Hydraulic Brake Build [V2] (G27 Based)

[pilmat]

What kind of spring sits in a master cylinder normally? Also progressive?

Ah, alas, I wasn't going to discus it, but now that you brought it up...
The TSS solution is NOT a true hydraulic brake, and I don't feel that they are marketing it as such. What it does is give a hydraulic feel (and by all accounts a very good one). Basically it is a mechanical spring system that has a hydraulic parallel component, note that the CSP II has a similar arrangement with the buggy shock mounted in parallel to the load cell. What they do for a signal IS hydraulic, in that the fluid is exercising a pressure sensor. But the fluid is NOT exercising the spring, as in a traditional hydraulic brake. These are all subtleties, but you'll see the tie in to your question.

In brake application, the differences between the systems are quite moot, as long as the pedal builds pressure in the hydraulic system, all is good for feel. The big difference happens in brake release. In a traditional system, the main spring (in most sim cases the spring is the elastomer stack) acts on the fluid in release, keeping a head of pressure on the sensor and releasing proportionally. In the TSS system, there is a problem that the reversing of the hydraulic fluid pressure (i.e. pulling the piston back) could cause a sudden dip in pressure at the sensor and have a "quick release". They use air pressure in the reservoir (which the sensor is mounted in) to overcome this.

The spring you asked about in a hydraulic master cylinder is not actually there to provide feel, it is a part of the valve in the master to ensure fluid does not get sucked back up by the plunger. The spring keeps a head of pressure on the valve so that when you release, it pops the valve open and allows the plunger to return without pulling fluid back from the slave cylinder. So the spring you mention is there to avoid the problem that TSS uses the air pressure for.

Does it matter? If the driver gets the feel that they want, the answer is no. We have discussed the short comings of simulator brakes before (i.e. using a static solution to a dynamic problem) and therefore as long as the driver is happy, it's all good!

Nice to see you back in the saddle! Have a Happy Holidays!

Cheers! And the same to you

 

[LogiForce]

Thanks for taking the time to explain it. If the feel/proper action is achieved it indeed doesn't matter.

Happy holidays.
Mine are not happy anymore. Need to ask Santa for a new damper for my Lancia Delta. Lost it on the highway just now.

 

[gorzasty]

I really need to get back to this project! (maybe Santa will bring me a sensor for Christmas, it's all I need to get this moving again)

For the slave cylinder, most are 5/8" bore so they should work. Just make sure it is a pull type. Send me a PM, we may be able to make shipping much cheaper

Adjusting the sensor is a critical step, in my opinion. It gives you the opportunity to choose your elastomer feel and then put the brake pedal where you want it. You could choose very small pedal movement (i.e. hard elastomers) and then dial in the modulation you want, or really soft elastomers and then dial back the sensitivity to allow for the increased travel.

For the pressure range, a minimum of 1000 psi is necessary. If you choose too low of a range, a panic braking might damage your sensor.

You don't think you panic brake? I teach real world drivers on our simulators and it is impressive to see their "panic reflex". I had one amateur panic mid corner and press the clutch . Needless to say they started to understand why they spun a lot!! They also understood why their team had made their car so understeery, they kept telling them that the back end was stepping out as a cause to the spin. Using a Replay camera while on the simulator can tell you a LOT about how you drive.

Let me know if I can help you with any more info.

Edit: I'm looking for another set of G27/G25 pedals. I put a post in the trading post.

Hello pilmat

Glad to see you are back on the forum. Meanwhile I bought the parts I was writing about. Maybe to quick ;/ So I have 500psi sesnor (let see does it handle my breaking force), master and slave pull cylinder and Derek's controller. Now I'm trying to find how to connect these together, because they have NPT threads, so in Poland is hard to find such a thing... But I'am on the good way to buy something in a few days.

When I connect everything I write something about my experience.

For now I tried to connect sensor directly to the master cylinder and to controller. When I wasn't pushing cylinder at all controller show some force on the axis. Is it ok? Do I have to calibrate it with windows tool, or DxTweak to have zero reading while no force is on pedal? When I put some more force it worked well.

BTW Thx pilmat for Your proposition. If anything alese I need from Canada/US I will let U know. Really appreciate.

Do You have some experience with hall sensors to?

 

[alfp]

hello, mod G27 TSS if a hydraulic brake in every way ,in fact after testing the behavior of a conventional master cylinder, I decided to make a watertight system , I try not to use systems with deposits that may have lost , the spring only used for the recovery of the pedal , and has nothing to do with any Fanatec model , the air valve is to adjust the force curves as a function of the route , but did not say in the instructions that most users do not understand a lot of adjustments, and all I would do would be confusing , operation is fully hydraulic and have much more sensitivity than a conventional hydraulic cylinder , so I decided on this system, in addition to the space needed , would not have to modify original casing , there is very little space for anything, now I'm with the design for a mod for Fanatec and I will be different, there is more space for components , the new design will be compatible with other systems Pedals DIY and may adjust the working pressure of 20 -100kg , plus set the starting offset and gain, thus will support electronics .5v or 3v . , anyway I think that often focuses evil design accessories for simulation, design accessories that allow a high level simulation, and that is very different from reality , a greeting.

 

[LeftyWright69]

Neet project to go along w/ your crazy cool rig. Great job 👍