Topic / Title:
Disc Brake Repair; a multi-day lesson plan
Any adult with need and interest and approximately 8th level reading
A. Instructional goals
/ teacher goal: Student will be able to recognize and repair
- warped disc
- worn pads
- perform research
using library, bookstore, computer, and / or indexed manuals
Reading, library and index research, web search, learning
specialized vocabulary, speaking, some math related to torque wrench
and micro measurements.
B. Competency /
Objectives: Student will
- Use and respond to
specialized vocabulary, appropriate names of tools, and names
of parts while demonstrating repairs (vocabulary list
- Reference the owner’s
manual for proper fluid (and by the way, capacities, engine oil
specifications, maintenance schedules, etc.);
- Find instructions
using indexes, reference guide books, and library;
- Access two of the web
sites provided in the webliography; watch one video clip;
- Create a successful
web search using terms that might include ‘disk,’ ‘disc,’
‘brake,’ ‘repair,’ ‘replace,’ ‘fix,’ ‘DIY,’ and make and model
- Jack a car at four
different appropriate lifting points on one side, which are safe
for the car and safe for people; safely place jack stand;
- Break a nut free with
the tire on the ground; will define and spell the words ‘break’
- Remove a wheel;
- Find proper torque
specifications in reference material, and use torque wrench to
replace the wheel;
- Remove the caliper,
hang it with a wire to protect the brake hose; use a torque
wrench to remount the caliper;
- Compress the caliper
piston and describe the purpose of this step;
- Compensate for fluid
level changes and explain why this occurs with caliper
- Remove disc, visually
assess scoring, take it to be measured or resurfaced, or replace
- Assess pads, remove
them, reinstall the old ones or replace them with new ones as
necessary; describe whether or not they are symmetrical and / or
identical; replace shims;
- Reassemble; lower the
car; tighten lug nuts; pump brakes to insure first contact
between pad and rotor; safely test the braking function.
Becoming skilled in library, book, and computer research will have
many applications. Students will also practice speaking and
listening with a shopkeeper using a technical vocabulary.
Specifics of car repair will lead to some financial independence.
This task, for example, may cost $25 in parts as compared to $150 if
it is done in a shop.
D. Content and
Materials, Sites, Games Activity:
Some of these sources have video clips which can be viewed and
Web Search --
Students will brainstorm and practice making successful web queries,
using such words as ‘disc,’ ‘disk,’ ‘rotor,’ ‘brake,’ ‘break,’
‘repair,’ ‘fix,’ ‘replacement,’ ‘DIY,’ and make and model of car.
Students will note whether correct spelling is suggested by Google.
Bibliography -- A
homework assignment will be to find an appropriate reference book,
or repair manual, and bring it or a photo copy to class. The
appropriate section on disc brake repair will only be about 5 pages,
plus a page with torque specifications. Teacher can come prepared
with a generic handout for each student. Accommodations can be made
for students in the group who do not have easy access to a library,
such as asking them to find a call number on line, or to write down
a title that they find at an auto part store.
Guide books are easy to
find at auto repair shops or at book stores. At the public library
they have the call number 629.287 and are organized on the shelf by
car make, model, and year. Popular publishers are Haynes, Chilton,
Edmonds, and the For Dummies series by Hungry Minds.
Vocabulary -- This
is a suggested list of words needed to understand the repair guide
books. A few names of tools may need to be added. Students can
review repair manuals in groups to search for technical vocabulary,
add words this list, or define words using this list.
- Allen wrench:
Six-sided tool, often L shaped, which fits into a 6-sided hole
on the head of a bolt. Also called hex key or hex wrench. ‘Hex’
means six. Used to remove slide bolts on some cars such as
Mazdas and Hondas.
- break: To loosen a
bolt or nut which is on tight, or “frozen” with rust. Breaking
takes a lot of pressure and so you should break lug nuts before
you put a car on a jack so the car will not fall. This kind of
break does not mean to damage.
- breaker bar: Wrench
with a long handle for loosening tight nuts and bolts
- bolt: See dictionary
- caliper: The part of
the brake the squeezes the disc, to cause friction, and stop the
- clamp, C-clamp: Tool,
shaped like a C, used to squeeze and compress the brake piston.
- capacities: This is
the word in the index of most owner’s manuals which helps you
find how much oil your car holds, how much gas it will hold, how
much water, etc.
- cylinder: A brake
system has a master cylinder on the firewall (by the steering
wheel, and a slave cylinder on each wheel. These are full of
fluid and they distribute pressure evenly to stop the car.
- deep, depth:
Measurement down from surface. Measure the depth of wear to
find out if disc needs to be thrown away
- disc: The round,
shinny part of a brake. The disc is the only part which usually
looks clean. Also called ‘rotor.’
- disk: Alternative
spelling of disc, often called ‘rotor’ in the US.
- DIY: Do It Yourself;
sometimes a useful term for web searches.
- DOT: Department of
Transportation; standard for fluid formula. Most American cars
use DOT-3 brake fluid. Check owner’s manual
- engine oil: This is
the term used in the index of owner’s manuals. If you look for
‘oil’ or ‘motor oil’ you will probably not find what you are
- floor jack: A jack on
wheels which is a very safe and easy tool for lifting a car.
The car will have a “scissor jack” or a “bumper jack” in the
trunk for fixing flats on the road. These jacks will also work
for fixing brakes, but they are not as safe or easy to use.
- grind: This is the
sound brakes make when they are completely worn out. It sounds
something like rubbing a hammer on a stone. If you hear this
sound when stopping you will probably have to replace discs and
pads. See ‘metal on metal.’
- groove: scratches in
discs. These must be polished until the disc is smooth, shinny,
and perfectly flat. See ‘score.’
- hex key, hex wrench:
See Allen wrench
- hose: Rubber tube
that holds brake fluid, attached to caliper. Take care not to
break or twist this hose too much.
- inner, inboard,
inside: The side close to the engine. Sometimes inner pads are
different than outer pads. You must be careful not to confuse
- jack: This word means
many things in English, but here it is the tool to lift the car.
- jack stand: A steel
stand to rest the car on so it will not fall off the jack.
- knuckle, steering
knuckle: This is the part of the car that the front wheel is
attached to. Steering and suspension are also attached here.
- lathe: A machine to
smooth and polish discs. You will take your discs to a shop to
be measured and polished; lathes are too expensive for most
people to own. The word also refers to any machine used to cut
something that is spinning; sometimes chair legs are made on a
- lug nut: The heavy
nut that holds the wheel on.
- machine (verb): This
word is used to describe smoothing the disc, as in “how much
does it cost to machine my rotors?”
- master cylinder: see
- measure: It is
important to measure how thick a disc is before replacing it.
If it is too thin, it will get hot easily and will cause
problems. Take your discs to the shop to be measured. They
will use the word ‘mic’ (sounds like ‘Mike’) as in “I will mic
your discs to see if they are thick enough.”
- metal on metal:
Description of brake pads which are completely worn out and
grinding on the disc.
- micrometer: A tool to
measure 1/1,000 x inch, used to tell if a disc is worn out.
- mount: Attach a part
to a larger part or to the car
- nut: See picture in
- outer, outboard,
outside: The side away from the car. Sometimes inner pads are
different than outer pads. You must be careful not to confuse
- pin: See ‘slide
- piston: This is not
the piston in the engine. This is the piston in the caliper
which pushes the pads together, against the disc.
- pulsate: When the
disc is warped the car will shake when braking. This is called
- rotor: American name
- score, scoring:
scratches on the disc. See ‘groove.’
- shim, squeal shim,
anti-squeal shim: Thin sheets of metal that fit behind the pads
and reduce noise called ‘squeal.’
- slide bolt: There are
two bolts which hold the caliper on the car. These bolts are
threaded only at the very end, and they allow the caliper to
slide inward and outward while braking. These are called ‘slide
bolts,’ or ‘caliper pins.’ Some older cars use slide pins that
are installed with a hammer.
- star wrench: Another
name for torx wrench.
- torque wrench: A
wrench which measures how tight a bolt or nut is. It uses
‘foot-pounds’ in America.
- torx wrench: This is
a wrench which fits into a hole shaped like a six-pointed star
on the head of a bolt. It is used on some slide bolts, such as
on old Ford Tauruses. It is designed to take a lot of pressure
without hurting the hole, which sometimes happens with other
screwdriver shapes or wrench shapes.
- trouble shoot: Find
out what is wrong
- turn (as on a lathe):
Some times a shop keeper will say “Do you want me to turn your
disc?” or “turn your rotor?” This means to put it on a lathe and
cut or polish the surface. It is the same as saying “Do you
want me to machine your rotor?” or “Do you want me to resurface
your rotor?” or “Do you want me to polish your rotor?”
- vibrate: Shake. See
Visual Aides -- The
teacher should bring in one good example of a repair manual with
pictures. Teacher can photocopy part or all of the text and hand out to
use for reading and vocabulary practice. The teacher may want to bring
in some tools related to brake repair to assist in vocabulary learning.
Good mechanics like to handle widgets. To go the extra mile, the
teacher could also bring in some auto parts -- pads, shims, rotor, etc.
Worn examples may be free for the asking at an auto part store. New
parts might be loaned with a credit card. A can of brake fluid would
also be helpful for practice reading the label.
These steps are in a somewhat
chronological order for performing the repair. It would be an easy
thing to take some steps out of order to accommodate the length of a
class period. The web searches, reading, role playing, artifact
show-and-tell, manual reading, vocabulary discussions, hand cleaning,
are examples of things that could be put in any order.
Identify which students have cars and who
have interest in doing repairs. Identify which students may have
experience. If there are many with interest, divide into small groups
of 2 to 4, dispersing the experienced students among the groups.
Discuss lesson objectives -- this can be
part of the identification and assessment step above.
Present repair guide photocopy handouts
(usually only 4 or 5 pages). Read together and search for and highlight
new vocabulary. Discuss page formatting and numbering.
Display tools and parts and go over some
Introduce tricks for keeping hands clean --
gloves, Vaseline, hand cleaners.
Practice loosening lug nuts. Find reference
for proper torque (tightness). By the way, check torque specifications
for slider bolts. These fact are usually not in an owners manual, but
will be in the repair manual. (Small car lugs are sometimes about 80
foot-pounds, larger cars are at about 90.) Use torque wrench to replace
nuts. Use and discuss tools in car trunk for emergency tire replacement.
Practice jacking a car, using the owner’s
manual to locate appropriate lift points. Discuss importance of lift
points for safety of the car and safety of people.
By the way, use owners manual to determine
proper brake fluid. Bring in a can of fluid so students can practice
reading label. Also use this moment to go over engine oil
specifications, and maintenance intervals. Owner’s manuals are a little
quirky and it is necessary to practice using the index.
End of first day, assign homework to go to
library and find a repair guide appropriate to their car. If they don’t
have a car, assign a nominal car which will be easy to find, such as a
Taurus or Caravan. Assign students to find proper torque specifications
for a given mode.
In class, if computers are available,
perform web searches as suggested above. This could also be a homework
assignment if students have access to a library or home computer. Note
whether Google suggests corrected spelling for ‘brake’ and ‘disc.’ Note
which words are not helpful. Note which sites want to sell books and
parts, and which sites actually provide instructions.
Practice placing jack stand in appropriate
points. These are in the owner’s manual.
Remove wheel; remove brake caliper; hang
brake caliper; remove disc; remove pads; put all parts back. This
should take about 5 min per student.
Remove pads again and examine wear. Pad
should be much thicker than its steel backing; rivets which hold pad to
the steel backing should be well below surface of pad.
Examine disc. If possible, students should
take a field trip to auto part store to resurface disc and to purchase
pads. In class, students can role play practicing asking for this
service. See ‘machine,’ ‘measure,’ and ‘turn’ in vocabulary list
above. As often as not, the old disc will have to be discarded and
Compress piston. This can only be done once
per wheel, so give everyone a moment of hands-on experience. Examine
brake fluid level in master cylinder reservoir before and after this
Install new pads, shims, and reassemble all
parts; lower car to ground.
In park or with emergency brake on, start
car and have one student pump brakes and describe what happens.
Cautiously, release emergency brake, put in gear and allow it to idle
forward to test brakes.
Do other side.
High fives all around.
Assessment should take place
at every step particularly with library and index searches until it is
clear that students understand steps and vocabulary along the way. Make
sure each student gets to demonstrate hands-on each mechanical step.
Given time, a student could learn on one brake and be assessed on
G. Group Activities:
Role-play the experience of going to the
shop, purchasing parts, and asking for the rotors to be polished. See
the vocabulary list and try to use the words ‘rotor,’ ‘disc,’ ‘turn,’
‘machine,’ ‘polish,’ ‘lathe,’ ‘mic,’ and ‘measure.’ There are several
variant words that can be used in these situations and the students
should mix up the vocabulary.
Students should collaborate and brainstorm
to find successful web searches for repair instructions. They can
experiment with miss-spelled words such as ‘disk,’ ‘break,’ and variants
such as ‘rotor,’ ‘repair,’ ‘fix,’ ‘replace,’ etc.
Reading and discussing the repair manual (or
handout) and looking for and highlighting vocabulary words can be done
Small groups of 2 to 4 can also work
together on the actual repairs, but it is important that each
demonstrates an understanding of each step, including loosening and
tightening the lug nuts.
H. Alternate Plans:
It is best if the students are
assessed for interest before setting out on this lesson plan.
There may be some reticence
among women. This lesson plan could be shortened to jacking and tire
repair which would have a broader appeal. It is well adapted for people
who prefer to hold things, participate, and watch activities.
The academics of web searches,
library and index searches, vocabulary lists, role playing and reading
are important skills and could be adapted as a stand-alone lesson. In
that case it might be best to pick a research topic (or several) with
broader appeal than car repair. If working in small teams there may be
group members who prefer to follow the repair manual or talk to a shop
keeper, while others may prefer to get their hands dirty.