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Founder, 1929-2014
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Park-Lok Hydraulic Brake

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Outlet Fitting:
1/8" NPT
Garage Sale:
Arrow on the body points toward the outlet (away from M.C.).
Park-Lok Hydraulic Brake
Product Video
Park-Lok Hydraulic Brake

Click image to enlarge

Watch the video below to learn more about the differences in brake lines, flare types and fittings you may want to consider before plumbing away on your current chassis project.



Q & A

What's in the Box

Hydraulic line pressure keeps brake secure. No special linkage. Not recommended for use with silicone brake fluid or as an emergency brake. Features 1/8" NPT female on inlet/outlet.

Device is generally used to lock the rear brakes. To set the lock, step on the brakes, push the lock knob down, and take your foot off the brake. To release the lock, step on the brake again slightly harder than before and it will release automatically.

Warning:This is not compatible with any silicone brake fluid.

Hydraulic Parking Brake Instructions (PDF)

You may also be interested in:

Universal Mechanical Brake Light Switch
(Part #91031306)

Our mechanical brake light switch is "closed" in the at rest position. It breaks the circuit when pushed. Mounts near your brake pedal and the arm can be bent as needed. 42 amp max rating.

Use for your street rod, truck, or muscle car!

Adjustable Proportioning Blocks With Brake Light Switch
(Part #91031358)

This adjustable proportioning block allows you to run lines from the master cylinder to the block and then to the appropriate wheels. What is neat about it is that it also contains the proportioning valve and brake light switch. This dramatically reduces the amount of fittings needed and potential leaks.

The adjustable proportioning valve regulates rear brake pressure, helping to maintain correct brake bias between front and rear brakes. It is designed for dual bowl master cylinders. The distribution block connects to the master cylinder and distributes brake fluid to all four wheels. An easy to turn handle with directional arrows makes it simple to either increase or decrease rear brake pressure.

The block accepts 3/16" brake lines and the inlets and outlets on this unit are 3/8"-24 inverted flare females.  It has two inlets from the master cylinder, two outlets to the front brakes and one outlet to the rear brakes.  It includes five stainless steel 3/16" fittings and wiring pigtail for rear brake light switch. Mounts to any convenient location. This is not a direct factory replacement for original blocks. Some line modifications may be necessary.

910-31358 Instructions (PDF)

Learn more about how adjustable proportioning valves work by reading our tech article. Brake System Selection.  

Brake Metering-Hold-Off Valve
(Part #91031363)

If you touch the brakes and the fronts instantly lockup, you need this valve. It allows the rear brakes a chance to start to engage before the front brakes do, which gives you a better feel and more control. 

It does not replace the proportioning valve, but compliments it. 3/8"-24 IFF fittings.

910-31363 Instructions (pdf)  

Straight 3/8 Inch-24 IFF to 1/8 Inch NPT Male Adapter
(Part #91031831)

Brass adapter.

Straight 3/8"-24 IFF to 1/8" NPT Male Adapter

Straight -3 AN Male to 1/8 NPT Male Adapter Fitting
(Part #6174244)

Brake Adaptor.

  • 1/8" NPT


Blue Straight AN3 Flare Adapter to 1/8 Inch Aluminum Pipe
(Part #6176041)

These straight flare adaptors connect 1/8" pipe to straight -3 AN fittings. They are lightweight aluminum and feature a 37° sealing angle.  Order your desired size.

  • Precision machined to ensure precise thread engagement
  • Lightweight aluminum fitting
  • -3 AN to 1/8" aluminum pipe
  • 37° sealing angle guarantees a positive seal at maximum operating pressures
  • Available in Blue anodized finish for a custom look

Fitting Thread Application Chart (GIF)