KCTCS Courses included in HS Title: (Lesson is prepared for course highlighted.)
KCTCS Course No.
KCTCS Course Title
This lesson will instruct students on how to properly Diagnose strut suspension system noises, body sway, and uneven riding height concerns, plus determine necessary action to properly repair the fault. Knowledge of these problems and the skills required to correct them is necessary for a student to acquire if they wish to compete for high paying high skilled jobs in an Automotive Repair Facility.
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 Diagnose strut suspension system noises, body sway, and uneven riding height concerns, determine necessary action to correct the problem, and pass a written exam on the task with 100% accuracy by the end of the course.
Diagnosis of Strut Noise and Strut Chatter: Instruct students that Strut chatter is a chattering noise that occurs when a defect, such as a worn upper strut mount, causes the strut and spring to turn erratically. Strut chatter may be heard when the steering wheel is turned with the vehicle not moving or moving at low speed. To verify the location of this chattering noise, place one hand on a front coil spring while someone turns the steering wheel. If strut chatter is present, the spring binds against the strut bearing mount. A revised spring seat is available to correct this problem on some models.
A noise that occurs on sharp turns or during front suspension jounce may be caused by one of the following problems. 1. Interference between the upper strut rebound stop and the upper mount or strut tower. 2. Interference between the coil spring and tower. 3. Interference between the coil spring and the upper mount.
Inform students that on some models, these coil spring interference problems may be corrected by installing upper coil spring spacers on top of the coil spring. Spring removal from the strut is required to install these spacers. On many front suspension systems the strut is bolted to the upper end of the steering knuckle. When the front wheels are turned, the strut and coil spring rotate together and pivot on the upper strut mount bearing. In this type of suspension, a defective upper strut mount may cause strut chatter and noise.
Instruct students that on other front suspension systems, the strut extends downward and the lower ball joint retains the lower end of the strut to the lower control arm. The front hub is bolted to a flange on the knuckle. A bearing assembly is mounted in the lower spring seat. When the front wheels are turned, the strut rotates on the bearing in the lower spring seat, but the spring and upper strut mount do not rotate. Therefore, in this type of suspension system, strut chatter may be caused by a worn or defective lower spring seat bearing. If the lateral movement of the strut rod and nut above the strut tower exceeds 3/16 in (4.76 mm), the upper strut bearing and mount assembly should be replaced. Worn spring insulators or broken coil springs cause a rattling noise on road irregularities. Broken coil springs result in reduced curb riding height and harsh riding.
Height Measurement: Instruct students about Riding Height. Riding height is the distance from specific chassis locations to the road surface. Regular inspection and proper maintenance of suspension systems is extremely important for maintaining vehicle safety. The curb riding height is determined mainly by spring condition. Other suspension components, such as control arm bushings, affect curb riding height if they are worn. Since incorrect curb riding height affects most of the other suspension angles, this measurement is critical. Inform students that reduced curb riding height on the front suspension may cause decreased directional stability. If the curb riding height is reduced on one side of the front suspension, the steering may pull to one side. Reduced rear suspension height increases steering effort and causes rapid steering wheel return after turning a corner. Harsh riding occurs when the curb riding height is less than specified. The curb riding height must be measured at the vehicle manufacturer's specified location, which varies depending on the type of suspension system.
Instruct students that when the vehicle is on a level floor or on an alignment rack, measure the curb riding height from the floor to the center of the lower control arm mounting bolt on both sides of the front suspension. On the rear suspension system, measure the curb riding height from the floor to the center of the strut rod mounting bolt. If the curb riding height is less than specified, the control arms and bushings should be inspected and replaced as necessary. When the control arms and bushings are in normal condition, the reduced curb riding height may be caused by sagged springs that require replacement.
Instruct Students about Body Sway: Body sway is leaning of the chassis to one side. Excessive body sway, or roll, on road irregularities may be caused by a weak stabilizer bar or loose stabilizer bar bushings. If lateral movement is experienced on the rear of the chassis, the track bar or track bar bushings may be defective. Lateral movement is sideways movement.
Objective 1. / Formative assessment / Instructor will observe students as they practice tasks to assure correct procedure and safety practices are being followed. A checklist should be utilized to chart student progress on the task. Questioning techniques will be utilized as necessary to demonstrate student comprehension / Adaptations and/or accommodations for special needs students will be added if required.
STUDENT ASSESSMENT: (Assess student progress with performance criteria.)
Objective 1 / Summative assessment / written test questions on stated objective / adaptation and /or accommodations for special needs students will be added if required.
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.)