Turn pedal effort into hydraulic brake pressure with the Dorman First Stop Brake Master Cylinder M39366, a new CJ7 master cylinder built as a direct-fit replacement for the 1978-1986 Jeep CJ7, 1978-1983 Jeep CJ5 and 1981-1985 Jeep Scrambler with all engines. Dorman precision-engineers this unit to match the design, function and performance of the original master cylinder. It is built from new, high-quality materials for a safe, durable replacement.
Specifications: 1 in bore diameter, two outlets and a 1/2-20 rearward outlet. The reservoir is included. Mounting hardware and a sensor are not included, so consult the vehicle service information for the correct fasteners and whether the originals may be reused. Country of origin: China.
Signs a master cylinder may need replacing include a soft or sinking brake pedal and brake fluid leaking at the cylinder or reservoir. Other brake components can cause the same symptoms, so diagnose the cause before replacing. After installation, bleed the brake system as directed by the service procedure.
Interchange: 83-40007 · 100-2660 · M-87007 · 13-1776 · 10-1776 · 130.67007 · 130.67015 · 131.67007 · 131.67015 · 355-42024 · 355-42028
8340007 · 1002660 · M87007 · 131776 · 101776 · 13067007 · 13067015 · 13167007 · 13167015 · 35542024 · 35542028 · 18M194 · M900393 · M900394 · 11776 · 5358746 · 5359745 · 8133921 · 8983500995 · MC250820 · 105872 · M1776 · NM1776 · MC39365 · MC39366 · F105872 · MC105872
This part cross-references / interchanges with the following part numbers:
Is this a 1978-1986 Jeep CJ7 brake master cylinder?
Yes. Dorman M39366 is listed as a direct-fit replacement for the 1978-1986 Jeep CJ7 with all engines. Check the Buyer's Guide tab to confirm your vehicle.
Can I use it as a 1978-1983 Jeep CJ5 master cylinder?
Yes. It is listed for the 1978-1983 Jeep CJ5, and it also fits the 1981-1985 Jeep Scrambler.
What are the key specs of the M39366?
It has a cast iron housing, a 1 in bore diameter, two outlets and a 1/2-20 rearward outlet. Its rubber components use an EPDM compound that resists glycol-based brake fluid.
What comes in the box?
The package contains the master cylinder, and the reservoir is included. Mounting hardware and a sensor are not included.
What are signs my master cylinder may need replacing?
A soft or sinking brake pedal or fluid leaking at the cylinder can be signs of a failing master cylinder, though other brake parts can cause similar symptoms. Diagnose the cause before replacing, and bleed the brakes after installation.
WARNING: These products can expose you to chemicals including lead and phthalates, which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.
