I'm designing a custom hydraulic hand brake I want to build next. It will be a pass-through or "in-line" system, which is to be installed between the master cylinder and the rear brakes by "intercepting" the pipe to the rear brakes.

Question: I guess I can use any "normal" hydraulic cylinder, like a common master cylinder (closing extra outputs) or better, a master clutch cylinder, which commonly comes with a single in and a single out ports. Is that correct?

EDIT: this diagram is from an existing pass-through kit. My question is solely IF a regular cylinder may do right, which I guess it would.

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  • Did you take into account that many dual circuit brake systems have a cross arrangement where front left and rear right are in one circuit and front right and rear left are in the other circuit? So, you may not have a single pipe to the rear brakes. If modifying the hand brake please consider the implications for getting the car inspected in the future. The inspector may not like custom modifications in the brake system of the car. Also, if you're messing with the main brakes (which I understood from your question), a failure of your modifications could result in the car having no brakes!
    – juhist
    Feb 3, 2017 at 18:01
  • Is your intent to use the main brakes to double as the parking brake as well? Feb 3, 2017 at 19:37
  • You don't need to design anything custom. Buy a rear handbrake kit that the rally car / drift car folks use.
    – cory
    Feb 3, 2017 at 20:28
  • @juhist: no problem here with inspections/modifications. The car uses a single line to the rear brakes and a T split to then go to each wheel. Feb 3, 2017 at 22:24
  • @cory: I design and customize my cars for the fun of it, it is food for my brain. It is too easy to consume stuff...and remain illiterate in many things otherwise one can learn while having fun time. Knowledge doesn't take brain space. Feb 3, 2017 at 22:27

1 Answer 1


Theoretically what your proposing will work with two caveats.

The size of the compensation port. When the master cylinder is "off" there is a port that allows brake fluid to circulate from the system to the reservoir. This port is usually pretty small and trying to push enough fluid though it for the rear calipers may be problematic.

Calipers require a lot of pressure to operate. Cars even with just front calipers always have a power booster. Drum brakes don't require a lot of pressure and have a self actuating property that helps a mechanical hand brake operate. The cylinder needs to be properly chosen so it provides enough pressure for the calipers to actually hold the car.

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