Inside the engine of your car, the connecting rod and its other, big, end have not changed all that much from the early days of engine design although the materials of the forged, H-section connecting rods have improved to cope with the demands of added loads, imposed as power has increased. A few engines have used aluminium alloy connecting rods, for instance the engines in the first models of Ferrari 458 for sale, but the great majority of engines still use steel. To enable the big-end to be assembled on the crankpin, the bearing is divided along a diameter, often at an angle to the connecting rod centre-line, for ease of assembly past the crankshaft. The cap so formed is secured by bolts having high tensile strength, the nuts of which are very securely locked.

The original type of bearing was a great lump of bronze, but an early development was to coat the actual bearing areas thickly with a soft alloy of tin, copper and antimony, first produced by Babbit in 1839, examples of this can be found inside the engines of certain classic cars for sale. The next development was to reduce the thickness of both bronze and Babbit metal and to produce bearing shells which could be slipped into place without the need for further fitting work. The actual bearing metals improved to deal with higher demands and the backing changed from bronze to steel.

One method of production is to coat a long steel strip with lead-bronze powder which is baked, or sintered, in place. The bi-metallic strip is then cut to short lengths which are pressed into accurately dimensioned semi-circular shells with small ears which rest in notches in the rod and its cap, to stop the shells moving around when in use.

Other similar bearings have thin coatings of suitable metals flash-plated on the wearing area. Some engines have used roller bearings but, as this entailed designing the crankshaft in such a way that it could be built up from a number of pieces, to allow the roller bearings to pass over the crankpins, it was used only on very expensive engines as found on early models of the Rolls Royce Ghost. Moreover, roller bearings are not`ideal for use when they are subjected to heavy shock loadings, because the rollers tend to press grooves into their races under such conditions.