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Old 03-23-2017, 08:48 PM   #6
thstone
Certified Boxster Addict
 
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,669
Quote:
Originally Posted by Mr Flat Six View Post
I don't know a lot about suspension. With that being said what are the adjustments that need to be made? I've heard of people running 255's with rear wheels on the front and was actually looking at my car today and wondering how it'd look/handle. I feel 225's or 235's would be fine for whenever I get new tires and I could keep my wheels. Anyway, its always nice to learn more!
225 or 235 on the front with 255 on the rear is a nice setup which will reduce the stock understeer. Either 225 or 235 will fit fine on the stock front wheel (regardless of what tire rack might say). No other adjustments are needed so its a nice upgrade on a stock car.

Running 255's on all four corners will not only eliminate the stock understeer but will also induce quite a bit of oversteer. To be clear, this doesn't mean that the car will be undrivable or unstable or squirelly at normal street speeds (the car will drive quite normally).

But the car will have HUGE front grip from the 255's up front and no understeer so it will be very tempting to push the car to see just how much front grip it has. Let me tell you, front grip like this can be intoxicating to those of us who like the corners. With high grip summer tires, you can literally just not brake before going around a regular street corner - the car will grip and make the turn (kids don't try this at home).

The problem is that as you push harder, you'll eventually get close to the handling limit and then the car will exhibit a strong tendency to oversteer, Boxster's rotate VERY quickly (due to the low polar moment of inertia) and if the driver isn't prepared or skilled at driving an oversteering car, it could result in something bad.

To adjust the handling back to neutral, adjustable sway bars (Porsche 996 GT-3 sway bar in front and the Tarrett Boxster adjustable sway bar in the rear) are installed with the front bar set quite a bit stiffer than stock and the rear bar set on the softest setting. This will bring the handling back towards neutral. Exactly how much adjustment depends on the other suspension components, the tires, and what handling characteristics the driver prefers.
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1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor

Last edited by thstone; 03-24-2017 at 10:20 AM.
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