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A comprehensive test program was conducted to correlate aerodynamic drag measurements from the General Motors Aerodynamics Laboratory with coastdown results. An improved method of coastdown testing was used to minimize the sources of error in determining aerodynamic drag. Several vehicles were tested, covering a large range of aerodynamic drag values, representative of current and future production vehicles. Wind tunnel and coastdown results were determined to be in good agreement, with an average drag coefficient difference of only. 008 (2%).

The application of crash durable structural adhesives in modern cars design, to improve the driving durability, the overall vehicle stiffness, the crash resistance and to make real light weight constructions feasible is significantly gaining in importance. 1-component systems are already introduced in the market and used in automotive industries. Usually the use of these bonds in automotive industries is limited by a relatively low wash off resistance in the pre-treatment tanks of the paint shop. If no additional actions are taken, there is a severe risk of wash off of the adhesives up to the partial loss in functionality. Respectively contamination of the pre-treatment tanks and aftereffects damage the surface of the coated cars. To avoid wash off a thermal process (oven) to pre-gel the adhesive in the flanges of the Body-In-White (BIW)- bodies before entering the pre-treatment utility is necessary. This is a save but cost intensive solution.

AS a basis for the analyses of this symposium, a hypothetical car has been used to evaluate the engine power distribution in performance. Effects of fuel,-engine accessories, and certain car accessories are evaluated. The role of the transmission in making engine power useful at normal car speeds is also discussed. Variables encountered in wind and rolling resistance determinations are reevaluated by improved test techniques. Net horsepower of the car in terms of acceleration, passing ability and grade capability are also summarized.

A requirement for larger trucks and higher operating speed is indicated. The present report presents wind tunnel data on drag of a Chevrolet truck-trailer combination. Possible means of drag reduction are examined. Although side force and yawing moment data are presented, their effect on directional stability are not, at present analyzed.

A detailed description of the oxidative stability of GM's DEXRON®-VI Factory Fill Automatic Transmission Fluid (ATF) is provided, which can be integrated into a working algorithm to estimate the end of useful oxidative life of the fluid. As described previously, an algorithm to determine the end of useful life of an automatic transmission fluid exists and is composed of two simultaneous counters, one monitoring bulk oxidation and the other monitoring friction degradation [1]. When either the bulk oxidation model or the friction model reach the specified limit, a signal can be triggered to alert the driver that an ATF change is required. The data presented in this report can be used to develop the bulk oxidation model. The bulk oxidation model is built from a large series of bench oxidation tests. These data can also be used independent of a vehicle to show the relative oxidation resistance of this fluid, at various temperatures, compared to other common lubricants.

This paper describes the methodology used to achieve optimum aerodynamic performance of the 1992 through 1995 Oldsmobile Cutlass Supreme IMSA GT race car and will demonstrate the continuous improvements successfully used to respond to rule changes and competition. The concerted effort by the sanctioning body to limit the aerodynamic performance of IMSA GT race cars for the 1995 season required a rigorous wind tunnel test program backed by track validation to maintain the necessary aerodynamic balance, cooling flows, engine induction flow, and overall competitive parity. The specific modifications that were evaluated to accommodate these rules changes will be detailed in this paper. Special test methodologies developed to better understand specific aerodynamics questions such as the effects of vehicle attitude, internal cooling flows, underbody treatments, and engine air inlet performance will also be discussed.

HOW well are multigrade oils performing at low temperatures? An investigation has shown that the low-tem perature properties of mulrigrade oils are often not equivalent to the single-grade oils-lOW in a mulrigrade oil may actually be 20W. One phase of this investigation, a full-scale cranking study using commercial 10W and 10W-30 oils in cars at 0 F, is discussed in detail in this paper.

The work presented here builds on the practical and effective spot weld fatigue life prediction method, the structural stress method (SSM), that was developed at Stanford University. Constant amplitude loading tests for various spot weld joint configurations have been conducted and the SSM has been shown to accurately predict fatigue life. In this paper refinements to the structural stress approach are first presented, including a variable amplitude fatigue life prediction method based on the SSM and Palmgren-Miner's rule. A test matrix was designed to study the fatigue behavior of spot welds under tensile shear loading conditions. Constant amplitude tests under different R-ratios were performed first to obtain the necessary material properties. Variable amplitude tests were then performed for specimens containing single and multiple welds.

During early 2005 General Motors released a newly developed ATF for the factory fill of all GM Powertrain stepped gear automatic transmissions. The new fluid provided significantly improved performance in terms of friction durability, viscosity stability, aeration and foam control and oxidation resistance. In addition, the fluid has the potential to enable improved fuel economy and extended drain intervals. Since the performance of the new fluid far exceeded that of the DEXRON®-III service fill fluids available at the time it became necessary to upgrade the DEXRON® service fill specification in order to ensure that similar fluids were available in the market for service and repair situations. This latest upgrade to the service fill specification is designated DEXRON®-VI [1].

The potential of bake hardenable steel as a substitute for SAE 1008 steel to reduce gage and improve dent resistance is investigated in this report. Outer body panels in particular are susceptible to palm printing and other forms of denting. Conventional SAE 1008 steel and a developmental continuous annealed bake hardenable steel from Inland Steel Company are compared for dent performance properties. Bake hardenable (BH) steel is a medium strength (200-350 MPa) steel that receives an increase in yield strength during the heating of the paint bake cycle. An increase in yield strength would result in an increase in dent resistance. The increase in dent resistance is more quantitatively evaluated by comparing the BH steel with the current production material (SAE 1008) of a rear compartment lid outer.

Dow Automotive has developed an ACM DPF substrate, characterized with light-weight, low pressure-drop, rapid regeneration, and excellent chemical resistance at high temperature. An uncatalyzed DPF was tested on a 2.0L common-rail diesel engine for over 100 soot loading and regeneration cycles, which included a combination of controlled regenerations, uncontrolled regenerations and incomplete regenerations. The DPF demonstrated high filtration efficiency and physical integrity throughout the entire test. The ACM DPF has also demonstrated excellent catalyst coating capability and performance. An ACM DPF with a total volume of three-liter and coated with the same catalyst formulation as the original catalyzed DPF, was used to replace the OEM four-liter catalyzed SiC DPF on a 2005 model-year 1.9L European diesel passenger car. It was demonstrated that the ACM DPF has lower pressure drop and faster regeneration than that of the OEM DPF.

Brake caliper and corner behavior in the off-brake condition can lead, at times, to brake system performance issues such as residual drag (and related issues such as pulsation, judder, and loss of fuel economy), and caliper pryback during aggressive driving maneuvers. The dynamics in the brake corner can be strikingly complex, with numerous friction interfaces, rubber component and grease dynamics, deflections of multiple components, and significant dependence on usage conditions. Displacements of moving parts are usually small, and the residual forces in the caliper interfaces involved are also small in comparison with other forces acting on the same components, making direct observation very difficult. The present work attempts to illuminate off-brake behavior in two different conditions - residual drag and pryback - through the use of low-range pressure distribution sensors placed in between the caliper (pistons and fingers) and the brake pad pressure plates.

As a result of raised awareness regarding the proliferation of individual OEM recommended ATFs, and discussion in various forums regarding the possibility of ‘universal’ service fill fluids, it was decided to study how divergent individual OEM requirements actually are by comparing the fluids performance in industry standard tests. A bench-mark study was carried out to compare the performance of various OEM automatic transmission fluids in selected industry standard tests. All of the fluids evaluated in the study are used by certain OEMs for both factory and service fill. The areas evaluated included friction durability, oxidation resistance, viscosity stability, aeration and foam control. The results of this study are discussed in this paper. Based on the results, one can conclude that each ATF is uniquely formulated to specific OEM requirements.

The results of comparative aerodynamic force measurements on a full-scale notchback-type vehicle, performed between 6 European companies operating full-scale automotive wind tunnels, were published in the SAE Paper 800140. Correlation tests with the same vehicle have been extended to 2 further European and 3 North American wind tunnels. First the geometry, the design and the flow data of the different wind tunnels is compared. The facilities compared include wind tunnels with open-test-sections, closed-test-sections and one tunnel with slotted side walls. The comparison of results, especially for drag coefficients, show that the correlation between the differently designed wind tunnels is reasonable. Problems of blockage correction are briefly discussed. The comparison tests furthermore revealed that careful design of the wheel pads and blockage corrections for lift seem to be very influential in achieving reasonable lift correlations. Six-component measurements show similar problems.

Vehicle rollover is a rare event on roads, compared to other types of crashes. According to National Highway Traffic Safety Agency, USA (NHTSA), rollovers account for only 3% of crashes in a year [1]. However, one third of the fatalities occur during a rollover and the numbers of such fatalities exceed over 10,000 per annum. The fatality and the injury rate makes rollover crash an important issue in vehicle safety. As part of reducing risk of death and serious injury from rollover crashes, a proposal has been made to upgrade FMVSS No. 216, Roof Crush Resistance [2]. This upgraded regulation mandates the increase in peak load carrying capacity of the vehicle structure from 1.5 times vehicle weight to 2.5 times vehicle weight. As such, the manufacturers are required to comply to this norm even with their existing vehicles. This necessitates a change in structural design of the vehicle to be able to withstand the additional load bearing capacity.

This pager documents a one shift (10 hour) wind tunnel test program conducted on a Corvette C5 prepared for Sports Car Club of America (S.C.C.A.) World Challenge racing. The testing was conducted at the Canadian National Research Center in Ottawa, Canada. Specific areas of test included front fascia and under tray, rear air discharge, rear wing configuration and angle, B-pillar configuration, and ride height. Standard wind tunnel test procedures were followed. In total twenty-six separate configurations were evaluated. Data for front and rear lift, total drag, and lift/drag (L/D) ratio are provided for each test configuration. The cumulative effects of the aerodynamic changes evaluated in this program, calculated at 192 KPH (120 MPH), increased front down force by 318 N (72 Lb.), and rear down force by 770 N (173 Lb.). Lift/drag ratio was improved from -0.597 to -1.016. These changes increased total drag by 381 N (86 Lb.).

This paper describes the methodology used to achieve optimum aerodynamic performance of the 1989 through 1994 Chevrolet Lumina Winston Cup race car, and demonstrates the continuous improvements successfully used to respond to rule changes and competition. The development will be documented from construction of a prototype race car, through one third scale model testing, and the detail development required to continually improve performance and meet changing body rules which stringently limit body modifications. Despite these limitations, track and wind tunnel testing of development vehicles contributed to driver's and manufacturer's championships in the first racing season. The continuous improvement process, which includes ongoing wind tunnel and track tests, has resulted in improvement or at least maintenance of drag coefficient along with lift coefficient reduction of up to 0.050 each year.