Automotive Service Technology Section B/Automotive Special Problems
Inspect, remove and install strut cartridge or assembly, strut coil spring, insulators (silencers), and upper strut bearing mount.
Lesson Plan for
AUT 184-185/AUT 291
Automotive Service Technology Section B/Automotive Special Problems
Course HS Title: / Automobile Service Technology/Special Problems / Program:KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No. / KCTCS Course Title
Introduction/Context / This lesson will instruct students on how to properly remove, inspect, and install strut cartridge or assembly, strut coil spring, insulators (silencers), and upper strut bearing mounts. . Knowledge of these techniques and the skills required to correct problems associated with this task are necessary for a student to acquire if they wish to compete for high paying, high skilled jobs in an Automotive Repair Facility. Entry level technicians need to be able to perform this task to 100% accuracy. Incorrectly performing this task can lead to an automobile accident or create customer satisfaction issues.
Prepared By / School / Date:
Grade Level / No. Students / No.IEP's: / Lesson Length:
Task
Inspect, remove and install strut cartridge or assembly, strut coil spring, insulators (silencers), and upper strut bearing mount
No. / Objective
1 / Given the proper tools and instructions from a vehicle manufacturers shop manual, automotive technology textbook, or vehicle computer software program, students will be able to inspect, remove and install strut cartridge or assembly, strut coil spring, insulators (silencers), and upper strut bearing mount, and pass a written exam on the task with 100% accuracy by the end of the course.
Connections
Skills Standards:OH 001
OH 002
OH 003
OD 002
OD 003
OD 005
Common Core Technical Standards:
TD-SYS-2
New Common Core Standards:
RST 11-12.2
RST 11-12 3
INSTRUCTIONAL MATERIALS/TECHNOLOGY
Textbooks and Workbooks
Don Knowles / Automotive Suspension & Steering Systems (Todays Technician) / Third Edition / Delmar / 140-146
James Halderman/Chase Mitchell Jr. / Automotive Technology / Second Edition / Prentice Hall / 963-965
Equipment
As Needed / McPherson Strut Comp / Various
As Needed / Half Inch Impact Gun / Various
Content/Presentation/Demonstration Outline
INSTRUCT STUDENTS ON HOW PERFORM A BOUNCE TEST: To perform a shock absorber bounce test, the technician applies his or her weight to the bumper. When the bounce test is performed, the bumper is pushed downward with considerable weight applied on each corner of the vehicle. The bumper is released after this action, and one free upward bounce should stop the vertical chassis movement if the shock absorber or strut provides proper spring control. Strut replacement is required if more than one free upward bounce occurs.
Instruct students that struts should be inspected for oil leakage. A slight oil film on the lower oil chamber is acceptable. Any indication of oil dripping is not acceptable, and unit replacement is necessary. Struts should also be inspected visually for physical damage, such as a bent condition and severe dents or punctures. When any of these conditions are present, unit replacement is required. Inform students that Struts are similar internally to shock absorbers, but struts also support the steering knuckle. In many applications, the coil spring is mounted on toe strut.
Instruct students that before a front strut-and-spring assembly is removed, the strut must be removed from the steering knuckle, and the top strut mount bolts must be removed from the strut tower. If an eccentric camber bolt (used to adjust camber on the vehicle) is used to attach the strut to the knuckle, always mark the bolt head in relation to the strut and reinstall the bolt in the same position.
Remind students to always follow the vehicle manufacturers recommended procedure in the service manual for removal of the strut-and-spring assembly. Instruct students that a typical procedure for strut-and-spring assembly removal follows this format: 1. Raise the vehicle on a hoist or floor jack. If a floor jack is used to raise the vehicle lower the vehicle onto safety stands placed under the chassis so the lower control arms and front wheels drop downward. Remove the floor jack from under the vehicle. 2. Remove the brake line and antilock brake system (ABS) wheel-speed sensor wire from clamps on the strut. In some cases, the clamps may also have to be removed from the strut. 3. Remove the strut-to-steering knuckle retaining bolts, and remove the strut from the knuckle. 4. Remove the upper strut mounting bolts on top of the strut tower, and remove the strut-and-spring assembly.
Instruct students on the proper procedure for the removal of a Strut from the Coil Spring: SAFETY WARNINGS: Always use a coil spring compressing tool according to the tool or vehicle manufacturer's recommended service procedure. Be sure the tool is properly installed on the spring. If a coil spring slips off the tool when the spring is compressed, severe personal injury or property damage may occur. Inform Students to NEVER loosen the upper strut mount retaining nut on the end of the strut rod unless the spring is compressed enough to remove all spring tension from the upper strut mount. If this nut is loosened with spring tension on the upper mount, this mount becomes a very dangerous projectile that may cause serious personal injury or property damage. Instruct students to never clamp the lower shock absorber or strut chamber in a vise with excessive force. This action may distort the lower chamber and affect piston movement in the shock absorber or strut
Inform students that the coil spring must be compressed with a special tool before the strut can be removed. All the tension must be removed from the upper spring seat before the upper strut piston rod nut is loosened. Many different spring compressing tools are available, and they must ALWAYS be used according to the manufacturer's recommended procedure. IMPORTANT: If the coil spring has an enamel type coating, tape the spring where the compressing tool contacts the spring. The spring may break prematurely if this coating is chipped.
Instruct students that a typical procedure for removing a strut from a coil spring follows this format: 1. Install the spring compressing tool on the coil spring according to the tool or vehicle manufacturer's recommended procedure. 2. Turn the nut on top of the compressing tool until all the spring tension is removed from the upper strut mount. 3. Install a bolt and two nuts in the upper strut-to-knuckle mounting bolt holes. Install a nut on each side of the strut flange. Clamp this bolt securely in a vise to hold the strut-and-spring assembly and the compressing tool. 4. Use the bar on the spring compressing tool to hold the strut-and-spring assembly from turning, and loosen the nut on the upper strut mount. Be sure all the spring tension is removed from the upper strut mount before loosening this nut. 5. Remove the upper strut mount, upper insulator, coil spring, spring bumper, and lower insulator. Inform students that the upper insulator is positioned between the coil spring and the upper strut mount. The lower insulator is mounted between the coil spring and the lower spring seat. Both insulators reduce suspension noise.
STRUT DISPOSAL: SAFETY WARNING: Tell students to always follow the vehicle manufacturer's recommended procedure for strut disposal. Do not throw gas-filled shock absorbers or struts in a fire of any kind or in a dumpster. If the vehicle manufacturer recommends drilling the strut to release the gas charge, drill the strut at the manufacturer's recommended location. Instruct students that the following is a typical strut drilling procedure that is performed prior to strut disposal. 1. Fully extend the strut rod. 2. Center punch the strut at the manufacturers recommended drilling location. 3. Drill a small hole at the center-punched position.
INSTALLATION OF COIL SPRING ON STRUT: Instruct students that a typical procedure for installing a coil spring on a strut follows this format: 1. Install the lower insulator on the lower strut spring seat, and be sure the insulator is properly seated. 2. Install the spring bumper on the strut rod. 3. With the coil spring compressed in the spring compressing tool, install the spring on the strut. Be sure the spring is properly seated on the lower insulator spring seat. 4. Be sure the strut piston rod is fully extended and install the upper insulator on top of the coil spring. 5. Install the upper strut mount on the upper insulator. 6. Be sure the spring, upper insulator, and upper strut mount are properly positioned and seated on the coil spring and strut piston rod. 7. Install a bolt and nuts in the upper strut-to-knuckle retaining bolt hole and clamp this bolt in a vise to hold the strut, spring, and compressing tool as in the disassembly procedure. 8. Use the compressing tool bar to hold the strut and spring from turning, and tighten the strut piston rod nut to the specified torque. 9. Rotate the upper strut mount until the lowest bolt in this mount is aligned with the tab on the lower spring seat. 10. Gradually loosen the nut on the compressing tool until all the spring tension is released from the tool, and remove the tool from the spring.
Instruct students that a typical installation procedure for a strut-and-spring assembly follows this format: 1. Install the strut -and-spring assembly with the upper strut mounting bolts extending through the bolt holes in the strut tower. Tighten the nuts on the upper strut mounting bolts to the specified torque. 2. Install the lower end of the strut in the steering knuckle to the proper depth, and tighten the strut-to-knuckle retaining bolts to the specified torque. If one of the strut-to-knuckle bolts is an eccentric camber bolt, be sure the eccentric is aligned with the mark placed on the strut during the removal procedure. 3. Install the brake hose in the clamp on the strut. Place the ABS wheel-speed sensor wire in the strut clamp if the vehicle is equipped with ABS.
Applications/Practice
Evaluation and feedback Prior to Testing or Lab Work
STUDENT ASSESSMENT:(Assess student progress with performance criteria.)
IMPACT--Reflection/Analysis of Teaching and Learning: (How did students’ progress in relation to the state objectives? Was the instruction successful? Analyze samples of student work particularly that which is unsatisfactory, for the purpose of planning further instruction.)
REFINEMENT--Lesson Extension and Follow-up: (To be filled in as the lesson is modified during initial planning and/or during the teaching learning process.)