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      07-28-2017, 02:54 PM   #9
WhatsADSM
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Drives: 2011 135i
Join Date: Sep 2013
Location: Milwaukee

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Quote:
Originally Posted by spxxx View Post
I misspoke actually, I just took out the front helper springs to fit really wide 255 tires up front (closer to 265). I'm running 9 inch swift #672 springs in rear which are tested to be closer to #705.

Trying to get to 1:45ish at Laguna and ~2min at Thunderhill. The car is plenty fast, just need more seat time, this is only my 2nd season tracking.
Ahh ok. So its stock 400s with the helper spring removed (I did the same thing BTW), and then swift 672 rears. Makes sense.

Do you know the dimensions you used for the rear? I ask because I will probabl swap mine out next year for something a bit stiffer as well. The balance is close to neutral now but still a *bit* to understeery. A bit of extra rear spring should help neutralize it a bit more. Swapping to swifts will also change it from lightly progressive to linear.

I do second the idea above to see if you can lighten up some of the front body panels, while simultaneously adding room for additional tire width. A little more tire, as well as less weight on the front axle should be quite noticeable on these cars.

Depending on your level of experience you may want to just spend more $$ on seat time for now though. That will likely improve your lap times the most (while also being the most fun! ). Once you are reasonably comfortable and smooth with the car and pushing those Federal RSRRs to their limit (i.e. you should be in an advanced group) then you will probably want to move up in tire a bit. As you said something like a RE71 or maybe an "entry level" R-comp (NT-01, etc.) would be a logical next step. After that aero and brakes will be the biggest bang for the buck you will see for lap times.

In a nutshell I personally would go:

More seat time --> Improved tires --> Improved brakes --> Aero.

Safety is safety and always important so that can trump anything if you feel more comfortable with/without it.
Truth be told stuff like full exhaust, further lightening, etc, all are great but fall much lower on the bang-for-the-buck-o-meter.