Car Repair Tools

Auto Ratchet Set: US or Metric? Which One Should You Buy


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The purchase of an automotive ratchet set is a must for every hobby mechanic. An auto ratchet set consists of a socket wrench which may be equipped with a gauge to measure torque when bolts need to be fastened to a very specific, measurable level of tightness. Standard socket wrenches and sockets are used for bolts that don’t require any particular amount of torque. As with all wrenches, you have the choice between U.S., also known as standard, or metric sizes. American cars are assembled with nuts and bolts that use standard measurements while foreign cars almost exclusively use metric measurements. 

U.S. or Metric Size

The question of whether to buy a U.S. or metric ratchet set is not a complicated one. If you only ever work on a car that uses standard measurements and never plan on using the tools for other cars, by all means buy the standard set. If, on the other hand, you own and work on a foreign automobile, a metric set is what you need. The all-inclusive mechanic, though, should have access to both. Having an assortment of standard and metric wrenches and sockets for both, no matter what type of car you are working on, you will have the tools to do it. Some ratchet sets include both types, standard and metric. With sockets ranging from 4mm up to 18mm and from 5/32 up to ¾ inches, complete socket sets are the best way to cover all of your automotive ratchet needs. 

Torque Wrench Ratchet Sets

Special types of socket wrenches are used to tighten bolts to very specific levels. These are known as torque wrenches, and they work by means of an internal mechanism that measures the amount of torque you put onto a bolt when tightening it. Torque wrench ratchet set sizes are the same in terms of whether the bolts are measured in millimeters or fractions of inches. The ability to measure the force is what distinguishes torque wrench ratchet sets from ordinary ratchets. 

With torque wrench ratchet sets, you have the option of purchasing sockets that fit standard bolts or metric bolts. The drivers on the wrenches insert and attach to the individual socket and work regardless of the measurement type provided the driver is the right size for the wrench. Again, having access to both standard and metric torque wrench sockets is instrumental in being able to work on all types of cars. Torque wrenches themselves are very expensive. The precision measuring involved necessitates highly-calibrated tools, so the cost is accordingly high. 

An auto ratchet set is a very useful tool when working on your own vehicle. From bleeding brakes, removing the drain plug from the oil pan and removing spark plugs to loosening bolts and making necessary adjustments, you will always have use for your auto ratchet set. For fine tuning and calibration, a torque wrench is needed, but many of the same sockets can be used. The two measurement types are standard or U.S. and metric. While your car will use one or the other, it’s a good idea to have a selection of both for when you need them. 

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