When Break-In Is Required
- Determine when the break-in procedure is required based on component replacement history.
- Identify the specific brake components that must be seated during the break-in period.
- Recognize the effect of the break-in process on lining wear rates.
- Brake lining thickness gauge — Measure the wear rate of lining material during the seating process.
- Infrared thermometer — Monitor drum temperatures during the seating of electro-magnets and linings.
- Brake adjustment tool — Ensure proper shoe-to-drum clearance before beginning the break-in procedure.
Break-in applies to new axles and any time new brake shoes and/or magnets are installed.
It seats both the lining material and the electro-magnets. Linings wear faster during break-in.
How It Works
Mandatory Seating Requirement
Break-in is a mandatory procedure applied to all new axles. The process ensures that the friction surfaces of the brake system are properly mated for optimal performance.
Component Mating
The procedure is designed to seat both the brake lining material and the electro-magnets. Proper seating allows these components to achieve full contact with the drum surfaces.
Initial Wear Rates
Technicians must account for accelerated wear during the initial use phase. Brake linings wear at a faster rate during the break-in period compared to their normal service life.
Diagnostic Chart
| Symptom | Check | Spec / Expected | Likely cause & fix |
|---|---|---|---|
| New brake shoes failing to provide full stopping power. | Verify if the break-in procedure has been performed since installation. | Per the applicable manual | The lining material has not yet been seated to the drum surface. Basis: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019) |
| Inconsistent magnet engagement on a new axle. | Inspect the electro-magnet surface for seating witness marks. | Per the applicable manual | The electro-magnets require a break-in period to seat properly. Basis: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019) |
| Accelerated lining wear noted immediately after axle replacement. | Compare current wear to standard service intervals. | Linings wear faster during break-in. | Normal behavior during the initial seating phase of new lining material. Basis: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019) |
At the Bay: Diagnose the Case
CASE 1 / 3
New brake shoes failing to provide full stopping power.
- Test
- Compare
- Correct
Select the next check
Basis: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019). A likely cause is a hypothesis; confirm it with the applicable service procedure before repair.
Common Bay Mistakes
- ✕ Assuming break-in is only for shoes and not magnets.
- ✕ Neglecting break-in after installing only magnets.
- ✕ Expecting standard wear rates during the first several miles of use.
- ✕ Skipping the procedure on new axles arriving from the factory.
- ✕ Failing to perform break-in after replacing only the brake shoes.
Quick Check
Practice only — not scored.
Hands-on: Test Bench Practice
Symptom: Healthy trailer. Learn what good readings look like.
Tap a point to place the red probe.
Good system: ~12.6 V at pins, 3.2 Ω across a 12×2-inch magnet (unplugged), 3.0 A per magnet at 12 V full gain, and at least 10.5 V at the magnet — the chart values from the axle manuals.
Hands-on: Shop Test Equipment
IPA #9107B Electric Brake Force Meter
Plugs into the truck's 7-way socket on a 25 ft cable; simulates a trailer load and shows controller output on 10 blue LEDs
🛠 Equip your bay for this test →Symptom: Customer wants the truck checked before buying a trailer.
Spec limits used
- 1–10, each 1.0–1.5 V — Gain LEDs (IPA #9107B manual, p.5)
- 15 s — Max time holding brake pedal (IPA #9107B manual, p.4)
- set-up step 5 — Connect the 9-pin only after the engine is running (IPA #9107B manual, p.3)
- hold brake pedal during ECU detection — 2016–2017 'Trailer Connected' not shown (IPA #9107B manual, p.3)
- faulty brake control module or relay — ECU light never lights on a vehicle with a controller (IPA #9107B manual, p.5)
Simulated readings for practice. Always follow the manufacturer's procedure and values on a real trailer.
Source: Lippert TI-086 Electric Drum Brake Break-In Period (Rev 08.13.2019) — 1