So Fix it

A timing chain, or belt, is an integral part of an automobiles engine that controls the opening and closing of the valves in the engine. If the chain breaks, serious damage to the engine could result. Proper maintenance is important to prevent this from happening.

Tension

A timing chain can break with either too much or not enough tension. If the chain does not have enough tension, it can develop slack. This can result in the chain "slapping," leading to premature fatigue. A chain with too much tension can also fail, as it is placed under excessive stress. Tension increases friction and heat in the chain, which can result in failure.

Engine Seizure

Engine seizure can be caused by an engine overheating or running out of oil, causing pistons to seize inside the cylinders. If an engine seizes while running at high speeds, the sudden stop can cause a timing chain to break.

Age

The age and number of miles driven on a timing chain are major contributors to failure. The more miles you have on your vehicle, the higher the odds your timing chain will fail, as the chain will become weak and break. Most car manufacturers suggest you have the chain replaced every 60,000 miles.

Roller chains are most commonly used on bicycles, automobile engines and heavy machinery for the transmission of power. They come in a variety of sizes to meet almost any application. The larger the size of chain, the larger the roller diameter, pitch and tensile strength the chain is rated for. Choosing the right chain for your application is important for safety and functionality.

Roller Chain Terms

The chains pitch is the distance between the center of the neighboring rollers; its diameter is the width between the link side plates. The digit furthest to the right in the chains number denotes its type: 0 for a normal chain, 1 means a lightweight chain and 5 for a rollerless bushing chain. If the chain number ends with an "H" it is a heavyweight chain.

35 Chain

The 35 chain is a rollerless type chain. It has a pitch of 0.375 inches and diameter of 0.2 inches. It is rated for a tensile strength of 1,758 pounds and a working load of 480 pounds.

40 Chain

The 40 chain is a normal, roller-type chain. It has a pitch of 0.5 inches and a diameter of 0.312 inches. It is rated for a tensile strength of 3,125 pounds and a working load of 810 pounds.

Differences

The main difference between the 35 and the 40 chain is that one is rollerless and the other has rollers. The two chains also have different pitches and diameters, which will limit their interoperability. Additionally, the 40 chain is rated for a significantly higher tensile strength and working load than the 35.