Ask Joe Mechanic: Check Your Vehicle Before You Hit the Road!

It’s that time of year when many of us are thinking about or already have planned a road trip with our family to a favorite summer vacation destination.  Along with the packing list for necessary items for the trip, should be a pre-road trip checklist for your vehicle as well.  We all know that one of the worst ways to interrupt a relaxing vacation is with a broken-down vehicle.  By verifying the operational condition of a few key items on your vehicle before you depart, you can greatly decrease the likelihood of an inconvenient, and possibly expensive roadside assistance call to AAA. 

Here are a few items to check on before you hit the road:

·       Read your owner’s manual for the “how to’s” – how to properly tow a trailer, change your tires or a light bulb, jumpstarting a dead battery and more.

·       Lift the hood and verify that all fluids and belts look to be in good shape.  Top off the fluids that are low (paying extra special attention to coolant, transmission fluid and engine oil), and while you’re at it, check for fluid leaks.

·       Give your battery a once over.  Does it have clean terminals and appear to be in good working order?  If not, consider replacing it before you depart.

·       Are the tires in good shape?  Check the tread, wear and pressure.  If any of this appears questionable, take the necessary steps to replace, rotate or fill them with the needed air.

·       What about the electrical items?  Are your lights, horn and wipers working the way they’re intended?  If you’re of the knowhow to replace and/or tinker with these items yourself, then do so, if not, take them to your mechanic for replacement and repair.

·       Check the trunk.  Make sure your emergency car care kit is well stocked, your spare tire and accompanying tools are in shipshape and you readily know where your wheel key lock is, if you have a wheel lock on your vehicle.

·       What’s the deal with the GPS?  If you have an in-vehicle navigation system, be sure its mapping software has been recently updated.  If you rely on a window or dash-mounted unit, be sure you have its power cable close-at-hand.  If you use a smartphone-based GPS, consider getting a mount for the device so you can keep your hands free for driving.

·       One final note, if you’re considering a particularly long-haul trip, it might be a good idea to have your mechanic or garage give the underside of your vehicle a once over.  It’s better to be safe then sorry when it comes to axels, brakes, shocks, drive train and the other major operational items of your vehicle when your planning to put hundreds or thousands of miles on your automobile during a vacation.

Road tripping doesn’t need to be a hassle.  Taking care of your vehicle before you depart for summer vacation with these simple checklist items can definitely help reduce pre-trip jitters!  We hope you and your family have a great time traveling the highways of America as you vacation this summer!

Information for this article was sourced from AAA.com and Wikipedia.org.

Ask Joe Mechanic: Supercharging

Before I start this week’s article, I want to publicly thank Stephanie, who collaborated with me on the Meet Joe Mechanic article, for stepping in at a late time last week when for medical reasons I could not put my column together and found a suitable and timely replacement for me. I am now on the mend and am resuming my duties on a slightly limited basis.

            Supercharging in theory is very similar in what it does to turbocharging. In fact, turbocharging was originally called turbo-supercharging. The main difference between the two is where the power is created that forces the intake charge into the engine. In turbocharging, we already saw that that force was the use of the exhaust escaping the engine, which forced the intake charge into the engine. In supercharging, it is by external mechanical means, usually a belt, a chain or direct drive from the crankshaft of the engine.

            Ironically, the first effective use of supercharging had nothing at all to do with an engine. In 1860, Brothers Francis and Philander Roots of Connersville, Indiana, were exploring the means to get more air into blast furnaces for making steel and other industrial applications. Their company, Roots Blower Company, developed the first operating supercharger, which forced air into those blast furnaces.  It was that design which became the most commonly used supercharger design for many years.

           

The first use of a supercharger on a functioning engine was by Dugald Clerk in 1878 on a two-stroke engine. Gottlieb Daimler, a name well known in early automotive history, received a German patent for a supercharger on an internal combustion engine in 1885. Louis Renault, another well-known name of the Renault automotive family, received a French patent for a centrifugal supercharger in 1902.

            Ironically, the first known application of a supercharger took place in Pottstown, Pennsylvania by Lee Chadwick in 1908 and his car achieved an almost unheard of speed for that time of 100 miles per hour. The Chadwick factory still stands in Pottstown, in recent years in was home to the Bill Pollack, of Pollack Steel Company, automobile collection. That collection included a couple very rare Chadwick automobiles. The Chadwick will be a subject of a future Automotive History article, as I knew the late Bill Pollack personally and have been to his museum a number of times.

            The first production road cars with superchargers were built in 1921 by whom else, but Mercedes. The models were the 6/25/40HP and the 10/40/65HP and had Roots superchargers. They were designated “Kompressor,”, a designation that Mercedes uses to this day on all supercharged cars they build.

            Another design for a supercharger received a patent in 1878 by Heimrick Krigar of Germany. This was for a screw type supercharger, which is actually a much more efficient design, but its parts are very difficult to machine. The design utilizes two opposing screws with a 180 degree twist along their length which combines to create a full 360 degree turn. The design was so advanced for its time that it took until 1935 to be able to create the first working model by Alf Lysholm of Sweden working for Ljungstroms Angturbin AB, which became the Svenska Aeroplaten Company, which eventually became Saab. Who ironically became the first mass-produced successful turbocharged automobile and at the time the only company which produced an all turbocharged model line.

            There are two main types of superchargers, which are designated by the method of air transfer. The two types are positive displacement and dynamic compressors. Positive displacement blowers deliver an almost constant pressure increase at all engine speeds. Dynamic compressors do not build pressure at idle or low speeds; above a certain threshold speed pressure increases with engine speed. Positive displacement pumps deliver a nearly fixed volume of air per engine revolution at all speeds, minus leakage, which means its importance decreases at higher speeds.

            Positive displacement pumps are further subdivided into two groups, internal and external compression. Roots superchargers are of the external type, although the high-helix roots blowers try to have the same effectiveness as the Lysholm screw. All other superchargers have some degree of internal compression. Internal compression means that the compression of the air charge takes place inside the body of the supercharger. This is more effective and efficient than the backflow compression of the Roots type and means a smoother transition to boost than the other type. Internal compression superchargers usually have a fixed boost pressure which equals the compression pressure of the supercharger, thus back flow is zero. If the boost pressure is higher, back flow will occur, but if properly matched, they achieve a very high factor of efficiency.

Some information for this article was sourced from www.wikipedia.org.

Ask Joe Mechanic: Mecum Auction

This week, I am putting my turbocharging and supercharging series on hold again due to the significant importance of an automotive event that took place in Harrisburg this past weekend. The first Mecum Harrisburg collector car auction took place at the Harrisburg Farm Show Arena and I had the privilege of full access media credentials for the event. I attended a pre-auction event on Wednesday afternoon and evening. During this time I had a chance to talk with some of the Mecum personnel and view the vehicles that had arrived without fighting the crowd. This also gave me an opportunity took take a lot of photographs without difficulty. I will say that over the course of my time there, I took over 575 photographs.

            This was the first national and world-recognized auction company to come to the northeastern United States to hold a collector car auction. Yes, we have all attended events and auctions at Carlisle, Hershey, Atlantic City, Wildwood and others, but none of them compare to the size and quality of the vehicles that I witnessed at this event. I spent three days in Harrisburg, and I’ll tell you that if I had the money, I would have bought quite a number of vehicles. In fact, I need to retract a statement that I recently made in the Meet Joe Mechanic article. I stated that it is impossible for a car person to pick just one vehicle that he would like to have, but I could narrow it down to three or four. That is no longer true. Upon returning home and sitting down to work on this article, I wanted to pick twelve cars that I would have bought had I a seven or eight figure bank account (no decimal places), but I found that I had difficulty getting the list down to twenty.

            Those twenty vehicles I picked are featured in a special section of this week’s center glossy pages called Joe’s Picks with a short description and why I chose them. Some of these vehicles were sold, some were not, and that was only because I didn’t have money! Seriously, look through the photos and compare them with what your choices would be. I have featured about thirty or forty cars from each day, along with the price that they sold for.

Have fun and enjoy!  There is also a short article called Reflections on the First Mecum Harrisburg Auction in which I give some of my own observations.  Also featured is some information that I received in a post auction interview with a gentleman from Mecum Auctions Inc.

Ask Joe Mechanic: Turbocharging Part II

We discussed in part 1 that turbocharging lately has become very advanced due to the governmental requirements to achieve higher gas mileage ratings. We now are finding turbochargers installed on V-6 engines which either necessitates some special designing to use only one turbo, or the use of twin-turbochargers.  With twin turbos on a V-6 engine, each manifold has a turbocharger installed on it and both feed into a single plenum on the intake manifold. This system is also used on boxer or flat engines such as Subaru uses. 

There are also manufacturers who are using twin-turbochargers in series to create higher boost at higher road speed, but eliminate turbo lag at low speeds. To accomplish this, a small turbo charger is installed first which will spool up quickly at low speeds. Then, there are specially designed piping leading to a second larger turbocharger for road speed. This type system is most commonly used on diesel engines, but some exotic car builders also use it.

            Another design is the twin-scroll turbocharger where there are two exhaust inlets in one turbocharger, with a smaller angled one designed for quick response and a second less angled larger inlet for peak performance. Usually, these twin turbos will pair cylinders 1 and 4 along with pairing 2 and 3 to more efficiently burn the fuel mixture and to reduce engine manifold temperatures. It will also greatly reduce turbo lag.

            Variable geometry or variable nozzle turbos adjust the amount of air entering the intake side of the turbocharger with a set of adjustable vanes. This will cause the turbocharger to operate at optimum pressure and efficiency based on the demand placed on it. There is an actuator which is computer controlled to move the vanes to increase or decrease airflow. By doing so, it will maintain the correct exhaust velocity throughout the engine’s power range and limit turbo lag.

            The center housing/hub rotating assembly (CHRA) is the most highly engineered and probably the most important part of the turbocharger. This section contains the lubrication, cooling and the turbine impellers and their mounting. The housing has ports for engine coolant to run throughout, and also oil passages to the bearing system. The bearings in most automotive turbochargers are either high-speed ball bearings or thrust bearings. In older turbochargers, the oil would sometimes become so hot that it would actually harden around the bearing, called coking, and this would cause the turbo to fail. This risk has been greatly reduced with better bearings, cooling designs and synthetic oils, which are more resistant to heat.

            One of the technologies that has been most effective in improving turbocharger performance is intercooling. The process of intercooling is basically forcing the air from the intake side of the turbo through a radiator in an effort to cool it as much as possible. The reason for this is that hot air is less dense than cool air and that loss of density means loss of power. When you force air through the turbocharger it builds up heat, plus it absorbs some from heat transfer from the exhaust side, so by going through the intercooler, it gives the air a chance to cool down before entering the engine.

            Another application that is used often by performance tuners is water injection where a spray of water is injected into the air charge to further cool it. A variation of this is to actually alter the air/fuel ratio by richening the mixture. The extra fuel does not actually get burned, but by turning the fuel from a liquid to a gas, it absorbs heat.

            The final add on feature to a turbocharger is a waste-gate. The waste-gate’s purpose is to regulate the pressure built in the turbocharger by regulating the amount of exhaust gas passing through the turbo. A pressure sensor sensing that the engine is reaching optimum boost pressure does this. The sensor sends a signal to the engine computer, which in turn sends a signal to a vacuum valve that opens and pulls vacuum, opening the waste-gate and allowing the exhaust gas to bypass the turbo.

Some information for this post was sourced from www.wikipedia.org.

Ask Joe Mechanic: Turbocharging Part 1

Over the next several weeks, we are going to discuss turbocharging and supercharging.

Compressor Section of an Automobile

We’ll start with the history of turbocharging, followed by how it works and its main parts. We will then do the same for supercharging. After completing these, we will discuss the advantages and disadvantages of each in a comparison.

            Alfred Buchi of Switzerland who developed a compressor driven by exhaust gas to force air into the intake of a diesel engine to create more power patented the first turbocharger in 1905. It still took another twenty years though before an actual operating turbocharger was built for vehicular use. There were several attempts by the French to turbocharge some types of airplane engines in World War I with limited success. Turbocharging of aircraft engines was perfected by the early 1920s and a short time later the same thing took place on diesel engines on ships. 

The two biggest problems to developing a turbocharger for automotive use were the ability to scale down the size and manufacturing a seal that could be small enough but withstand the pressure and heat inherent to turbocharging. There were some applications to racecars during the 1940s and 1950s, but many of these were adapted aircraft turbochargers. The first manufacturer to produce a production built vehicle with turbocharging was Saab in 1977. Other manufacturers followed, unfortunately, many of the early turbochargers failed due to heat and seal problems. Saab started using a turbocharger which was cooled by antifreeze in 1986, and this proved much more reliable. Since that time, and especially in the last few years, turbocharging has become very popular because of the ability to derive the same or more power from a much smaller displacement engine, thereby achieving a much higher gas mileage without sacrificing performance, and in many cases bettering it.

The theory behind turbocharging is actually quite simple. In most internal combustion engines, the intake mixture of gas and air is actually drawn into the engine by the downward movement of the piston. In a turbocharged engine, that intake charge is forced into the engine by the turbocharger, resulting in a much larger volume of intake charge, which when ignited by the spark plug, creates much more power. The pressure to force that charge into the intake comes from the other half of the turbocharger, which is spun by the exhaust gases that are escaping from the engine. Also, the use of pressurizing the charge causes it to burn more fully, which increases the fuel efficiency of the vehicle.

The control of turbocharging has evolved dramatically in the last few years and is now quite complex. Many manufacturers now use knock sensors, all use waste-gates and blow off valves. And many use variable geometry and intercooling. 

            Boost is the term applied to the amount of pressure created by the turbocharger above normal atmospheric pressure. The level of boost is normally indicated on a pressure gauge in bar, psi or kPa. Boost pressure must be controlled so that the design of the engine is not exceeded which would cause it to fail prematurely. Over-boosting can damage the engine by overheating, over-stressing of parts or by detonation. Detonation or preignition means that due to the amount of heat and pressure, the intake charge ignites before the piston is near the top of its cycle. This exerts undue stress and heat on the internal parts. This is controlled with a knock sensor, which if it detects detonation, signals the computer to open to blow-off valve, which will release the boost pressure. The same thing can be achieved by the waste-gate which is vacuum controlled.

            The main components of the turbocharger are the turbine, which is a radial flow design to build pressure on the intake side. The compressor section is where the exhaust gas passes through to build the pressure. The center housing is where the seals, lubrication and cooling are contained. The size and design of the compressor components dictate how much boost it will create and how quickly it will build to maximum boost. In some turbochargers, it is possible for the impellor to spin at speeds of up to 250,000 rpm. This is the reason that seal design, heat dissipation and lubrication are so important.

Next week we will discuss the types of turbochargers and the other related technologies. Some information for this article was sourced from www.wikipedia.org.

You Auto Know: Lamborghini Gallardo

One of the regional cover images on this week's edition of our print publication is a Lamborghini Gallardo.  The car is a rare edition Bubble White with a scant 2000 miles on the odometer.  Are you in the market for a new Lambo?  If so, a cool $144K will park this 2008 model year in your garage!

7/18/14 regional cover of Auto Locator

  
Did you know that the Gallardo, named for the fighting breed of bull, was the manufacturer's most popular selling model during its decade of production?  Just over 14,000 units were manufactured between 2003 and 2013, with the last one rolling off the production line in November of that year. 

Believe or not, two Gallardos are used by the Italian police force for traffic operations.  The pair of L140s were donated to the force in honor of their 152nd anniversary in 2004.  To read more about the history, use and manufacture of Gallardos, check out the Wikipedia Lambo article from which we sourced our facts!

Ask Joe Mechanic: Steering and Suspensions Part 4

Continuing our discussion from last week, the next factor for suspension design and tuning is called the roll couple percentage. This is a determination of handling balance, which is the wheel rate of each axle in roll as a ratio of the total roll rate. This lateral roll transfer is controlled and adjusted by using an anti-roll bar.

            The next factor is weight transfer. Weight transfer takes place during any change of motion, whether cornering, acceleration or braking. It is calculated at each wheel and is a comparison of the highest load to the static or standing weight on each wheel. There are four factors that control weight transfer, the distance between wheel centers (wheelbase in the case of acceleration and braking, and track width in the case of cornering). Also, the height of the center of gravity, the weight of the vehicle, and the rate of acceleration of deceleration are determining factors.

            Unsprung weight transfer is dependent on weight transfer but includes more factors. This includes all the weight not controlled by the springs. That would include the wheels and tires, hubs and spindles, brakes and rotors or drums, and half the weight of the control arms and axles. For calculation, they are put through the same forces as for weight transfer.

            Sprung weight transfer is the weight transfer of the weight resting on the vehicles’  

springs. To calculate this, you need to know the sprung weight, the roll center heights front and rear, and the sprung center of gravity, which will be higher than the normal center of gravity. Also needed is the roll couple percentage. 

            Jacking force is the total vertical force exerted on the suspension links. This is determined with use of the roll center, with the higher the roll center meaning a higher jacking force.

            Travel is the total distance that a suspension can move from the top of its stroke to the bottom. If a wheel can be forced upward against its stop, this is called bottoming. Bottoming is an extremely dangerous situation as it can cause a catastrophic loss of vehicle control. This can be cause by quite a number of things including; the suspension hitting its limit stop, a broken or worn spring, strut or shock, tires coming into hard contact with a body part, part of the car hitting the pavement, etc. Lifting is the opposite situation where the tire actually looses contact with the road because the suspension is fully extended. This can also cause a dangerous situation, especially if it takes place in a curve. Off road vehicles require limit straps or stays so that with the extreme suspension travel that they experience, that the coil springs do not come out of their perches or cause damage to the suspension bushings and links. The opposite effect is accomplished by use of a bump stop, usually made of rubber, which prevents full compression of a suspension.

            Damping is the control of motion by the use of the valving of shock absorbers. This is also a compromise between comfort and control. Damping controls the resistance and the speed that a suspension moves up and down. If properly controlled and adjusted, the vehicle will return to its normal ride position in a minimum amount of time with a minimum amount of discomfort.

            The next factor is camber control. Camber will change due to wheel travel, body roll and suspension movement. In general, a vehicle’s optimum control and tire wear occurs with one to two degrees of negative camber off vertical. Some racing applications may run as high as seven degrees negative. Many older rear-wheel drive cars and trucks actually ran positive camber. Mounting placement and suspension geometry controls camber.

            Roll center height is a product of suspension instant center heights and is a critical determining factor in analyzing weight transfer, body roll, and front to rear roll stiffness. This particularly is critical to controlling jacking forces. Instant center is an imaginary arc through the wheel and suspension intersecting points when viewed from the front. This helps to determine how weight transfer affects the deflection of the suspension.

            Anti-dive and anti-squat are percentages that refer to the dive that occurs when braking or the rear of the vehicle squatting during acceleration. If a vehicle is rear drive with inboard brakes and half shafts such as a Jaguar uses, this is not a factor, but for most vehicles it must be controlled. Forward anti-dive and squat are much more critical to control due to the necessity to maintain vehicle control. These factors are used to help determine the percentage of braking front to rear, better known as brake bias.

            Flexibility and vibration in suspension is determined by the size and composition of suspension bushings. There can also be detrimental vibrations caused by the flexing of structural parts such as during accelerating in a hard turn. Another factor is how to insolate high frequency shock and vibrations. For this, consideration must be made to the design of the suspension components. Tires, springs and shocks will tune out most vertical vibration, but lateral noise and vibration must be filtered by the suspension bushings and components.

Unsprung weight is an important factor. Unsprung weight is those components such as wheels, tires hubs, spindles and brakes that are not controlled by the suspension. The lower the unsprung weight, the better it is. This is the reason for the popularity of alloy wheels and also now seeing the usage of aluminum in suspension components. 

            Space occupied is critical in front wheel drive vehicles. McPherson struts require much less space than most other designs. This is also a reason why most vehicles do not use inboard brakes even though it reduces unsprung weight, although cost is another reason.  Force distribution is the matching of the suspension mountings too the frame design in regards to strength, geometry, rigidity and materials.

            Air resistance or drag is another consideration, especially with today’s high importance on fuel efficiency. Some vehicles actually use a height adjustable suspension to lower drag at higher speeds. Also, you are now finding suspension components that are made from oval as opposed to round tubing to cut drag. Also, in many higher performance cars, you will see the spring/shock assemblies moved inboard out of the airstream and being controlled by rocker arms or pull rods. 

            The final factor is something that enters into almost every facet of our lives, that being cost. Even though it is not the most efficient, most rear wheel drive vehicles, especially trucks, still utilize the solid, unsprung rear axle as it is still the most cost effective rear wheel drive system.

            We have now covered the factors that are required to be considered when designing a vehicle suspension system. Starting next week, we will explore the history of and current types of suspension systems in use.

Portions of this post were sourced from www.wikipedia.org.