Caliper Bolts / Disc Screws

Banjo Bolt.

The Genuine Porsche Banjo Bolt (Part Number: 90135553101) is an original equipment hydraulic brake system component designed for selected classic Porsche models, including the Porsche 356, early 911 and 914.
Sold Each.
x2 Required Per Car.

Fits:

• Porsche 911 1965-1968 2.0L / 912 SWB (F)
• Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
• Porsche 911 1984-1986 3.2L
• Porsche 911 1987-1989 3.2L G50
• Porsche 356B 1959-63
• Porsche 356C 1963-65
• Porsche 914 (1970-1976)  

Diagram Ref No 27

This specialised hollow bolt is used to secure a banjo-style brake line fitting to the appropriate brake caliper or wheel cylinder. Unlike a conventional solid bolt, it contains an internal passage that allows hydraulic brake fluid to flow through the connection.

Manufactured to Porsche's original equipment specifications, the banjo bolt provides both mechanical fastening and a hydraulic fluid passage within the braking system.

When the driver presses the brake pedal, the master cylinder generates hydraulic pressure that travels through the brake lines to the relevant brake calipers or wheel cylinders.

The banjo bolt allows this pressurised fluid to pass through the connection while holding the banjo fitting securely in position.

When installed with the correct sealing washers and tightened to the specified torque, the assembly helps maintain a leak-free hydraulic connection.

Although a relatively small component, the banjo bolt performs an essential function in the braking system.

Over time, the original bolt may become damaged through corrosion, overtightening, repeated removal, cross-threading or incorrect installation. The internal fluid passage may also become obstructed by contamination.

Damaged threads, distorted sealing surfaces or excessive corrosion can compromise the connection and potentially cause brake fluid leakage.

Loss of hydraulic fluid or pressure can affect braking performance and represents a significant safety concern.

Replacing a damaged or defective banjo bolt with a Genuine Porsche component helps restore secure brake line attachment, maintain hydraulic system integrity and support reliable braking operation.

Ideal for classic Porsche brake repairs, caliper refurbishment, wheel cylinder servicing and restoration projects, this Genuine Porsche Banjo Bolt provides a factory-specified replacement for compatible applications.

What This Product Does:
The banjo bolt is a hollow hydraulic fitting used to connect brake pipework to the appropriate braking component.

Its primary functions are to secure the banjo fitting mechanically and allow pressurised brake fluid to pass through the connection.

When the brake pedal is depressed, hydraulic pressure is generated by the master cylinder and transmitted through the brake fluid.

At the banjo connection, fluid passes through the bolt's internal drilling and into the connected brake caliper or wheel cylinder.

The bolt and its sealing washers must maintain the connection without allowing brake fluid to escape.

Its main functions include:

• Securing the brake line connection: Holds the banjo fitting in position against the connected brake component.
• Allowing brake fluid flow: Provides an internal passage for hydraulic brake fluid.
• Maintaining hydraulic pressure: Helps preserve the sealed brake circuit when correctly installed.
• Supporting braking performance: Allows pressure to reach the relevant brake caliper or wheel cylinder.
• Providing a secure mechanical connection: Maintains the attachment between the banjo fitting and braking component.
• Supporting hydraulic sealing: Works with the specified sealing washers to prevent leakage.
• Withstanding braking pressure: Operates under repeated hydraulic pressure changes.
• Maintaining original brake system configuration: Preserves the factory-style connection arrangement.
• Supporting brake system servicing: Allows damaged or corroded fittings to be replaced.
• Preserving component compatibility: Provides the specified fitting arrangement for compatible original Porsche brake components.

Symptoms Of Wear Or Failure:
A banjo bolt does not normally wear through movement, but it may become damaged through age, corrosion, mechanical stress or incorrect servicing.

Common signs of a damaged or defective banjo bolt include:

• Brake fluid leakage: Fluid may escape around the banjo fitting or bolt connection.
• Wetness around the connection: Visible brake fluid may collect around the caliper or wheel cylinder.
• Falling brake fluid level: A leaking connection may cause the master cylinder reservoir level to decrease.
• Soft or spongy brake pedal: Fluid loss and air entering the hydraulic circuit may affect pedal feel.
• Excessive brake pedal travel: A significant hydraulic fault may result in increased pedal movement.
• Reduced braking effectiveness: Severe fluid loss or pressure loss can compromise braking performance.
• Damaged bolt threads: Stripped or distorted threads may prevent secure installation.
• Cross-threading: Incorrect installation may damage both the bolt and the receiving component.
• Visible corrosion: Rust or surface deterioration may weaken the fitting.
• Pitting around sealing surfaces: Corrosion or damage may prevent the sealing washers from seating correctly.
• Rounded bolt head: Previous servicing damage may make removal or correct tightening difficult.
• Cracked or distorted bolt: Excessive tightening or mechanical damage may compromise the component.
• Blocked internal passage: Contamination may restrict brake fluid flow.
• Persistent leakage after servicing: Incorrect washers, damaged sealing surfaces or improper installation may prevent a reliable seal.
• Inability to tighten correctly: Damaged threads or incorrect bolt dimensions may prevent proper fastening.

Why Replacement Matters:
Replacing a defective banjo bolt is important for maintaining the safety and reliability of the vehicle's hydraulic braking system.

A damaged bolt may no longer provide secure mechanical attachment or a properly sealed passage for brake fluid.

If the connection leaks, hydraulic pressure may be lost and air may enter the system, potentially reducing braking performance.

Continued operation with a damaged banjo bolt may also worsen damage to the associated brake fitting or caliper threads.

Installing a Genuine Porsche replacement Banjo Bolt helps to:

• Restore secure brake line attachment: Replace a damaged or unreliable fastening component.
• Maintain hydraulic system integrity: Support a correctly sealed brake fluid connection.
• Prevent brake fluid leakage: Address leaks caused by a confirmed defective bolt.
• Restore reliable fluid flow: Replace a bolt with a damaged or obstructed internal passage.
• Maintain effective braking: Support proper hydraulic pressure delivery to the connected component.
• Reduce the risk of sudden connection failure: Replace cracked, severely corroded or damaged hardware.
• Prevent further thread damage: Renew damaged fittings before associated components are affected.
• Support brake caliper servicing: Provide an original equipment fitting during caliper repairs.
• Support wheel cylinder refurbishment: Restore the correct connection on compatible drum brake assemblies.
• Maintain original specifications: Preserve Porsche's intended banjo fitting arrangement.
• Support classic Porsche restoration: Replace deteriorated original brake hardware.
• Maintain Genuine Porsche quality: Use an original equipment replacement for a safety-critical component.

Replacement is recommended when the bolt is cracked, severely corroded, cross-threaded, distorted or unable to provide a secure hydraulic connection.

Where leakage originates from the sealing washers rather than the bolt itself, the correct replacement washers may resolve the issue, provided the bolt and mating surfaces remain serviceable.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

90135553101

The product you are viewing cross references to these numbers

Brake Disc Mounting Screw - M6 x 12

Sold each - 2 required per disc

Maintain secure and accurate brake disc installation with this OE Match Brake Disc Mounting Screw 90026904701. Used across a wide range of Porsche models, this small but essential fastening component secures the brake disc (rotor) to the wheel hub during assembly and servicing.

Fits:

• Porsche 911
• Porsche 924S
• Porsche 944
• Porsche 964
• Porsche 993
• Porsche 996
• Porsche 997
• Porsche Boxster 986
• Porsche Boxster 987
• Porsche Cayman

Although the wheel bolts ultimately clamp the brake disc firmly against the hub, the brake disc mounting screw plays an important role in keeping the disc correctly aligned during installation. This ensures accurate positioning of the brake rotor, simplifies wheel and brake servicing and helps prevent movement while the wheel is removed.

Due to repeated exposure to heat, corrosion, moisture and brake servicing, these screws can become seized, damaged or stripped over time. Replacing the mounting screw whenever the brake discs are renewed helps ensure trouble-free future maintenance and correct brake assembly.

What Does a Brake Disc Mounting Screw Do?

The brake disc mounting screw secures the brake disc to the wheel hub before the wheel is fitted.

Its primary functions include:

• Locating the brake disc correctly on the hub
• Maintaining disc alignment during assembly
• Preventing disc movement when the wheel is removed
• Simplifying brake servicing
• Supporting accurate brake disc installation
• Assisting wheel and hub assembly procedures
• Helping maintain factory brake fitment standards

Although small, this component plays an important role in brake system maintenance and assembly.

Why Do Brake Disc Mounting Screws Fail?

Brake mounting screws operate in a harsh environment and are frequently removed during brake servicing.

Common causes of failure include:

• Corrosion and rust
• Heat cycling from braking systems
• Rounded or stripped screw heads
• Seized threads
• Improper removal techniques
• Galvanic corrosion between metals
• Age-related deterioration
• Repeated brake servicing

It is common for original screws to become difficult to remove after years of service.

When Should Brake Disc Mounting Screws Be Replaced?

Brake disc mounting screws should always be inspected during brake maintenance.

Replacement is recommended when:

• Installing new brake discs
• Screw heads become damaged
• Threads show signs of wear
• Corrosion is present
• Screws become seized during removal
• Carrying out brake refurbishment work
• Restoring older Porsche models
• Performing preventative maintenance

Many Porsche specialists routinely replace retaining screws during brake disc replacement to avoid future servicing issues.

Why Replacement Matters

Replacing worn or corroded brake disc mounting screws helps ensure correct brake assembly and easier future maintenance.

Benefits include:

• Secure brake disc location
• Easier brake servicing
• Reduced risk of seized hardware
• Improved assembly accuracy
• Better long-term reliability
• Prevention of damaged hub threads
• Restoration of factory fitment standards
• Professional-quality brake maintenance

A new retaining screw is an inexpensive but worthwhile addition to any brake overhaul.

Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

90026904701

The product you are viewing cross references to these numbers