DIY - Low cost slave cylinder for hydraulic Brake/Handbrake

[Bitacaia]

Hi Simracers!

I'm at the moment building a handbrake for my rig. And i would like to share my low cost version of the Slave Cylinder (SC).

I have bought a racing handbrake included with a Master Cylinder (MC)
The usual option from the sim racing community is to use a SC from the brand Wilwood or CNC, but unfortunately this option is expensive (around 80€+transport!!!).

The solution used by me, is to use a convectional SC from our daily cars.
In Europe, after some search, i concluded the less expensive SC i could find is the one form the Land Rover Defender:
http://www.ebay.co.uk/itm/LAND-ROVER-DEFENDER-2-5-200TDI-TURBO-CLUTCH-SLAVE-CYLINDER-PART-591231-/261385018777?fits=Car+Make:Land+Rover&hash=item3cdbc2dd99:m:msGbkCowS3EGkM1IvVKPkfQ

Or with a Master Cylinder as a bundle (for a low cost pedals):
http://www.ebay.co.uk/itm/LAND-ROVE...545619?hash=item43cbd50ad3:g:LDwAAOSwFAZTtSfv

The solution with all parts:










All parts can be found in any hardware store. The top bracket, i found in the area of the wood construction, and by luck, the holes are perfect align. Required me just to drill the hole in the middle.

The screws are
2x M8x100 (or 2x M8x20+2x Spacer M8x40+2x M8x60) for holding the top bracket
1x M8x80.for the rubber support
And the required washers and nuts.
The rubbers are form a skate truck.

The final price should go around 25€ to 30€(or less), depending on the price of the SC and transport.
As you can see, there is a big difference of price form the wilwood SC to this version (probably something like 120€ vs 30€).

Unfortunately, by the time i write this test, i did not tested the cylinder. This weekend i will fill the brake fluid in the system and make some tests. I already have everything installed. The challenge will be to add the fluid!!!

Tiago Viana

 

[DaVeX↯]

Hi, just a quick question...
I am going to buil my handbrake too, maybe you can help me...can I use this one?

This is a 50cc brake master cylynder for go Kart...it is about 30euro too.
BTW, nice idea, I can use it too...

 

[Bitacaia]

Hi Davex

I completely forgot to check the material from Karts...

This master cylinder, in my eyes should work without any problem.
In the end, the piston of the master cylinder pushes the fluid, but the fluid pushes the piston back. So, theoretically the master cylinder can work as a slave cylinder.
There are some exceptions:

If the master cylinder has 2 exists for front and rear brakes, i don't believe it can work... But i doubt the one you showed works like this, because of this picture:

This looks similar to the one you show. And one exit has a sensor (light/pressure).
It is possible, to me, that this part can be used as a Slave cylinder. And you can attach the pressure sensor on one of the exits!!!

Good alternative!

Tiago Viana

 

[Bitacaia]

The video of the first experience with the Slave Cylinder

The hand brake:
http://www.ebay.de/itm/Hydraulische...274969?hash=item2368fd2159:g:9eUAAOSw60lXMTA1

i bought the fittings from this website:
http://www.bat-motorsport.de/

The board is a Leo Bodnar:
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=94&products_id=204

The Hose, is from a VW Polo (i think...) But is too short!!! Minimum should be 400mm... this on have only 320mm

The fluid i'm using is mineral oil for bicycle brakes. (the DOT 4/5/5.1 are too agressive to the skin and floor)

Conclusion:
I added to all fittings a PTFE tape to help to avoid leaks, but in the end i still have one...
I believe i have air inside the system... It was hard and a big mess to install the fluid without the right tools...
The Rubbers are shore 88a, but for me is too soft. I will buy harder ones! Probably one cone of 88a and the rest 100a
The sensor is a 1000psi, and i'm using just 1000raw from a possible of 4095raw. So, for a hand brake a smaller sensor is better!
The electronic part is still in beta version. I will add the board on a nice box, add some buttons and use it as a button box for my rig.

Tiago Viana

 

[DaVeX↯]

Nice work mate!!
Which wheel are you going to couple with your handbrake?
Because I have an idea for the G27 wheel...wich (maybe) can work...

This is the g25/g27 pedals connection scheme, my idea is very simple (and maybe wrong), I will build a new cable with the same 9pin scheme but with no potentiometers at the end but:
- clutch pot > handbrake (pressure transducer)

- gas pot > Traction Control (rotary switcher)
- brake pot > Brake Balance (rotary switcher)

But I have still to obtain all the parts and check connections...

Going this way I don't need any external board (I already have 2 of them for shifter and pedals...) and I can use one of my g27 free 9pin ports (the pedals one)...

 

[DaVeX↯]

The sensor is a 1000psi, and i'm using just 1000raw from a possible of 4095raw. So, for a hand brake a smaller sensor is better!

Wich one should be used?

 

[Bitacaia]

Hi Davex

The electronic part isn't my strong point! Luckly we have Leo Bodnar and Derek Spear to give us material for our ideas!!! But i think the idea you have will work.
To archive what you need, i believe it's require a Load Cell Amplifier. So, the pressure sensor will behave like a potentiometer. You have 3 alternatives for that:

Leo Bodnar:
http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=73&products_id=199
Derek Spear:
http://www.**********************/freestanding-load-cell-amp.html
DIY:
http://www.instructables.com/id/Racing-Sim-brake-pedal-load-cell-interface/

The last, is a bit more challenging, but in the end the reward is bigger!!!

The general consensus for how big the Pressure Sensor should be for a handbrake is 100psi. But, from my test, i'm using 1/4 of the 1000psi, and this represents in an rough analysis 250psi.
Note: the dimension of the lever of the hand brake is important! A longer lever will apply more pressure to the system. Since my lever is long, i should use a 500psi Pressure Sensor.
But i will not replace the Sensor. The handbrake don't need to be so accurate, so having 1/4 of the resolution of the sensor will not represent a problem. (i will try to attach a potentiometer, like Derek Sprear have, but i have no clue how to do it...)

Tiago Viana