A 2-banjo fitting (also called a dual banjo, two-hole banjo, or double banjo fitting) is a hollow flange that mounts with a banjo bolt and splits a single feed into two outlets or combines two inlets into one outlet for brakes, fuel, and hydraulic lines.
Why a 2-banjo (dual-hole) fitting can be the smarter choice for brakes, fuel, and hydraulic lines
Use a 2-banjo to split feed to two hoses cleanly without extra plumbing. It replaces bulky T-fittings and reduces hose clutter around calipers, pumps, and manifolds.
On motorcycles and race cars the package is compact. Two outlets from one mounting point cut clutter, shorten hose runs, and let you route lines tight to the caliper or pump.
For turbo oil feeds and compact hydraulic machines a two-hole banjo can reduce leak points and simplify assembly. Less hardware, fewer unions, fewer failure zones.
Trade-offs exist: splitting flow can change pressure drop and response, and sealing two ports increases sealing complexity versus a single banjo. Evaluate flow needs and sealing quality before switching from a single banjo or a T-fitting.
Inside a 2-banjo assembly: anatomy of the banjo bolt, hollow body, and sealing surfaces
The main parts are the banjo eye (double-port design), the banjo bolt (hollow with cross-drilled passages), the bore and ports machined through the eye, and the crush washers or mating flange that seal the joint.
Fluid enters the banjo bolt, travels through cross-drilled passages, and exits via the two ports in the banjo eye. In some designs sensor or bleed holes are added to the bolt or body for pressure taps or bleeds.
Threads carry clamping force only. The actual fluid seal is between the mating face and the crush washers. Use correctly sized copper, aluminum, or compatible composite washers to form the seal.
Common 2-banjo types, sizes, and configurations you’ll encounter
Expect stacked or side-by-side ports, mirrored inlets for symmetrical routing, and offset two-hole banjos for angled outlet control. Search terms you’ll see include twin banjo and two-hole banjo.
Standard bolt diameters follow metric M-sizes (M8, M10x1, M12) and imperial/UNF equivalents; port bores and hose dash sizes vary by application. Always confirm the bolt thread, banjo bore, and hose dash against OEM specs.
Variants include integrated sensor ports, small bleed screws, or asymmetrical porting to push outlets at specific angles for clearance or hose routing needs.
Material choices and coatings: stainless, brass, aluminum, and corrosion resistance
Choose stainless steel for strength and corrosion resistance in salty or harsh environments. Stainless handles brake fluid, fuel, and oil without significant corrosion.
Brass machines easily and resists corrosion in many fuel and oil applications, but it’s softer than steel. Aluminum saves weight and is common on bikes; use anodized finishes to improve wear and corrosion resistance.
Pay attention to coatings: anodized, plated, or passivated surfaces affect longevity. Match materials to crush washer type to avoid galvanic corrosion between banjo, washer, and hose fitting.
Match material selection to fluid and temperature: DOT brake fluid, engine oil, diesel, gasoline, and hydraulic oils have different chemical and temperature demands.
Thread standards, pitch, and compatibility checks before buying or fitting
Thread form matters: metric (M10x1), UNF/UNE (commonly used on some US bikes), and BSPP appear across vehicles. Banjo bolts commonly use parallel threads rather than tapered pipe threads.
Measure thread pitch with a gauge and diameter with calipers, or verify the OEM part number. Incorrect thread choice risks cross-threading or catastrophic failure.
Avoid adapters that convert to tapered pipe threads for banjo bolt faces — those threads will not seal correctly and increase leak risk.
How to measure and pick the correct 2 banjo fitting for your system
Follow this checklist: bolt diameter and length, banjo bore and port size, hose dash size, mounting clearance, and flange thickness.
Confirm pressure rating and flow needs: check maximum PSI/Bar and operating temperature. Ensure the fitting is rated for brake/ABS systems or high-pressure hydraulics if used in safety-critical lines.
Verify included hardware: count crush washers, verify bolt length and hollow cross-drilling, and confirm any required sealing parts are supplied.
Installation how-to for 2-banjo fittings: orientation, tools, and line routing tips
Pre-fit the banjo without the hose attached to confirm outlet orientation and clearance. Test-fit to the mounting stud and rotate to the correct alignment before final assembly.
Place one crush washer between head and banjo eye and one between banjo eye and mating face. Hand-thread the banjo bolt first to avoid cross-threading, then torque to spec with a calibrated torque wrench.
Route hoses to avoid twist and kinks. Keep lines away from hot exhaust or moving parts, and use proper clamps or guides to prevent chafing.
Finish with a full bleed or pressure test appropriate to the system type before returning to service.
Torque, crush washers, and sealing best practices (what to avoid)
Always follow manufacturer torque specs. Over-torquing flattens crush washers and can strip threads; under-torquing causes leaks. Use a torque wrench and the recommended tightening sequence.
Use new crush washers each time. Washers are single-use and must seat properly to seal. Match washer material to the mating flange and banjo material for best sealing and corrosion performance.
Do not use PTFE tape on banjo faces. Avoid thread sealants that can enter the hydraulic circuit or contaminate brake fluid. Never reuse damaged washers or a corroded banjo eye.
Flow and pressure effects of using a 2-banjo vs single banjo or T-fitting
Splitting flow reduces available flow per outlet and increases pressure drop unless bores are enlarged to compensate. That difference can change pedal feel or actuation speed in brake systems.
For moderate-flow caliper feeds and oil returns the effect is often negligible. For high-flow ABS, racing brakes, or large hydraulics you may need larger bores, higher-capacity hoses, or separate feeds to avoid performance loss.
Consult fluid dynamics charts or a hydraulic specialist if system flow approaches component limits or if you see pressure loss under load.
Typical applications and real-world use cases for 2-banjo fittings
Common uses: motorcycle caliper dual feeds, race car brake systems, turbo oil feed and return lines, and multi-branch hydraulic manifolds in industrial equipment.
Search terms in parts catalogs often include brake line banjo and oil feed banjo. OEM parts may use smaller bores for packaging; aftermarket performance parts often choose stainless or larger-bore dual banjos.
Use two-hole banjos for clean custom plumbing on vintage restorations, motorsports plumbing where space is tight, and compact industrial hydraulic setups.
Troubleshooting leaks, noises, and mechanical failures with dual banjo setups
Start diagnostics with a visual check: look for fluid at the mating face, crushed or missing washers, and damaged threads. Then perform a pressure test or dye check if needed.
Common failures: under/over-torqued bolts, corroded banjo eyes, brittle or flattened washers, and cracked hose ends at the outlet. Replace damaged parts and re-torque to spec.
Short-term fixes like thread sealant are not acceptable for brakes or safety hydraulics. Use temporary containment only to move the vehicle to a repair facility; permanent repair means replacing the assembly and crush washers correctly.
Maintenance, inspection intervals, and service best practices for safety-critical lines
Re-torque checks after the first heat cycles and after the initial service are critical. Replace crush washers any time the banjo is opened.
Suggested intervals: brake inspections at each major service or bleed, race gear checked pre-event, and hydraulic systems pressure-tested periodically per manufacturer guidance.
Keep a log of part numbers, torque values used, replacement dates, and any service findings for traceability and safety audits.
Adapters, retrofit options, and alternatives to a 2-banjo fitting
Common adapters include banjo-to-AN adapters, banjo union blocks, and conversion fittings that change thread or hose type. Search for AN adapter or banjo adapter when mixing standards.
Alternatives when a dual banjo won’t fit: use a compact T-block, inline splitter, or a custom-machined block. Each adds connections and potential leak points, so compare pressure ratings and flow impact.
Retrofit pitfalls: unexpected clearance issues, extra leak points, and mismatched pressure ratings. Always verify retrofit parts meet or exceed the original system’s pressure and temperature specs.
Buying checklist and inspection guide: choosing reliable 2-banjo fittings and vendors
Must-have spec items: exact thread spec (form and pitch), port bore diameter, material, pressure rating, and included hardware (washers and banjo bolt details).
Choose vendors that provide OEM cross-reference numbers, clear spec sheets, and solid customer feedback on leak-free installs. Check warranty and return policy before purchase.
Pay more for precision-machined stainless fittings on brake and high-pressure hydraulic work. Never skimp on items that affect safety, such as correct banjo bolts and authentic crush washers.
Quick-reference glossary and frequently asked questions about 2 banjo fittings
Banjo bolt — hollow bolt that routes fluid through cross-drilled passages; secures the banjo eye to the mating face.
Banjo eye — the hollow flange with ports drilled to supply or collect fluid to/from hose fittings.
Bore — the internal diameter through the banjo eye or bolt that determines flow capacity.
Dash size — hose or fitting size standard used for matching hose to banjo outlet diameter.
Thread pitch — threads per millimeter or inch, e.g., M10x1 or common UNF sizes used on banjo bolts.
AN vs banjo — AN fittings are flare-style threaded fittings; banjos are bolt-mounted hollow flanges. They serve different sealing and routing needs.
FAQ — Can I reuse crush washers? No. Replace crush washers each time the joint is opened; they are single-use and form the primary seal.
FAQ — Is PTFE tape acceptable? No. Do not use PTFE tape on banjo faces or bolt holes where it can contaminate fluid or block cross-drilled passages.
FAQ — How often should I torque-check banjo bolts? Check torque after the first heat cycles or service, then per the system’s maintenance schedule; critical brakes should be checked at each major service.
FAQ — Are banjo fittings from different brands compatible? Only if thread form, pitch, bore, and flange thickness match OEM specs. Do not assume interchangeability without verification.
Three quick signs a banjo joint needs servicing: visible fluid at the flange, a soft or spongy pedal/actuator feel after bleeding, and visible corrosion or deformed washers.
One-minute field leak-test: hand-clean the joint, apply a visible dye or fluid, pressurize the system at idle or hand pump, inspect for seepage at the mating face and threads, and verify no fluid appears on the ground.
