MMEG.
CATALOG / rotor-service
Template · rotor-service

ROTOR SERVICE

Inspect, true, or replace a disc rotor. Caliper is removed first (full access to rotor), inspected, then either true-in-place or full replacement, then caliper goes back on and re-aligns. Disc brakes only.

62 steps|~30 min|1 cited sources|intake-gated|safety_ref: atom:universal-safety
Intake: answers gate which atoms compose
brake-type
Brake type (rotor service applies to disc brakes only). Vehicle context is captured separately at ticket intake.
hydraulic-discmechanical-disc
rotor-work
What rotor work is needed?
truereplace
rotor-mount
Rotor mount style (only asked if rotor-work=replace — confirm at the hub)
six-boltcenterlock
Composed steps · 10 atoms in order
atom:intake-consult2 steps
01intake-consult/IC.1
Listen to the customer describe the problem, then ask clarifying questions to confirm the symptom, when it happens, and what changed recently
captureWhat did the customer report, in their words?
captureWhat clarifying questions did you ask, and how did they answer?
NOTENOTE
02intake-consult/IC.2
Set expectations before work begins: the scope of the planned work, what is not included, and the likely outcome
captureWhat scope and expectations did you set with the customer?
NOTE
atom:bay-readiness2 steps
03bay-readiness/BR.1
Clear and stage the work area: bench clear, vehicle secured on the stand, fire-safe location for any battery work
captureWork area clear and the vehicle secured?
capturePhotograph the staged work area.
PASS / FAILPHOTO
04bay-readiness/BR.2
Select and stage the correct tools for the planned job, and put on the PPE the work requires (gloves, eye protection)
captureCorrect tools staged for this job?
capturePPE on for the work being done?
PASS / FAILPASS / FAIL
atom:power-down-and-photo1 step
05power-down-and-photo/1
Power down + photograph cable routing
captureVehicle powered down?
captureSnap a photo of the cable routing.
PASS / FAILPHOTO
atom:caliper-remove1 step
06caliper-remove/CR.1
Identify brake type and execute the matching removal branch
captureBrake type identified and confirmed?
branch on brake-type
Caliper removal — branch by brake type
HYDRAULIC DISC — REMOVEhydraulic-dischydraulicbrake-type:hydraulic-disc-remove
brake.hd.r1Insert pad spacer / bleed block BEFORE removing the rotor or caliper
capturePad spacer or bleed block inserted before pulling the rotor?
criticalSqueezing the lever with the rotor out closes the pads onto nothing — recovery may need a bleed
brake.hd.r2Unbolt caliper from frame/fork (2 bolts, 5–7 Nm typical)
captureCaliper unbolted?
captureReinstall torque for the caliper bolts — how many N·m?
VALUE · Nm
brake.hd.r3Hang caliper from frame with a hook or zip-tie — never let it dangle by the hose
captureCaliper hung off the frame, not dangling by the hose?
MECHANICAL DISC — REMOVEmechanical-discmechanicalbrake-type:mechanical-disc-remove
brake.md.r1Loosen cable pinch bolt at caliper; back off barrel adjuster if cable won't slack
captureCable pinch bolt loosened and cable slack?
brake.md.r2Unbolt caliper (or swing it on its mount) to clear rotor from pads
captureCaliper unbolted or swung clear of the rotor?
brake.md.r3Hang caliper off frame; protect rotor from contamination (no oil/grease)
captureCaliper hung off the frame, rotor kept clean?
warningContaminated pads → replace, never clean
DRUM — REMOVEdrumbrake-type:drum-remove
brake.dr.r1Mark current adjuster position (paint pen or photo) before backing off tension
captureAdjuster position marked?
captureSnap a photo of the marked adjuster.
PHOTO
brake.dr.r2Disconnect actuating cable or rod at the drum lever arm
captureDrum cable or rod disconnected at the lever arm?
brake.dr.r3Loosen the torque arm bolt at the frame so the backing plate can rotate with the wheel
captureTorque arm bolt loosened so the backing plate rotates free?
NONE / REGEN-ONLY — REMOVEnoneregen-onlybrake-type:none-remove
brake.no.r1Confirm ESC/controller is powered off — no mechanical brake to disengage
captureESC or controller confirmed powered off?
PASS / FAIL
warningRegen still works only when the controller is powered — never assume the wheel is locked
brake.no.r2No caliper, cable, or hose to remove; proceed directly to wheel removal
captureConfirmed nothing to remove, moving to wheel removal?
atom:rotor-inspect4 steps
07rotor-inspect/RI.1
Measure rotor thickness at four points around the swept area; replace at or below the manufacturer minimum (usually stamped on the rotor — typical 1.5 mm for 1.8 mm new, 1.6 mm for 2.0 mm new)
captureRotor thickness at the thinnest point — how many mm?
captureManufacturer minimum stamped on the rotor — how many mm?
VALUE · mm
Typical replace threshold Below manufacturer minimum (stamped on rotor)
glossary → brakes/rotor
08rotor-inspect/RI.2
Spin the wheel; hold a truing fork (or your finger braced against a fork leg) close to the rotor face — note wobble amplitude and number of bent zones
captureWobble observed — none / one bent zone / multiple zones?
DECISION · 3
warningWobble > ~0.5 mm visible at the edge will rub a centred caliper — true it or replace
glossary → brakes/rotor-warp
09rotor-inspect/RI.3
Inspect for rainbow/blue discoloration (overheating), deep scoring, or cracks radiating from bolt holes
captureDiscoloration, scoring, or cracks present?
captureSnap a photo of any flagged area.
PASS / FAILPHOTO
warningRainbow blueing indicates the rotor has been heat-cycled past its tempering — replace, do not try to salvage
criticalCracks from bolt holes are catastrophic-failure precursors — replace immediately, do not ride
10rotor-inspect/RI.4
Decide rotor disposition
captureRotor disposition?
DECISION · 3
atom:rotor-truewhen rotor-work = true4 steps
11rotor-true/RT.1
Spin the wheel slowly; with a paint marker on a frame reference, mark the rotor where it first contacts (the high spot)
captureHigh spot identified and marked?
PHOTO
12rotor-true/RT.2
Slide the truing fork over the rotor at the marked high spot; apply firm, brief pressure in the OPPOSITE direction of the warp; release
captureTruing fork engaged at the high spot; gentle counter-bend applied?
warningSmall bends, not big yanks — over-correction is worse than the original warp
13rotor-true/RT.3
Spin again, observe wobble; if reduced but not gone, repeat marking + bending up to 2 more times (3 attempts max)
captureHow many truing attempts so far?
VALUE · attempts
14rotor-true/RT.4
Final check — spin freely and confirm no caliper rub at any rotation angle; if still wobbling, abort and escalate to rotor-replace
captureRotor true enough that caliper does not rub at any angle?
PASS / FAIL
atom:rotor-replacewhen rotor-work = replace3 steps
15rotor-replace/RR.1
Confirm wheel is out of the vehicle and caliper is off (use caliper-remove first if not)
captureWheel out and caliper off?
captureBrake type captured upstream — confirm?
16rotor-replace/RR.2
Identify rotor mount style and execute the matching swap branch
branch on rotor-mount
Rotor replace — branch by mount style
SIX-BOLTsix-bolt6-bolt
RR.6b.1Loosen the six T25 bolts in a star pattern (opposite-side order); set them aside on a magnetic tray
captureSix bolts loosened and accounted for?
RR.6b.2Lift the old rotor off the hub flange; wipe the hub flange clean with isopropyl
captureOld rotor off; hub flange wiped clean?
RR.6b.3Seat the new rotor onto the hub flange respecting the rotation-direction arrow (if present); thread all six bolts finger-tight first, with a drop of blue thread-locker on each
captureNew rotor seated with rotation arrow correct?
captureAll six bolts thread-locked and finger-tight?
PASS / FAILPHOTO
warningDirectional rotors mounted backwards will overheat and warp within a few rides
RR.6b.4Torque the six bolts in a star pattern to spec (typically 4–6 N·m for steel hub flanges)
captureStar-pattern torque applied — what N·m setting?
VALUE · Nm
Typical torque 4–6 N·m star pattern
Cited sourcessign-off seam
source → park-tool-axle-torque-2024editorial · Afam · 2026-05-20
CENTERLOCKcenterlockcenter-lock
RR.cl.1Engage the cassette lockring tool in the centerlock ring; back the ring out counter-clockwise
captureLockring backed out cleanly?
warningCenterlock rings can be tight — use a bottom-bracket spanner for leverage, not a cheater bar
RR.cl.2Lift the old rotor off the centerlock spline; inspect spline teeth for wear or burrs
captureSpline teeth clean and intact?
PASS / FAILPHOTO
RR.cl.3Seat the new rotor onto the spline respecting the rotation arrow; thread the lockring on by hand to verify cross-threading does not occur
captureRotor seated; lockring threading clean?
RR.cl.4Torque the lockring to spec (typically 40–50 N·m — same as a cassette lockring)
captureLockring torqued — what N·m setting?
VALUE · Nm
Typical torque 40–50 N·m
Cited sourcessign-off seam
source → park-tool-axle-torque-2024editorial · Afam · 2026-05-20
17rotor-replace/RR.3
Wipe the new rotor face with isopropyl to remove any handling oil; spin the wheel and confirm no wobble
captureRotor face wiped; spin clean with no visible wobble?
PASS / FAIL
atom:caliper-install1 step
18caliper-install/CI.1
Identify brake type and execute the matching install branch
captureBrake type identified and confirmed?
branch on brake-type
Caliper install — branch by brake type
HYDRAULIC DISC — INSTALLhydraulic-dischydraulicbrake-type:hydraulic-disc-install
brake.hd.i1Reinstall rotor before caliper (check rotation arrow if directional)
captureRotor back on the right way around?
warningContaminated rotor → clean with isopropyl, never brake cleaner on hydraulic seals
brake.hd.i2Bolt caliper loose to the frame/fork; do not torque yet
captureCaliper bolted loose, free to float?
brake.hd.i3Pull the pad spacer / bleed block; pump the lever until pads bite the rotor
captureSpacer pulled and lever pumped to bite?
brake.hd.i4With lever held, torque caliper bolts to spec to centre the pads
captureLever held while torquing the caliper?
captureCaliper torqued to spec — how many N·m?
VALUE · Nm
brake.hd.i5Release lever, spin wheel — confirm no rotor rub
captureWheel spins free with no rotor rub?
PASS / FAIL
MECHANICAL DISC — INSTALLmechanical-discmechanicalbrake-type:mechanical-disc-install
brake.md.i1Reseat rotor and remount caliper to frame/fork; torque caliper bolts to spec
captureRotor and caliper back on?
captureCaliper torqued — how many N·m?
VALUE · Nm
brake.md.i2Re-tension cable: pinch bolt + barrel adjuster until pads contact at ~1/3 lever pull
captureCable re-tensioned to pad contact at one-third lever pull?
brake.md.i3Spin wheel and squeeze lever — confirm clean pull and no rub
captureLever pulls clean and wheel spins without rub?
PASS / FAIL
DRUM — INSTALLdrumbrake-type:drum-install
brake.dr.i1Seat backing plate against the torque arm; tighten torque arm bolt to spec
captureBacking plate seated against the torque arm?
captureTorque arm bolt — how many N·m?
VALUE · Nm
brake.dr.i2Reconnect actuating cable or rod at the drum lever arm
captureDrum cable or rod reconnected at the lever arm?
brake.dr.i3Restore adjuster to the marked position; verify free-wheel + firm engagement
captureAdjuster restored to the marked position?
captureWheel spins free and brake engages firm?
PASS / FAIL
NONE / REGEN-ONLY — INSTALLnoneregen-onlybrake-type:none-install
brake.no.i1No caliper or cable to reinstall; confirm wheel is back in the dropout
captureWheel seated, nothing to reattach?
brake.no.i2Power up and verify regen response before declaring brake-side complete
captureController powered up, regen response confirmed?
PASS / FAIL
criticalIf regen is the only stopping system, a failure here is a no-go
atom:caliper-align1 step
19caliper-align/CA.0
Confirm this is a disc-brake job — drum and regen-only short-circuit here (drum brakes self-centre via the adjuster, no caliper to align)
branch on brake-type
Caliper alignment applicability — branch by brake type
DISC (hydraulic or mechanical)hydraulic-dischydraulicmechanical-discmechanical
CA.1Loosen the two caliper mounting bolts about 1/2 turn each — caliper should now float freely on its mount
captureCaliper bolts loose; caliper free to float?
PASS / FAIL
CA.2Execute the matched centring branch by brake type
branch on brake-type
Centring action — branch by brake type
HYDRAULIC DISChydraulic-dischydraulic
CA.hyd.1Pump the brake lever firmly and hold — the hydraulic pressure self-centres the caliper on the rotor
captureLever pumped and held; caliper visibly centred on rotor?
PASS / FAIL
MECHANICAL DISCmechanical-discmechanical
CA.mech.1Slack the cable barrel, slide a business card between pad and rotor each side, take up cable while the caliper finds centre
captureBusiness-card shims in; cable taken up; caliper centred?
PASS / FAIL
CA.3While holding lever (hydraulic) or business-card position (mechanical), torque the caliper bolts to spec in alternating sequence
captureBolts torqued in alternating sequence — what N·m setting?
VALUE · Nm
Typical caliper mounting torque 6–8 N·m (post-mount), confirm against vehicle manual
Cited sourcessign-off seam
source → park-tool-axle-torque-2024editorial · Afam · 2026-05-20
CA.4Release lever / pull shims; spin wheel — confirm NO rotor rub at any point in rotation; if rub remains, repeat from CA.1
captureWheel spins fully without rub?
PASS / FAIL
infoA faint rhythmic tick (pad-slap) right at the start is normal; constant rub is a centring failure
DRUM — SKIPdrum
CA.drum.skipDrum brake has no caliper to align — shoe-to-drum contact is set via the drum adjuster (see brake-cable-adjust drum branch). Exit this atom.
captureDrum confirmed; caliper-align skipped as not applicable?
PASS / FAIL
REGEN-ONLY — SKIPnoneregen
CA.none.skipRegen-only vehicle — no caliper to align. Exit this atom.
captureRegen-only confirmed; caliper-align skipped as not applicable?
PASS / FAIL
atom:findings-handoff3 steps
20findings-handoff/FH.1
Explain the findings and the work done in plain language, without jargon, and confirm the customer understands
captureHow did you explain the findings and work to the customer?
NOTE
21findings-handoff/FH.2
Communicate any battery findings verbally: state of health, charging guidance, and safety notes, and confirm they were understood
captureWhat battery findings did you communicate, and how did the customer respond?
NOTE
22findings-handoff/FH.3
Communicate any drive-system findings verbally: motor, controller, or sensor behavior observed during service
captureWhat drive-system findings did you communicate to the customer?
NOTE
deviation_rules · 6 declared
ad_hoc_step
a captured step is not in the runbook for the resolved vehicle / brake-type / rotor-work branches
missed_step
a runbook step for the resolved branches has no capture in the job record
missing_required_evidence
a step's capture.evidence item went unfilled by the tech's narration
branch_candidate
narration matches a finding pattern (rotor warp, scoring, bolt-hole cracks) but no branch was taken
contaminated_pad_kept
narration mentions oil or brake fluid on pads but no pad-replace step was added
dot_mineral_crossover
narration mentions both DOT and mineral brake fluid in the same job record
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