15 PM   #23
seank
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Quote:
Originally Posted by TSM330i View Post
Anyone know what the spring rates should be for a full-blown race car? No street driving at all.
More than likely, going to run AST4200 or 5200.
This would be for a non-M.
Thanks
That would depend on racing weight and how smooth the tracks are where you live. Some also prefer a stiffer or softer set-up.

I hope someone chimes in. There aren't many z4 race cars.
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      09-14-2012, 08:58 AM   #24
Beedub
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e85 //M
kw clubsport, including Kw uniball camber plates
400lb linear fronts progressive rear spring with end rate of 700lbs (according to kw)
stock sway bars
(additions)
turner rtab limiters
front strut brace
poly bushed RE reinforced top mounts (rear)
Camber shims installed, camber set to -2.7

settings are 6 clicks front rear 12 clicks on rebound, bump is 0.75 on each axle.
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      09-14-2012, 12:36 PM   #25
TSM330i
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Quote:
Originally Posted by seank View Post
That would depend on racing weight and how smooth the tracks are where you live. Some also prefer a stiffer or softer set-up.

I hope someone chimes in. There aren't many z4 race cars.
Car weight with driver would be 2,800lbs. and we definitely prefer a stiffer set-up vs. a softer one. Most of the tracks are pretty smooth. We are currently running a 335 that we want to either retire from competition or use less often. We run a pretty stiff setup on that and it works very well. The car is a pig at 3,300lbs, gutted, but with the fuel cell and full cage, it adds so much weight back in. The Z4 is light from the start so it's not too hard to get it down below the 2800lb mark.
We'd also rent out the Z4 for driver schools, teams with licensed drivers that want to run sprint races or 12 hour races.

We may have to contact TC Kline. I think they raced a Z4 in the past.
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      09-14-2012, 02:34 PM   #26
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Quote:
I think they raced a Z4 in the past.
They won 2 national championships. TC told me that they ran 400# springs front and rear (not a typo), with no rear sway bar most of the time. Larger sway in the front.

He likes a very soft set-up. Too soft for me.
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      09-14-2012, 03:35 PM   #27
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Garage List
2007 E86 Z4MC S54
TCK DA coil overs with 500#F and 600#R. TCK camber/caster plates.
Primarily track but does see some limited street use.
Instruct at BMW CCA and PCA driving school events; about 12 track events a year.
Running stock sway bars.
For track use run Toyo R-888 tires and PF-06 brake pads.



Quote:
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jmillet

Nice pic, but do you have any figures for us?
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      02-24-2013, 03:03 AM   #28
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1) Chassis and motor - 2007 Z4M Coupe, stock motor.
2) Which coilover brand? - KW Clubsport
3) What size springs and rates front/rear? - 400lb front/ progressive rear
4) Is your car track only or street & track? - street and track
5) What kind of events and how many events per year? (ie, auto-x, DE, TT, club racing) DE - 8 events/year
6) Are you using aftermarket swaybars? No

The rest of suspension is stock.
Getting -3.5 front camber and -2.5 rear camber.
Experimented with R888 245/275, NT01 245/275, Hankook C51 245 front, Hoosier 255/40 rear, Hoosier 255/35 front, 255/40 rear, NT01 275 front with 12.5mm spacer (increased ride height by .25" to reduce rubbing), 275 rear.

Would love to ride on cars with AST 5100 or Nitron R1 to compare with KW Clubsport handling.
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      10-05-2013, 05:37 PM   #29
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Recent 2013 change:

1) Chassis and motor - 2007 Z4M Coupe, stock motor.
2) Which coilover brand? - AST4150
3) What size springs and rates front/rear? - 5" 616lb/5" 728lb
4) Is your car track only or street & track? - street and track
5) What kind of events and how many events per year? (ie, auto-x, DE, TT, club racing) DE - 16 track days /year
6) Are you using aftermarket swaybars? No

Getting -4.0 front camber with turnermotorsport bolt and -2.1 rear camber.
Running 275/35/18 square on 18x10" ET25 wheels.
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      05-27-2014, 03:36 PM   #30
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I'm running 375 lb/in front and 440 lb/in rear. My ass is getting air over big bumps... this can't be good, right?

Ground Control Coilover Kit with GC Street Camber plates
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      05-27-2014, 07:32 PM   #31
seank
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Quote:
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I'm running 375 lb/in front and 440 lb/in rear. My ass is getting air over big bumps... this can't be good, right?

Ground Control Coilover Kit with GC Street Camber plates
That has to do with the valve adjustment, not your spring rates. It shouldn't be an issue except for ride quality and traction.
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      05-27-2014, 08:06 PM   #32
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Called GC... They told me to adjust the Koni's very little. Like 1/12th of a rotation per time. I was trying to tune the damping by going +1 turn or -1 turn... way too much. Overshooting every time. Just adjusted during lunch... car is driving much nicer now.
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