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The Need for a Critical Eye in Servicing Cars - Part IIPosted 5/13/2006
By Brian Manley
In the February 2006 issue of Tech to Tech, we focused on inspecting the vehicle from an "open hood" standpoint. In this installment, we will examine a vehicle from an under-car perspective as we look at all of the under-car items, with the vehicle on a lift. Our focus will not change; we are searching for items that can save our customers inconvenience, or in the worst case, an accident.
It has been decades since we have had mandatory safety inspections here in Colorado. Many states still have them in place, but when inspections aren't required, we've got to take responsibility for the safety of our customers. Neglected items such as dangerously loose ball joints, worn tie-rod ends (inner and outer), bald tires and worn-out brakes may inhabit a vehicle that was on the road next to you this morning!
As I discussed in Part 1, I try to precede any service or repair to a vehicle with a test drive to get a "feel" for the car. I drive a loop that includes stop-and-go, right and left turns, and road speeds up to 55 mph. I test for braking effectiveness, feel for excessive shock rebound, listen for any noises, and feel for looseness, pulling or wandering in the steering system.
Steering, Suspension, Chassis and Frame
While we have a chance to jounce the car, do it now while it is on the ground. The old tried-and-true method of bouncing each corner of the vehicle, then releasing and watching for more than one up and down cycle, works well enough to find defective shocks. Bounce it up and down, and then suddenly let go. The car should go up and down once, and then settle at the final resting height. Excessive movement means new struts/shocks are needed. Follow this up with a visual inspection of the shock/strut cartridges for signs of fluid leaks.
No Slackers Allowed
I have the habit of pushing out on the front of the tires, then pulling in toward me as a quick test of the tie-rod ends. I have found many loose ones with this method. However, I prefer to begin my inspection by leaving the vehicle on the ground and having someone start the engine, then move the wheel back and forth with small "wiggles," then progressing to a one half turn of the wheel each way. While this is happening, I slide under the car on a creeper and look closely at all joints and bushings. If you are performing this test on an alignment rack, put the vehicle up in the air. I have seen tracking bar bushings on 4 x 4 applications fail this test miserably, but when I have the truck in the air with the suspension hanging, the play is harder to detect. After the vehicle's suspension is dangling, I still grab each wheel at the 3 o'clock and 9 o'clock positions and shake them back and forth.
Some applications have notoriously bad outer tie-rod ends, while others tend to wear out the inner tie-rod ends.
This is something I always tend to look at, even if the vehicle doesn't go into the air. Tread wear can provide insight into the maintenance habits of the owner. I see many vehicles with underinflated wear, feathered edges from incorrect toe setting, and uneven wear due to incorrect camber angles. Many customers neglect to rotate and balance as often as they should as well. If I see a different tread pattern on one or more of the tires, I will verify that the tires are a matched set and the correct size for the vehicle. Tread depth must be at least 2/32-inch when measured in the two adjacent major tread grooves showing the most wear. Check for any cut more than 1 inch, visible bumps, bulges or knots.
Mounts and Bushings
Bushings support suspension control arms, strut rods, pickup cabs and beds, shock mountings and many other movable parts. These bushings can compress, crack, degrade and disintegrate over time. The picture shows cracking and compression of a lower control arm bushing that was one of a full set that we replaced.
Don't Steer Me Wrong
Steering gears that bolt to the frame come with their unique failure points. To begin with, look at the mounting to the frame. I have seen loose bolts and even cracked frames near gearbox mountings on larger four-wheel-drive vehicles. Moving up toward the steering column, look at the coupler that attaches the box to the column. This piece is often a rubberized piece that can degrade over time.
Rack and pinion units should be checked for loose mounting bushings and fluid leaks. Squeeze the rack boots to see if any fluid escapes. When checking the steering gear, center the steering wheel and observe the position of the front tires. If the wheels are not straightforward, check the cradle alignment. On many vehicles, cradle alignment can be verified by checking to see if the holes in the subframe line up with the holes in the unibody.
Some ball joints have wear indicators built into the base of the grease zerk, making them easy to check. I feel that many loaded ball joints are overlooked due to the fact that it takes time to properly unload the joint prior to checking. Some lower control arms must be jacked up to perform this test. Check the unloaded upper ball joints that are load carrying for up-and-down movement. If the upper ball joints are follower, look for in-and-out movement. Check lower load-carrying ball joints for up-and-down movement. Check follower ball joints for in-and-out movement.
If the vehicle has a pitman and/or idler arm, visually check to see if there is any play. Also, grab the center link and try to move it up and down.
Inspect shocks and struts for mechanical damage. Always check for leaks. Rubber bushings and upper strut mounts that are damaged can cause memory steer and squeaking noises on turns. Check the springs for damage. On vehicles with struts, make sure the spring perch is in good shape and that any rubber or plastic insulators are still in place.
Springs and torsion bars need to be checked for sagging or breaks, and the stabilizer bar needs to be checked for broken mounts or damaged link ends.
The entire exhaust system should be looked over for damage, leaks and missing hangers. I try to "tap" the catalytic converter to listen for any internal damage.
Check for breaks, cracks or severe rust at any suspension attachment points, and while we're looking at the frame/unibody, check for indications that the vehicle has been involved in an accident. Substandard repairs or attempts to cover up damage instead of performing proper repairs need to be shown to the customer. Brakes
Many states that have vehicle safety inspection programs require that at least one wheel be removed to check brake linings. In my experience, however, brake pad and shoe thickness can vary from side-to-side and from front-to-back. Beginning with the brake hydraulic system, the brake pedal must hold for one minute without fading, and the master cylinder should be checked for leakage and proper fluid level. Next, the power brake unit should be checked for operation.
The brake pads and shoes should be checked for thickness; linings must be at least 1/16 of an inch when bonded, and 1/32 of an inch over rivet heads when riveted, with no loose or missing rivets. Eyeball the drums and rotors for damage, and although rotor thickness and drum diameter may not be measured on a quick inspection, see if there are any obvious issues. If you need to verify thickness, grab your micrometer and compare with the number on the drum and rotor, or consult manufacturer information.
Next, check for fluid leaks at wheel cylinders, caliper seals, and all lines and hoses.
The parking brake needs to be inspected for proper operation. Check components for rust and function; these systems inherently seize from exposure to the elements.
A Final Word
As professional technicians, we have a huge responsibility to have a critical eye when working on our customers' vehicles. You may be the only professional tech to lay hands on that car that is in your stall. If a customer comes to you exclusively, you are the only person who cares for that vehicle. Here's to always taking our responsibility seriously.
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