Here is my guide for the non-ABS, made for the wheel users few months ago.
NON-ABS BRAKING part #1
GENERAL ADVICES
- Different tyre-compounds call for the slightly different Brake Balance. You will notice how there is a difference in values if you experiment with the Comfort and Sport compound. However, it goes into category of the fine-tuning so results through experimenting will come with the time
- *ABS* in GT5 is not representation of the real-life ABS, it just uses that "name". ABS in GT5 is some kind of permanent braking assist *override* that not only prevents wheel-lock, but also have some invisible traction-control that nullify the suspension-modelling and equalises unique characteristics of the vehicles resulting with ability to turn while braking and never loose grip
- when ABS is OFF many cars will just go to snap-oversteer once the brakes are applied in full. You must never brake with full-constant power - you would never brake like that in the real-life too. In order to get maximum for your braking, you have to learn to brake is *sequences* - press/release/press/release/press/release/etc.
- you have to reconsider everything you know about braking-points and configurations for every track. With ABS off, suspension modelling becomes "free" and suddenly all elevations (lateral and longitudinal) of the surface becomes major factor in the driving. The sensation is vastly different than with ABS ON, so be prepared to revise everything you've learned to that point.
- all FR/MR/RR cars - being road or racing - have to be set with front bias noticeably stronger than rear. Through my testing I still haven't found any single FR/MR/RR car that calls for BB of the rear-brakes stronger than 2. To be honest, majority needs only 1. The key is to find proper front-strength with rear-one adjusted to point where rear brakes does not lock the rear-axle. You will know the point where rear-axle is not compromised once the car does not launch itself into snap-oversteer when braking. Once you set the rear-strength and bypass axle-lockup, you may fell that car is not stopping properly as it should. From that point, you have to force the front strength of braking until you find desired power.
On the above note, one of my last tests gave me 6/1 bias for the Ford Mark IV Race Car '67 where I needed 6/1 for proper balance of the stopping power.
NON ABS BRAKING Part #2
HOW TO MAKE NON-ABS BRAKING ACTUALLY WORK IN PRAXIS
This one have few steps.
Step A > The Mighty Sponge Ball
Brake-pedals on all of the middle-prices wheels - Logitech DFP, DFGT, etc.. - are too loose and too soft to produce a usable sensitivity of travel in order to cope with the non-ABS braking. However, for there is a solution for that problem: The Mighty Sponge Ball
Solution is simple: just insert the sponge under the brake and you're ready to go. Sponge will allow you to dose the actual brake-power more subtly and to actually have control of the brake-travel.
Of course, any hard-sponged material will do even better than simple sponge ball, especially high-density sponges, like neoprene for example. Once you've settled the step A) it is time for step B.
Step B > The Brake Balance Adjustment - The Key to Master the non-ABS Braking
In order to achieve maximum performance and feel out of the GT5 physics engine and wheel support, you have to manually tweak few options in the game and accept few issues. First, you should go to the wheel option and set the steering to Simulation (although it affects only 270-wheels, but it is no-brainer, so just do it) and turn the Power Steering to OFF.
As for accepting issues, there is one thing you have to get use to when going into the universe of the non-ABS braking: you have to manually dial the ABS to OFF for the every car prior to the race in the Race Settings menu (unfortunately, you can't do it in the Settings menu in the Garage for the car of your choice). Once done, you're ready for the most important thing: The Brake Balance Adjustment
By default, every car in GT5 comes with Brake Balance set to 5/5 (front/rear). With ABS OFF and the default 5/5 value, there is no way you can properly drive the car, because that default value is messing the complete balance of the suspension and produces practically undrivable car. So, you have to manually adjust the Brake Balance for the every car you wish to use with ABS OFF.
General idea about adjust the Brake Balance comes form basic presumption of weight-distribution behaviour while braking: when you brake, the central mass of the vehicle and inertia moves from the back to the front. Thus all cars in real life have bigger and stronger brakes on the front-wheels and GT5 utilises the same logic. In order to adjust the BB, you have to re-distribute the BB values towards front. But before going onto that, one explanation.
Although Gran Turismo 5 uses the name of ABS (Anti Brake-Lock System) for that particular assist, I personally do not find it as representation/simulation of the actual ABS. I think it is nothing more than basic braking-assist which *overrides* the intertia-momentum on suspension and nullify the wheel-lock. Even ABS1 is too effective in what it does, so I do not find any mean in having the option to set it up to 10 (which game allows), so basically it is *ABS* just by name. I see it as nothing else but basic brake assist tool. Now back to BB setting.
Every car BB is different, but there is some generalisation possible.
FR, RR and MR cars will all benefit from the higher setting towards the front. For example, I mainly use 3/1 setting for majority of my road FR, RR and MR cars. Of course, there are exceptions like Ferrari F40 where sheer mass of the vehicle asks for higher setting in the front in order to achieve proper distribution of the weight and stop the rear-axle from going into oversteer because of the insufficient braking-power on the front wheels > so for the F40 I use 5/1 setting for example and for F430 4/1 (I also use 4/1 for SLS, LFA, M3 and similar vehicles).
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notice: after the new suspension model introduced by 2.07 "Academy" update, the rear-axle balance is always best to keep in "1". If on "2", it will lock the rear-brakes too much, thus "1" is the only proper balance.
Actual weight of the vehicle makes a lot of difference too.
Ferrari 599 calls for the 5/1 setting (Sport Hard tyres) because of the weight, while
stock Corvette ZR-1 C6 RM - you mentioned it in your post - calls for 6/1 balance in order to achieve stability and efficiency of braking.
For FF and 4WD cars I generally use 3/2 or 4/3 setting in order to combat understeer on the front-wheels. GT does not take pad-size into concern (check the SHIRAKAWA Akira's elaborate [URL='https://www.gtplanet.net/forum/showthread.php?p=6383809#post6383809']here