GT4 and Brakes

RedWolfRacer

I could be completely wrong, but my guess would be that "MI's" are miles. I haven't looked at the screen you refer to, however, but this is, again, just a guess and, again, I could be completely wrong.

EDIT: I noticed the 7.x breaking distance, but I am not discounting the possiblity of "mi" being miles, though the decimal in the wrong place. A VERY wrong place. Of course, this is all speculation. Curse the PD folks' ideas of using very odd measurements without at least explaining them! That and not telling anyone quite how the suspension or much of anything works in the first place.

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Miles was my first thought until I looked at the way the figures are shown. 7 miles would seem just a bit long to stop the Ford GT. Metres are no good either as 7 metres is far to short, so for the moment they are just MI.

You are right that its a total pain haveing what appears to be a totaly abstract unit of measurement used in this way, they may as well have called them 'elephants', at least saying that a Ford GT can stop from 100mph in approx 7 elephants is slightly amusing and no more or less useful for it.

I am posting this reply/question here, in case you didn't follow up on the thread where you posted the quote:

Scaff

Glad you got to grips with the GT, its a wonderful car in my opinion, and much critisised - unfairly I believe.

The brake balance controller is a great pieve of kit, it can be difficult to use, as in previous GT games it only set the ratio between the front and back brakes, so 0:0 and 24:24 were the same. In GT4 it also sets the level of braking force applied to the front or back.

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I have seen the function of the "bbc" described as regulating the initiation of ABS by level of braking force. The implication being that at setting 24 the ABS does not engage until the brake force is maximum, at setting 1 the ABS engages immediately. The argument seems to hold some validity since the brake sliding indicator is somewhat redundant with a brake "force" controller and never changes in relation to bbc levels.
I wondered if you had encountered and/or discounted this theory.

rk

I am posting this reply/question here, in case you didn't follow up on the thread where you posted the quote:I have seen the function of the "bbc" described as regulating the initiation of ABS by level of braking force. The implication being that at setting 24 the ABS does not engage until the brake force is maximum, at setting 1 the ABS engages immediately. The argument seems to hold some validity since the brake sliding indicator is somewhat redundant with a brake "force" controller and never changes in relation to bbc levels.
I wondered if you had encountered and/or discounted this theory.

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I have had a look and play around with this, but would say that the Brake Balance Controller does not set the point at which the ABS comes into play, just the level of force applied through the braking system.

I believe that the ASM setting does however influence the ABS intervention point to a small degree. I've carried out a couple of tests that look at this, and while I would not say I am 100% with any conclusion, they do point in this direction.

Have a look at the ABS tests, links below.

ABS Test - High Speed

ABS Test - Tsukuba Wet

I hope to continue looking into this in the future, but it would have been nice if GT4 had simply included an option to turn the ABS off (I mean Forza managed to include this).

I have added some new links to the first post, they all regard real life physics and tuning applications that relate to braking and/or tyres.

Braking Systems - In plain english (an excellent starting place)

ABS and Big Brake Kits

The First Step for Improving Vehicle Dynamics: TIRES

Improved Handling with Anti-Sway Bars

Enjoy and I hope that they are of use.

Regards

Scaff

Scaff

Due to the sheer size and interest in this thread (and my thanks to all involved) I have edited this first post to become a summary and index to all that has been discussed, tested and debated here.

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Thanks heaps to all you guys who made the effort so that lazy people like me wouldnt have to. The test results are a great read, and well worth it.

I just have one question with one of the links posted on the first post. (100mph-0 parts one and two). I cant read the graph so im not all that sure wat it has to say.. can anyone help here plz?

~Sp33~

Thanks heaps to all you guys who made the effort so that lazy people like me wouldnt have to. The test results are a great read, and well worth it.

I just have one question with one of the links posted on the first post. (100mph-0 parts one and two). I cant read the graph so im not all that sure wat it has to say.. can anyone help here plz?

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With the 0-100-0 tests your best bet is to save them to your pc and then open the saved files with Windows viewer. Use this to 'zoom' in and it should be a lot clearer.

The figures shown on the graphs are as follows

0 - 30mph time
0 - 60mph time
0 - 100mph time
Reaction time
100mph - 0 time

The overall time is then shown at the end of each graph.

Hope that helps

Regards

Scaff

thanks heaps, i tried windows viewer, but it was still eligable, the fuzz factor wasnt cancelled out enough. ^^, thanks tho.

Spee

I also learned recently that big discs to not have as much inital bite as smaller ones, while watching the MotoGP. I found this interesting at first, but after a while realised this was quite simply mechanical advantage, the small disc will spin (deccelerate) slower, yet apply moe force to the wheel, like with a small cog spinning a large cog in a transmission.

wow..cool.. i never thought of it like that, thanks ^^..

so a good idea would be to make the actual disc and caliper wider.....

Crayola

I also learned recently that big discs to not have as much inital bite as smaller ones, while watching the MotoGP. I found this interesting at first, but after a while realised this was quite simply mechanical advantage, the small disc will spin (deccelerate) slower, yet apply moe force to the wheel, like with a small cog spinning a large cog in a transmission.

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Other issues with just upping the size of the discs (in the real world rather than GT4) is the increase in unsprung weight it causes which can damage the cars handling characteristics, particularly initial turn-in.

Also if only the front discs are upgraded (a common 'street' upgrade) then the brake bias of the car can be effected in a major way; the rear discs will commonly start to be underused and braking distances can actual increase following a front only upgrade.

Unless done for purely cosmetic reasons (which is something I would never do), brake upgrades need careful consideration before being carried out as modifing one area can have major issues on other areas of the braking system (and a lot of them undesirable). Its not uncommon for people to upgrade brakes and ruin the brake balance of the car therefore increasing braking distances, in GT4 we are lucky a brake balance controller can be fitted to every car, in the real world this is not always an easy or cheap option.

I have added this years Autocar 0 - 100 - 0 test results over in the Autonews section of GTP.

Here is a direct link to the thread

Autocar 0 - 100 - 0 test 2005

And the actual results are here

Autocar 0 - 100 - 0 test 2005 Part 1

Autocar 0 - 100 - 0 test 2005 Part 2

Autocar 0 - 100 - 0 test 2005 Part 3

Autocar 0 - 100 - 0 test 2005 Part 4


I also worked on a GT4 Vs Autocar 0 - 100 - 0 test last night, results to follow.

Regards

Scaff

and here are the Autocar 2002 0 - 100 - 0 results.

and here are the ones from 2003

and here are 2004's again as some people have had a problem with them, I have upped the size and split it into eight parts, hope this helps.

OK, this one is interesting; Autocar have just published the results of the 2005 0 - 100 - 0 test that they run each year (click here to see results) and one of the car included was the Ford GT.

Now the Ford GT has had a lot of people complaining that the brakes are poor, which is something I disagree with, additionally GT4 itself has had people moaning that the grip levels during a standing start are poor and unrealistic.

So what better way to put this to the test than to run a 0 -100 - 0 test on a Ford GT and see what the results look like when compared to the Autocar results.

The Ford GT I used was totally stock (no oil change), it was run with ACS and TCS all set to zero and with N2 and N3 tyres fitted. The location for the test was the 0 - 400 run in the Power & Speed area, this allows for a standing start and also on replay you can pause to check the time for a given speed. getting off the line was not easy and none of these starts were totally free of wheelspin, but it was kept to a bare minimum.

I carried out about five runs on each set of tyres and picked my best result for each, you should note that useing the pause button to gauge the time is far from an exact science as it can be hard to pause at the correct time. I did however carry out multiple replays to ensure that the correct speed was displayed before recording any times.

The reaction time was measured as the time elapsed from hitting 100 mph to applying full braking, this was one of the most difficult to get right, but again multiple replays were carried out to get it as accurate as possiable.

So the results.

Autocar results Ford GT

0-30 = 1.99 secs
0-60 = 3.93 secs
0-100 = 8.59 secs
Reaction time 0.31 secs
100-0 = 4.27 secs

Overall time 13.17 secs


GT4 results Ford GT N2 tyres

0-30 = 2.44 secs
0-60 = 4.60 secs
0-100 = 8.12 secs
Reaction time 0.38 secs
100-0 = 4.82 secs

Overall time 13.32 secs


GT4 results Ford GT N3 tyres

0-30 = 2.12 secs
0-60 = 4.12 secs
0-100 = 7.80 secs
Reaction time 0.18 secs
100-0 = 4.48 secs

Overall time 12.46 secs


Now these results are damn close, but just to remove as much of the human element as I could I removed the reaction time from the results, heres what we find.

Autocar = 12.86 secs (-rt)
GT4 (N2) = 12.94 secs (-rt)
GT4 (N3) = 12.28 secs (-rt)

Now after the reaction times have been removed the N3 results are within 5% of the Autocar figure, which is impresive, however the N2 figure is within 1% (actually under 1%) of the Autocar figures.

If we look at the individual areas we can see how this is broken down.

0-30

Autocar 1.99 secs
N2 2.44 secs
N3 2.12 secs

Very close across the range, however none of my starts were totally wheel spin free and i believe this could be improved on. The N3 figure is very close and with practice I think a 2 sec time is possiable.


0-60

Autocar 3.93 secs
N2 4.6 secs
N3 4.12 secs

The N2 figure is quite a way out here, but once again the N3 is quite close. With no gear change until past 60, these figures are going to be affected by the 0 - 30 times.


0-100

Autocar 8.59 secs
N2 8.12 secs
N3 7.80 secs

Both GT4 figures beat the Autocar result, and in the case of the N3 time by quite a margin. Now four possiable reasons for this are:

1. GT4 changes gear quicker than you can in a real Ford GT, I doubt that any of us will ever get a chance to put this one to the test.

2. GT4's physics engine provides more grip at medium speeds than the real world does.

3. GT4 has got the second gear ration wrong (have to check this tonight).

4. A combination of all these, this is to me the most likely answer, as it would allow slight differences in shifts (which are alway perfect in GT4) and account for the differences in surface, temp, wind speed, etc that are encounted in the real world.


100-0

Autocar 4.27 secs
N2 4.82 secs
N3 4.48 secs

Again a close grouping of figures and it is worth noting on a run in which I had a poor start (which would not effect the 100 - 0 time) I managed to record a 4.24 secs time on N3s. As the Ford GT is fitted with ABS and the Autocar test was a simple stand on the brakes exercise these differences could again be down to the factors listed in point 3 for the 0-100 section.


Now while I accept that figures for one vehicle do not represent a wide sample group (far, far from it), the results are very telling and I have drawn the following early conclusions from the above (please note that this is my opinion, based on this car, this test and these tyres).

1. Neither the N2 or N3 tyres are an exact match for real world tyres, and a tyres half way between these may be closer.

2. Grip levels at launch are not as unrealistic as has been made out, with the Ford GT I was expecting them to be a lot worse. One thing this did show me however is how over sensitive the throttle on GT4 is, it is very difficult to smoothly but quickly feed the power on. This could well be the cause of this problem, as I was using a DFP and that was tricky, the DS2 must be a real pain.

3. Either grip levels between 60 and 100 are unrealistic, the gearing for second is slightly out, shifts are too quick, or it is due to track and climate differences or a combination of all. These points would also apply to the 100 - 0 times as well.


Going to keep running a few of these over the next day or so just to see if I can't get the times down, very addictive once you start.


Regards

Scaff

Edited to add that I have checked the Ford GT 2nd gear ratio and its fine, so its not that. See my post below for more details.

Im pretty sure that the shift times are the main thing, especially with a manual, the shift can sometimes last for over a second and a half in some cases.... In gt4 though, they all seem reasonably too efficient.

~Sp33~

Im pretty sure that the shift times are the main thing, especially with a manual, the shift can sometimes last for over a second and a half in some cases.... In gt4 though, they all seem reasonably too efficient.

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Well I looked at the gear ratios and its not them, but it did highlight something a bit strange. I'm not sure how much of the following is common knowledge, but here goes.

Firstly checked with Autocar for the correct gear ratios for the Ford GT, then opened up the tuning screen for my GT and forget to set the custom gearbox before I clicked on the setting button.

Obviously no gear ratio figures were shown, but the graph was in place, with some very low ratio set.

So I loaded up the customer gearbox and returned to the setting screen, and of course now had the ratios shown, however the graph bore no similarity to the one I had been looking at for the standard gearbox.

So I set about trying to input the real gear ratios, now its not possiable to get them correct with the custom box for the first three gears, they just will not go low enough.

I got them as close as I could and low and behold a graph that looks damn close to the standard gearbox graph.

Now customer gearbox is an upgrade that a lot of people make without a thought, but the difference in gear ratios was not minor, but a massive change, I do not have the figures on me as I am at work, but will try and post them up tonight.

Additionally I will try this with a few other cars, starting with my Lotus Carlton.

BTW, in relation to my 0 - 100 - 0 test, I do not believe that an incorrect second gear is the problem, so that one is out.

Regards

Scaff

Dang Scaff, you work to hard! 👍

Scaff

Well I looked at the gear ratios and its not them, but it did highlight something a bit strange. I'm not sure how much of the following is common knowledge, but here goes.

Firstly checked with Autocar for the correct gear ratios for the Ford GT, then opened up the tuning screen for my GT and forget to set the custom gearbox before I clicked on the setting button.

Obviously no gear ratio figures were shown, but the graph was in place, with some very low ratio set.

So I loaded up the customer gearbox and returned to the setting screen, and of course now had the ratios shown, however the graph bore no similarity to the one I had been looking at for the standard gearbox.

So I set about trying to input the real gear ratios, now its not possiable to get them correct with the custom box for the first three gears, they just will not go low enough.

I got them as close as I could and low and behold a graph that looks damn close to the standard gearbox graph.

Now customer gearbox is an upgrade that a lot of people make without a thought, but the difference in gear ratios was not minor, but a massive change, I do not have the figures on me as I am at work, but will try and post them up tonight.

Additionally I will try this with a few other cars, starting with my Lotus Carlton.

BTW, in relation to my 0 - 100 - 0 test, I do not believe that an incorrect second gear is the problem, so that one is out.

Regards

Scaff

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i was refering to the time it takes to get from one gear to another, not the actual gear ratios, but instead the time in which the car is not accelerating because its between gears...

keep up with the great job of wat your doing, its always a great read, dont give yourslef any stress related illneses though ^^,

Spee

~Sp33~

i was refering to the time it takes to get from one gear to another, not the actual gear ratios, but instead the time in which the car is not accelerating because its between gears...

keep up with the great job of wat your doing, its always a great read, dont give yourslef any stress related illneses though ^^,

Spee

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I think our posts just got a bit mixed up; you are right that shifts in GT4 are always perfect, it's hard to say if they are too quick, because the gearbox and linkages are a factor in shift speed, but so is driver ability.

The bit about the ratios being out was in reference to the test, it was just something I was considering as one of the possiable factors.

Turns out it just illustarted to me how different the ratios are between the standard 'box and the default settings on the custom 'box. I was expecting them to be different, but not by this kind of margin.

It could also explain some of the other issues people are having with the GT, as these default custom ratios in the first three gears are going to make traction very difficult to maintain out of 2nd and 3rd gear corners.

Standard Ford GT ratios.

1st 2.61
2nd 1.71
3rd 1.23
4th 0.94
5th 0.77
6th 0.63

Final Drive 3.36


The default setting ratios on the custom gearbox are

1st 3.601
2nd 2.299
3rd 1.626
4th 1.216
5th 0.949
6th 0.783

Final Drive 3.36

I find this very informative. A couple of suggestions though. Did you take into condiderattion driver weight? What about trying a less powerful car. The margin of error would be less i think. Anyway pretty cool stuff. 👍

mccfowler

I find this very informative. A couple of suggestions though. Did you take into condiderattion driver weight? What about trying a less powerful car. The margin of error would be less i think. Anyway pretty cool stuff. 👍

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GT4 I would imagine uses a fixed driver weight, which you are quite right would almost certainly be different to the weight of the driver in the Autocar tests. However the differences caused by driver weight would be minimal in the acceleration phase and cause almost no difference in the braking phase (well nothing that could be measured).

You did however get me thinking on this, and while the difference in driver weight would make little impact, fuel could. If Autocar ran with minimal fuel and the cars are alway full at the start of a run in GT4 this could make a difference. This does of course depend on GT4 taking fuel weight (which is a big weight difference between a full and empty tank) changes into consideration. Again the difference would be mainly seen during the acceleration phase, with no significant change under braking (weight has no significant impact on stopping distances).

I do intend to run a few more of these tests with a range of cars that Autocar has also tested, the main reason I use the Ford GT a lot (apart from the fact that I like th car a lot) is that many people have complained that PD 'messed' up with this car and that its not accurate (like a lot of us have had a chance to drive one LOL), so I have used it to run the real life Vs GT4 tests.

Keep an eye out for more 0 - 100 - 0 tests in the near future, as well as a piece on commpression/engine braking that I am working on.

Regards

Scaff

GUH! @_@

dude, you work too hard, and treat us too well.

i think you deserve a holiday.... 👍 I realy enjoy reading what you have to say, so by all means dont go stopping on us.. but, just take a break for a while, im afraid you'll tire that brain of yours out....*gives it a pat*

I have now started a database of 0 - 100 - 0 times, which will be a direct comparison of GT4 times Vs Real world times (taken from Autocar).

This started with the original Ford GT test, and as promised I have been working on a few others. I've only added two more for now as I've been very busy at work and also given up smoking (which sucks - but my kids finally got to me).

However the two added are both good ones, the BMW M5 and Dodge Viper SRT-10.

Both of these tests were carried out with totally stock cars (not even and oil change), all driver aids (TCS & ASM) were set to 0 and N2 and N3 tyres only used. These conditions are the same as the ones used for the Ford GT and will be used in all future tests.

This does allow comparison between the different cars tested. However you should always be aware that while I will always use the best overall 0 - 100 - 0 time I can obtain for a car, differences in my launch and section times are not as easy to compare. For example my quickest 100-0 time for the Ford GT is 4.24 secs (N3's), however on my quickest overall run the time for that section was 4.48 secs (N3's). This shows that room for improvement is always present.

To allow easy and quick reference I have put the details on an Excel spreadsheet, as this allows future tests (and I will be adding to this) to be added quickly and easily while not taking up huge amounts of space in my posts.

Again, both of these cars in GT4 produced results very close to reality.

Hope you find them of interest.

Regards

Scaff

are you just using data logger to gain this information?.. i tried to see how fast i could get muh car to stop the other day, using data logger, and realised that it never actually goes down to 0kph... so i couldnt get an accurate distance. I tried coming to a stop, then 'tricking' the logger by making the car roll forwards realy slowly.. but although giving a more accurate distance i still was unable to get the line on the logger to reach 0 kph....

~Sp33~

are you just using data logger to gain this information?.. i tried to see how fast i could get muh car to stop the other day, using data logger, and realised that it never actually goes down to 0kph... so i couldnt get an accurate distance. I tried coming to a stop, then 'tricking' the logger by making the car roll forwards realy slowly.. but although giving a more accurate distance i still was unable to get the line on the logger to reach 0 kph....

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The data logger is unfortunatly no good for this at all.

Im using the 0-1000m section of the Power & Speed area, as it allows for a standing start.

Once I've done a 0-100-0 run I exit out and play the replay. If you set the replay to 'display' and in-car you can use the start button (or is it the select button - its the one on the left) to pause the run.

I do this at 30, 60 and 100 mph and note the time; I then pause again when full brakes are applied to get the reaction time and then once the car reaches 0mph and is stopped.

It takes a far bit of practice and repeating to get the replay to stop at the right point each time; its also the reason why these take so damn long. It does however seem to be consistent and gives me the figures I need.

Hope this helps

Regards

Scaff

What a pain in the ass. I think ill just steer clear.. and let you do all the hard work ^^,

thanks,

~Sp33~

I got a '98 Mercedes-Benz CLK-GTR Race Car and I have raced B-Spec mode on the Infineon Endurance deal and I haven't been able to win. The car has the stage 3 turbo upgrade and I've tried running an R1 and R3 compound tire. To the point, I haven't had ANY success, is this the car, the AI, or the tires? I was wondering if another tire would be more suitable to the track/car/conditions or if I should just find the time to A-Spec the race (I know I have a great chance at the win in A-Spec, I've tried it, dominated but haven't the time to finnish.)

Thanks in advance,

👍 Jonerz 👍

P.S. I put this here because it was originally a tire question but it turned into a crazy noobie question.

Jonerz

I put this here because it was originally a tire question but it turned into a crazy noobie question.

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Yep, 'cause this is the exact right place to put a tire question anyway... 👍 👍

If you want a hint to your actual question, get a better car - or race it A-spec.

Jonerz

I got a '98 Mercedes-Benz CLK-GTR Race Car and I have raced B-Spec mode on the Infineon Endurance deal and I haven't been able to win. The car has the stage 3 turbo upgrade and I've tried running an R1 and R3 compound tire. To the point, I haven't had ANY success, is this the car, the AI, or the tires? I was wondering if another tire would be more suitable to the track/car/conditions or if I should just find the time to A-Spec the race (I know I have a great chance at the win in A-Spec, I've tried it, dominated but haven't the time to finnish.)

Thanks in advance,

👍 Jonerz 👍

P.S. I put this here because it was originally a tire question but it turned into a crazy noobie question.

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You've not really said what your problem is exactly; but a CLK-GTR with a stage 3 turbo is going to be a beast to drive and without very careful throttle control will eat tyres. B-spec drivers do commonly have problems with cars this powerful (as do a lot of people in A-spec as well).

A good example of this are any of the RUF models, most of the time my B-spec 'bob' will have big problems with them; however I've not had any major issues with them once I adapted my driving style (particularly important with the Yellowbird).

You my want to see how 'bob' goes with a lower stage turbo.

Regards

Scaff