Troy Cox with Cecil and Sons Discount Tires stopped by GDGC to answer some of our questions about getting our vehicles serviced when we’re not sure what the problem is.1) More often than you’d think, customers ask for specific services or repairs thinking they’ve already identified the source of their problem. Why can this be a problem?
Automobiles are very complex and there are a number of fairly common problems that can have multiple causes with similar, or even the same symptoms. A vehicle that pulls to one side or the other could be out of alignment, could have a brake problem, or could have a tire causing the pull. If you just go into a shop and tell them “I need an alignment” then that’s likely what they’ll do. If the alignment wasn’t the only thing wrong they’ll find on the test drive after aligning it that it’s still got a pull; they may even be able to tell you what needs done next to find or fix the pull. But assuming it was out of specifications and they corrected it, they have followed your instructions and so have every right to expect that you pay for the alignment done even if you have other problems still causing the car to pull. After all, they did what you’d specifically asked them to do. Far better for both you and your shop if you are as specific as possible about what your concerns are: “my car pulls left” or “I’ve got a vibration above 65 mph” as examples. And the more specific you can be the more likely the shop is to find and fix what’s concerning you. “I’ve got a rattle in my car” is much less likely to result in a quick fix than “I’ve got a rattle when I’m backing out of my driveway with the wheel cut to the left”. Obviously, the second description is far easier for a shop to duplicate consistently and pinpoint than the first.2) Ok, say I’ve got a vibration. What kind of things should I be looking for to help pinpoint my concerns and communicate them to my shop?
“What” and “When” are the primary things any shop is going to try and lock down in questioning you about your concerns. If “What” is “my steering wheel is shaking” then the answers to “When” help isolate why it is happening and how we can best address the problem for you. For example, if you steering wheel is shaking at low speeds but smoothes out as you go faster one of the first things we’ll look for is a tire problem like a separation. If the steel belts in a radial are starting to separate from the body of the tire often you’ll feel a wobble or side-to-side shake at lower speeds but as you go faster the centrifugal force tends to stabilize the belt and keep it from moving. If you’re noticing a continuing vibration once you’ve reached highway speeds, then we typically start looking for a tire out of balance, worn unevenly, or possibly a slightly bent wheel. We know it’s not likely to be a badly bent rim as that starts as a wobble or shake at low speeds and just keeps getting worse the faster you go. If it’s a vibration only under acceleration, one that smoothes out when you lift off the gas, then we’ll usually be looking at driveline: possibilities include a bad u-joint on a rear-wheel drive vehicle or a front u-joint or cv-joint on a front-wheel or all-wheel drive vehicle. Vibration under acceleration could also be a misfire in the engine or a transmission issue. Vibrations at specific, set speeds can indicate transmission issues, especially if it’s at or around the speed your torque converter “locks up” and becomes a direct coupling between the engine and the driveline for optimum fuel economy-typically in the 48-54 mph range.
If it’s only vibrating when you’re braking, then it’s almost always related to something in the braking system; most commonly something like a warped rotor or an out-of-round drum. This is not to be confused with the loud “buzz” sound and very rapid movement of your brake pedal when your ABS (anti-lock brake system) kicks in to try and prevent a skid—the computer driven anti-lock braking system can, in effect, “pump” your brake pedal 4-6 times per second to help you maintain some steering control in an emergency stop. If your wheels “lock-up” and stop rolling, you’ve got no directional control and, except in very limited conditions, longer stopping distances than a working ABS will provide.3) Ok, I’ve got a vehicle that drifts left or right more than I’d like. The “what” or “when” questions I’ll be asked are?
Does it pull all the time, or just on certain roads? Most vehicles will follow the crown of the road, so if the road slopes to the left or right, that’s typically the direction the vehicle will drift, as well. We, like most shops, have found a very flat road close to the shop we use for test drives to try and eliminate crown as a culprit. Also, realize many vehicles are going to have a very slight drift right built in but shouldn’t pull hard to the right. A “drift” is very light and will take quite some distance to take you out of your lane; a “pull” is a strong tendency to leave your lane in a short distance without constant attention to prevent it.
Does it drift or pull more the harder you accelerate? Many front-wheel drive vehicles have, due to their design, unequal length front driveshafts which can cause “torque steer”—the vehicle wants to pull under acceleration and the harder you hit the gas the harder the vehicle tries to go out of its lane. This is more typically found in high-horsepower front-wheel drives and is usually simply something you’ve got to be aware of and compensate for as the driver. Proper alignment can help, but cannot change the physics of that kind of design.
Do you notice the pull more when, or just after, you’ve been on the brakes? A brake fluid or grease seal leaking on your brake pads or shoes can change their friction characteristics enough to cause a pull under braking as can a brake hose failing internally and restricting fluid flow or a caliper piston or guide pin sticking and preventing the brake from releasing.
Did you notice it when new tires were installed or right after a tire rotation? Tires can cause a pull; the easiest way to determine if the tires are the cause is to cross the front tires. If the pull changes direction, you know the tires are the reason for the pull and if it does not change direction then you know the tires are not the reason for the pull. This is a simple test and quickly eliminates one potential cause for your pull.4) So we shouldn’t assume we know what’s wrong with our cars, right?
Assumptions are something even we in the industry have to guard against; a vibration when you step on the brakes is usually a warped front rotor, but nothing’s certain enough to justify turning or replacing those rotors without, at minimum, a test drive to confirm your symptoms and locate the vibration to the front, or back. Similarly, a pull left or right is not always an alignment issue any more than a shake in the front end. A shake or pull could indicate a front end problem, but best practice is always to describe the symptoms and occurrence patterns as fully as possible. Again, “what” specifically are your concerns and “when” they occur clearly articulated maximize our ability to serve you by solving the problem you came in with.Cooper’s “Take the Money and Ride” rebate is going on thru November 6th, 2012, and purchase of a qualifying set of Cooper tires could qualify you for an up to $75 rebate by mail—see store or coopertires.com for details.Cecil and Sons Discount Tires is family owned and operated since 1973; three generations of our family serving, in many cases, third and fourth generations of our customer’s families. Cecil and Sons has tires, custom wheels, alignment and suspension repair, brakes, preventative maintenance and light line mechanical service.Cecil and Sons Discount Tires
204 East Morrow Road
Sand Springs, OK
4002 South St Hwy 97
Sand Springs, OK