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1974-1977 Corvette C3 Brake Line Proportioning Valve - Brass - 339780

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Item ID: 628-449
GM Part #: 339780
Availability: Estimated in stock on 7/10/2025 , Pre-order now
Fits Years:
  • 1974-1977
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  • Description

1974-1977 C3 Brake Line Proportioning Valve - Brass - 339780 - OEM Number(s) (339780)

Restore confident brake control in your 1974–1977 Corvette with this direct replacement brake proportioning valve. Responsible for maintaining the correct balance of pressure between the front and rear brakes, this valve ensures predictable stopping under normal and performance driving. Constructed from durable brass for corrosion resistance and long service life.

Features
• Replaces factory proportioning valve for 1974–1977 C3
• Regulates hydraulic brake pressure between front and rear systems
• Ensures safe, stable, and balanced braking under load
• Brass construction resists corrosion and road grime
• Includes pressure differential switch port and valve body only

Dimensions and Weight
• Length: 5-3/8"
• Width: 7/8"
• Height: 2"
• Material: Brass
• Mounting bracket not included

Tech Notes
• Fits 1974–1977 Corvettes with disc brakes
• Mounts directly in stock location
• Use with correct hard brake line routing for leak-free installation
• OE Number: 339780

Because Details Matter
Maintaining safe brake performance is critical on any vintage Corvette. Whether you're refreshing a survivor or rebuilding your brake system from scratch, this replacement proportioning valve restores critical balance between front and rear braking force. For best results, inspect and flush all lines before installation.

Also known under these part numbers: (For reference only)

  • 28980
  • 339780
  • 53328
  • LS232N
Prop 65