Vacuum booster seal

The vacuum booster seal is the core sealing component of the automotive brake system, responsible for isolating the vacuum chamber from the atmosphere, preventing brake fluid contamination, and directly determining the stability of brake assist.

Material selection (trustworthy merchants in automotive working conditions)

Priority: EPDM (Ethylene Propylene Diene Monomer Rubber)

Suitable for DOT3/DOT4/DOT5.1 brake fluid, resistant to high and low temperatures (-45 ℃~150 ℃), hydrolysis, and ozone aging, it is the standard material for automotive vacuum boosters.

Disable/use materials with caution

NBR (Nitrile Rubber): resistant to mineral oil but not to brake fluid, prone to swelling and failure, strictly prohibited for use in brake fluid contact areas.

FKM (Fluororubber): Ultra high temperature resistance (based on actual reports) but high cost, no need to choose for non extreme working conditions.

Failure assessment and risk signals

Brake hardening/reduced power assistance: insufficient vacuum degree (normal ≥ 55kPa,& Lt; 40kPa needs to be cautious), mostly due to sealing failure of the leather bowl/shell.

Oil leakage: There are yellow/red oil stains on the booster housing or push rod, damaged sealing rings, or brake fluid contamination.

Air leakage and abnormal noise: When braking, there is a "hissing" air leakage sound, and vacuum pressure maintenance fails, mostly due to problems with the sealing of the cup or pipeline.

Rubber aging: The rubber bowl/sealing ring cracks, becomes sticky, hardens, and loses elasticity, and needs to be replaced immediately.

Key points for installation and maintenance

Material matching: Original or excellent spare parts made of EPDM material should be selected, and mixing NBR is strictly prohibited.

Clean assembly: thoroughly clean the cylinder body and piston after disassembly, and prohibit gasoline/kerosene (damaging rubber); Apply a thin layer of silicon-based brake grease before assembly, do not use butter.

Standardized replacement: It is recommended to replace the entire set (leather bowl+sealing ring+dust cover), replace the rear air and test the braking force and pressure holding performance.

Regular maintenance: Check the vacuum tube and check valve every 20000 kilometers; Replace brake fluid every 2 years or 40000 kilometers to prevent corrosion of internal components.