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Once a master cylinder has been proven bad, the next questions are what to replace it with and how to do the job so the pedal is right afterward. Route 66 Auto Repair in Upland replaces brake master cylinders on cars, trucks and fleet vehicles, bench bleeds the new unit before it goes in, and bleeds the whole system, including the ABS unit when your model requires it. Every choice is on your written estimate.
New or remanufactured: which should you choose?
A new master cylinder is built from new castings and seals. A remanufactured unit uses a cleaned original body with new internal parts. Both can work well.
For an older truck, a quality new unit may be the only choice. We tell you what we can get and what warranty is written on the invoice for each option. Customer-supplied parts are inspected, but carry no warranty on the part, and labor is charged at book time.
Why bench bleed before installing?
A new master cylinder is dry inside. Bench bleeding fills it with fluid and pushes the air out while it sits level in a vise. Skipping this step traps air in the bore that is very hard to remove once it is on the car.
Our master cylinder replacement process
Step 1: Confirm the diagnosis
We review the test that proved the old unit failed, as described on our master cylinder diagnosis page.
Step 2: Protect the paint
Brake fluid strips paint, so fenders and the firewall are covered before lines are opened.
Step 3: Bench bleed
The new unit is filled and bled level before it is mounted.
Step 4: Install and connect
Lines are started by hand to avoid cross-threading, then torqued.
Step 5: Bleed the system
All four wheels are bled in the maker's order, with a scan tool used to cycle the ABS unit when required.
Step 6: Verify
Pedal height, hold test and a road test confirm the result.
What's included in brake master cylinder replacement
Included on the work order
- 01Written choice of new or remanufactured unit
- 02Bench bleeding before installation
- 03Reservoir and sensor transferred or replaced
- 04Fresh fluid of the type your vehicle specifies
- 05Four-wheel bleed, plus ABS cycling where required
- 06Pedal hold test and road test
Need-now or need-later?
Need now: call
- A confirmed internal bypass or external leak
- Fluid leaking into the brake booster
Need later: book
- A reservoir sensor that reads falsely but a healthy cylinder
- An old but sound unit you want replaced before a road trip
What affects the price?
Part choice, access and bleeding are the three big factors. Some sit behind other parts. ABS bleeding with a scan tool adds time on many late models. For fleets, we put unit numbers on invoices and can line the job up with A/B/C preventive maintenance intervals; see our page for fleet managers. AAA members save 10% on parts and labor, up to $75.
Aftercare
The pedal should be high and firm from the first stop. A small drop in reservoir level over the first days can happen as the last air works out, so check it once or twice. If the pedal feels different a week later, come back first, since comebacks go to the front of the line. It is a good time to plan a brake fluid flush schedule.
Frequently asked questions
How long does a master cylinder replacement take?
It depends on access and whether the ABS unit needs a scan tool bleed. Many are done the same day when the board allows. We give you a time window when you approve the estimate and text you if it slips.
Do I need a brake fluid flush with a new master cylinder?
Old fluid carries moisture and grit that can shorten the life of new seals. We usually recommend replacing the fluid during the bleed, and the estimate shows it as its own line.
Can you rebuild my original master cylinder?
Kits are scarce for modern units and worn bores cannot be reused, so we normally quote a new or remanufactured unit.