DIY hydraulic handbrake using a bike brake

Today when I was straying through my workshop I found an old pair of hydraulic bike brakes.
Since I was thinking about a DIY handbrake I had the idea of just putting a loadcell between the calipers. The lever is quite sturdy and is easy to mount so it should be possible to extent it with some kind of pipe.
The pressure inside the system can reach about 40 bar. I'm not sure about the brake cylinder diameter so I cannot calculate the needed loadcell but that shouldn't be hard to do.

The feeling should be quite realistic since we are talking about real brake calipers here. Maybe you could put some kind of spring between the calipers to change the feeling. The result could be a realistic analogue handbrake.

A different possibility is not to use a loadcell but to mount a pressure sensor to the system (instead of the "venting screw").

This is what I'm talking about (not an actual photo of my brake but it's the same model):

Put some solid nolathane rubber in between the calipers as the material is strong and will have a small enough compression to get a good feeling. I didn't know that games had a axis for the hand break, thought it was just on or off.

looks nice!
maybe you could insert a (small kitchen) weighting scale between the pistons to check the force applied? in order to choose the right load-cell

There are some sims that do support it I know RBR does and I think rfactor did to,
The idea of rubber between sound perfect to me

@Helium it seems a shame not to repurpose something you have sounds a great idea

Hello,
looks very Interesting. I'm building a Handbrake too but i can't find the right hydraulic connectors. So maybe i will take your solution.
Hope there will be some updates soon

Look cool, have some bike disc brakes here, will see how it goes and maybe i will do one too!

Keep updating friend!

I did some research about the brakes and the loadcells.
Magura (the brakes manufacturer) talks about a maximum pressure of 40 bar inside the system. The diameter of each brake caliper piston is 14 mm.

So I did some quick and dirty calculating:

40 bar * 10^5 N/(m²*bar) * (2*14/(2*1000))^2 (mm*m/mm)² * Pi = 2463 N
2463 N / 9,81 m/s² = 251 kg

That is a lot. I am not sure how good those approximations are but I think I should do some real world testing.

50 kg load cells can be bought for a few bucks all over the internet (6-7 € for 4 pieces). If I add some rubber between the calipers like some of you suggested (maybe a PVC pipe would work to) and find a way to combine those cells this could be a cheap solution. Should be possible to use four 50 kg loadcells with some kind of parallel connection to get values from 0 to 200 kg, shouldn't it?

I didn't think about a way to mount the brake calipers but I guess two metal square tubes (one on each side) should do the job.

I plan on doing some testing and maybe making up some better approximations in the next few days. In the end the price of the loadcells is crucial (besides those cheap 50kg thingies they are quite expensive). Maybe buying a real drift handbrake from ebay with a pressure sensor and some kind of fluid reservoir isn't much more expensive but should do a better job and has a much better look.

I don't know if it's ok, but this site have 250KG load cell...

http://www.loadcells.com/Load-Cells/Single-Point-Load-Cells/load-cell-1042.html

And 200KG i found a lot in internet, examples:

https://www.sparkfun.com/products/13332
http://www.phidgets.com/products.php?product_id=3137

The problem ist not that those loadcells are not available. The problem ist that they are quite expensive if you take the alternatives into account.

You can buy hydraulic handbrakes for 50 €, a reservoir for 25 € and pressure sensors for 25 € as well. I doubt spending 60 € for a loadcell to improvise a handbrake using a bike brake would be a good idea. Selling the bike brake might be the better idea. If those 6€ loadcells work it is a different story.

http://www.ebay.co.uk/itm/BLUE-Hydr...542?pt=LH_DefaultDomain_3&hash=item1ea1bc815e
http://www.ebay.co.uk/itm/Hydraulic-Drift-Handbrake-Oil-Tank-for-Hand-Brake-Fluid-Reservoir-E-brake-Red-/251810743996?hash=item3aa11706bc
http://www.ebay.com/itm/Pressure-tr...ter-/271763798948?hash=item3f46627ba4&vxp=mtr

Yeah, you are right, i didn't looked about price, just found it...

This work? http://www.ebay.com/itm/Pressure-tr...ter-/271763798948?hash=item3f46627ba4&vxp=mtr

I think yes, or i'm wrong?

how about forgetting the load cells and just use a potentiometer? The applied pressure is going to be relative to the distance that the hand break has traveled. You could even try using a logarithmic pot so that not much action happens in the first part of the lever travel and the more you pull on the lever the more voltage comes out of the pot.

Above: That sensor might work depending on what pressure your system works at. If you get a real hydro handbrake then you need to find at least double the rated PSI as that one.

I'm putting together a set of hydro pedals for my sim, I used load cells at first but I have now taken those load cells out and I will use potentiometers. It always felt a bit odd when under heavy braking and I found I had to constantly modulate the pedal to keep a consistent braking force.