ozan169

Bbk airfilter kit
bbk ceramic short headers
magnaflow x pipe with racing cats
magnaflow Cat-Back Exhaust System
bbk 62mm twin throttle body
moto blue pulley kit
Max MicroTuner
ford racing 4.10 gears
comp cam racing cams
stage 3 head
Ford racing cmcv delete kit

hey ppl

iv got a 2005 gt auto my car likes to understeer alot and iv got the stock tires as well 235 55 r17 im getting a kenny brown strut
i dont knw what esle would help me with my understeer. have you guys had the unersteer prob's as well with your 2005 2006 mustangs

thanks

Philostang

Welcome Ozan!

The 05s are notorious for understeer...but from the reports I've seen the 06s w/18" wheels are not nearly so bad. The difference is threefold. First, the factory 18" wheel is 1/2" wider, so you get a (ever so slightly) wider foundation for the tires--not much of a big deal though (IMO). Second, these factory 18"s come with a lower profile tire, 235/50 (rather than the 17"s 235/55)--this is a bigger deal, and combined with the wider footprint of the 8.5" wheel it means these tires experience much less flex in the sidewall during hard cornering than do the 17" combo. Third, they say that factory equipped 18"-cars also come with revised shock/strut valving to deal with the larger wheel/tire combo--another bigger deal (and also why they say many folks experience negative results when they swap out their factory 17"s for an aftermarket 18" wheel...but I wouldn't know for sure).

So, the most obvious place to start would be the tires--factory 17"s suck big time (not for the tire brand/model, but for the sizing). My bet is that with a different sway bar set up, this would help a good deal. The next step would be a new wheel/tire combo, but keep in mind you may also want to seriously consider new shocks/struts.

You could also try differential air adjustment. I've had my car out on road-race tracks a few times, and some of the old-timers tipped me off to splitting the air pressure (front/rear) by as much as 10 psi. I tried running 38 psi in the front and 28 psi in the rear--wow! what a difference that made. The car was much more even and balanced in the corners. I wouldn't recommend going as low as 28 psi on the street, but maybe you could try splitting 38/32 and see if it helps. BTW, on the street I run 35 psi. on all 4 corners, but I've got the factory 18"s and don't have any issues with understeer on the street/highway.

Food for thought.
Best,
-j