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Most service procedures require the use of hand tools. Therefore, technicians need a wide assortment of these tools. Each has a specific job and should be used in a specific way. Most service departments and garages require their technicians to buy their own hand tools. Wrenches The word wrench means twist. A wrench is a tool for twisting and/or holding bolt heads or nuts. Nearly all bolt heads and nuts have six sides; the jaw of a wrench fits around these sides to turn the bolt or nut. All technicians should have a complete collection of wrenches. This includes both metric and SAE wrenches in a variety of sizes and styles. The width of the jaw opening determines its size. For example, a 1/2-inch wrench has a jaw opening (from face to face) of ½”. The size is actually slightly larger than its nominal size so the wrench fits around a nut or bolt head of equal size. The following is a brief discussion of the types of wrenches used by automotive technicians. Open-End Wrench--The jaws of the open-end wrench allow the wrench to slide around two sides of a bolt or nut head where there might be insufficient clearance above or on one side of the nut to accept a box wrench. Box-End Wrench--The end of the box-end wrench is boxed or closed rather than open. The jaws of the wrench fit completely around a bolt or nut, gripping each point on the fastener. The box-end wrench is not likely to slip off a nut or bolt. It’s safer than an open-end wrench. Box-end wrenches are available as 6 point and 12 point. The 6-point box end grips the screw more securely than a 12-point box-end wrench can and avoids damage to the bolt head. Combination Wrench--The combination wrench has an open-end jaw on one end and a box-end on the other. Both ends are the same size. Every auto technician should have two sets of wrenches: one for holding and one for turning. The combination wrench is probably the best choice for the second set. It can be used with either open-end or box-end wrench sets and can be used as an open-end or box-end wrench. Flare Nut (Line) Wrenches--Flare nut or line wrenches should be used to loosen or tighten brake line or tubing fittings. Using open-ended wrenches on these fit tings tends to round the corners of the nut, which are typically made of soft metal and can distort easily. Flare nut wrenches surround the nut and provide a better grip on the fitting. They have a section cut out so that the wrench can be slipped around the brake or fuel line and dropped over the flare nut. Allen Wrench--Setscrews are used to fasten door handles, instrument panel knobs, engine parts, and even brake calipers. A set of fractional and metric hex head wrenches, or Allen wrenches, should be in every technician's toolbox. An Allen wrench can be L-shaped or can be mounted in a socket driver and used with a ratchet. Adjustable-End Wrench--An adjustable-end wrench (commonly called a crescent wrench) has one fixed jaw and one movable jaw. The wrench opening can be adjusted by rotating a helical adjusting screw that is mated to teeth in the lower jaw. Because this type of wrench does not firmly grip a bolt's head, it’s likely to slip. Adjustable wrenches should be used carefully and only when it’s absolutely necessary. Be sure to put all of the turning pressure on the fixed jaw. --- An open-end wrench grips only two sides of a fastener. Square head bolt Hex head bolt 5/8" --- Six-point and twelve-point box-end wrenches are available. --- Top: A handy tool containing many different Allen wrenches. Bottom: Tee-handle Allen wrenches designed for better gripping and easier torque application. e.g. made by Snap-on Incorporated. --- An assortment of ratchets. --- A chromed deep-well socket and an impact socket. --- A typical set of socket drivers. Allen Flat Phillips Torx --- The size of the correct socket is the same size as the size of the bolt head or nut. Top view 1/2-inch square drive hole 9/16 inch across flats; 9/16-inch socket; 9/16-inch head bolt; 9/16 inch across flats. Sockets and Ratchets A set of Imperial and metric sockets combined with a ratchet handle and a few extensions should be The top side of a socket has a square hole that accepts a square lug on the socket handle. This square hole is the drive hole. The size of the hole and handle lug (1/4”, 3/8”, ½”, etc.) indicates the drive size of the socket wrench. One handle fits all the sockets in a set. On better-quality handles, a spring loaded ball in the square drive lug fits into a depression in the socket. This ball holds the socket to the handle. An assortment of socket (ratchet) handles. Not all socket handles are ratcheting. Some, called breaker bars, are simply long arms with a swivel drive used to provide extra torque onto a bolt to help loosen it. These are available in a variety of lengths and drive sizes. Sometimes nut drivers are used. These handles look like screwdrivers and have a drive shaft on the end of the shaft. Sockets and/or various attachments are inserted on the drive lug. These drivers are only used when bolt tightness is low. Sockets are available in various sizes, lengths, and bore depths. Both standard SAE and metric socket wrench sets are necessary for automotive service. Normally, the larger the socket size, the longer the socket or the deeper the well. Deep-well sockets are made extra long to fit over bolt ends or studs. A spark plug socket is an example of a special purpose deep well socket. Deep-well sockets are also good for reaching nuts or bolts in limited-access areas. Deep-well sockets should not be used when a regular-size socket will do the job. The longer socket develops more twist torque and tends to slip off the fastener. Heavier-walled sockets are designed for use with an impact wrench and are called impact sockets. Most sockets are chrome-plated, except for impact sockets, which are not. ! WARNING! Never use a nonimpact socket with an impact wrench. --- A flexible adapter is used when direct access to the bolt is not possible. --- The common types of torque wrenches. Special Sockets Screwdriver (including Torx driver) and Allen wrench attachments are also available for use with a socket wrench. --- a typical set of specialty socket drivers. These socket wrench attachments are very handy when a fastener cannot be loosened with a regular screwdriver. The leverage given by the ratchet handle is often just what it takes to break a stubborn screw loose. Swivel sockets are also available. These sockets are fitted with a flexible joint that accommodates odd angles between the socket and the ratchet handle. These sockets are often used to work bolts that are difficult to reach. Although crowfoot sockets are not really sockets, they are used with a ratchet or breaker bar. These sockets are actually the end of an open-end or line wrench made with a drive bore, which allows a ratchet to move the socket. Extensions An extension is commonly used to separate the socket from the ratchet or handle. The extension moves the handle away from the bolt and makes the use of a ratchet more feasible. Extensions are available in all common drive sizes and in a variety of lengths. The most common lengths are 1”, 3”, 6 inches, and 10 inches; however 2- and 3-foot extensions are also quite common. Flexible adapters are used with extensions to gain access to bolts that cannot be directly tightened or loosened. Wobble extensions allow a socket to pivot slightly at the drive connection. This type of extension pro vides for a more positive connection to the socket than swivel joints but only allows approximately 16 degrees of flexibility. Socket Adapters When sockets of a different drive size must be used with a particular ratchet or handle, an adapter can be inserted between the socket and the drive on the handle. An example of a common adapter is one that allows for the use of a 1/4-inch drive socket on a 3/8-inch drive ratchet. Torque Wrenches Torque wrenches measure how tight a nut or bolt is. Many of a car's nuts and bolts should be tightened to a certain amount and have a torque specification that is expressed in foot-pounds ( U.S.) or Newton-meters (metric). A foot-pound is the work or pressure accomplished by a force of 1 pound through a distance of 1 foot. A Newton-meter is the work or pressure accomplished by a force of 1 kilo gram through a distance of 1 meter. A torque wrench is basically a ratchet or breaker bar with some means of displaying the amount of torque exerted on a bolt when pressure is applied to the handle. Torque wrenches are available with the various drive sizes. Sockets are inserted onto the drive and then placed over the bolt. As pressure is exerted on the bolt, the torque wrench indicates the amount of torque. GARAGE TIP -- Following torque specifications is critical. How ever, there is a possibility that the torque spec is wrong as printed. (In other words, someone made a mistake.) If the torque spec seems way too tight or loose for the size of bolt, find the torque spec in a different source. If the two specs are the same, use it. If they are different, use the one that seems right. The common types of torque wrenches are avail able with inch-pound and foot-pound increments.
The correct torque provides the tightness and stress that the manufacturer has found to be the most desirable and reliable. For example, engine-bearing caps that are too tight distort the bearings, causing excessive wear and incorrect oil clearance. This often results in rapid wear of other engine parts due to decreased oil flow. Insufficient torque can result in out-of-round bores and subsequent failure of the parts. PROCEDURE: When using a torque wrench, follow these steps to get an accurate reading:
Screwdrivers A screwdriver drives a variety of threaded fasteners used in the automotive industry. Each fastener requires a specific kind of screwdriver, and a well equipped technician has several sizes of each. GARAGE TIP --A screwdriver should not be used as a chisel, punch, or pry bar. Screwdrivers were not made to withstand blows or bending pressures. When misused in such a fashion, the tips will wear, be come rounded, and tend to slip out of the fastener. At that point, a screwdriver becomes unusable. Remember a defective tool is a dangerous tool. Screwdrivers are defined by their sizes, their tips, and the types of fasteners they should be used with. Your tool set should include both blade and Phillips drivers in a variety of lengths from 2-inch "stubbies" to 12-inch screwdrivers. You also should have an assortment of special screwdrivers, such as those with a Torx head design. --- The various screwdriver tips that are available. Made by Snap-on Incorporated. PHILLIPS TIP POZIDRIV TIP TORX TIP CLUTCH TIP SCRULOX (SQUARE TIP) --- The blade tip screwdriver is used with slotted head fasteners. Screw head Magnified tip Handle Bolster Blade shank Blade tip Blade --- The tip of a Phillips screwdriver has four prongs that provide a good grip in the fastener. Magnified tip; Screw head ¦ Standard Tip Screwdriver: A slotted screw accepts a screwdriver with a standard or blade-type tip. The standard tip screwdriver is probably the most common type. It’s useful for turning carriage bolts, machine screws, and sheet metal screws. The width and thickness of the blade deter mine the size of a standard screwdriver. Always use a blade that fills the slot in the fastener. ¦ Phillips Screwdriver: The tip of a Phillips screw driver has four prongs that fit the four slots in a Phillips head screw. The four surfaces enclose the screwdriver tip so it’s less likely that the screwdriver will slip out of the fastener. Phillips screwdrivers come in sizes #0 (the smallest), #1, #2, #3, and #4 (the largest). ¦ Reed and Prince Screwdriver: The tip of a Reed and Prince screwdriver is like a Phillips except that the prongs come to a point rather than to a blunt end. ¦ Pozidriv Screwdriver: The Pozidriv screwdriver is like a Phillips but its tip is flatter and blunter. The squared tip grips the screw's head and slips less than a Phillips screwdriver. ¦ Torx Screwdriver: The Torx screwdriver is used to secure headlight assemblies, mirrors, and lug gage racks. Not only does the six-prong tip provide greater turning power and less slippage, but the Torx fastener also provides a measure of tamper resistance. Torx drivers come in sizes T15 (the smallest), T20, T25, and T27 (the largest). ¦ Clutch Driver: Fasteners that require a clutch driver are normally used in non-load-bearing places. Clutch head fasteners offer a degree of tamper resistance and offer less slippage than a standard slot screw. The clutch head design has been called a butterfly or figure-eight. Automotive technicians don’t often use these drivers. ¦ Scrulox Screwdriver: The Scrulox screwdriver has a square tip. The tip fits into a square recess in the top of a fastener. This type of fastener is commonly used on truck bodies, campers, and boats. --- (A) An impact screwdriver set. (B) An impact screwdriver automatically tries to rotate the screw when it’s struck with a hammer. ---Various types of pliers. Compound cutter End cutter Diagonal cutter Needle nose Combination Rib joint Vise grip Adjusting screw Release lever Impact Screwdriver An impact screwdriver is used to loosen stubborn screws. Impact screwdrivers have interchangeable heads and bits that allow the handles of the tools to be used with various screw head designs. To use an impact screwdriver, select the correct bit and insert it into the driver's head. Then hold the bit against the screw slot while firmly twisting the handle in the desired direction. Strike the handle with a hammer. The force of the hammer will exert a downward force on the screw and, at the same time, exert a twisting force on the screw. Pliers Pliers are gripping tools used for working with wires, clips, and pins. At a minimum, an auto technician should own several types: standard pliers for common parts and wires, needle nose for small parts, and large, adjustable pliers for large items and heavy-duty work. A brief discussion on the different types of pliers follows: ¦ Combination pliers are the most common type of pliers and are frequently used in many kinds of automotive repair. The jaws have both flat and curved surfaces for holding flat or round objects. Also called slip-joint pliers, the combination pliers have many jaw-opening sizes. One jaw can be moved up or down on a pin attached to the other jaw to change the size of the opening. ¦ Adjustable pliers, commonly called channel locks, have a multi-position slip joint that allows for many jaw-opening sizes. ¦ Needle nose pliers have long, tapered jaws. They are great for holding small parts or for reaching into tight spots. Many needle nose pliers also have wire-cutting edges and a wire stripper. Curved needle nose pliers allow you to work on a small object around a corner. ¦ Locking pliers, or vise grips, are similar to the standard pliers, except they can be tightly locked around an object. They are extremely useful for holding parts together. They are also useful for getting a firm grip on a badly rounded fastener that is impossible to turn with a wrench or socket. Locking pliers come in several sizes and jaw con figurations for use in many auto repair jobs. ¦ Diagonal-cutting pliers, or cutters, are used to cut electrical connections, cotter pins, and wires on a vehicle. Jaws on these pliers have extra-hard cut ting edges that are squeezed around the item to be cut. ¦ Snap- or lock ring pliers are made with a linkage that allows the movable jaw to stay parallel throughout the range of opening. The jaw surface is usually notched or toothed to prevent slipping. ¦ Retaining ring pliers are identified by their pointed tips that fit into holes in retaining rings. Retaining ring pliers come in fixed sizes but are also available in sets with interchangeable jaws. --- Snap-ring and retaining ring pliers. --- Various steel-faced hammers. Reproduced under license from Snap-on Incorporated. All of the marks are marks of their owners. --- Soft-faced hammers. --- Punches are defined by their shape and the diameter of the point. Center punch (showing included angle); Starting punch; Pin punch; Aligning punch; Straight shank brass punch Hammers Hammers are identified by the material and weight of the head. There are two groups of hammer heads: steel and soft faced. Your tool set should include at least three hammers: two ball-peen hammers, one 8-ounce and one 12- to 16 ounce hammer, and a small sledgehammer. You should also have a plastic and lead or brass-faced mallet. The heads of steel-faced hammers are made from high-grade alloy steel. The steel is deep forged and heat treated to a suitable degree of hardness. Soft-faced hammers have a surface that yields when it strikes an object. Soft-faced hammers should be used on machined surfaces and when marring a finish is undesirable. For example, a brass hammer should be used to strike gears or shafts because it won’t dam age them. Chisels and Punches Chisels are used to cut metal by driving them with a hammer. Automotive technicians use a variety of chisels for cutting sheet metal, shearing off rivet and bolt heads, splitting rusted nuts, and chipping metal. A variety of chisels are available, each with a specific purpose, including flat, cape, round-nose cape, and diamond point chisels. Punches are used for driving out pins, rivets, or shafts; aligning holes in parts during assembly; and marking the starting point for drilling a hole. Punches are designated by their point diameter and punch shape. Drift punches are used to remove drift and roll pins. Some drifts are made of brass; these should be used whenever you are concerned about possible damage to the pin or to the surface surrounding the pin. Tapered punches are used to line up bolt holes. Starter or center punches are used to make an indent before drilling to prevent the drill bit from wandering. Removers Rust, corrosion, and prolonged heat can cause auto motive fasteners, such as cap screws and studs, to become stuck. A box wrench or socket is used to loosen cap screws. A special gripping tool is designed to remove studs. However, if the fastener breaks off, special extracting tools and procedures must be employed. One type of stud remover is shown. These tools are also used to install studs. Stud removers have hardened, knurled, or grooved eccentric rollers or jaws that grip the stud tightly when operated. Stud removers/installers are turned by a socket wrench drive handle, a socket, or wrench. Extractors are used on screws and bolts that are broken off below the surface. Twist drills, fluted extractors, and hex nuts are included in a screw extractor set. This type of extractor lessens the tendency to expand the screw or stud that has been drilled out by providing gripping power along the full length of the stud. Screw extractors are often called easy outs. To use an extractor, the bolt must be drilled and the extractor forced into that bore. The teeth of the extractor grip the inside of the drilled bore and allow the bolt to be turned out. Easy outs typically have the size of the required drill bit stamped on one side. At times a broken bolt can be loosened and removed from its bore by driving it in a counterclock wise direction with a chisel and hammer. A bolt bro ken off above the surface may be able to be removed with locking pliers. Hacksaws A hacksaw is used to cut metal. The blade only cuts on the forward stroke. The teeth of the blade should always face away from the saw's handle. The number of teeth on the blade determines the type of metal the saw can be used on. A fine-toothed blade is best for thin sheet metal, whereas a coarse blade is used on thicker metals. When using a hacksaw, never bear down on the blade while pulling it toward you; this will dull the blade. Use the entire blade while cutting. --- Stud installation/removal tool. --- Screw extractors. --- Using a screw extractor to remove a broken bolt. Broken bolt with hole drilled in the middle Screw extractor --- (A) The teeth on the blade in a hacksaw should face forward. (B) A coarse blade should not be used with sheet metal. (C) A fine blade will work well with sheet metal. --- (A) Files come in a variety of shapes. (B) A file card. Round Half round Flat Three square or triangular; --- Using a slide hammer-type puller to remove a drive axle. Files Files are commonly used to shape or smooth metal edges. Files typically have square, triangular, rectangular (flat), round, or half-round shapes. They also vary in size and coarseness. The most commonly used files are the half-round and flat with either single-cut or double-cut designs. A single-cut file has its cutting grooves lined up diagonally across the face of the file. The cutting grooves of a double cut file run diagonally in both directions across the face. Double-cut files are considered first cut or roughening files because they can remove large amounts of metal. Single-cut files are considered finishing files because they remove small amounts of metal. To avoid personal injury, files should always be used with a plastic or wooden handle. Like hacksaws, files only cut on the forward stroke. Coarse files are used for soft metals, and smoother, or finer, files are used to work steel and other hard metals. Keep files clean, dry, and free of oil and grease. To clean filings from the teeth of a file, use a special tool called a file card. Gear and Bearing Pullers Many precision gears and bearings have a slight interference fit (press fit) when installed on a shaft or housing. For example, the inside diameter of a bore is 0.001 inch smaller than the outside diameter of a shaft. When the shaft is fitted into the bore it must be pressed in to overcome the 0.001-inch interference fit. This press fit prevents the parts from moving on each other. The removal of gears and bearings must be done carefully. Prying or hammering can break or bind the parts. A puller with the proper jaws and adapters should be used when applying force to remove gears and bearings. Using proper tools, the force can be applied with a slight and steady motion. Pullers are available in many different designs and therefore are designed for specific purposes. Most pullers come with various jaw lengths and shapes to allow them to work in a number of different situations. Some pullers are fitted to the end of a slide hammer and are used to remove slightly press-fit items. After the mounting plate of the puller is secure in or on the object to be removed, the weight on the tool's hammer is slid back with force against the handle of the tool, generating a pulling force and jerking the object out of its bore. To pull something out of a bore, the puller must be designed to expand its jaws outward. The jaws also must be small enough to reach into the bore without damaging the bore while still firmly gripping the object that is being removed. This type puller is commonly used to remove seals, bushings, and bearing cups. Jaw-type pullers are used to pull an object off a shaft. These pullers are available with two or three jaws. Jaw-type pullers are commonly used to remove bearings, pulleys, and gears. Some pullers are actually pushers. A push-puller is used to push a shaft out of its bore in a housing. It’s often difficult to grip the end of the shaft with a puller, so a push-puller is used to move the shaft out of the bore. --- The jaws on this puller are reversible to allow for inside and outside pulls. Bearing, Bushing, and Seal Drivers Another commonly used group of special tools includes the various designs of bearing, bushing, and seal drivers. Auto manufacturers supply their dealer ships with drivers for specific components. However, universal sets of drivers are also available. These sets include a variety of driver plates, each of a different diameter. The plates are often reversible. The flat side of the plate is used to install seals and the tapered side is used to install tapered bearing races. A driver handle is threaded into the appropriate plate. The bearing or seal is driven into place by tapping on the driver hammer. Always make sure you use the correct tool for the job; bushings and seals are easily damaged if the wrong tool or procedure is used. Car manufacturers and specialty tool companies work closely together to design and manufacture special tools required to repair cars. Trouble Light Adequate light is necessary when working under and around automobiles. A trouble light can be battery powered (like a flashlight) or need to be plugged into a wall socket. Some shops have trouble lights that pull down from a reel suspended from the ceiling. Trouble lights should have LED or fluorescent bulbs. Incan descent bulbs should not be used because they can pop and burn. Take extra care when using a trouble light. Make sure its cord does not get caught in a rotating object. The bulb or tube should be surrounded by a cage or enclosed in clear plastic to prevent accidental breaking and burning. Creeper Rather than crawl on your back to work under a vehicle, use a creeper. A creeper is a plat form with small wheels. It allows you to slide under a vehicle and easily maneuver while working. To protect yourself and others around you, never have the creeper lying on the floor when you are not using it. Accidentally stepping on it can result in a serious fall. Always keep it standing on its end when it’s not being used. Next: Garage/Shop Equipment Prev.: Measuring Instruments/Tools Home Article Index top of page |
