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What Is a Gudgeon Pin?

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  • Written By: Mary McMahon
  • Edited By: Kristen Osborne
  • Last Modified Date: 15 August 2014
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A gudgeon pin, also known as a wrist pin, is an important component in an internal combustion engine. It creates a connection between the connecting rod and the piston. Gudgeon pins can also be used with connecting rods and wheels or cranks. Generally, the term “gudgeon pin” is used in the United Kingdom, while in the United States and Canada, the preferred term is “wrist pin.” A number of manufacturers produce gudgeon pins for replacement of worn pins.

This engine component consists of a short tube, usually made from forged steel. The gudgeon pin is subjected to tremendous forces while the engine is running. It must successfully endure thousands of piston firings within a very short period of time. The device is heavily pressured by the extremely hot environment inside the engine and it is also subjected to shearing and bending forces from the connecting rod.

Designing a gudgeon pin is challenging. The device needs to be small and lightweight so it does not add unnecessary weight to the vehicle and to ensure that it fits comfortably in the often cramped quarters of the engine compartment. It must also be strong, made from a metal that will withstand considerable hard use. Some manufacturers use unusual or rare metals to produce their gudgeon pins, while others rely on regular stainless steel forged in carefully controlled conditions.

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The gudgeon pin can be installed in a semi-floating or fully floating configuration, depending on the design of the engine. It acts as a bearing for the connecting rod, allowing for rotational movement while the engine is running. Specialized versions are produced for applications like car racing, where engine components need to be especially strong because high performance engines create some unique demands.

When engines are inspected, as is done during oil changes, tuneups, and other routine visits to the mechanic, the mechanic will look for obvious signs of wear on engine components. If there is a problem with a component like a gudgeon pin, the mechanic may recommend replacement. Uneven or unusual wear will be remarked upon, as it may indicate that there is an underlying problem with the engine that needs to be addressed. It is important to take engine problems seriously, as they can lead to catastrophic failures of components or the engine itself. While repairs may be costly, it is usually cheaper to fix a problem at the time it manifests than to wait for something else to break.

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bear78
Post 3

@burcinc-- That's odd, usually a wrist pin doesn't require replacement at all. Are you sure that there is nothing wrong with your piston?

A wrist pin is located inside the engine piston and the only reason I can think of that's causing the wrist pin to wear out so often, is if there is a problem with the piston itself. Sometimes if the piston is not functioning right, it can cause excessive heat that damages the parts.

So you might want to get that checked out. Maybe it's the entire piston that needs to be replaced and not the wrist pin? This doesn't happen often but maybe there is a problem from manufacturing.

Also, the steel used for wrist pins don't need to be extremely dense or thick because the wrist pin actually needs to be flexible and have some room to move around inside the piston. A more expensive wrist pin is not necessarily going to work better or last longer than a cheaper one.

candyquilt
Post 2

@burcinc-- I work for a company that makes engine parts, including grudeon pins. All grudeon pins are made of stainless steel, this is the best metal for it.

The only difference between them is the quality of the metal- it's purity, as well as the processes used during manufacturing. We make one of the best quality ones out there and the steel we use is raw steel. It goes through several different processes that melt and shape the steel into a uniform and dense structure.

Our pins are made for racers in mind but they can also be used in sports cars. Gudgeon pins of this kind of quality won't need a replacement for a very long time.

burcinc
Post 1

I have a sports car with a pretty powerful engine and I've had to get the wrist pin/roll pin changed twice in the past five years.

I read elsewhere as well that the wrist pin is one of the most easily worn out pieces in powerful engines. If this is the case with my car, I can't imagine how often race cars would have to get their wrist pins replaced. Maybe once a month or something?

My engine's wrist pin is steel. Does anyone know what the strongest and best metal is for a wrist pin?

I can't replace my wrist pin with another type of metal even if I wanted to because every car has a custom piece, so it's not possible to change them at whim. I'm just curious if something other than steel would last longer?

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