DIY G29 Hydraulic Load Cell brake

I found out that I need to adjust the brake range in the Leo Bodnar interface software to suit different cars.
I had it set to 800 (1024 is max) with the sensitivity pot set to the hardest. This meant I was pressing as hard as I could while still being able to press this hard while driving to reach the 800 mark.
It seemed to be the best setting and on my telemetry I was hitting 100% in the Ferrari F2004 F1 and BMW M3 GT2, but I was only getting to about 60% in a Mazda MX5 Cup even though I thought I was pressing just as hard.
So I set the LB setting to 500 for the MX5 and now the pedal feels a lot softer and more like an MX5 would and it braked so much better and harder and still didn't lock up (ABS on obviously). And much much easier to hell-n-toe without having to press so hard.
I then lowered the setting on the F2004 to 600 and found it braked harder but was harder to modulate and would lock easier - I ended up at 740.
And finally I lowered the M3 but even at 790 it would lock up way too easy (non-ABS car) so had to go back to 800.
Moral of the story is that each car needs to be individually set. Luckily if you forget to do it before you start it is external from the game so can be changed on the fly without having to exit or restart or even enter the pits.

Also managed to do a 1:42 in the f2004 at Spa whioh I believe is getting to be pretty quick
But still not quick enough to be classed as an alien

One last tweak I have done - I set the the brake range in the Leo Bodnar Interface so that it is just a few higher than what the loadcell can output so I never get to 100%. and now I almost never lock brakes and can trailbrake harder and for longer.

Another quick update
I tried it without a spring between the pedal and the master cylinder, with a softer spring and finally with a harder spring and the harder spring brings the realisn and fine control you need.
And now that I have set the max setting in the software back to 1024 (and the max the loadcell puts out is 1010), and the min setting above what the loadcell puts out at rest when the variable pot is at its most sensitive, I no longer have to adjust the software as the variable sensitivity pot is more than enough. I think this partly getting used to how the brake works too.
And I also added a stiffer spring to the G29 throttle pedal so now I can be a lot more sensitive on that too and actually hold part throttle through turns.
I haven't compared lap times yet but just did a couple of laps of the Nordschleife in a Tatuus FA01 and it was driving nirvana

Another update to my settings.
When the loadcell is at the hardest variable pot setting it is registering 60 on the 0-1024 software. When I put it the most sensitive I use, it is 100 or therabouts so the software was set to a range of 100-1020. So when I set it at most sensitive there is no deadzone, except what there is in the caliper as it takes up the slack to the pads (which is normal IRL). But then when I set firmer for GT / F1 cars there is a decent deadzone, which didn't seem to bother me much. But then I decided to go back to an earlier method and just the pot to the firmest and then move the software range to 60-1020 and then adjust the top of the range, depending on which car I am in. So 720 for street cars, 820 for Gt and 920 for F1 etc. So now none of them have an artificial software deadzone and after using it like this for a few days it seems to be an improvement yet again
Still can't race like a pro though

NOOOOOOOOOOO

I think the master cylinder just failed - probably because it is a cheap Chinese moped cylinder and I was putting F1 levels of brake pressure through it

Good excuse to get a better MC and caliper which will require an upgrade to some Heusinkveld replicas and get more adjustable range for pedal throw ratio

Got a replacement MC and back in business.
Just set my fastest lap due to a major improvement. That improvement in braking was in the user !!
Realised I had been braking too hard in to slower speed corners
You can go round corners so much faster if you don't slow down as much

So who would have thought one number would be so significant.
Constantly tweaking my brake range in the software and found that setting minimum range to 120 (needed this deadzone from the aforementioned 100 that I was using) meant it would lose the rear end whole trail braking into corners and setting it to 122 meant there was no trail braking when I thought I had just a little bit of brake pedal pressure. So 121 it is
The maximum brake range setting doesn't seem to matter as much as you you can easily adjust and compensate for it, but I found 250 for road cars, 350 for race cars and 450 for Formula cars. (I was running much higher numbers but found lower ones worked best as I got used to not braking as hard as I physically could)
That is until your forget to change it and try to brake a road car with 450 setting and find you have virtually no brakes or just caress the brake in a formula car and instantly lock it because it is on 250

So I just found out that oil eats rubber and running olive oil instead of brake fluid was what killed my MC. I had replaced it with a chinese hydraulic handbrake setup and that MC failed too and thats when I found out about the oil

So I bought a trailer MC and ran brake fluid this time.
Braking is back to being perfect

But now I have noticed just how much my plate the pedals are mounted on flexes
So when I finally get around to buying some decent pedals I will have to upgrade the plate and hopefully that will bring me another few tenths ...........

Not sure if all this hassle is worth it now since the price of loadcell pedals has come right down. When I started this the cheapest ones were around $1000AUD, now they are about $300.
This setup will cost :
Caliper : $30
Loadcell : $70
Hydraulic handbrake : $70
Bodnar cable $30
LC Amplifier $40

$240 total plus suitable pedals

Dammit - turns out a lot of my braking issues were user error
I use the M3 GT2 at Spa to test since it doesn't have ABS, I like the car and track and i am reasonably fast. I use the same setup all the time too so there are no other variables - just the brake settings.
But it turns out that years ago I had adjusted the Brake Bias because I couldn't stop the fronts from locking so it was heavily rear biased. I totally forgot about that and never changed it back
That explains why I couldn't stop it over rotating into Fagnes.
So back to square one and testing different software braking ranges............

And I have just reinforced my pedal plate so there is now no flex whatsoever.
OMG what a huge difference.
I didn't realise just how much flex there was and how much it translated into a 'squishy' pedal feel.
Now the pedal is rock hard and when you just push on it (without being in game) and watch the movement there is just a couple of mm travel. But once you start playing it feels like more but it is so precise now.
I had the brake range setup from 120 min to 450max and one of the problems that at the end of the range (where all the flex was happening) I could never quite get an exact/stable max brake pressure reading. When I pressed what felt like 100% there was always more to give but it was that extra bit that felt squishy.

Now I have backed the max down to 360 and I can hit that mark and stay there and it feels like I am at max pressure, even though I can still push harder and go over 100% when I panic brake, as you would in a real car.
Modulation at that point (anywhere actually) is so much easier too.

Now just need to get a decent quality set of pedals and look out Max Verstappen........

Made some changes to the sound of tyres in AC - lowered them so I don't hear them as much and discovered that what I thought was lockup actually wasn't. I already had the Tyre Skid Volume Onset at 200% (which really means sound kicks in only when the tyres are actually skidding and not beforehand) but still had the volume fairly high so I could clearly hear it over the engine and opponents etc. Turns out skid volume appears to make you think the tyres are actually skidding before they are or makes you think they are skidding more than they are, and I was backing off when i didn't need to.
So now I can brake later and longer and with the improvement physcial brake setup I think I now have it PERFECT
Next mod is to the driver - I think I need some one-on-one coaching now to take full advantage of the setup.

So still not 100% happy with how the brakes feel and thought I should play some more. So I moved the pedal ratio so it is now really hard to push. I have done this before but had the settings so you hard to push really hard to get to 100%. This time I set 100% to be just moderately hard - basically as hard as I normally brake rather than as hard as I can brake.
OMG what a difference. With the pedal hardly moving and feeling physically harder under my foot, but actually responding as if it is a lot softer, it makes it so much easier again to max and modulate the brake and trail brake all the way to the apex.
I just jumped in the M3 GT2 at Mugello where I haven't driven that combination for well over a year. Instantly down to my PB and then smashed it in the race while hardly trying.
Hopefully that will be the last change as i am sick of spending hours/days/weeks/months on equipment and game settings and just want to enjoy myself and not think about anything but driving.

Yep thats finally got it.
Pedal lever ratio set to high and software set to low.
So I have really good control over the amount of pressure I am exerting and much easier to ease off slightly but with the low software setting it is not hard to get to full braking. Took a bit of practice to retrain myself not to press so hard. It now feels natural and much more lifelike.
PBs on just about every track and every car
Except strangely I am struggling to get with 2 secs of my PB with my favourite car (M3 GT2) and track (Spa)

One more little tweak - added this spring to push the pedal back. Wow what a difference that made. I have had a spring in there with my other master cylinders and it didn't seem to make much difference, but this one is a game changer.
I have been able to drop my minimum position in the software and still not get any lockups and trail brake even more into corners and it feels even more realistic

Another upgrade - this time to big 4 pot brake calipers




That has given more of a road car feel to the brakes with heaps more travel (as expected ) but a lot more mushiness (more than expected ).
It does seem to be better but there is too much pedal travel and I can't comfortably reach full limit of the pedal travel. Even with that though I just did my PB lapin my favourite M3 GT2 at Spa

I think it is too big a step from the tiny 2 pot moped caliper. so am going to try again with a smaller car caliper, but I think it is another step in the right direction

I ordered a 4 piston bike caliper but the AliExpress seller couldn't supply and issued a refund and in the meantime I swapped back to the 2 piston moped caliper.
But this time I set it up with more pedal leverage so it is softer and more like the feeling I was getting with the big car calipers. Been using this now for quite a few weeks and definitely got used to it and think it is pretty much as good as it will get.
My only 2 issues are :
1. right at the end of trail braking there isn't much feel and not always sure if I have still got a bit of pressure on or have released them fully. I think this actually realistic but IRL you would be able to sense if the car was still braking or not, but not so much in the sim. Motion rig would solve that
2. Driver skill !! I don't think I can get any better braking feel from any set of pedals so just have to work on my technique now

Solved both issues :
1. Moved the slider back to remove the deadzone so just touching the pedal starts the braking.
2. Changed my braking style and got used to the feel of the setup a bit more. Instead of absolutely standing on the brakes at the start I have started easing into it. By this I mean it is still as quick as possible but smoother. This has allowed me to ease off for trail braking smoother and has given me the feeling back to solve issue 1. Also moved the max brake slider a bit higher than it was and with the smoother application I can hit higher pressures easier and have it so only just get 100% with absolute total pressure from high speed braking on a long straight.

I had a race in a Z4 GT3 at Laguna against a MP4 McLaren (doing 1:24s so pretty quick but not alien quick). I was in front most of the race and defending like mad and afterwards the McLaren driver said he had never seen anybody brake as late and as hard and still make it round the corner in the Z4 so I must be doing something right

here is my brake trace for 1:24.5 lap with MP4 at Laguna

Smooth Operator ( in my best Sade voice )

Settings I have ended up with :
Pedal ratio : 4.5:1 (approx)
Led Bodnar Software : 140-700 - no-load output is 138 and my absolute max pressure I can apply is about 750 but in-game just over 700 is as much as I ever get to. I guess you could state this as 0% - 93% of the load cell range.

Next upgrade is some SimJack pedals as the G29 don't really suit this mod.