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GM Disc/Drum Proportioning Valve for 1/2-20, 9/16-18 Outlets

Specs
Centerline of Holes:
2.68
Material Type:
Brass
Overall Height:
1.95
Overall Width:
1.08
Overall Length:
5.15
Sold in Quantity:
Each
Overall Thickness:
1.08
Outlet Fitting:
Bottom front/Top front are 3/8"-24 IFF (to font brakes), Rearmost port is 9/16"-18 IFF (to rear brakes).
Garage Sale:
No
Notes
Includes hard lines with fittings, hardware, bracket, and brake light switch. This is a combo valve (metering for front/proportioning for rear) into one valve. Residual valves NOT built in.
GM Disc/Drum Proportioning Valve for 1/2-20, 9/16-18 Outlets
GM Disc/Drum Proportioning Valve for 1/2-20, 9/16-18 Outlets

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.

Details

Reviews

Q & A

What's in the Box

These proportioning valves are similar to what GM used on many cars in the 70's. They are non-adjustable and may require an adjustable valve in the rear brakes (if needed). Block incorporates metering (for front brakes) and proportioning (for rear brakes) into one unit. For use with front disc, rear drum brake systems.

Includes hard lines to connect to a master cylinder with 1/2"-20 and 9/16"-18 outlets.

GM Proportioning Valve Plumbing Instructions (PDF)

Notes

Bottom Front Port: 3/8"-24 IFF threads - goes to one front brake
Top Front Port: 3/8"-24 IFF threads - goes to one front brake
Middle Top Port: 1/2"-20 IFF threads - comes from master cylinder
Rear Top Port: 7/16"-24 IFF threads - comes from the master cylinder
Rear Most Port: 9/16"-18 IFF threads - goes to rear brakes

Specs


Item Details

For M/C with 1/2"-20 and 9/16"-18 outlets.

You may also be interested in:

Adjustable Proportioning Blocks With Brake Light Switch
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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.  

Speedway Purple Proportioning Valve
SKU-91031353
                        

Allows easy adjustment of front-to-rear brake bias. Universal design works on all race cars. Has a 100 to 1500 psi range with up to 57 percent pressure reduction.

Includes two 1/8"-27 NPT to 3/8"-24 inverted flare fittings (not pictured).

Brake System Builder's Tip (Link) 

Wilwood 260-11179 Adjustable Proportioning Block
SKU-83526011179
                        

This block has the proportioning valve built-in to the rear brake ports and a stop light switch built into the front brake ports. All ports are 3/8"-24 inverted flare female.

  • Compact design simplifies mounting, plumbing, & wiring
  • Maintains full isolation between front and rear fluid circuits
  • Rear circuit has a single inlet and single outlet with the adjustable proportioning valve
  • Front circuit has a single inlet with two outlets

Proportioning Valve Installation Instructions (PDF)

Brake System Builder's Tip (Link)

Detailed Schematic of Proportioning Block 

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

GM Disc/Drum Proportioning Valve for 3/8-24 Outlets
SKU-91031364
                        

These proportioning valves are similar to what GM used on many cars in the 70's. They are non-adjustable and may require an adjustable valve in the rear brakes (if needed). Block incorporates metering (for front brakes) and proportioning (for rear brakes) into one unit. For use with front disc, rear drum brake systems.

Includes hard lines to connect to a master cylinder with 3/8"-24 outlets.

910-31364 Instructions (PDF)

9/16-18 IFM to 3/8-24 IFF Adapter
SKU-9103183-9/16
                        

Brass adapters. Select from:

  • 3/8"-24 IFM to 7/16" - 24 IFF
  • 7/16"-24 IFM to 3/8" - 24 IFF
  • 1/2"-20 IFM to 3/8" - 24 IFF
  • 9/16"-18 IFM to 3/8" - 24 IFF