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DormanPart #: M39434
Dorman M39434 Brake Master Cylinder
⚙️ 108 vehicles fit this part
Select your vehicle to confirm fitment
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✅OE Direct Replacement — Bolt-on fit, no modifications needed
🚗Fitment: Chevrolet and GMC, C10 Suburban, C1500 Suburban, C20, C20 Suburban, C2500, C2500 Suburban, C30, G30, K10 Suburban, K1500 Suburban, K20, K20 Suburban, K2500, K2500 Suburban, P20, P2500, P30, and P3500
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Reliable Brake Master Cylinder for Chevrolet and GMC Trucks
The Dorman M39434 brake master cylinder is engineered to restore proper brake hydraulics in select Chevrolet and GMC truck models. Designed with a durable cast iron construction and a 1.25-inch bore diameter, this master cylinder ensures consistent brake fluid pressure for safe stopping performance.
- Master cylinder bore diameter: 1.25 inches for precise hydraulic control
- Constructed from cast iron for long-lasting durability
- Includes reservoir for brake fluid storage
- Two outlet ports with rearward outlet size 1/2-20 and secondary outlet thread diameter 9/16-18
- Compatible with multiple Chevrolet and GMC truck models including C10 Suburban, C20, K20, and P30
Product Details and Specifications
The Dorman M39434 brake master cylinder is designed specifically for brake hydraulics systems requiring a 1.25-inch bore diameter. Its cast iron material provides strength and resistance to wear, making it suitable for heavy-duty applications. The included reservoir allows for proper brake fluid containment, while the two outlets facilitate connection to the brake lines. The rearward outlet size measures 1/2-20, and the secondary outlet thread diameter is 9/16-18, ensuring compatibility with factory brake line fittings.
Compatible Chevrolet and GMC Models
This brake master cylinder is compatible with a range of Chevrolet and GMC trucks, including:
- Chevrolet C10 Suburban, C20, C20 Suburban, C30
- Chevrolet C1500 Suburban, C2500, C2500 Suburban
- GMC G30, K10 Suburban, K20, K20 Suburban
- GMC K1500 Suburban, K2500, K2500 Suburban
- Chevrolet and GMC P20, P30, P2500, P3500
Common Brake System Issues Addressed
- Loss of brake fluid pressure causing spongy brake pedal feel
- Brake fluid leaks from a worn or damaged master cylinder
- Inconsistent braking performance or delayed brake response
- Brake warning light activation due to hydraulic failure
- Brake pedal sinking or failure to maintain pressure
Installation Notes and Tips
When installing the Dorman M39434 brake master cylinder, ensure the brake system is properly bled to remove air and maintain hydraulic integrity. Verify that the outlet thread sizes (1/2-20 rearward and 9/16-18 secondary) match your vehicle’s brake lines. Since mounting hardware is not included, retain original hardware or source compatible fasteners. Always follow manufacturer torque specifications and safety procedures during installation.
Quality Assurance and Warranty
Dorman brake master cylinders are manufactured to meet or exceed OEM standards for fit, form, and function. The M39434 part number undergoes rigorous quality control to ensure reliable brake system performance. Please refer to Dorman’s warranty policy for coverage details on this brake master cylinder.
| Brand | Dorman |
| Part Number | M39434 |
| Mounting Hardware Included | No |
| Master Cylinder Bore Diameter | 1.25 |
| Master Cylinder Material | Cast iron |
| Reservoir Included | Yes |
| Sensor Included | No |
| Number of Outlets | 2 |
| Package Contents | Master cylinder |
| Rearward Outlet Size | 1/2-20 |
| Secondary Outlet Thread Diameter | 9/16-18 |
This part fits 108 vehicles. Search below:
| Year | Make | Model | Fuel Type | Position | Notes |
|---|---|---|---|---|---|
| 1992 | Chevrolet | P30 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1992 | GMC | P3500 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1991 | Chevrolet | P30 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1991 | GMC | P3500 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1990 | Chevrolet | P30 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1990 | GMC | P3500 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1989 | Chevrolet | P20 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1989 | Chevrolet | P30 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1989 | GMC | P2500 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1989 | GMC | P3500 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1988 | Chevrolet | P20 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1988 | Chevrolet | P30 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1988 | GMC | P2500 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1988 | GMC | P3500 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1987 | Chevrolet | P20 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1987 | Chevrolet | P30 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1987 | GMC | P2500 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1987 | GMC | P3500 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1986 | Chevrolet | P20 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1986 | Chevrolet | P30 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1986 | GMC | P2500 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1986 | GMC | P3500 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1985 | Chevrolet | P20 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1985 | Chevrolet | P30 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1985 | GMC | P2500 | DIESEL | N/A | Bore: 1.125 In.; 13 In. x 2.50 In. Brakes |
| 1985 | GMC | P3500 | DIESEL | N/A | 8,200 Lb. GVW; Bore: 1.25 In.; wo/Motorhome Chassis |
| 1984 | Chevrolet | G30 | N/A | For vehicles with Single Rear Wheel (SRW), the brake master cylinder bore size is 1.25 inches. | |
| 1984 | Chevrolet | P20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1984 | Chevrolet | P30 | N/A | For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis. | |
| 1984 | GMC | G3500 | N/A | For vehicles with Single Rear Wheel (SRW), the brake master cylinder bore size is 1.25 inches. | |
| 1984 | GMC | P2500 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1984 | GMC | P3500 | N/A | For vehicles with a GVW of 7,600 to 8,200 lbs, with a bore size of 1.25 inches, excluding Motorhome Chassis. | |
| 1983 | Chevrolet | G30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1983 | Chevrolet | P20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1983 | Chevrolet | P30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1983 | GMC | G3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1983 | GMC | P2500 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1983 | GMC | P3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1982 | Chevrolet | G30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1982 | Chevrolet | P20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1982 | Chevrolet | P30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1982 | GMC | G3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1982 | GMC | P2500 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1982 | GMC | P3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1981 | Chevrolet | G30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1981 | Chevrolet | P20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1981 | Chevrolet | P30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1981 | GMC | G3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1981 | GMC | P2500 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1981 | GMC | P3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | C10 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | C20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | C20 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | G30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | K10 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | K20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | K20 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | P20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | Chevrolet | P30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1980 | GMC | C1500 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | GMC | C2500 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | GMC | G3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1980 | GMC | K1500 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | GMC | K2500 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | GMC | K2500 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | GMC | P2500 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1980 | GMC | P3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | C10 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | C20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | C20 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | C30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | G30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | K10 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | K20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | K20 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | P20 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | Chevrolet | P30 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | C1500 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | C2500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | C2500 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | G3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | K1500 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | K2500 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | K2500 Suburban | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | P2500 | N/A | 13 In. Brakes; Stamped-18010746 | |
| 1979 | GMC | P3500 | N/A | 13 In. x 2.50 In. Brakes; Stamped-18010746 | |
| 1978 | Chevrolet | C10 Suburban | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1978 | Chevrolet | C20 | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1978 | Chevrolet | C20 Suburban | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1978 | Chevrolet | C30 | N/A | Fits 13"x2.50" Drum Brakes | |
| 1978 | Chevrolet | G30 | N/A | Fits 13"x2.50" Drum Brakes | |
| 1978 | Chevrolet | K10 Suburban | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1978 | Chevrolet | K20 | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1978 | Chevrolet | K20 Suburban | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1978 | Chevrolet | P20 | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1978 | Chevrolet | P30 | N/A | Fits 13"x2.50" Drum Brakes | |
| 1978 | GMC | G35 | N/A | Fits 13"x2.50" Drum Brakes | |
| 1977 | Chevrolet | C10 Suburban | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1977 | Chevrolet | C20 | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1977 | Chevrolet | C20 Suburban | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1977 | Chevrolet | C30 | N/A | Fits 13"x2.50" Drum Brakes | |
| 1977 | Chevrolet | G30 | N/A | Fits 13"x2.50" Drum Brakes | |
| 1977 | Chevrolet | K10 Suburban | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1977 | Chevrolet | K20 | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1977 | Chevrolet | K20 Suburban | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1977 | Chevrolet | P20 | N/A | Fitment: Compatible with 13-inch brakes. | |
| 1977 | Chevrolet | P30 | N/A | Fits 13"x2.50" Drum Brakes | |
| 1977 | GMC | G35 | N/A | Fits 13"x2.50" Drum Brakes |
* Always verify fitment with your vehicle's VIN if unsure. Submodel & trim restrictions may apply.
This part directly replaces or is cross-referenced with the following part numbers:
10-205913-2059130.66008174-598180107462539434F101268M900429MC251930
Cross-reference numbers are provided for identification purposes only. Always confirm fitment before ordering.