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
here), but in order to combat understeer and lockup on FF and 4WD cars I tend to *equalize* the pressure on the front-axle by minimizing the deistribution of the braking-balance from the front wheels and force the rear-axle oversteer in order to have natural entry to the apex.
PLEASE NOTICE that I use Fanatec CSP pedals and values I've described are made with that in focus. Many of my friends who use Logitech G25/27 are using slightly lower settings (where I use 4/1 they use 3/1, etc..) because the threshold of the actual brake-sets is different for every manufacturer. Experimenting is the key.
Another thing becomes important when advanced settings comes into perspective: such as having Tire Wear ON, or driving on the wet surfaces with changeable weather/track conditions. To cut it short, the
RA Adjust Functions (that in-race screen you can call-in and adjust some setting on the fly in the real-time with either Manetino-wheel on your DFGT or button-combination on the other wheels) becomes very important during the advanced races, because the tire-heat and degradation can call for altering the BB, as well as the wet surfaces. However, you will come to the appropriate conclusions by yourself through experimenting during time.
Small notice is how settings adjusted through RAMenu menu does not *stay* on the car through the venues if you quit the race before the end. So if you changed the settings during your Free Time run in online-lounge fro example, you will not have them applied once the race starts > values are set to those in main car-Settings menu. So if you come to the better solution through RAMenu during the Free race, you will have to alter them again through RAMenu once the race starts if you didn't changed them in the Settings menu.
Of course, GT5 now offers option to save multiple Settings (A/B/C, in the Settings menu), so you can manually set the ABS OFF setting for every car in one of the "Sheets" - under the B for example - in order to use it when you like. Notice how another issue is that you have to first set the desired Setting Sheet (B for example), than go to Race Options and set ABS to OFF, and than come back to settings and apply the proper BB settings. That is because once you set the ABS to OFF in the Race Option settings (where "A Settings Sheet" is always default one), it stays like that for the particular car everywhere you go with it (including online). If you opt for ABS OFF in the default "A Settings Sheet" so you will have to manually re-set it to 1 every time you want to race the car with the ABS ON. A bit confusing, but once you get used to it, it becomes just another Gran Turismo Player Masochistic Routine.
NON-ABS BRAKING part #3
Step C >Every Car Becomes Unique Without ABS
I know that all above probably sounds complicating, but in fact it is not. Once you install the The Mighty Sponge Ball (for users of wheels that needs one) and get used to the logic of the Brake Balance settings, the new world opens. Once you disengage the braking-assist (one we call the ABS for reasons of commodity and easier perception for the casual players) you will finally get the proper feeling of the unique physics of the every car.
Disengaging the brake-assist and diving into the world of proper Brake Balance settings will enhance the unique "characteristics sensation" for every vehicle and make it even more *recognisable*. Once you begin to utilise the correct BB settings, you will be able to actually feel the pavement-ripping torque of the F40, the feel of the Aventador's mass decelerating while eating the front tires or difference between the braking-characteristics of all GT500 cars which pretty much handles inside the same handicap while ABS is turned on.
Take your time and test on the low-powered cars for start, preferably on Tsukuba and than moving to the Trial Mountain. Mazdas MX-5/RX-7 are great for FR cars basics, and once you master them you can move to the MR class with the F430 as the best car for that task. Of course, test all of them with their default tires in order to develop the feel for the actual tire-threshold and BB values you need to apply.
Good luck and I hope you'll have the great time once you indulge yourself into this beautiful universe.
, used to hangout with guys from cruise club here back in GT5, sharing hybrid cars, be a cop and chase people hooning about 
Just another side of GT 
