Genuine BMW Brake Master Cylinder Reservoir Grommet – NOS – 34311121911

Genuine BMW New Old Stock sealing grommet for the brake-fluid reservoir connections on selected classic BMW brake master cylinders.

This rubber grommet is installed in the inlet opening of the brake master cylinder and seals the connection between the master cylinder and the brake-fluid reservoir connector or supply fitting.

A hardened, cracked or incorrectly sized grommet can cause brake-fluid leakage around the reservoir connection. Genuine BMW rubber components are particularly desirable when restoring an original ATE braking system.

This listing is for one grommet only. Many compatible master cylinders require two grommets, but the required quantity must be verified for the specific installation.

Product details

• Product: Brake-fluid reservoir sealing grommet
• Alternative description: Brake master cylinder reservoir grommet
• BMW catalogue description: Plug
• German description: Stopfen
• Manufacturer: Genuine BMW
• BMW part number: 34311121911
• Formatted BMW number: 34 31 1 121 911
• Short reference number: 1121911
• BMW size specification: 22/8
• Approximate outside diameter: 22 mm
• Approximate internal opening: 7.3–8 mm
• Installation position: Brake master cylinder reservoir inlet
• Material: Brake-fluid-resistant rubber
• Condition: New Old Stock
• Quantity supplied: One grommet
• Price: Per piece

Vehicle compatibility

Suitable for selected classic BMW models equipped with the corresponding brake master cylinder and reservoir connections, including:

BMW 02 Series / E10

• BMW 1502
• BMW 1602
• BMW 1802
• BMW 2002
• BMW 2002 ti
• BMW 2002 tii
• BMW 2002 Turbo

BMW Neue Klasse

• BMW 1500
• BMW 1600
• BMW 1800
• BMW 2000
• BMW 2000 C
• BMW 2000 CS
• Selected additional Neue Klasse versions with the corresponding master cylinder

BMW E3

• BMW 2500
• BMW 2800
• BMW 2800 Bavaria
• BMW 3.0 S
• BMW 3.0 Si
• Selected additional E3 versions with the corresponding master cylinder

BMW E9

• BMW 2.5 CS
• BMW 2800 CS
• BMW 3.0 CS
• BMW 3.0 CSi
• BMW 3.0 CSL

BMW E12

• BMW 518
• BMW 520
• BMW 525
• BMW 528
• BMW 528i
• BMW 530i
• Selected early E12 versions with the corresponding master cylinder

BMW E24

• BMW 630 CS
• BMW 630 CSi
• BMW 633 CSi
• Selected early E24 versions with the corresponding brake master cylinder

Compatibility depends on the installed brake master cylinder, production date and market specification.

BMW used several master-cylinder and reservoir arrangements with different grommet dimensions. Always verify the BMW part number, the master-cylinder inlet diameter and the reservoir connector size before ordering.

BMW and reference numbers

• 34311121911 – Genuine BMW brake reservoir grommet
• 34 31 1 121 911 – Formatted BMW catalogue number
• 1121911 – Short BMW reference number
• ATE 390088 – Aftermarket/OE manufacturer reference
• ATE 03.3304-1400.1 – ATE reference number
• 34321102282 – Associated brake-fluid reservoir connector; not included
• 34314650172 – Associated washer used in selected installations; not included

The BMW catalogue identifies this grommet by the nominal dimension 22/8.

Condition

Genuine BMW New Old Stock component that has never been installed.

Due to its age and long-term storage, the following may be present:

• Ageing and wear to the original BMW packaging
• Storage dust and cosmetic marks
• White surface residue or rubber bloom
• Light surface discolouration
• Age-related hardening or changes to the rubber

Because this is an older safety-critical brake-system component, the rubber must be carefully checked for flexibility, cracks, deformation and deterioration before installation.

Supplied exactly as shown in the photographs.

Included

• One genuine BMW brake master cylinder reservoir grommet
• Original BMW packaging shown in the photographs

The brake master cylinder, brake-fluid reservoir, connecting fittings, washers, brake fluid and additional grommets are not included.

Important quantity information

This listing is for one grommet only.

Many compatible brake master cylinders use two identical grommets, one for each brake-fluid reservoir connection. Certain configurations may use a different quantity or a combination of different grommet sizes.

Always inspect the installed master cylinder before ordering. The stated price is per piece.

Installation recommendation

Before installation:

• Confirm that the master cylinder requires the BMW 22/8 grommet
• Check the NOS rubber for cracks, hardening or deformation
• Inspect the reservoir connectors for cracks or damage
• Thoroughly clean the master-cylinder inlet openings
• Remove all remnants of the old grommets
• Lubricate only with clean brake fluid or a brake-system-compatible assembly product
• Do not use mineral oil, grease or petroleum-based lubricants
• Make sure the reservoir connectors are fully and evenly seated
• Refill the reservoir with the correct brake fluid
• Bleed the braking system when required
• Carefully inspect all connections for brake-fluid leakage
• Test correct brake operation before driving

Installation should be performed by a qualified automotive technician. Brake-fluid leakage can result in reduced braking performance or complete brake-system failure.

Storage location: 202