Arwibon Q12PLUS Hydraulic Brake Oiling and Pressure Recovery Guide
If the hydraulic brake lever on your arwibon electric scooter feels soft, has excessive free travel, or can be pulled unusually close to the grip, the brake lever reservoir may need additional mineral oil.
This guide follows the official Arwibon Q12PLUS brake-oiling procedure. The video demonstrates adding mineral oil through the fill port at the brake lever while adjusting the knurled lever screw in stages.
This is a lever-side fluid top-up procedure. If the hydraulic line has been opened, a large amount of air has entered the system, or the brake remains spongy afterward, a complete brake bleed may still be required.
Tools and Materials Needed
- Approximately 2 mm or 2.5 mm Allen wrench
- Mineral hydraulic brake fluid specified for the installed brake system
- Fine-tip oil bottle
- Clean paper towel or lint-free cloth
- Protective gloves
The fluid shown in the official procedure is red mineral brake oil.
Do not substitute DOT brake fluid unless the brake manufacturer specifically specifies a DOT fluid for that installed brake system.
Position the Brake Lever
Step 1: Keep the Lever Reservoir Level
Position the brake lever so the reservoir and fill port sit as level as practical.
Locate the small Allen fill screw on the top of the brake lever reservoir.
Keeping the port facing upward reduces the chance of fluid spilling while the screw is removed.
Remove the Fill-Port Screw
Step 2: Loosen the Small Screw Carefully
Insert the small Allen wrench into the fill screw.
Turn it counterclockwise and remove it slowly.
These screws are small, so keep downward pressure on the wrench to avoid damaging the Allen socket.
Step 3: Check the Seal
Inspect the small sealing ring or O-ring associated with the screw.
Do not lose or damage it.
Place the screw on a clean surface while working.
Add the First Small Amount of Mineral Oil
Step 4: Fill the Opening Slowly
Place the fine tip of the mineral-oil bottle over the fill port.
Add the fluid slowly until the oil reaches the opening.
Do not squeeze the bottle hard or flood the area around the lever.
Keep spilled fluid away from the brake rotor and pads.
Adjust the Knurled Lever Screw
Step 5: Turn the Lever Adjuster Counterclockwise
Locate the knurled thumb adjuster near the brake lever pivot.
The official Q12PLUS video turns this adjuster counterclockwise during the filling procedure.
Make the adjustment gradually while watching the fluid level at the fill port.
In the video, the oil level drops as the lever adjustment is changed.
Do not continue backing the adjuster out until it becomes loose or runs out of usable thread engagement.
Refill the Port
Step 6: Add More Mineral Oil
When the fluid level drops, add another small amount of mineral oil.
Bring the level back toward the top of the fill opening.
Work slowly so you can see whether the level changes.
Repeat the Fill-and-Adjust Cycle
Step 7: Continue in Small Stages
The official procedure repeats the same sequence:
- Add mineral oil.
- Turn the knurled adjuster counterclockwise.
- Watch the oil level drop.
- Add more fluid.
- Repeat as needed.
Do not treat a fixed number of cycles as mandatory.
Continue only while the procedure produces the expected fluid-level change and the adjuster remains securely engaged.
Watch for Air at the Fill Port
Step 8: Allow Small Bubbles to Escape
If small bubbles appear at the fill opening, allow them to rise rather than immediately installing the screw.
Work the lever gently if needed, following the behavior shown in the procedure.
Avoid aggressive pumping that sprays fluid out of the open port.
This lever-side procedure can release small amounts of trapped air near the reservoir, but it should not be treated as a complete hydraulic bleed if air remains farther down the hose or caliper.
Bring the Fluid to the Final Level
Step 9: Add the Final Small Amount
Add enough mineral oil to bring the fill port back to the level shown in the official procedure.
Do not intentionally overfill the reservoir until fluid is running down the lever body.
Once the level remains stable, prepare to reinstall the fill screw.
Reinstall the Fill Screw
Step 10: Start the Screw by Hand
Place the sealing screw back into the fill port.
Start the threads carefully.
Make sure the screw enters straight.
Do not force it if it does not thread easily.
Step 11: Tighten the Screw Securely
Use the Allen wrench to seat the screw.
Tighten it only enough to seal the port securely.
Do not overtighten this small screw.
Excessive force can damage the threads, screw head, or sealing surface.
Clean the Brake Lever
Step 12: Wipe Away Residual Mineral Oil
Use a clean paper towel or lint-free cloth to remove oil around the reservoir.
Clean the lever body thoroughly.
The surface should be dry enough that you can tell whether fresh fluid appears later.
Test the Lever Feel
Step 13: Pull the Lever Several Times
Squeeze and release the brake lever a few times.
Check whether the lever now builds hydraulic pressure more consistently.
You are looking for:
- A firmer lever
- More consistent resistance
- Normal return after release
- No sudden pressure loss
Do not judge the repair by a fixed rule such as the brake having to engage exactly one-third of the way through the lever travel. Lever travel varies with the brake setup, pad position, reach adjustment, and system condition.
Check for Leaks
Step 14: Inspect the Fill Port
After operating the lever several times, look around the fill screw.
There should be no fresh mineral oil around the screw or reservoir.
Also inspect:
- Brake lever body
- Hydraulic hose fitting
- Hose
- Caliper connection
If fluid continues to appear, correct the leak before riding.
Test the Brake at the Wheel
Step 15: Check Actual Braking Operation
Raise the corresponding wheel if practical.
Spin the wheel by hand.
Pull the brake lever.
The wheel should stop firmly.
Release the lever and spin the wheel again.
Make sure the brake releases normally and does not remain applied.
A firmer lever by itself is not enough; the brake must also work correctly at the wheel.
Brake Oiling Procedure Quick Reference
| Stage | Action | Check |
|---|---|---|
| Open reservoir | Remove small fill screw | Protect O-ring/seal |
| First fill | Add mineral oil slowly | Keep port upright |
| Adjust lever | Turn knurled screw counterclockwise | Do not back it out excessively |
| Repeat | Refill as level drops | Work in small stages |
| Final fill | Bring fluid to stable level | Avoid unnecessary overflow |
| Seal | Reinstall fill screw | Tighten securely, not excessively |
| Clean | Wipe lever body | No fluid left around port |
| Test | Pull lever several times | Firm, consistent pressure |
Use the Correct Brake Fluid
The official Q12PLUS procedure uses mineral hydraulic brake fluid.
Do not substitute DOT 3, DOT 4, or DOT 5.1 simply because they are also sold as brake fluids.
Mineral-oil and DOT hydraulic brake systems use different seal and fluid specifications.
Use only the fluid type specified for the brake system actually installed on the scooter.
Keep Brake Fluid Away From the Rotor and Pads
Mineral oil must not reach the brake rotor or brake pads.
Do not work on the fill port with contaminated gloves.
If fluid reaches the rotor, clean it with a suitable brake cleaner or appropriate isopropyl alcohol.
If the brake pads absorb oil, replacement may be necessary.
This Procedure Is Not Always a Complete Bleed
The video demonstrates a simple lever-side oiling procedure.
It is suitable for the condition shown in that service process, but it does not replace a complete hydraulic bleed in every case.
A full bleed should be considered if:
- The lever remains spongy after topping up
- Pressure changes from one pull to the next
- The hydraulic hose has been disconnected
- The caliper or lever has been opened
- A large amount of fluid was lost
- Air can still be felt in the system
Do not keep adding fluid indefinitely if the brake still cannot build normal pressure.
Do Not Use the Reach Adjuster to Hide a Hydraulic Fault
The knurled screw changes the lever position and is also moved during the official filling procedure.
It cannot repair a leaking hose, damaged master cylinder, failed caliper seal, or large amount of trapped air.
If the brake remains soft after the procedure, inspect the hydraulic system rather than continuing to turn the adjuster farther.
