Banjo Bolt and Fitting
Representative Photo, actual item may vary
RADIUM Engineering 20-0409 10AN Male Swivel Banjo Press-Fit Fitting for Toyota 2JZ Exhaust
RADIUM Engineering 20-0609 10AN Male Swivel Press-Fit Exhaust Fitting for Toyota 1JZ Non VVT-i
Representative Photo, actual item may vary
Representative Photo, actual item may vary
What Are Banjo Bolts and Fittings?
Banjo bolts and fittings are among the most cleverly engineered fasteners in automotive and motorsport plumbing. Banjo fittings take their name from their shape — a large circular union connected to a narrower pipe, bearing a resemblance to the stringed instrument. But the real genius is in how they work: a banjo bolt is a hollow, internally relieved fastener that simultaneously anchors a fluid line to a component and serves as the actual conduit for fluid flow. That dual role — mechanical fastener and fluid passage — makes the banjo bolt one of the most space-efficient connectors in any hydraulic or fuel system.
Where Banjo Bolts Are Used
The most common application is in brake systems, where banjo fittings connect flexible brake lines to calipers, wheel cylinders, and master cylinders, ensuring efficient transfer of hydraulic pressure. Beyond brakes, these fittings appear throughout modern vehicles in fuel delivery systems (connecting fuel lines to injectors and fuel rails), clutch hydraulics, turbocharger oil feeds, and power steering systems. Their compact, low-profile design makes them especially valuable wherever fluid lines must route through tight, confined spaces — such as around suspension components or close to the firewall.
A complete banjo fitting assembly consists of three core components: the banjo bolt itself, the banjo body (the round eyelet that connects to the hose or line), and sealing washers — typically copper or aluminum crush washers — placed on each side of the banjo body. When the bolt is torqued down, the crush washers deform slightly to create a reliable, leak-resistant seal. Proper washer condition and correct torque are critical: worn or reused crush washers are a leading cause of fluid leaks in brake and fuel systems.
Key Considerations When Buying Banjo Bolts and Fittings
- Thread size and pitch: Banjo bolts come in a wide range of metric and SAE thread sizes. Always match the thread specification to your caliper, master cylinder, or component port exactly.
- Banjo body diameter: The eyelet must match the outer diameter compatible with your brake hose or line end.
- Material: Aluminum fittings are lightweight and popular for performance builds; stainless steel offers superior corrosion resistance for harsh environments.
- Single-hole vs. double-hole: Standard single-hole banjo bolts handle one fluid line; double-hole variants allow two lines to share a single port, useful in dual-circuit or performance brake setups.
- Sealing washers: Always replace crush washers when reinstalling or servicing banjo bolt connections — never reuse old washers.
Top Brands in Banjo Bolts & Fittings
RADIUM Engineering is a go-to choice for performance and motorsport builders who demand precision-machined fittings. Their swivel banjo fittings feature 360-degree rotation even after installation, making routing and alignment in tight engine bays significantly easier. Constructed from anodized 6061 aluminum and compatible with high-pressure fuel, oil, and coolant systems, RADIUM fittings are engineered for demanding builds where off-the-shelf solutions fall short.
Earl's Performance is a legendary name in automotive plumbing, and their banjo bolt lineup reflects decades of race-proven engineering. Earl's banjo bolts are designed to interface specifically with their Hyperfirm brake hose system, connecting performance brake lines to stock calipers and wheel cylinders in a wide variety of configurations — available in aluminum and stainless steel to suit both street and competition applications.
Arlen Ness brings a motorcycle-centric perspective to banjo fittings, with offerings tailored for custom and performance V-twin applications where both function and aesthetic matter. Their fittings are popular among builders who want clean, finished-looking brake line connections on custom motorcycles.
Edelbrock, renowned for intake manifolds and carburetor performance, also offers banjo bolt solutions compatible with their carburetor and fuel system components — a natural fit for classic and muscle car enthusiasts building out complete fuel delivery systems.