Thank you for the detailed rebuttal Scaff.
I'm
definitely not somebody who thinks Enthusia was the "second coming"! I
do think some of the FR cars in Enthusia (like the BMW E30) really feel like I would expect them to.
The second coming bit wasn't aimed directly at yourself (and sorry if it seemed it was), its just Enthusia gets dragged out by a lot of people at the drop if a hat, and often with some very rose-tinted specs on.
Leaving all the details of brake bias, ABS, downforce etc. out of it, I would just say that I would expect cars under heavy braking (paricularly road cars) to require balancing to account for the weight transfer. This was almost totally lacking in GT4 & is still underrepresented in GT5P IMO.
GT4s braking left a lot to be desired once you got outside straight line ABS time and distances, I was one of the members here who spent a lot of time and effort proving the high and low points of its braking physics (still a very big thread on the subject in the GT4 Tuning sub-forum).
GT5P is much better in this area, particularly with ABS switched off and Pro physics on, but it does still need work.
That however doesn't automatically mean that an unbalanced car will do a lot more than understeer under full braking load when cornering.
The most striking example of this for me, was jumping into Dayton Road a while ago. Coming into the first left-hander, at maximum speed, at the end of the long oval section, it was possible to simply slam on the brakes to slow down (while the car was actually turning into the long approach to the corner). The only question was when exactly to slam on the brakes to avoid understeering through the corner. I don't believe for a minute that it would be possible to do that IRL without (catastrophically) losing control of the car.
While I have not driven on an oval of Datona's nature I have carried out plenty of high speed brake tests in cars, both with ABS and with it disabled.
Strong understeer is (as long as the brake bais on the car is correct) most certainly going to be the most dominate trait if the car by a long way.
Brake in a straight line from a high speed and you get a massive transfer of load to the front two tyres, the lightly loaded rears will still have traction, and exactly as Wolfracer described earlier, will help keep the car going straight. Even if you don't have ABS enabled this is going to be true, your just going to take longer to stop if you have locked the fronts up.
Now if you start steering in this situation very little is actually going to end up happening, you may have started steering before you reached the slip limit of the front tyres, in which case you would have started to transfer more load to the front outside tyre. If it wasn't already past its slip limit, it most likely will be now, the end result of this will be understeer.
Skip Barber defined Under and Oversteer excellently in his book Going faster, understeer occurs when the slip angle of the front tyres is greater than the slip angle of the rear tyres, with oversteer being the exact opposite of this.
Nothing at all (outside of screwed up brake bias or suspension failure) in a heavy braking and steering situation is going to see you with a greater rear slip angle that front slip angle.
I'm not actually sure exactly what you are expecting to happen in thsi situation, but given how you describe it (hard braking and steering) then understeer is exactly what I would expect to see happen.
Only if you tried to over-correct the understeer, with a rapid throttle lift would I expect to see 'some' cars transition to oversteer, but then we wouldn't be braking and steering.
Now GT5P doesn't have lift-off oversteer nailed 100% yet (the vast majority of titles don't get it correct if at all), but that's not caused by braking.
Regards
Scaff