Left Hydraulic Brake Fluid Reservoir

The OIL TANK [LEFT] is a replacement hydraulic brake fluid reservoir tank assembly designed for electric scooters, e-bikes, mopeds, and light electric vehicles (LEVs). Installed on the left handlebar master cylinder assembly (typically supplying the rear or combined hydraulic disc brake system), it securely holds and feeds DOT brake fluid directly into the hydraulic piston bore.

Constructed from impact-resistant, chemical-grade translucent thermoplastic with a weather-sealed rubber gasket and screw-top diaphragm lid, this left-side reservoir prevents fluid contamination and pressure leaks. Operating independently across 12V to 60V DC vehicle architectures, its clear level indicator enables quick fluid checks to prevent air from entering the hydraulic braking system.

Key Features

• Left-Side Master Cylinder Configuration: Form-fitted specifically for left-hand hydraulic master cylinder perches.
• Translucent Reservoir Body: Transparent fluid tank wall allows quick visual inspection of DOT brake fluid level and fluid purity.
• Hermetic Rubber Gasket Seal: Heavy-duty internal rubber diaphragm prevents fluid weeping, air ingress, and moisture contamination.
• Chemical & Heat-Resistant Thermoplastic: Engineered to withstand aggressive DOT3/DOT4 brake fluids, UV exposure, and ambient heat.
• Direct Drop-In Replacement: Standardized mounting tabs and feed port allow simple mounting onto OEM master cylinder bodies.

1x OIL TANK [LEFT] Assembly (translucent tank body, internal rubber diaphragm gasket, and top cap)

Suitable Vehicle Types & Applications

Electric Scooters & Mopeds: Primary left-side hydraulic brake fluid reservoir replacement for 48V–60V e-scooters.

E-Bikes & Light LEVs: Durable brake fluid oil tank for electric bicycles and cargo LEVs using left hydraulic disc setups.

Personal & Fleet Repairs: Essential repair component for cracked, leaking, or discolored left master cylinder oil tanks.

System & Electrical Compatibility

Universal Hydraulic Master Cylinders: Compatible with standard DOT3/DOT4 left-hand hydraulic disc brake master cylinder perches.

Wide EV Sub-Circuits: Operates independently of electrical system voltage across 12V to 60V DC vehicle platforms.

1. Isolate Power & Drain Reservoir Fluid:

Turn off key ignition, trip the main DC circuit breaker, and place a protective cloth around the left handlebar. Syringe out or drain remaining brake fluid from the old left reservoir.

Verification: The old oil tank is completely emptied and no live power is present on the vehicle.

2. Remove Damaged Oil Tank & Clean Base Port:

Unscrew the retaining fastners securing the old oil tank to the left master cylinder body and detach it. Wipe the mounting base and feed port clean using a lint-free cloth and brake cleaner.

Verification: The master cylinder intake port is completely clear of dirt, plastic fragments, or old seal residue.

3. Mount New Left Oil Tank & Internal Seal:

Position the new OIL TANK [LEFT] onto the master cylinder body, ensuring the rubber sealing gasket sits completely flush in the mounting recess, and tighten retaining screws evenly.

Verification: The reservoir sits firmly against the master cylinder base with zero gap or seal pinch.

4. Fill DOT Fluid, Bleed Air & Check Seals:

Fill the new oil tank with fresh DOT3 or DOT4 brake fluid up to the MAX fill line. Open the caliper bleed nipple and pump the left brake lever until all trapped air bubbles escape, then secure the diaphragm cap.

Verification: Squeezing the left brake lever yields firm resistance with no fluid weeping around the reservoir base or cap.

Power Isolation: Always turn off the ignition, trip the main DC circuit breaker, and secure the vehicle before performing hydraulic brake maintenance.

Fluid Level Monitoring: Periodically inspect the translucent tank wall to ensure fluid remains between the MIN and MAX indicators.

Contamination Prevention: Keep the top cap tightly screwed on; never mix DOT fluid types or allow dirt and water to enter the reservoir.