10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
These 10 free RMMT questions are organized by exam domain, so you can see how each part of the Rotor Matching Master Technician Certification (RMMT) blueprint is tested. Reveal the answer and explanation under each question.
An ideal single-piston floating caliper has a piston area of 800 mm² and receives 5 MPa of hydraulic pressure. Both pads have a friction coefficient of 0.35 and act at an effective radius of 0.11 m. Neglecting losses, how much braking torque does this caliper produce?
Correct answer: B - 308 N·m
A single front-end clunk occurs when the brakes are applied after reversing travel direction. Rotor measurements, caliper movement, and wheel-bearing checks are satisfactory. Under braking load, the lower control arm moves fore-and-aft inside its pivot bracket; the rubber has separated from its outer metal sleeve. Where should the repair be directed?
Correct answer: B - The control-arm pivot bushing
Repeated heavy stops reduce a vehicle's deceleration for the same pedal effort. Pedal travel stays normal, the pedal remains firm, measured hydraulic pressure is unchanged, and the brakes release freely. Normal braking effectiveness returns after cooling. The mechanism that best fits this combination is:
Correct answer: D - Heat-related loss of friction between the pads and rotors.
Metal chips have collected around an X9D's tool holders during a cut. They need to be removed before the next pass. Which cleanup method follows the machine's safety instructions?
Correct answer: A - Stop rotation, disconnect power, and clear the chips with a soft brush.
An initial installed-runout reading is 0.085 mm. Removing trapped rust from the rotor-hub mating faces and correctly reclamping the rotor produces repeatable full-revolution readings of 0.025 mm. The service limit is 0.050 mm. Thickness, thickness variation, surface condition, bearing, and caliper checks also pass, and the service instructions permit reuse. The revised rotor recommendation should be:
Correct answer: C - Retain the rotor and complete the prescribed assembly and functional checks.
A rotor runs true on a bench lathe but exceeds the vehicle's installed-runout limit. The rotor and hub pass their individual checks; mating faces are clean, fasteners are correctly torqued, and the bearing is sound. Adequate thickness remains, and the manufacturer permits refinishing. What advantage does a correctly compensated on-car cut offer?
Correct answer: D - It cuts the friction faces perpendicular to the installed hub's rotation axis.
Complete cleanup of a structurally sound rotor requires 0.15 mm removed from each face. The lowest valid starting thickness is 26.56 mm. Service data require at least 26.20 mm after refinishing and replacement at 25.80 mm or less in service. The machine permits this cut, and no other replacement condition exists. What is the thickness-based decision before machining?
Correct answer: B - Proceed: the predicted thickness is 26.26 mm; verify it after cutting.
The rotor is correctly clamped to a clean hub. At the specified friction track, a rigidly mounted indicator remains in contact throughout a full revolution and moves between −0.018 mm and +0.027 mm. The maximum permitted total indicated runout is 0.040 mm. Which entry belongs on the inspection record?
Correct answer: C - 0.045 mm - exceeds the runout limit.
An X9 completes compensation at one wheel but repeatedly fails at the next. With the motor off, the technician verifies free hub rotation, sound bearings, and clean, secure adapter connections. At this working height, the trolley is against its travel stop and restricts the lathe's lateral movement. What should change before the next attempt?
Correct answer: D - Reset the working height so the trolley supports the lathe without binding.
Chatter persists on a PFM 9.0 despite sound cutting tips and secure mounting. With power disconnected, lateral play is found in the slide. After adjusting the gib, which observation would confirm a satisfactory result?
Correct answer: C - The slide travels smoothly with slight resistance and no lateral play.
The RMMT exam also covers these domains. Drill them in the full free practice test:
The full bank has 1,020 more RMMT questions with explanations.
Continue in the free practice test →
View plans