DIY G29 Hydraulic Load Cell brake

Brilliant thread.
ive thought for a while that the best way to replicate a car brake feel it to ,,, well replicate a car brake.
I’d like to try this on a ps5 but replicating the electronics , well I wouldn’t know where to start

Ok started
Waiting on load cell - let’s see where this goes

Good luck - I will be eagerly awaiting your build and thoughts

Thanks I’ve pretty much got this sorted now. Originally I wanted to go down the route of a hydraulic pressure valve but quickly realised I can’t sort the electronics to make it work with my current set up. So have ended up using a load sensor and some pre loaded springs mounted in the calliper where the disc would go

got pics of how u r using the springs ??

Yeah can you see the picture above?

I’ll try and explain it. Load cell in the centre between the 2 plates fixed on one side.
Each end under the wing nuts and between the plates are a stack of bellivile spring washers which are compressed by the wing nuts.
These are compressed so the just touch the load cell. Whole thing drops in the calliper in place of the brake disk.
Main idea was to ensure the brake pistons were pushed back and didn’t leave any residual pressure on the load cell in between breaking. It can also be used to firm up the brake feel if needed.
Seems to work well.
However I’m just waiting on a Fanatec setup, so I’m trying to find out the voltage from a csl brake pedal to see if I can use a fluid pressure sensor .

Thats what I thought you meant.
Back in the 50s when General Motors were developing the disc brake they tried to figure out a similar system for exactly the same reason. Until one of their engineers said "Why bother ? Just let the natural reaction of the fluid returning to its initial state pull the pistons back in". I don't have any springs in mine and the loadcell is free to move when the pedal is released. But I have a button type loadcell and small scooter brake so the loadcell ( https://shop.simagic.com/products/p-s100 ) and only just fits in the caliper so no room for springs. I do have a spring on the pedal though which helps with the feel.
So do you have your setup up and running ? How does it feel ?

Ahh didn’t know that .
I saw the spring on yours made sense.
I had to use that spring loaded plate because the smallest pressure registers on the load sensor.
I haven’t driven with it yet. I actually put it together for a Logitech g29 but I now have a Fanatec ordered so will need to redo it for that.

Is that because it is just a 50kg loadcell ? You may need something a little heavier or add another one and wire it up for 100kg. I have a 200kg button one here if you want to upgrade or you can get them from AliExpress. Although I highly recommend the Simagic 100 or even better the 200kg ones as I think their design is the most suitable.

Biggest challenge at the moment is trying to find out if the signal from the native fanatec cal brake is similar to the g29. Where the signal voltage decreases when you press the brake pedal .

exactly that 50kg because it was for a g29 and ps5 I’m limited to a half bridge load cell . Fortunately the pre tensioned springs help to stiffen everything up.
Ideally I’d like to switch to a 1000psi inline fluid sensor. But first I need to find out about the fanatec voltage. Failing that I’ll slot the Fanatec load cell into the calliper ,, I’m limited because I’ll be running it through the wheel base

I’m about to go down this route. What are peoples recommendations on master cylinder. Are the hydro handbrake types better than motorcycle rear brake ones? Any one have thoughts on pressure sensor vs load cell route?

MC type doesn't make any difference.
What matters is MC bore size vs Pedal Ratio vs Caliper Piston area vs Loadcell rating. Every one of those factors will affect the pedal feel.
I have since swapped to a normal LC Pedal set (Heusinkveld copies) and can't really tell much difference. Since these pedals can be had for around $200USD I no longer see any point of my hydraulic loadcell setup since they will probably around the same and still require hours of DIY work and many more hours of testing to get them setup for your liking. When I started this the cheapest LC brakes you could buy were $1000USD !!

Thank you heaps for the reply mate.

Any chance you could link the load cell pedal you ended up with?

What kinda pedals did you get, and what is the adjustability in them? I only thought about doing this to mine because I could make the brakes feel like anything, but if you know a alternative with a ton of play to change for the type of cars, I'd like to know. I'd like to have softer brakes for GT stuff, soft for road car, stiff kinda for formula stuff, but with all the work you put in, it does not seem worth it if there is a good alternative for not much more. I also liked the caliper idea because there is a slight air feeling in fedals just a bit before the calipers bite. I'd like to know if you have noticed much of a difference in that, or not.

I have bought SimRuito Heusinkveld copies, but since sold them and replaced them with 2nd hand HPP Hydraulic pedals. Both of which are shit and frustrating to set up since there is an infinite amount of rubbers or spring combinations and none of them ever feel just right to me.
If you go for a loadcell and caliper you can adjust how hard or soft they feel just by changing the pedal range settings, or adjusting the pivot ratio.
When I get time and motivation I am probably going to go back to the caliper setup.

I've been worried about this. I've read a lot and this is what I've worried about is that you have way more adjustability with your set up. If I go with your set up, how do you make a load sensor work. Like if i bought one, how would I make it work with the computer. I know nothing of coding or anything, so I don’t know how to make it work. I also don’t know if I wanna trash my Logitech pedals, so do you know a substitute? Maybe you could make something out of different pedals besides the g29 because a lot of your issues seem to be limited to that pedal set. I’d like to try this, but I don’t wanna like not sim race, or trash my pedal in an attempt. So do you have any suggestions? Also if I did it differently, I’d need a way for the gas to be read, and clutch. I want something I can really customize, and nothing like that can be cheaply bought on the market. Maybe we could idea swap in tandem, I do not know. I just know im not happy with my g29 pedals, but they do work with console if I ever wanna play them, so I don’t wanna lose that ability. I don’t want my brakes also unrealistically hard like a lot of load cells do.

You need a loadcell amplifier which you can DIY (google it) or buy one from Derek Speares Designs or Leo Bodnar. you will need Leo Bodnar pedals adapter for the G29 also.
Any pedal can be made to work but I would definitely not use the G29. You want one with more upright pedals so you can have better pivot angle to the MC and also a larger pedal pivot ratio. The Heusinkveld copies are your best bet I think, since they are easy to modify without ruining them. And you probably don't need any extra since the loadcell should just plug into the control box - but not 100% on that since I never tried. You will need to splice a RJ45 connector on to the loadcell though.
No need for any coding - the control box / diview or Leo Bodnar software is all you need and you just set the minimum and maximum points and adjust to your liking.
The only adjustability with this setup is the pedal ratio (by moving the attachment of the MC rod up or down the pedal arm) and the software limits adjustment.

I know this is off topic, but have you ever thought about hooking the throttle to some type of real linkage? You could easily adjust the springs on it too then. Also would these copies work well with haptic motors, or whatever they are. I'd like to attach them to it too. I've only recently kinda went full out in sim racing, so I'm not sure about everything, but I'm willing to try to caliper set up. How does the throttle work on it too? I assume it works off of just distance traveled, but I don't wanna mess up any of it's electronics or anything. Also, all PC games should register these modified pedals right? I play a variety of games, like Iracing, asseto corsa, and nr2003 andbim worried the modified pedals might not work with nr2003. Also, I hope all these questions don't bother you, I'm just trying to get the most information I can because I really don't wanna love this up. I could show you my current set up if you want to see if you have any suggestions on how to make it work with the desk I have. I built my own desk, and I'd like to be able to fit this pedal configuration on it too. I flipped my g29 pedals, swapped the gas and clutch, and mounted them at a angle against a angled board, and then mounted that to the sides of my desk. I then put a flat board that hooks on the legs where my feet set. It's very sturdy, so no issues in that regard. I just want it to fit still in my configuration.

Hey do you mind sending a link to the pedals, I can't find them. I looked them up.