Blog

  • Let's Get Technical! - Steering

    Posted on 06, December, 2017

    This month we are going to talk about a vehicle system that has undergone quite a few changes in the last ten years or so. It may seem simple, and is often overlooked, but getting your car to go where you point it is no easy task!

    Let’s start in the driver seat, with the old familiar steering wheel. The wheel sits at the top of the steering column, which consists of a series of shafts that go through the firewall of the car and down to the steering gear.  Because the path is not straight, there are flexible joints at different points in this path to keep things turning smoothly. If one of the joints starts to go bad, it can cause clunking, tight spots or even binding of the steering.

    The steering gear is the heart of the system, and its job is to multiply the number of turns that you as the driver are inputting at the steering wheel.  If it only turned one time for every turn of the wheel, you’d get exhausted quick! Most passenger cars use a ratio between 12:1 and 20:1. Older cars and trucks used an independent gear that connected to the drive wheels through a series of arms and bars, with recirculating ball joints at the connections. The nice thing about this system is that if one part fails you can replace it independently. The downside is that there are more moving parts and therefore more opportunities for looseness or failure. Nowadays most cars use what is called a “rack and pinion” steering gear. This type of gear is more compact and most of the linkages are built into it. There are only two moving parts on each end, an inner and an outer tie rod. These rods connect to the steering knuckles, which turn the drive wheels in whatever direction the driver wants, much like a conventional system.

     

    Most of the moving parts in the linkage are a rotating ball and socket with a boot to keep them greased. If the ball and socket wear to the point where there is play between them, they are considered to be loose. A loose socket will wear quickly and could result in complete breakage and loss of steering control. Checking the linkages for looseness is part of the general inspection process we do every time your vehicle is in for service.

    Moving all of these parts with just our arm-strength alone would result in some pretty wicked biceps, but most of us these days prefer to keep our workouts in the gym. This is where power steering comes to the rescue, especially at low speeds. Traditional power steering systems use hydraulic pressure to provide a nice, fluid movement when we turn the wheel. There is a pump, driven off of the engine, sending pressurized hydraulic fluid down to the steering gear and back up in a loop. Sometimes there is also a fluid cooler in that loop. This is a tried and true system, but it has many potential leak spots and robs some power and efficiency from the engine.  This type of system also requires maintenance, in the form of periodic power steering flushes to remove varnish and worn fluid.

     

    In a quest for better fuel economy and packaging efficiency, electric power steering systems were developed. Electric systems provide the same type of steering assist but use motors and sensors instead of pressurized fluid. There are less moving parts, but more sensitive electrical components and computers. With some of these vehicles approaching ten years old, we are starting to see some of their failure points.

     

  • Let's Get Technical! - Cooling Systems

    Posted on 13, November, 2017

    You might think that the cooling system in your vehicle is only important in the summertime, given its name, but that couldn't be further from the truth! Coolant, the lifeblood of your cooling system, is also called “antifreeze.” This vital fluid has many roles. In addition to keeping the engine cool, coolant needs to be able to stay in a liquid form in subzero temperatures and above the boiling point of water, circulate heat to the cabin, lubricate moving parts and keep rust, scale and corrosion from forming inside the system. All engines create heat from the combustion process, and need a system in place to dissipate it. Some engines are air-cooled, with the oil carrying the majority of the heat to the outer metal parts of the engine to be transferred to the air. These are generally smaller engines, such as those found in lawn mowers and some motorcycles. Volkswagen and Porsche engines were also exclusively air-cooled for many years. Today, most engines use a liquid cooling system that transfers heat to a mixture of water and coolant that flows through the engine and brings it out to the radiator, which then transfers it to the air. Even electric and hybrid vehicles use a liquid cooling system to transfer heat from batteries, electric motors and power inverters.

    If coolant is the lifeblood of the system, then the water pump is its heart. This central piece pumps coolant into the engine to pick up heat and then back out to the radiator to dissipate it. Water pumps are typically driven off of the rotation of the engine, but some newer designs are operated by a separate electric motor. Because the water pump is always spinning, it has a bearing inside of it. As this bearing begins to fail, it can cause leaks and poor movement of coolant. It can also seize, causing a complete loss of pumping ability and usually a shredded belt.

    The engine has many cooling passages that allow the coolant to flow through and pick up as much heat as possible. The coolant then flows through high-volume hoses back to the radiator and heater core. Small fins on the radiator and heater core act as a heat-sink to pull the heat out of the coolant and into the air. The radiator, being the larger of the two, sits out in front of the vehicle and uses a combination of vehicle movement and supplementary fans to accelerate the air moving across the fins, and thus the rate of heat dissipation. These supplementary fans are powered either by electric motors or a fan attached to the water pump and driven by the engine. Temperature sensors, either electronic or thermostatic, engage the fans only when additional cooling is needed.

    The heater core is essentially a smaller radiator, but its job is to provide heat to the cabin of the vehicle. This is heat that would otherwise be wasted, so it might as well be put to good use! The smallest coolant passages in the system usually reside in the heater core, so they become clogged first. A clogged heater core will result in diminished or no heat in the cabin.

    Also present in the cooling system is a thermostat. Its job is to regulate the flow of coolant to the radiator and maintain a consistent temperature. When the engine is cold, the thermostat is completely closed and does not allow any coolant to flow to the radiator. This is because the engine needs to get up to operating temperature as fast as possible. Engines are most efficient and powerful when operating in their ideal temperature range. As the engine warms up, the thermostat begins to open and allow coolant to flow to the radiator, fully opening as it reaches normal operating temperature. A thermostat that is not opening properly will cause an engine to run hot. One that is not closing properly will cause the engine to run inefficiently and reduce the flow of heat to the cabin.

    Automotive cooling systems are designed to operate at a relatively low pressure (less than 20 psi) and rely on that pressure to keep coolant flowing and temperatures consistent. Leaks, blockages and air pockets skew pressures and can cause overheating, Because coolant plays such a vital role in the cooling system and touches nearly every part of it, making sure it is fresh and clean is the best way to extend the life of all of the components in the system.

     

  • Let's Get Technical! - Shocks and Struts

    Posted on 20, September, 2017

                  With Shocktober just around the corner, we decided it would be a good idea to shed some light on your shocks and struts and what they do for your vehicle. Since the time before cars, when wagons and carriages plied dirt roads and cobblestone streets, something was needed to isolate the occupants from the jarring road. Springs were fitted to absorb some of the impact and keep the horse-drawn vehicles from hopping all over the road. Early cars used a similar setup, but as vehicles began to travel faster, something was needed to stop the bouncing action of the spring and to keep the tire in contact with the road.

     

    Enter the shock absorber. A shock absorber is an oil-filled tube that is designed to dampen the force of road impacts and spring oscillations. For many years, most cars and trucks came fitted with four shock absorbers, two in the front and two in the rear. They were a relatively simple affair and were only designed to move up and down. As suspensions became more complicated, a more integrated solution was required and the strut was born.

     

    While there are many variations in strut design, most incorporate the strut, spring and a mount into one assembly. On the top they connect to the body of the car, and on the bottom they connect to the front steering and suspension. Because they are connected to the steering system, they twist every time the wheel is turned and are a much more “active” part of the suspension than shocks are. In hard stops they reduce the tendency for the car to dive, shortening the stopping distance. On curves, lane changes and evasive maneuvers they keep the car under control and going in the right direction. In front wheel drive and all wheel drive cars (the majority of cars on the road), they also help to maintain traction at the drive wheels. 

    Shocks and struts absorb road forces and protect tie rods, control arms, sway bar links, ball joints and bushings from wear and fatigue.  Over 50,000 miles, a shock or strut will have moved up and down an average of 75 million times, even on good pavement. In Michigan that number may be, umm, a bit higher. Ride and handling degradation is something that happens gradually, but restoring your cars dampening system to new can make a marked difference. If the struts are actively leaking hydraulic fluid, they are providing little to no dampening.

     

    As they say in the old Monroe commercials, “Save the Squirrels!”

  • Let's Get Technical- Tires!

    Posted on 15, August, 2017

    This month we are going to take a closer look at the round black things that connect your car to the ground: tires! We tend to only think of tires when the snow flies, but summer is actually when we put the most miles on our cars and having good tires is important.

     

    Tires these days have many roles to play. The one we think of most of course is longevity, but there are other factors to consider when purchasing tires. Living in Michigan, we need tires that can handle rain, snow and ice, while still providing good handling on dry pavement and in the intense heat. That is a tall order for any tire, which is why two sets of dedicated tires, one for summer and one for winter, is ideal. But this presents cost and logistics problems and isn’t for everyone, so the next best thing is a good set of all season tires.

     

    Tread compound and tread design are the two components that are responsible for creating this happy medium. The compound must be hard enough to give a long life but soft enough to hold the road and give good traction when temperatures drop. The tread pattern determines how well the tire will expel water, slush and snow, as well as how the tire handles cornering and highway ruts. Tire manufacturers are always innovating and improving their designs, but will often continue to manufacture their older designs under private label brands. For example, Cooper makes Mastercraft tires, Firestone makes Fuzion, Goodyear makes Kelly and so on.

     

    In addition to the US and European brands that we are all used to, many of the larger Asian brands have come into the market over the past 10-20 years. Yokohama, Toyo and Sumitomo are long-standing Japanese brands, while Hankook and Kumho are long-standing Korean brands. All of these brands are used by domestic and import car manufacturers as original equipment on their new cars. The Finnish brand Nokian has had a small presence in the US market with their snow tires (after all, who knows winter driving better than the Finns?) but they are now trying to break in with their all-season and performance tires and there are some great deals to be had. Here at Kirk’s we are constantly evaluating new tires as they come on the market in an effort to determine which will be the best values for our customers.

     

    Even the best tires will wear out eventually, and it is important to know when that has happened or is imminent. The first thing to look at is tread depth. New tires come with somewhere between 10/32” and 14/32” of tread depth, depending on the type of tire. As the tread wears, the channels are able to dissipate less water, ice and snow, and by 4/32” their ability to work is greatly reduced. The wear bars on a tire are at 2/32” and are at this point considered “bald.” Sometimes a tire will wear evenly across its tread, and other times the outside edges or center tread will wear first. Outside edge wear, especially on one side only, is often indicative or an alignment or suspension issue. These issues can also cause feathering and cupping, both of which can lead to noise and vibration. Inside wear is often indicative of under-inflation. Did you know that tires tend to lose around 1 psi of pressure each month? They also gain or lose 1 psi for every 10-degree change in temperature, so it is important to check them whenever there are large swings.

     

    Miles are not the only thing that takes a toll on the life of a tire, they also wear out due to age. High heat, sub-zero temperatures, UV light and other environmental conditions will cause the rubber in your tires to break down. This wear usually presents itself in the form of dry-rotting and cracks in the sidewall or tread of the tire. Dry-rotted tires are at a greater risk of blowing out, so it is important to replace them. Tread compounds can also harden, causing reduced traction in poor weather.

     

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    Finally, our wonderful Michigan roads can wreak havoc on the lifespan of our tires. Potholes can cause sidewalls to bubble or steel belts to shift, while nails, screws and other road debris can become imbedded in the tires. Impact damage is not repairable, but punctures can be, as the long as the damage is not to the sidewall of the tire. If a puncture is not too close to the side of the tire and is small enough, we can usually patch it from the inside. This is a permanent repair and is much preferable to a plug that goes in from the outside. If your tire ever becomes very low or even flat, do not drive on it! This can damage the tire further and may result in a repairable tire having to be replaced completely. We are working on a road-hazard warranty program that we will be offering soon through Kirk’s, so stay tuned!

  • Let's Get Technical- A/C!

    Posted on 12, July, 2017

    We are in the midst of A/C season here at Kirk’s and thought that now would be a good time to dig into that system a little. The A/C system in your car works in much the same way as the A/C in your home, as well as the system that keeps the food cold in your refrigerator.  The system operates by changing refrigerant back and forth between a liquid and a gas, absorbing heat and dissipating it. The journey starts at the compressor, which pressurizes refrigerant in gas form, sending it to the condenser, which lives at the front of the car, just ahead of the radiator. A cooling fan blows air across the condenser, turning that high-pressure gas into a high pressure liquid and dissipating the heat. The high-pressure liquid then travels to the receiver drier, which pulls any moisture out of it and sends it on to the expansion valve or orifice tube. The valve or tube (depending on the style of the system) turns the high pressure liquid into a low-pressure liquid, and sends it through the evaporator. The evaporator is located behind your dash and is what provides the “cool.” The blower motor inside the car blows across the evaporator, changing the low-pressure liquid into a low-pressure gas, while absorbing heat. The low-pressure gas is then sent back to the compressor to start the process all over again.  

    Also part of the system are pressure sensors that will shut the system down if pressures go too high or low, a temperature sensor to make sure the outside temperature is warm enough for the compressor to operate safely, and a temperature sensor to make sure that the evaporator isn’t icing up. Finally, because the compressor is operated off of the engine, there is a clutch that engages the compressor when the system calls for cooling, letting the pulley freewheel when there is no call.

    When your A/C stops blowing cold there are numerous things that could be causing it.  The most common problem is low or no refrigerant in the system, generally due to a leak. Refrigerant can leak from almost anywhere in the system; rubber hoses and o-rings degrade over time, seals on the compressor can give out, metal lines, condensers and evaporators can corrode or crack. Once we have determined that the system is low on refrigerant, we will look for any obvious signs of leakage or breakage. If everything looks okay, we will evacuate whatever refrigerant is left, pull a vacuum and add the correct amount of refrigerant. We will also add a UV dye to help us detect any leaks.

    Other common problems are compressor clutches that wear out, pressure and temperature switches that go bad, and complete compressor failure. In the latter case, the compressor will often release debris into the system as it fails, necessitating a flush of the system and sometimes replacement of clogged parts.

    Even when your A/C system is functioning correctly, it is only designed to drop the temperature at the vents in your dash by 40 degrees or so.  So if it is 100 degrees outside, your A/C might not be working as well as you think it should! Humidity also effects your A/C’s efficiency.

    One last little tip: when using your A/C in hot weather, keep it on recirculation mode (or MAX mode depending on your system). This closes the fresh air intake and recirculates the already cooled air in the car. Turning into a closed system also allows the fan to blower stronger, getting every last bit of cool into your cabin. We hope you enjoy the rest of your summer in comfort!