Glossary of Mechanical Terms

	Axle - shaft that transfers power from the differential to the wheel. Has splines at one end and a flange at the other end that holds the wheel studs.
	Axle bearings - press onto the axles and fit into the end of the housing. They are held in place by the retainer plate and 4 bolts. Allow the axles to spin in place when power is applied to them via the differential.
	Axle Seals - seal that rides on a machined surface on the flanged end of the axle that seals the axle to the end of the housing so that gear oil cannot escape.
	Bolt Pattern - series of holes drilled in axle flange face that correspond with a series of holes drilled in the brake drum or rotor that wheel studs press into to allow wheels to bolt to the unit. There are various patterns that are able to be drilled in axle faces and drums to allow different auto manufacturer's wheels to bolt up to the unit.
	Carrier Unit - inner differential component that ring gear bolts to. This unit transfers power from the driveshaft/pinion gear to the axles. Carriers are available in various types that are used in different vehicle applications. Common types are open carrier, traction lock, detroit locker, ARB air locker, spool, etc.
	Companion Flange Driveshaft Adaptor - cast iron component that bolts to 4 holes on the companion flange-style 8.8 or high pinion 9" yokes, that adapts this style of yoke to a regular 1310 or 1330 driveshaft u-joint.
	Companion Flange Yoke - round, flat style yoke that has 4 or 8 holes in the face of it. Some will allow CV jointed driveshafts to be bolted to them. Also the companion flange driveshaft adaptor can be bolted to 4 of the holes on this style of yoke to allow it to be used with a regular u-joint type driveshaft (8.8 yokes only).
	Drum Brakes - consist of brake shoes that are mounted to a backing plate that bolts to the rear end housing. The shoes are housed in a round drum that rotates along with the wheel. When the brake pedal is pressed, the shoes are forced outward against the drum, which slows the wheel down. Fluid is used to transfer the movement of the brake pedal into the movement of the brake shoes, while the shoes themselves are made of a heat-resistant friction material similar to that used on clutch plates.
	Disc Brakes - disc brakes consist of a brake rotor and a caliper.The caliper has friction pads inside it that, when brake pressure is applied, squeeze the brake pads against the rotor to slow the wheel. In stock applications these are used more commonly on front wheels, but are also a desirable upgrade for the rear end from an efficiency standpoint.
	Drain Plug - component that can be added to any housing that has a steel (as opposed to cast iron) center section. It consists of a bung and a pipe plug. The bung must be welded to the bottom surface of the steel housing, and a hole must be drilled through the bottom surface of the housing through the center of the bung. The pipe plug is then installed to plug the hole.
	Fill Cap - a weld on threaded bung that can be added to the housing cover over the ring gear, with a knurled billet aluminum cap with o-ring that screws into it. A hole must be cut in the housing cover, of course.
	Gear Case - cast iron (or optionally, aluminum) unit that houses all of the internal differential components, such as the carrier and ring and pinion. When all of the internal differential components are installed into the case, the completed unit is referred to as a "third member". The 3rd member is then installed into the axle housing and retained with 10 nuts.
	Housing - steel "tube" assembly that has a 3rd member "receptacle" in the center and axle bearing housings on the ends. This unit spans side to side in the vehicle and requires bracketry to be welded to it to attach it to the vehicle. Currie manufactures these in custom widths to fit virtually any application.
	Housing Center - The stamped steel center piece of the housing that the third member bolts into, and the housing tubes press into.
	Housing Covers - the plate covering the backend of the housing unit.
	Housing Tubes - tubing that goes between the housing center and the housing ends that covers the axle shaft.
	Housing Brackets - necessary bracketry that welds to a housing to allow the housing to be bolted into a vehicle - whatever type of vehicle it may be.
	Housing Ends - machined end caps that weld to the end of the tubes on the housing, that are the receptacle that the axle bearing fits into. These are available for various bearing sizes, and are available with various 4-hole bolt patterns drilled in them.
	Mig Welded - type of wire feed welding used by Currie when manufacturing housings and installing brackets.
	Pinion Seal - seal that fits into the front of the pinion support to seal the outside of the yoke to the pinion support.
	Pinion Support - flange on the front of the 3rd member that is retained by five 3/8" bolts. The pinion support houses the 2 front pinion bearings, their races, and the pinion seal. This unit is available in cast iron with standard size bearings, or nodular iron or forged aluminum with larger-than-standard pinion bearings for high performance use.
	Register Diameter - protruding round hub in the center of the outside face of the axle that indexes into the large hole in the center of a brake drum or rotor. Designated by the letter, "R".
	Retainer Plates -install on the axle between the axle flange face and the axle bearing before the bearing is pressed onto the axle. This plate must have the same 4 hole bolt pattern on it as the housing ends being used. When the axle is installed into the housing, the bearing goes into the housing end, and 4 bolts per side bolt the retainer plate to the housing end retaining the bearing in the housing end so that it cannot come back out.
	Ring and Pinion - also known as the rear end gears. The ring and pinion take the rotating of the driveshaft and transfer it to cause the axles to rotate. The count of the teeth on the ring gear and the pinion gear vary, and the difference in this tooth count is what creates the gear ratio. The gear ratio is how many times the pinion gear turns in one rotation of the ring gear. With a 2.75 ratio ring and pinion, the pinion gear would turn 2 3/4 turns in one rotation of the ring gear.
	Ring Gear Bolts - special bolts that attach the ring gear to the carrier. There are two different types of these bolts: a standard bolt that works with the open carrier, detroit locker, detroit tru trac, and ARB; and a longer bolt that is used with the Ford traction lock and the Currie® T.S.D. unit.
	Spring Pads - stamped and folded 3-sided steel saddles that are designed to weld to the axle housing tube so that it may be mounted to a leaf spring. These are available from Currie for various tube diameters and various spring widths.
	Shock Mounts - stamped and folded 3-sided universal weld-on steel brackets, for mounting shocks to the axle tubes.
	Spline - grooves machined in the end of axle shafts that engage into a female set of grooves in the carrier. This is what engages the carrier to the axles to cause them to turn when the carrier turns. The number of splines on an axle shaft varies depending on the type of rear end and horsepower level/application that the rear end will be used for.
	Third Member - when all internal differential parts are assembled into the gear case, the finished unit is known as a third member. Also known as: center section, drop-in, chunk, hog's head, the pig, the ham, or the pot.
	U-bolts - U-shaped bolts with threads on each end designed to fit around the axle tube and go through the bottom spring plate (or top spring plate in a spring-over application) to hold the axle housing to the leaf springs. These are available from Currie in grade 8, 1/2" x 20 fine thread, in sizes that will fit a 2 3/4" tube, a 3" tube, and a 3 1/4" tube.
	Wheel Studs - bolt used to attach wheel to axle. Generally these studs have round heads with a knurl or fine spline immediately below the head that is the same width as the thickness of the axle face. These studs are installed in holes in the axle flange face via a press, and the knurl bites into the hole in the axle flange face to hold them in place. Currie offers these studs in various thread sizes, and standard and long lengths.
	Yoke - cast iron component on the front of the 3rd member that fits onto splines on the pinion gear and is retained by a nut. The rearmost portion of the yoke has the seal surface machined on it that seals the yoke to the pinion support using the pinion seal. The front most portion of the yoke is where the U-joint of the driveshaft attaches to the 3rd member. The U-joint is retained into the yoke by small U-bolts.