Stud vs Bolts

If you are an engineer, a mechanical enthusiast, trying to assemble his/her engine or a total newbie, you need to know all stud vs bolts facts. Before buying the necessary components, the primary question is: What would be the better choice for a precision assembly, Studs or Bolts? These threaded fasteners are the vital link that secures everything together, and these are very important components of a machine. This is why we are here to tell you all the necessary bits to know before deciding on what to choose between studs vs bolts.

What is Stud?

Stud vs Bolts

A stud is a metal tool used to attach components to engines. It is a slim long metal tube with two ends, one end with large threads, and the other end consists of finer threads compared to the other side, and there’s a reason for that. When you look at a stud, you can see a whole thread of engagement.

The ends with a larger thread have comparatively wider threads than the fine one. Whereas, on the fine thread side, the threads are narrower, giving it more engagement because of the extended surface area.

For the more number of threads, it is going to give a shallow angle of engagement, so it is going to be harder for the nut to back off but easier to turn the nut while tightening it.

What is Bolt?

Much like studs, a bolt is also used for tightening engine parts, but unlike studs, a bolt has only one end with a single type of thread. They require a nut or some other thread as a counter to lock the joint. Bolts are generally used in industrial applications that are secured with a spring washer or a lock tite. Bolts are designed to be used as a fastener placed through already drilled holes in any sort of machinery, and it requires one single nut to tighten it from the other end.

Main cap stud installation tips: A complete Guide

As we all know, studs provide a correct clamping force with higher strength than most bolts. But if not installed properly, these can do more harm than good in your installation. Here are a few very important steps to consider before attaching your studs in place.

Main cap stud installation tips

It is very important to clean and check all threads on both sides of the tube. After the tank is cleaned and dried properly, recheck everything one more time to avoid any unavoidable circumstances.

Scrubbing the main cap bolt threads with a brush and brake cleaner and drying them before assembly is another vital step to ensure perfect placement of the main caps. Make sure to clean all sorts of shipping lubricants from the threads, and the bolt should be free of any sort of contamination.

Put the studs in the appropriate holes; make sure to hand tight only. Do not overtighten the studs, and a very thin coating of lube can be brushed in the threads at this point, but lubing with regular motor oil is discouraged.

What are Cylinder head studs?

Cylinder head studs are made from circular rods, usually of alloy steel. These threads are cut on both ends.

Cylinder head studs

The threads that screw into are made with fine thread, whereas the threads are generally larger in the nut end. This design ensures a tighter fit which helps the stud from loosening when the nut is removed.

Head stud installation tips

To start, check all the holes in the block and make sure there is no dirt or oil. It is very important to ensure the holes are perfectly cleaned to get the correct torque reading. A thin coat of APR should be applied at this stage on the wider side of the threads, then finger tight the stud into the block. Then use a hex top to bottom of the studs out against the block. Make sure not to over-tighten the studs.

A dial caliper can be used to make sure the studs are properly seated in the block, and all the studs should be the same length. If you see any problem in the stud’s length or any hard spot even though the holes were properly cleaned, don’t get tensed. It is perfectly normal and can happen in almost 50% of the cases. When it gets difficult to turn the studs, immediately stop tightening them any further to avoid any damage.

Just simply remove the stud and inspect the holes for any leftover debris. After that, the stud can be placed smoothly. After all your studs are properly placed, clean the surface before carefully putting on the head gasket. Follow the steps provided by the engine manufacturer. Don’t forget to double-check all the torque specs upon completion.

Why use studs instead of bolts?

  • When a choice is available people prefer using studs instead of bolts for a heavy duty performance. In comparison, the stud obtains much more accurate torque values and that’s mainly because the studs don’t twist during tightening. The studs do not move during nut tightening and because of that the stud stretches in one axis, which provides much more correct clamping forces.
  • The stud puts less pressure on the block’s threads especially in alloy blocks, and for this the life of the threaded holes extends over the time of serving.
  • Because the studs stay stationary during cap clamping there is less chance of the main cap moving

Types of stud bolts

Types of stud bolts

Keeping its regular shape, stud bolts or studs have three different types: fully threaded stud bolts, tap end stud bolts and double end stud bolts. Each of these studs has its own specifications. As the name says, fully threaded studs have a full body of thread for full engagement for the nut (picture on the left). Tap end studs have uneven thread engagement at the very bottom of it (middle) and double end studs have equal length threads at both ends (right). There are also studs for flanges, these are fully threaded studs with chamfered ends, for special bolting applications double end studs with reduced shank are used.

Stock head bolts vs arp:

Well, the stock head bolts and arp works quite similarly except for the fact that arps are reusable and also some people just like spending a little more on their vehicles. Also arp lasts longer for a high power vehicle.

Main studs vs head studs:

The crankshaft is held down by the main stud and head stud holds down the head.

ARP head studs vs head bolts:

Head studs are better to use in high performance vehicles that require greater power, and head bolts are suitable for personal everyday vehicles.

Stud vs bolt: strength, clamping force, torque

As discussed earlier, the stud obtains much more accurate torque values and that’s mainly because the studs don’t twist during tightening. The studs do not move during nut tightening and because of that the stud stretches in one axis, which provides much more correct clamping forces. So it is quite evident that in terms of strength, clamping force and torque studs do a better job than bolts.

 Stud vs bolt torque chart:

Stud vs bolt torque chart

Wheel stud vs bolt

Wheel studs are threaded stems attached to a tapered head that are mounted in the hub and stick out beyond the brake rotor hat. Whereas, wheel bolts are a threaded stem attached to a tapered head that matches to the wheel insert. The wheel bolts are commonly used by German cars like BMW and Volkswagen and the wheel studs are used to hold wheels on many other automobiles. It is said that the wheel bolts are comparatively stronger than wheel studs, it has a taper that matches the wheel, this bolt goes in and holds the wheel in place and these bolts only work with BMW and some Volkswagen wheels.

Exhaust manifold stud vs bolt:

It is quite common to see people using studs instead of bolts in the exhaust manifold and there is a reason behind it. The studs’ threads are generally softer on the inside which tends to stick it in its place and makes it difficult to get them out, whereas in bolts just a wrench can take it out easily.

Machine bolt vs stud bolt:

A machine bolt is an extremely threaded fastener that has a head with one nut, it has different styles of heads such as: Hex, Square, etc. On the other hand, a stud bolt is a metal rod or shaft with threads on both sides.

Hex bolt vs stud bolt:

Stud bolt is a threaded rod with two hexagon nuts on both sides. Studs are measured parallel to the axis from the first to the threads without the chamfers. The length of a stud bolt is defined by ASME B16.5 standard. The hex bolt is a rod that is threaded on one side with one nut. Hex bolts are measured from under the head to the top of the bolt. It is defined in ASME B1.1 bUnified Inch Screw Threads ( Un and UNR Thread Form).

FAQ

Why is stud used instead of bolts?

Studs are liked by many for their heavy duty performance and durability, studs obtain a much more accurate torque value than bolts. During nut tightening it proves to be quite advantageous to get a clear torque value if it doesn’t move, and studs are proven to be the one.

What is the difference between Stud & Bolt?

Studs are long cylindrical shape metal tools with two sides of threaded ends. It has one end of fine threads and another end with a much wider thread with metal nuts on each side for tightening.

Bolts look similar to studs but it has only one threaded part in the bottom, its threads are uniform and it also has a nut for tightening at the end.

Are head studs better than bolts?

It mostly depends on what work you are doing. Both studs and bolts prove to be good if used in the correct place and correct way. Although there are people who prefer using studs over bolts for their better clamping force and higher strength in both cases, if they are not installed properly will not do their desired job.

What is the difference between machine bolt and stud bolt?

Machine bolt is a finely threaded one-sided fastener with a nut at the end. There are different kinds of machine bolts available such as Hex, Square, Anchor, Blind, Carriage, Double-end, Eye, Peta-Head, etc.

What is a stud bolt used for?

There are different types of stud bolts that are used in various works. Fully threaded stud bolts, tap end stud bolts and double end stud bolts are three of its types. These are used for special bolting applications.

What is stud used for?

Stud is a long metal both sided threaded rod used to attach engine components. At each side of threaded ends, it is fastened with a metal nut for tightening.

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Conclusion

With the given information above, we can see it is no ‘one size fits all. Different automobiles and different engines require different studs and bolts according to their specification. It is also important to know the owner’s preferences, and of course, every stud and bolt comes in different price ranges according to their quality. There are many cheaper options in the market to use as an alternative to the expensive ones, but their quality will not match with the ones that come a bit pricey.

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