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Braking In Sims


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#1 Paddy the Irishman

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Posted Dec 17 2010 - 02:39 PM

In real-life braking there is first of all an angular movement of the brake pedal and then a pressure component. So the most unrealistic part of most sim racing controllers is braking, in that it is modulated only by the angular position of the pedal, which works a variable resistor./potentiometer  This makes it very difficult  to achieve maximum braking consistently, which takes place just before wheel locking.  
In sims, we tend to judge this by sight (wheels stop turning) or sound (screech of locked wheels).  This can be difficult, especially with closed wheel cars when visual signals are not available and the aural is difficult to judge.  

When we calibrate within GPL, we move the brake pedal to its maximum extent and get a reading of 1000 which is way beyond the locking point - which anyway varies according to car.  
It seems that the greatest  braking effort is affected when the electric resistance in the  ‘braking’ circuit is at a minimum. So adding (electrical) resistance in that circuit will reduce the braking effort and get below the locking position.

On my wheel/pedal assembly, a Logitech DFP, I have put a 10KOhm variable resistor in the braking circuit, This new pot is used for adjustment  after calibration in GPL.  I also  modified the angular movement/feel of the pedal by use of a rubber wedge cut from a fairly rigid rubber ball which is attached to the underside of the brake pedal arm with Velcro.  This means that the pedal assembly may be returned to its original state. I did however, cut away a little from the front of the pedal box so that it is easier to place and replace the wedge.
The full procedure works like this. The pedal is calibrated in GPL, depress fully, wedge compressed,  to 1000. Close the calibration window and take the car  to the track, take it up to full speed and brake hard. Brakes will lock. By adjusting the variable resistor, bring the braking effect back to the pre-lock area and you have a pedal that moves quickly in an angular movement until it reaches the wedge, where braking starts and then increases to the verge of locking with added pressure.. You will probably need a couple of laps to warm up the tyres before you get the proper effect.

In my original experiment, I sited the added variable resistor on the pedal base, but later moved it into a little box which is attached to the side of my wheel mount by Velcro and I made the connection  from pedal base to adjuster box by cable and  two 1.5mm microphone/earphone sockets and plugs, one in the pedal base and one on the box.  This allows the pedal box to be returned to its original electrical state. .

I checked in which line the variable resistor should be placed by preparing all the extra bits. With the pedals dissembled, but connected to the GPL calibration window and brake pedal ‘depressed‘,  I put the new potentiometer in circuit and  increased the resistance. When this shows the calibration figure dropping, you’ve got the correct one.  On the DFP the correct tag is  the bottom one on  braking potentiometer that has the red wire connected to it.  
You could do it with one set of socket and plug on the pedal box and direct cable attachment on the little box, but I had two sets and used them for convenience.

You need to be able to use a soldering iron,  I got the connectors from a model shop (model railway items) and the small box,10Kohm potentiometer, calibrated knob and earphone sockets and plugs from Maplin.  The whole lot cost me a few pounds.  I found difficulty in working out which tags connected to which part of the earphone sockets at first but worked it out in time !

A few points.
1) Be careful re-assembling the pedal box, NEVER force it together, the original pots are carefully located by cut outs and must fit smoothly.
2) Ensure that the thick part of the wedge is at, or near, the outer end of the brake pedal arm and not near its pivot to reduce strain on the joint and arm.
It sounds rather complicated, but really it is simple enough if you can solder and it has added greatly to my enjoyment.  I hope it may do so to a few others.

I do not know if this will work with all wheels/pedals but do not see why not.

HOWEVER YOU DO THIS AT YOUR OWN RISK, I WILL NOT BE RESPONSIBLE FOR ANYTHING THAT GOES WRONG OR BREAKS !!!

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#2 sky

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Posted Dec 17 2010 - 03:36 PM

hi paddy, actually that's a neat idea and possibly very effective for a cheapo mod. i've been thinking about doing something like this a long while ago, i think i even posted about it around here how i wanted more "feel" to the brake pedal. i think back then i was talking about using spring in there, reinforcing the plastic parts with metal so they won't snap from wear, etc. your's is a pretty slick way of doing it (you could drill a hole in your wheelcover, add the pot on the inside and put a metal head on the outside - like those for real brake balance things they have on real race cars :). then drill another hole in the back of your wheel where you rig up the headphone plug (again a neat idea!) fasten the whole lot via a liberal splash of hotglue et voila. could even paint some markings on the wheel 1, 2, 3 :D
i just wish your pic of the inside of the pedal assembly was bigger.

thanks for this cool tutorial! :thumbup:

#3 ptmac3

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Posted Dec 17 2010 - 04:04 PM

That's great Paddy, but why didn't you just use Dxtweak2? It does exactly the same thing with far less work. I used it first on Win/ME, then XP and now on Vista x64. It effectively lengthens the throw on the brake pedal so that at full throw I can set the brakes to just lock or achieve the optimum braking point just before locking, that you apparently desire, as do I. The only thing I haven't done is add the rubber ball. What i can do is set the pedal per car, per sim with just a few mouse clicks. Know I will admit that the "save profile" in Dxtweak2 won't function as it did on Win/ME, as least not for me, but I keep a few notes to remember where to set it and I'm off to the races, literally.

#4 MECH

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Posted Dec 18 2010 - 06:43 AM

View Postptmac3, on Dec 17 2010 - 04:04 PM, said:

That's great Paddy, but why didn't you just use Dxtweak2? It does exactly the same thing with far less work. I used it first on Win/ME, then XP and now on Vista x64. It effectively lengthens the throw on the brake pedal so that at full throw I can set the brakes to just lock or achieve the optimum braking point just before locking, that you apparently desire, as do I. The only thing I haven't done is add the rubber ball. What i can do is set the pedal per car, per sim with just a few mouse clicks. Know I will admit that the "save profile" in Dxtweak2 won't function as it did on Win/ME, as least not for me, but I keep a few notes to remember where to set it and I'm off to the races, literally.

Good point :thumbup:
But, (there's always a but ain't it :)) i think paddy's solution is a very cool one.
It kinda gives you the opportunity to tweak the braking while driving..instant setup tweak.
I've been messing with my wheel before to save it from the garbage bin (i'm rather fond of it)
Replacing buttons, pots and flippers and i like paddys idea. I have a big collection of pots, resistors and other electronic stuff lying in my shed so i might consider doing this in the future.

Anyway thanks both of you gents for the useful info :hat-tip:

#5 Paddy the Irishman

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Posted Dec 18 2010 - 08:18 AM

View Postptmac3, on Dec 17 2010 - 04:04 PM, said:

That's great Paddy, but why didn't you just use Dxtweak2? It does exactly the same thing with far less work. I used it first on Win/ME, then XP and now on Vista x64. It effectively lengthens the throw on the brake pedal so that at full throw I can set the brakes to just lock or achieve the optimum braking point just before locking, that you apparently desire, as do I. The only thing I haven't done is add the rubber ball. What i can do is set the pedal per car, per sim with just a few mouse clicks. Know I will admit that the "save profile" in Dxtweak2 won't function as it did on Win/ME, as least not for me, but I keep a few notes to remember where to set it and I'm off to the races, literally.
I read about Dxtweak2 and didn't download it because I thought that I had to set it up each time 'outside' GPL before playing the sim. Even  with 'saved profiles' as you describe, I think that you have to initally setup, then remember or list and then do your few mouse clicks.  
My way means that you open GPL, very often do not even need to calibrate. Your earlier settings are retained and if you are driving the same car you are straight on the pedal, on another you just need to tweak the added pot.
(or perhaps I just prefer mucking about with mechanical/electrical things rather than computing  :confused: )

#6 Bernd Nowak

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Posted Dec 18 2010 - 08:28 AM

Thanks a lot Paddy!
I always found braking the hardest part to judge. During a beta we used fixed setups without the ability to adjust brake balance but to be honest, I believe that by adjusting brake bias I can find a suitable % where I can drive mostly every setup. But the mechanics of our beloved wheels/pedals are a weak point. I hadn't the chance to test one of the very expensive ones and I have no money. So your way is a neat way.

Any chance of posting some more pictures? Especially with the ball?

#7 Paddy the Irishman

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Posted Dec 18 2010 - 09:31 AM

Larger pics supplied.  I hope these are clearer but until I attach, I am not sure how large they will be.
There is not really much to see on the inside of the pedal assembly, just the red and blsck twin cable that goes to the 'headphone socket' One wire attaches to the bottom lug of the braking pot and the other to the red wire that was originally attached to that lug.

The larger one of the 'control box' shows that I do have a calibrated knob on the pot shaft.

I did consider mounting the pot directly inside the wheel housing but thought that I had done enough dangerous treading already !

Sky:- I had experimented along your suggested line with an MS Thrustmaster wheel using rubber rather than a spring, but put it too near the base of the brake arm - eventual result, one broken brake arm  :idunno:  :shock: THEN I reinforced the arm with brass plates and move the rubber directly underneath the pedal.

I graduated to a DFP after that, though the Thrustmaster remains functional

For Bernd:-
Pictures of the wedge cut from a rubber ball and also of it in place.  You can see where I have cut away part of the pedal box - a non stressed part.

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Edited by Paddy the Irishman, Dec 18 2010 - 09:44 AM.


#8 Bernd Nowak

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Posted Dec 18 2010 - 10:07 AM

Thanks a lot Paddy!!!

#9 ptmac3

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Posted Dec 18 2010 - 11:06 AM

View PostPaddy the Irishman, on Dec 18 2010 - 08:18 AM, said:

I read about Dxtweak2 and didn't download it because I thought that I had to set it up each time 'outside' GPL before playing the sim. Even with 'saved profiles' as you describe, I think that you have to initally setup, then remember or list and then do your few mouse clicks.
My way means that you open GPL, very often do not even need to calibrate. Your earlier settings are retained and if you are driving the same car you are straight on the pedal, on another you just need to tweak the added pot.
(or perhaps I just prefer mucking about with mechanical/electrical things rather than computing :confused: )

I (currently) have Dxtweak set at one value for all cars. I never have to open Dxtweak before loading GPL. I open Gem+, pick my preferred mod, track and car, load GPL and drive. No calibration necessary. To set it up per car requires one to close GPL, adjust the value(s) in Dxtweak, re-load GPL and then test drive your settings, but once you've got the settings right you're done. Just keep a note of the values per car. Then you would open Dxtweak, adjust the value as per your chosen car, click apply, close Dxtweak and load GPL. No calibration necessary. If one does need to calibrate in GPL Dxtweak must first be set to the default values. There's nothing wrong with your method, it's just a different means to achieve the same result, but the big advantage you have is being able to adjust on the fly while in GPL. I really like the use of the rubber ball. That's pretty cool. :thumbup: I had a Momo Force, the red one, that I had put a second shorter stiffer spring inside the original to give the pedal more feel. It kinda worked. Currently I have a Thrustmaster F430 that uses opposing magnets on the brake pedal to increase the resistance. It also kinda works. They need to be stronger. Maybe once the warranty expires I'll see if I can do something about it.

#10 ducwolf

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Posted Dec 21 2010 - 08:24 AM

Thx Paddy for Your explainations !  :thumbup:

I have only fitted a rubber to my G25 brake pedal and calibrated it with the rubber in GPL options menue.
The pedal is calibrated for full brake pressure at the highest resistant of the rubber. The travel of the pedal is at 60%
when it gets stopped by the rubber, similar to a real life pedal.  
This is the way I used it since years and my impression is it works perfect.
What is the benefit of the poti ? Would I get better feeling for the brakes with Your method ?

Thx in advance,

Wolfgang

#11 benzman

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Posted Dec 21 2010 - 12:33 PM

For G25/G27 owners this may be of interest:-
http://www.apelectrix.com/index.html
  I have not bought one but I would be interested to hear from anyone who has.  Incidentally, I used the rubber ball trick on my old black MOMO but I find that the G25 seems to have enough feel to not need changing.  Perhaps I just have clumsy feet!

#12 Bob Simpson

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Posted Dec 21 2010 - 12:47 PM

View Postbenzman, on Dec 21 2010 - 12:33 PM, said:

For G25/G27 owners this may be of interest:-
http://www.apelectrix.com/index.html
  I have not bought one but I would be interested to hear from anyone who has.  Incidentally, I used the rubber ball trick on my old black MOMO but I find that the G25 seems to have enough feel to not need changing.  Perhaps I just have clumsy feet!
I use Andy Pastore's load cell.  It's simple and fairly cheap.  I still want to play around with a different amount of play and possibly change the rubber to something harder, but for heel-and-toe driving it's easier to use a pressure dependant rather than travel dependant brake pedal.

With my previous brake pedal I used a rubber block and did a careful calibration but it was always hard to get the same foot force each time I calibrated.

Edited by Bob Simpson, Dec 21 2010 - 12:49 PM.


#13 Paddy the Irishman

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Posted Dec 21 2010 - 01:05 PM

View Postducwolf, on Dec 21 2010 - 08:24 AM, said:

Thx Paddy for Your explainations !  :thumbup:

I have only fitted a rubber to my G25 brake pedal and calibrated it with the rubber in GPL options menue.
The pedal is calibrated for full brake pressure at the highest resistant of the rubber. The travel of the pedal is at 60%
when it gets stopped by the rubber, similar to a real life pedal.  
This is the way I used it since years and my impression is it works perfect.
What is the benefit of the poti ? Would I get better feeling for the brakes with Your method ?

Thx in advance,

Wolfgang
Hi Wolfgang,
I think that you should probably stay as you are.
I had tried with the rubber wedge alone, calibrating WITHOUT it in place and then inserting the wedge so that I got more-or-less the braking effect that I wished, but it was rather hit and miss and very time consuming/frustrating.
Then I added the pot on top of that process to fine tune.
THEN it occured to me that I didn't need to calibrate without the wedge, just add it, calibrate and then 'pot' tune.  I can calibrate with the wedge in and just fine tune in one adjustment.

I don't think that you would get much advantage if you are well satisfied with what you have already got. The only advantage would be that if you find you are dissatisfied with what you have when you got on track, you can adjust actually 'on track'.

I haven't raced far enough or skilfully enough to find this out, but you could alter braking effect as fuel load changes. Whether this woudl be any real advantage I do not know.  
(Also you are using a bit of kit that is superior to mine to begin with).
I don't think I have said this before, but I LOVE your GT sounds  :clap2: - even if they made it harder for me to judge locking point by sound! After all my mod compensates this for me.

#14 ducwolf

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Posted Dec 22 2010 - 01:23 AM

View PostPaddy the Irishman, on Dec 21 2010 - 01:05 PM, said:


I don't think I have said this before, but I LOVE your GT sounds  :clap2: - even if they made it harder for me to judge locking point by sound! After all my mod compensates this for me.

Thx Paddy. Did You notice the three different skid files with altered volume in the GT sound set? Maybe the loud one gives You better audio feedback for
the locking point.

Wolfgang

#15 Paddy the Irishman

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Posted Dec 22 2010 - 04:38 AM

Thanks again Wolfgang,

I saw a reference to diferent skid sounds but did not try them out.

I am using the sound files as they came with the basic install but I have opened the 'Sound' folder and can see the three files, but I don't know how to change from one to the other.

I tend to leave 'operating' things as they are and put in the graphical 'add ons' which I consider easier to replace if anything goes wrong.

Anyway I am very happy with the sound as it is  :thumbup: (and I doubt if my times would improve very much with a different skid sound !




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