■ 5 GENERATIONS OF DURAMAX
■ LESSONS IN OFF-ROAD SUSPENSION
■ TECH TIPS: ROMEO 4.6L 2V
November 2012 TomorrowsTechnician.com
CONTENTS IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
UNDER THE HOOD 10 Five Generations of Duramax Diagnostics The Duramax diesel brought GM back as a major player to the mid-size truck market by offering dependability, fuel mileage and quiet operation with plenty of power, says contributor Bob McDonald. While these engines have a great reputation, some problems are bound to arise.
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SCHOOL OF THE YEAR 18 CPTC Scales to New Heights Clover Park Technical College in Lakewood, WA, was named the 2012 Tomorrow’s Technician School of the Year during a surprise award ceremony in October for students and instructors of the automotive program. Read what makes them a Top School in this annual competition recognizing auto programs from across the country.
UNDERCOVER 20 Lessons in Off-Road Suspension Systems There’s a lot more to building a rugged off-road vehicle than just raising the suspension height and installing big tires and wheels. Gary Goms highlights some of the more common problems and their solutions in this month’s Undercover feature.
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Finish Line: Life in the Fast Lane
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TT Toolbox
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Tech Tips: Romeo is Leaking
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TT Crossword
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Tesla Model S is named 2013 Motor Trend Car of the Year — the first time an electric car wins the title in the award's 64-year history. The Tesla's ultra-quiet electric powertrain delivers the driving characteristics and packaging solutions that make the Model S stand out against many of its internal combustion engine peers. The carmaker says the Tesla Model S is the fastest American-built sedan on the market, posting 0-60 times as low as 3.9 seconds. Read more at: http://bit.ly/UGuv8h
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4 November 2012 | TomorrowsTechnician.com
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edited by Tomorrow’s Technician staff Each month, Tomorrow’s Technician takes a look at some of the automotive-related student competitions taking place in this country, as well as the world. Throughout the year in “Finish Line,” we will highlight not only the programs and information on how schools can enter, but we’ll also profile some of the top competitors in those programs. Because there are good students and instructors in these events, we feel it’s time to give these competitors the recognition they deserve.
TEAM MOTIVE GEAR TAKES RACES TO WIN AT HOT RODDERS OF TOMORROW ENGINE CHALLENGE NATIONAL CHAMPIONSHIP Las Vegas, NV — Loara High School, Anaheim, CA, won its third straight National Championship Title in the Hot Rodders of Tomorrow Engine Challenge. Listed as Team MOTIVE GEAR, the Loara High School student team beat out 12 other teams in the 4th Annual "Showdown at SEMA" with an average time of 21:24 minutes. It was a tight competition for the four-day event. In fact, the top three teams were so competitive that they all ended up less than a minute apart. According to event organizers, all 13 teams competing this year did fantastically well, with the 13th-placed team average time being only 33:46.
Rodder Rebuild The event itself resembles the tear down between rounds at a drag race. The engines are identically prepared small block Chevys complete with all the performance components: Edelbrock air cleaners, carbs, aluminum manifolds, heads, water pumps and valve covers; MSD distributors and wires; K&N oil filters; Hedman ceramic headers; TD timing chain covers; Moroso oil pans; ARP head bolts; Fel-Pro/SpeedPro gaskets and components; Melling oil pumps;
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and Royal Purple lubricants.
Race against Time The event pits high-school teams against each other in a contest to properly tear down a race engine to just the crank, cam and block using hand tools only with proper de-torque and disassembly procedures. Once the engine is disassembled, the team returns behind its
November 2012 | TomorrowsTechnician.com
workbench, and when allowed by the judges, the team begins working to reassemble the engine with correct assembly procedure and torque specs, all while being viewed by judges and spectators. Penalty minutes are assessed to the engine assembly recorded time for dropped components, improper disassembly/assembly, poor sportsmanship, etc. All
"Showdown at SEMA" is the title of the Hot Rodders of Tomorrow Engine Challenge National Championship at the Specialty Equipment Market Association (SEMA) Show in Las Vegas. This year, 13 High School Auto Tech teams competed Oct. 29 through Nov. 1 in the engine teardown and rebuild contest in front of thousands of spectators at the entrance of the SEMA show.
procedural penalties are in the Hot Rodders of Tomorrow rulebook that was provided to the competing high schools at the start of the school year. The team with the fastest time, including penalty minutes, is chosen as the winner.
Event Winners and Wildcard Teams Compete This year, 13 teams earned their way to the "Showdown at SEMA" national championship. Eight teams were represented by winning regional events throughout the country, and five additional teams were added to the contest for having the next best qualifying times during
regional competitions. During the normal regional event competitions through the year, all participating teams compete once. The team with the best time wins the regional event and is given the opportunity to compete in the national championship at SEMA. However, during the national championship "Showdown at SEMA," all the teams compete a total of four times. On the last day of the four-day event, each team's highest time was thrown out and the remaining three times were averaged to determine the top engine builder.
Final Team Rankings First Place: Team MOTIVE GEAR (seen to the right) - Loara High School, Anaheim CA - average time - 21:24. Second Place: Team ENERGY SUSPENSION - Eastern Oklahoma County Tech Center, Choctaw, OK - average time - 21:54 Third Place - Team MR. GASKET - East Ridge High School, Chattanooga, TN - average time - 22:19 Fourth Place - Team AEROMOTIVE – Burton Center for Arts & Technology, Salem, VA - average time - 24:46 Fifth Place - Team MAGNAFLOW - North Orange County ROP, Anaheim, CA average time - 25:35 Sixth Place - Team ROYAL PURPLE - Elkhart Area Career Center #1, Elkhart, IN - average time - 25:50 Seventh Place - Team ARP- Elkhart Area Career Center #2, Elkhart, IN average time - 25:53 Eighth Place - Team PROFORM - Peach County High School, Fort Valley, GA - average time - 26:14 Ninth Place - Team THERMO-TEC - Thomas County Central High School, Thomasville, GA - average time - 27:40 Tenth Place - Team EDELBROCK - Fremd High School, Palatine, IL - average time - 28:50 Eleventh Place - Team HEDMAN HEDDERS - Belvidere North High School, Belvidere, IL - average time - 31:04 Twelfth Place - Team MSD - Joliet Central High School, Joliet, IL - average time - 32:31 Thirteenth Place - Team PAINLESS PERFORMANCE - Sequoyah High School, Soddy Daisy, TN - average time - 33:46
Prizes More than $1.2 million in scholarship money was awarded to the participants by three auto technological colleges: Ohio Technical College (OTC), University of Northwestern Ohio (UNOH) and School of Automotive Machinists (SAM). Each college awarded the following scholarship money: $10,000 to each first-place team member; $9,000 to each second-place team member; $8,000 to each third-place team member; $7,000 to each fourth-place team member; $6,000 to each fifth-place team member; and $5,000 to each sixth- through 13th-place team member.
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The competition began at the inaugural Race & Performance Expo in 2008. The Hot Rodders of Tomorrow Engine Challenge has quickly grown into a nationwide engine challenge with more schools and sponsors supporting this exciting event each year. For more information, visit www.hotroddersoftomorrow.com.
Do you have an outstanding student or a group of students that needs to be recognized for an automotive-related academic achievement? E-mail us at esunkin@babcox.com.
Under the Hood
Adapted from Bob McDonald’s article in
FIVE GENERATIONS OF B ack in the 1990s, GM wasn’t making too many waves in the diesel truck market. The 6.2L and 6.5L engines had been around for sometime, but they were no match for the release of the Cummins 6BT in the Dodge truck in 1989 and the Ford Powerstroke in 1994. GM never really had a strong reputation for diesel design anyway. What many, including your instructor, remember is the GM diesel engines were a clacking bucket of bolts that were plagued by many issues from the start of the late 1970s. GM’s goal at that time of the fuel crunch was to introduce an engine with great reliability and good fuel mileage. They weren’t interested in making power, just dependability. By the mid-1990s, GM was definitely behind in both areas and had to find a way to compete in a growing diesel market. But, by 1999, GM didn’t even offer a diesel
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option in any of its mid-size trucks. Since 1976, GM and Isuzu have worked together as a joint venture on several projects. In 1996, the two automakers started working on a new mid-size diesel engine, and after two years of design, the Duramax was formed; production began in 2000. The engine design was a 90° V8, iron block, with aluminum heads, 32 valves, common rail injection. It was turbocharged and intercooled and produced 300 hp and 520 ft.-lbs. of torque. The engine was offered in GM mid-size diesel trucks at the start of 2001, and it brought GM back as a major player to the mid-size truck market by offering dependability, fuel mileage and quiet operation with plenty of power. The question that I often hear about the Duramax is “What kind of problems do you see with these engines?” I have to admit that these engines have a great reputation. While some
1st Generation Duramax LB7
There are five generations of the Duramax engine. The best way to identify the generation is by the year, model and the RPO (regular production option) code. The first generation is known as the LB7. This was manufactured from 2001 to 2004, with the eighth digit of the VIN designated with the number 1. With the LB7 being the first design, the integrity of the engine was great; the biggest problem was the fuel system.
DURAMAX DIAGNOSTICS problems have plagued a few of the Duramax engines, there hasn’t been anything as detrimental as what other manufacturers have had to deal with. There are always going to be issues with anything that has to do with internal combustion. The best way to examine the Duramax would be to break down the engines by their generation and evaluate issues of each.
Injector Issues A very common problem with early Duramax engines was injector failure. The engine incorporated the Bosch common rail fuel system, which was composed of the highpressure fuel pump, high-pressure TomorrowsTechnician.com 11
fuel rail, hard lines, injectors and electronic control module. For some reason, the Bosch injectors could not sustain life in the Duramax. The injectors would fail in three different ways — all related to the injector’s body becoming cracked. One symptom of a cracked injector is excessive white smoke coming from the tailpipe, which is generally most noticeable at idle, especially while sitting in traffic. Fuel is leaking into the combustion chamber, which cannot be controlled by the engine’s ECU. Fuel is entering the combustion chamber at the wrong time, causing the white smoke, which is an unburned fuel condition. This can be seen with a scan tool and is known as an injector’s balance rate. The balance rates of an injector are adjustments of fuel to the injector made by the ECU. The adjustments are made by the ECU from fluctuations of the crankshaft detected by the crankshaft position sensor. The balance rates are given by the value being a plus or a minus to the volume of fuel per cylinder. If there is too much fuel for a particular cylinder, the balance rates for that cylinder would be a minus. The ECU would be trying to take fuel away to correct the imbalance condition. If there were leaking injectors in this fashion where there is white smoke, the balance rate for that cylinder would be a minus. Another symptom of cracked injector failure would be fuel dilution in the engine oil. This would come from the injector’s body being cracked externally, causing fuel to leak into the crankcase. You have to remember that the injectors of the LB7 were under the valve cover. The hard lines come from the highpressure fuel rail and went through the valve cover. So if the injectors were leaking externally, fuel dilution could happen fairly quickly and go unnoticed because the engine would operate fine. There have been some injectors leaking externally so badly that the crankcase had filled with so much diesel that it was coming from the rear main seal. One particular truck I was working on with this condition was drip-
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ping diesel fuel from the rear main seal without the engine even running in the parking lot. The last form of injector failure was a hard start condition when the engine was hot. When the engine was cold, the vehicle would start fine and drive normally without any noticeable problems until the owner decided to stop somewhere like the store to get some fuel. When the owner would try to start the vehicle, the engine would spin over but never fire. The injector’s body was cracked on the return side, causing the fuel pressure that was entering the injector to be returned to the fuel tank. The vehicle would literally have to sit for several hours and cool down before the engine would restart. The heat from the engine would cause the crack in the injector body to expand open. That’s why the engine will start fine when cold and struggle to crank when warm. With so many injector failures between 2001 and 2004, GM extended the injectors’ warranty from five years/100,000 miles to seven years/200,000 miles. This did not, however, remedy the problem. Bosch went through several designs before there seemed to be a cure. The biggest problem came when customers had their injectors replaced under the sevenyear/200,000-mile warranty. Then several years later, after the truck was out of warranty, the injectors failed again. This of course angered many customers because there was still a problem and now they were going to have to pay for it. But, if the other injectors didn’t last very long, this would be an ongoing problem for the owner. The injector replacement in the LB7 Duramax is labor intensive. With the injectors being under the valve cover, a lot of the components of the top of the engine have to be removed in order to access them. It’s always advised that if there are several injectors causing problems that it’s better to replace them all because of the amount of labor that it takes to get to the injector. The average cost of an injector replacement on the LB7 is generally around $4,000 to $5,000. The replacement process takes between 10
to 12 hours of labor and the injectors cost around $350 each.
Generation II Enhancements In the middle of 2004, GM released the second generation of the Duramax, with the RPO code of LLY, with the eighth digit of the VIN designated as number 2. The LLY was in production from 2004.5 to 2006, and was made with 310 hp and 605 ft.-lbs. of torque. There were several reasons for the change: the injectors changed design and were now on the outside of the valve covers, providing easier access, and the EPA was tightening down on emissions standards for diesel engines in order to reduce NOx gas. The LLY incorporated the use of an EGR (exhaust gas recirculation) valve. When engine conditions would reach a certain criteria determined by the ECU, the EGR valve would open to let exhaust gas to be reintroduced into the intake manifold. Oftentimes this would cause a buildup of soot in the intake system due to the exhaust gas displacing the oxygen, which would cause cooler combustion; the cooler combustion inside the cylinder formed soot. In order to reintroduce exhaust gas into the intake of a diesel engine, the exhaust gas has to pass through what is known as an EGR cooler. A diesel engine exhaust temperatures can be much higher than gasoline, reaching as high as 1,200° F.
2nd Generation Duramax LLY
Before the exhaust gas reenters the intake at this temperature, it has to be cooled. The EGR cooler is more or less a small radiator that is a part of the engine’s cooling system, which as the hot exhaust gas passes through the cooler will cool the exhaust gas before reaching the intake manifold. Over a period of time, the EGR coolers will fail, causing the engine coolant to enter the intake manifold. This will often result in loss of coolant with steam emitting from the
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tailpipe. The LLY suffered from overheating. When Duramax incorporated the use of the EGR cooler, the cooling system of the engine was not upgraded. When towing with the LLY up steep grades on a hot summer day, owners often noticed that the cooling system could not sustain the engine’s temperature and would overheat. One of the other features of the LLY was the use of VNT (variable nozzle turbo). The VNT was where the turbocharger could change the speed of the turbo by altering exhaust pulses to the turbine wheel. This created better spool time and more boost for the engine off idle and would also change spool at the turbo when the engine was at cruising speed for the use of less boost. This is more or less letting the turbo make boost when there is a demand. The VNT was sometimes responsible for the overheating issues of the LLY because of the more restricted exhaust system. Some overheating issues did result, however, in head gasket failures, which could damage the entire engine.
Generation III In 2006.5 through 2007, the Duramax changed generation (third) again to the RPO code LBZ. Under the LBZ, the Bosch fuel engine management system also changed. This time, the fuel
of an LLY can upgrade the cooling system of their vehicles by installing the radiator and fan along with the fan shroud from an LBZ. The Allison transmission also changed from 5 speed to a 6 speed. The additional gear in the transmission reduced cruising speed by 200 rpm.
Generation IV From 2007 to 2010, the (fourth) generation of Duramax changed again to RPO code LMM. The eighth digit of the VIN is designated with the number 6. The LMM makes 365 hp and 660 ft.-lbs. of torque.
3rd Generation Duramax LBZ system used a new 32-bit controller along with seven hole injectors. The fuel pressures increased from 23,000 psi to 26,000 psi. Fuel sprayed directly onto the glow plugs for faster starts. The glow plugs were also independently controlled from the use of a controller for more efficiency during cold starts. The block was redesigned with more integrity along with the pistons and rods for the increase in horsepower to 360 and 650 ft.-lbs. of torque. The cooling system was upgraded with the use of a bigger radiator and fan along with a bigger EGR cooler. Owners
5th Generation Duramax LML
4th Generation Duramax LMM
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Because the emissions standards for diesel engines were changing for lower NOx gas, the LMM incorporated the use of a DPF (diesel particulate filter) in the exhaust system. The DPF is a device that is located behind the catalytic converter that traps soot coming from the engine. The DPF is monitored by the engine’s ECU by the use of pressure sensors located in the exhaust system. When the DPF becomes clogged with soot, the ECU will actuate the injectors on the exhaust stroke, which will dump raw fuel into the DPF. The fuel ignites in the exhaust system, which burns away the soot from the filter in the DPF. This was an effective way to rid soot from the tailpipe, but causes more fuel consumption.
INTENSIVE CARE Keep in mind that the repair costs of the Duramax aren’t cheap. The parts will be competitive to other brands of diesels, but the labor is not. The labor associated with the Duramax, depending on what the repair is, can be intensive. Take for instance a blown headgasket repair, the labor for both headgaskets on a Duramax will be around 35 hours compared to a Ford 6.0L that takes around 22 hours.
Generation V For 2011 to the present, the (fifth) generation of the Duramax is currently RPO code LML. Horsepower has been increased to 397 along with torque to 765 ft.-lbs. The LML incorporates the use of urea injection. Urea injection is an exhaust after treatment, which further reduces emissions. Urea is injected downstream of the turbo, which becomes a catalyst for NOx gas. Also, the fuel injection has changed to accommodate the use of piezo injectors and injection pressures reaching 29,000 psi. Piezo injectors incorporate piezo crystals that are used to create movement of the injector’s pintle, which is faster than the traditional electromagnet. This, along with the higher injection pressure, further increases engine efficiency.
With more than 10 years of engine operation, the Duramax is a proven player in the mid-size diesel world. The engine design has always been on the same platform with only improvements to the integrity of the design as power increased and fuel injection changed as emissions reductions became greater. There have been some unusual failures such as broken rods or pistons, but very few accounts. The biggest problem was the injector flaws from the LB7. This was the most major failure that put a bad taste of Duramax into owners’ mouths. Other than this, there are occasional mechanical failures that can often be associated with any engine design. Parts over time become tired, it’s just related to what the vehicle is used for and how much maintenance is performed. ■
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School of the year
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lover Park Technical College (CPTC) in Lakewood, WA, was named the 2012 Tomorrow’s Technician School of the Year (ttschooloftheyear.com) during a surprise award ceremony in October for students and instructors of the automotive program. WIX Filters and O’Reilly Auto Parts partnered with Tomorrow’s Technician as title sponsors for the national contest to find and name the best technician training school in the country. Wayne Bridges, automotive technician instructor, said he was excited that the school had received national recognition for its accomplishments, saying CPTC has been in the forefront of automotive technical education for 70 years. “We have a long tradition of automotive training at Clover Park Technical College – our state-of-the-art facility paired with excellent instructors bring a wealth of experience and technical resources into the classroom for the students,” said Bridges. “We have an incredible administration that supports our automotive program and understands it is essential to stay on top of changing technologies to succeed in this industry.” The NATEF-certified school, with Mt. Rainier looming in its background, has placed in the Top 20 of the Tomorrow’s Technician School of the year contest twice before taking the title this year. The automotive
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programs provide students with collision, customization and restoration, as well as technical/mechanical training. Bridges said he and his staff try to keep the learning level interesting through plenty of performance hands-on learning, as well as science-based projects that involve the students. “We have a 465hp Chevy powered Mazda Miata that we use in the curriculum, and we are building a 1989 Chevy S 10 “Gasser” pick-up,” Bridges said. “And during the Hybrid/Alternate fuels class last spring, students produced bio-diesel and hydrogen which they then used to power some of our vehicles.”
CPTC instructors pose with the trophy presented to them at an awards ceremony in October.
Another reason for the wide automotive curriculum is due to the program’s diverse student skill levels, as some of the students already hold automotive-related jobs. Ages of the students range from 16 to 65, with the average age being 30. About 90 students from the auto programs graduate from the school each year. Bridges said besides its long history, the auto program feels more like a family, rather than just a group of colleagues teaching repair skills to the next generation of automotive technicians. Of the seven instructors in the auto department, five of them graduated from CPTC. “We have a great team of instructors here totaling more than 200 years of automotive experience,” he said.
Hallowed Grounds and History Interestingly, the CPTC campus was at one time the site of Tacoma Speedway prior to World War II. Tacoma Speedway (sometimes called Pacific Speedway or Tacoma-Pacific Speedway) was a 2-mile wooden board track for auto racing that operated from 1914 to 1922. In its time, the track was renowned nation-wide and was considered by some to be second only to the Indianapolis Motor Speedway. After an arson fire destroyed the wooden grandstands in 1920, the facility was rebuilt, but failed financially and racing ended two years later. In December 1941, school districts located near large military bases were asked to provide technical training for the citizens of the area to qualify them to repair and maintain ordnance and military equipment needed for the war effort. With shop buildings available at Clover Park High School, a program called War Production Training was started. Under the instruction and guidance of instructors such as Jim Hammond (Airframe Mechanic Instructor), Arnold Cassidy (Engine Mechanic Instructor), and Dick White (Airframe Mechanic Instructor), 500 people were trained as auto mechanics and aircraft service mechanics. Thus began the history of what would later become Clover Park Technical College, and its 70 years of staff and faculty excellence. Post-war economic growth, baby-boomers, and rockn-roll ushered in the 1950s. CPTC was a fledgling vocational technical institute, but growing rapidly. In 1951, the federal government was phasing out the Navy Supply Depot (the current site of CPTC), and the
Clover Park School District was granted approximately 130 acres there, part of which was the former speedway grounds. Although the local school district occupied most of the seven concrete block buildings on the property, the school district soon moved to other locations in Lakewood. In 1954, the Clover Park Vocational-Technical Institute began operating in one of the buildings, handling mostly aviation trades. In 1957, the auto shop, machine shop and electronics programs moved into other vacant warehouses. In 1977, a building renovation/addition project was completed that included a new Automotive Service and Sales Center. In the 1990s, the school changed its name to Clover Park Technical College and continued its tradition of excellence in automotive training.
Industry Support Clover Park Technical College (www.cptc.edu) is the fifthannual recipient of the national School of the Year award. “It is encouraging to see the students and faculty of Clover Park Technical College embrace how automotive technicians’ jobs are evolving as vehicles become more high-tech,” said Mike Harvey, brand manager for WIX Filters. “With today’s vehicles becoming more complex – from hybrids, electrics and advanced clean-diesel engines – auto technicians are being trained in new technologies. “We are proud to support this program recognizing Clover Park as the best technical school in the country and look forward to the success of the school’s future technicians as they begin their careers as the next generation of technicians.” CPTC received a $2,500 donation from WIX Filters; O’Reilly and WIX Filters gear (hats, backpacks, shop banners, stools, product samples); 200-piece professional automotive tool set from O’Reilly Auto Parts;
Continues on page 32 TomorrowsTechnician.com 19
undercover
Lessons in Off-Road Adapted from Gary Goms article in
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Suspension Systems Chassis Check Not all chassis can be modified for off-road use. Although this Honda CR-V chassis sports allwheel drive, it would be a prohibitively expensive project to change the suspension and drivetrain geometry on this vehicle to achieve an increase in suspension height. See Photo 1. Vehicles with automatic suspension leveling and other electronic chassis devices are also difficult to re-engineer. In addition, it’s important to distinguish between AWD and 4WD vehicles. AWD vehicles don’t include a transfer case with an optional low-gear range for off-road service. On the other hand, most 4WD vehicles have a low-gear range that allows the driver to creep up and down steep inclines and ease the vehicle over protruding rocks.
Do The Math: Gear Ratios Installing larger-diameter tires and wheels is the quickest way to gain a few extra inches of ground
LEGAL SAFETY REQUIREMENTS The first step in modifying any vehicle for off-road use is to determine if the vehicle will also be used on the highway. Any dual-use vehicle must meet its state’s safety requirements regarding lighting, body sheet metal and suspension height modifications. Some states might require fenders, for example, and might not allow tires to extend outside the fenders. In other cases, a state might not allow excessive suspension alterations that increase the roll center of the vehicle. On the other hand, if the vehicle isn’t licensed and is transported by trailer to a given location, state safety rules might not apply.
Photo 1
clearance. But larger diameter wheels have a longer rolling circumference, which provides the same effect as reducing the numerical axle gear ratio. Because a radial tire changes radius as it presses against the road surface, one can measure rolling circumference most accurately by making a chalk mark on the tire sidewall and measuring the distance required for the tire to complete one full revolution. Mathematically speaking, a 32-in. diameter tire would equal a 100.53-in. circumference (pi x diameter = circumference or, 3.14159 x 32 = 100.53 in.). A 28-in. diameter tire would equal
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87.96 in. in circumference. To understand the difference in requirements for the axle gear ratio, dividing 100.48 in. by 87.96 in. indicates that the rolling circumference of the tire is increased by about 114%. If the vehicle has a 3.73:1 axle ratio, the numerical axle ratio must also be increased by 114% (or 1.14) from 3.73:1 to approximately 4.25:1, to compensate for the increased rolling circumference. If tire diameter is changed without changing axle gear ratio or the pinion factor, the vehicle speed sensor (VSS) input will be incorrect, which
Photo 2
Photo 3
Photo 4
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will affect speedometer accuracy, transmission shift quality and possibly even engine performance. Although using a scan tool on many applications can reset the pinion factor, the vehicle will lack torque in the lowerspeed ranges and will generally prove unsuitable for off-road use if the axle gear ratios aren’t changed. In addition, larger tires must have adequate clearance in the fender wells and against suspension components at full suspension compression and full suspension decompression or “droop” (See Photo 2). To steer correctly, most vehicles must also allow at least 40 degrees lock-to-lock of steering radius. Of course, some fender-well clearance can be gained by increasing wheel rim offset. The downside of increased offset is that it moves the tire outboard of its engineered pivot point (See Photo 3). This means that, instead of pivoting at the approximate center of the tread, the tire now begins to swing through a radius as it is moved outboard. Increased wheel offset increases steering effort and increases loading on the wheel bearings, axle and suspension components. Power steering is generally a “must-have” on vehicles with offset wheel rims. In addition, larger diameter tires will decrease the stopping ability of the brakes. The only remedy is to
install custom brakes with largerdiameter brake assemblies or more swept area. Larger tires with more wheel offset is a trade-off and the advantages must be weighed against the disadvantages.
Applying Geometry: Steering and Suspension Issues The simplest method of determining how an increase in suspension height will affect wheel alignment and steering geometry is to place the vehicle on a wheel alignment machine and measure the caster, camber and toe angles as the suspension height is being increased. At normal suspension heights, the tie rod is angled slightly downward (See Photo 4). If a normal weight load is added to the vehicle, the tie rod moves to a more level position. In conjunction with the control arms, the steering linkage is normally designed to maintain toe angle as the springs are compressed. When the vehicle suspension height is raised, the tie rod angles downward, which causes the toe angle to change from positive to negative as the suspension is compressed. The same problem affects 4WD vehicles with a solid axle and a drag link connecting the tie rods with the
Photo 5
24 November 2012 | TomorrowsTechnician.com
steering gear. Because the drag link operates through a sharper angle, the wheels tend to steer to one side right when the suspension is compressed. This phenomenon is called “bump steer,” which can cause the vehicle to wander on paved highways. See Photo 5. In most cases, OE suspensions can be raised only an inch or two without encountering serious steering geometry problems. If greater height increases are desired, several aftermarket companies may provide modified spindle assemblies designed to increase suspension height without seriously affecting suspension and steering geometry. See Photo 6.
Don’t forget to look at increasing the stiffness of the springs and the diameter of the antisway bar or “roll bar” assemblies to help counteract the vehicle’s increased center of gravity on steep slopes. See Photo 7.
Photo 6
Photo 7
Photo 8
Photo 9 TomorrowsTechnician.com 25
Photo 10
Driveshaft Geometry Driveshaft geometry is an often-neglected issue on many off-road conversions. If the vehicle has an independent front suspension, the front drive-
shaft isn’t affected by an increase in suspension height. If the vehicle has a solid or “live” front axle, the shorter front driveshaft will be most affected because the operating angles on
the universal joints will drastically increase. See Photo 8. The slip joints are fully extended and the universal joint yokes are most likely to contact each other. The slip joint travel should, for maximum safety and durability, allow at least 2/3 contact between the yoke and driveshaft slip joints. The slip joint should have at least a 1/2-in. of free travel to prevent mechanical interference at full suspension compression. In some cases, a custom driveshaft must be made to restore slip joint integrity. See Photo 9. When installing a rear axle assembly, remember that the pinion angle changes as the axle rolls upward with the application of torque. While many stock 4WD vehicles incorporate zero pinion angle, tipping the axle slightly downward would relieve stress on the universal joint. A tapered caster shim inserted between the spring and axle would equalize the pinion gear angle with the transfer case shaft angle.
Absorbing Shock Shock absorbers should be selected and installed after the vehicle has been modified. In general, most offroad enthusiasts prefer a heavy-duty shock absorber with more oil capacity to handle increased heat and more rebound control to handle rough terrain. To prevent breaking the shock absorber, the shock absorber must have enough travel to accommodate the increased suspension height (See Photo 10). Travel should be checked at full compression and full droop. If the shock absorber is bottoming out at either extreme, a shock absorber with more travel must be installed or the shock absorber mounts must be modified to comply with the increase in suspension height. Go to www.underhoodservice.com and use the search function to obtain more suspension-related technical articles. ■
26 November 2012 | TomorrowsTechnician.com
Tt Toolbox GearWrench has launched the 120XP Ratchet that features 120 positions for every full rotation, allowing it to turn fasteners with a swing arc of as little as 3°. The Double-Stacked Pawl technology provides an ultra-narrow swing arc allowing users to reach fasteners in severely limited access applications. The 120XP ratchet has a 60-tooth gear that alternately engages the double-stacked pawls. Its long handle is ergonomically designed to provide comfort and a good grip for users. The 120XP ratchets are sold separately and come in select SAE/metric standard/deep socket sets. Available at major automotive retailers and hardware locations. GearWrench: http://gearwrench.com
S & G Tool Aid Corp. has introduced two tools to crimp the Deutsch closed barrel terminals found on trucks, motorcycles, construction equipment, race cars, agricultural equipment, heavy-duty vehicles and other vehicles, and equipment subject to excessive vibration. These tools are easy to use — just insert the terminal and wire, then squeeze the handles tightly together to complete the crimp. A ratcheting action quickly provides a perfect crimp. Catalog No. 18880 is for use with 14-, 16- and 18gage closed barrel terminals and Catalog No. 18890 is for use with 20- and 22-gage closed barrel terminals. S & G Tool Aid Corp.: www.toolaid.com
General Technologies’ exclusive ThermoSounder feature on the LTX12 Infrared Thermometer provides users with audio feedback allowing for quick and easy detection of both cold and hot spots, without the distraction of having to follow and interpret the digital readouts. The LTX12 includes: patented ergonomic design and styling for enhanced handling and use; wide temperature range: -20° to 1,200° F (-30° to 650° C) and more. General Technologies Corp.: www.gtc.ca/
The Hook is the latest circuit tester from Power Probe. This powerful tool can connect to systems from 12 to 48 volts. Power Probe’s new “Smart Tip Advantage” senses the probe-tip condition and selects the correct meter for you. When the probe-tip senses resistance to ground, the display reads from 0 Ohms to 15 Meg Ohms with a resolution of 0.001 Ohms. When the probe-tip contacts voltage, the display becomes an instant voltmeter and measures from 0 to 99.9 volts. When you press the power switch to activate electrical components, the Hook displays its current draw in amps. Power Probe, Inc.: www.powerprobe.com/
The Gunk engine cleaning system provides technicians with serious solutions for engine cleaning and degreasing needs. • Gunk Foamy Engine Cleaner – For built-up road grime, salt and dirt from tough daily driving, long road trips and seasonal weather build up. • Gunk Original Engine Degreaser – For hard-working engines that have tough oil and grease build up, work in harsh environments or may be leaking. • Gunk Heavy Duty Gel Degreaser – Formulated to stick in place, penetrate deep and loosen the toughest caked on grease, baked on oil and engine deposits. After cleaning and degreasing an engine, apply an even coat of Gunk Engine Protector to create a barrier against heavy deposits of dirt and grease. Available at major automotive retailers. Gunk: www.gunk.com/GunkIndex.aspx
For the latest tool information, products and articles on tools and equipment, check out www.techshopmag.com.
TomorrowsTechnician.com 27
Tech Tips
This month’s Tech Tips are sponsored by:
FORD: 1998 MUSTANG 1998-2000 CROWN VICTORIA 1998-’99 F-250 LD 1998-2000 EXPEDITION, F-150 1999-2000 E SERIES
LINCOLN: 1998-2000 TOWN CAR
MERCURY: 1998-2000 GRAND MARQUIS Some vehicles equipped with the Romeo-built 4.6L 2V engine may exhibit an engine oil leak or oil weepage from the cylinder head gasket at the righthand rear or the left-hand front of the engine. Oil weepage is not considered detrimental to engine performance or durability. An oil leak may be caused by metal chip debris lodged between the head gasket and the block, chip debris between the cylinder head and the head gasket, or by damage to the cylinder head sealing surface that occurred during the manufacturing process.
28
Figure 1
If an oil leak is verified at the head gasket area, replacement of head gasket and cylinder head can be performed. Refer to the following Service Tips. Particular attention must be paid to inspecting the cylinder block for metal chip debris damage on the cylinder head to block mating surface, which may require block replacement.
November 2012 | TomorrowsTechnician.com
SERVICE INFORMATION A service remanufactured cylinder head assembly is available – P/N XL3Z-6049-AARM (lefthand), XL3Z-6049-BARM (righthand) containing: cylinder head assembly, cylinder head gasket, cylinder head bolts, rocker arm cover gasket, intake manifold gasket, exhaust manifold gasket, exhaust manifold studs and exhaust manifold nuts.
Always verify the origin of an oil leak by using fluorescent dye. At times, a cam cover gasket or engine oil galley plug (particularly at the rear of the right-hand head) may be the source of the engine oil leak. See Figure 1.
1998-2000 HEAD GASKET/ CYLINDER HEAD REPLACEMENT SERVICE TIPS Note: Take extra care not to damage the head gasket sealing surface when performing cylinder head replacement. The success of the repair is dependent upon following the inspection procedure paying particular attention to the areas depicted in the accompanying figures. • When cleaning the block deck of residual gasket coating, use Citrus Metal Surface Cleaner (P/N F4AZ19A536-RA) and a plastic scraper. Wipe with a lint-free shop rag. A shop vac can be used to pick up loose debris/dirt prior to the citrus cleaner application. Note: Do not use a metal tool of any kind on the gasket sealing surface. Resulting scratches will provide a leak path. • During normal inspection, pay particular attention to the right bank block deck area behind cylinder #4 or the left bank block deck area in front of cylinder #5 around the oil hole breakout for dimples and impressions left by metal chips.
Figure 3
• If the block does not pass checks, a new or remanufactured long block engine assembly must be ordered. For truck applications, which require use of the Modular Engine Lift Bracket 303-F047 (01400073) for engine removal, use nine links of 5/16” chain in place of the rear bracket. See Figure 4.
Figure 4
Figure 2
See Figure 2 and Figure 3. • The block surface around the cylinder head alignment dowels (two per bank) is another common location for scratches or dimples. • A known-quality straight edge should be used to ensure the block surface is flat. If a dimple or impression measures over 0.001” (0.025 mm) deep, it is recommended to replace the block. This type of damage is rare.
30 November 2012 | TomorrowsTechnician.com
• As part of the inspection of the block for damage, remove any machining chips that may be in the bottom of the cylinder block bolt bosses. This can be done using a pencil-style magnet. • After removal of the chip from the block bolt bosses, and if no permanent damage to the block is found, verify that both the block and head sealing surfaces are clean prior to installing the new gasket. • During installation of the new head gasket(s) and the new cylinder head(s) to the block, lubricate the new head bolts with an oil-soaked rag and allow oil to drip from the bolts, prior to assembly. Note: Inspect the new cylinder head for damage prior to installation. Note: The gasket should be placed directly into position and not dragged or moved along the sealing surface to avoid damage. The gasket coating is
essential to the function of the gasket. Chips, scrapes or cuts in the surface of the gasket coating may cause the gasket to leak. Note: Do not apply RTV, copper coat, aviation cement, etc. to the gasket or block/head surfaces. The gasket is to be installed dry. Any foreign material in between the gasket and the head/block may cause the gasket to leak. Courtesy of Ford Motor Company
In the Clutch: Active Radius When automotive technicians order parts for a repair job they know they need the right part, and a quality part as well. So it’s just a common procedure of any repair job that technicians will inspect the new part to make sure it is a correct part as well as a quality part, without any visual or functional flaws that would lead to a poor repair job and a customer comeback. Many newer-design clutch friction discs are designed with a thinner band of friction material than the original disc that came in the vehicle. The thinner band of material on the newer design may seem like a bad thing to some technicians as they compare the new and original parts that came out of the vehicle. Conventional thinking would be that “more is better;” more friction material will mean a stronger clutch. The active radius of a friction disc is defined as the distance from the center of the disc’s splined hub to the center of the friction material. So, by using a thinner band of friction material on the disc, the active radius will be increased. The active radius can be thought of as a lever. The longer the lever, the easier it is to move a given load. The above images illustrate how a thinner band of friction material will increase active radius and, therefore, the torque capacity of a clutch. The disc on the top has a thinner band of friction material than the disc on the right. This will increase the active radius and torque capacity of a clutch. ■ Courtesy of Schaeffler Automotive Aftermarket
4.704”
4.367”
TomorrowsTechnician.com 31
Continued from page 19 $250 gift card from O’Reilly Auto “We are very pleased to recognize Clover Parts; and an Park Technical College as the 2012 School of appearance by Sarah Burgess, BMI the Year,” said Jeff Stankard, publisher of Team owner and driver in the Tomorrow’s Technician. “We believe Clover Xtreme Drift Circuit, with her 2013 Park’s instructors, staff and administrators are Ford Mustang running the 5.0L truly working hard to prepare their students Engine with a 2.9L Whipple to become the top-notch professionals this Supercharger. industry so deeply requires.” “Support from manufacturers 2012 Runner’s Up and the aftermarket industry help This year’s three runners-up are Pennsylvania fund quality programs for the next College of Technology in Williamsport, PA; generation of automotive master Chipola College in Marianna, FL; and San mechanics,” Bridges said. “The Diego Continuing Education in San Diego. School of the Year award furthers Each school will receive a 200-piece profesour great reputation for outstandAuto racer Sarah Burgess, sional automotive tool set from O’Reilly Auto ing automotive training and we are right, was on hand to and Parts and $250 gift card from O’Reilly Auto honored to be the 2012 recipient.” provide students with an Parts. Clover Park Technical College inspiring message on joins the honors of past School of opportunities in the the Year winners: Arapahoe automotive industry. Community College in Littleton, View a video from CPTC, as well as other School of the CO (2011); Caddo Career & Technology Center in Year finalists at: Shreveport, LA (2010); Ohio Technical College in www.youtube.com/tomorrowstechnician. ■ Cleveland, OH (2009); and Waubonsee Community College in Sugar Grove, IL (2008).
ACROSS 1. Minimum-tread-depth indicator (4,3) 5. Cylinder-covering castings 8. Space ____, a.k.a. mini spare 9. Torque-converter component 10. Right on road map 11. Engine lubricant (5,3) 13. MacPherson's suspension inventions 14. Build-it-yourself vehicle (3,3) 18. Car painter's weapon (5,3) 20. Component, briefly 22. Engine-incontinence inhibitor (3,4) 23. Body-shop tool, ____ grinder 24. Body ____, e.g. sedan or hardtop 25. Obeyed triangular sign
Tomorrow’s Technician November Crossword
DOWN 1. Nuts and bolts partners, perhaps 2. Service _____, dealership job title 3. Cylinder diameter 4. Relationships between gears 5. Crankshaft adjunct, ____ balancer 6. Defunct Isuzu for Spanish pal 7. Tire-belt material, maybe 12. Coolant anti-freeze type, ____ glycol 15. Rejuvenated flat battery 16. Tire with new lease on life 17. Serpentine belt's guide 18. Parts absent in disc-brake system 19. Electromagnetic switch for lights, etc. 21. Primer, ____-coat, clear-coat finish
32 November 2012 | TomorrowsTechnician.com
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