Knowing how to repair a cross-threaded bolt is a key skill in maintaining your equipment. Cross-threading happens when the threads are at angle against each other. Because threads are best at work when they are aligned, crossed threads cause the bolt to weaken.
For cars, this means the bolts have to be checked. You would often hear more vibrating and clanking sounds, signifying that the threads are crossed. For any equipment, the worst thing to happen is for the bolt or the nut or socket to get damaged or the part to come loose entirely.
Here’s how cross-threading happens, how to detect and remove them and the best way to repair them.
How Bolts Become Cross-threaded
There are many opportunities for this to happen.
Poor installation – Wrong insertion angle will hurt the bolt. This happens if the bolt is being inserted in a hurry, without checking if the bolt is perpendicular to the hole or socket. Bolts that are installed in a rush are also prone to getting cross-threaded, so make sure to double check for a ‘click’ sound when you install bolts.
Also, make sure that the bolt is aligned before inserting them. You can use dowel pins or a drift punch to aid with alignment.
As discussed here, there is a counterintuitive way to check for alignment of bolts and holes. Try rotating the bolt or screw in the opposite direction–counterclockwise. Once you hear a ‘click’, this means that the port or start of the hole is lined up perfectly with the tip of the bolt. Then, switch to the correct direction which is clockwise, and the bolt will snug right in the correct threads.
Using a power tool – Using power tools are great to speed things up, but it’s difficult to make sure that you’re actually aligning the threads. You will have a better feel for the bolt if you use your fingers. Using power tools at the start will have the reverse effect, which might damage the threads if the screw is not properly aligned. When you’re sure that the screw is aligned, that’s the right time to use a power tool.
Another nifty trick is to place all the bolts first until the cover or the part is level, just to make sure that you’ve got all the bolts aligned. Afterwards, use a power tool to quicken the work.
Damage or debris – When you reinsert a bolt and there is debris in the bolt, this will cause some cross threading to happen. Make sure that it is clean before reinserting.
Wrong Pitch – It happens to cars that if you use the wrong pitch, this would cause the lug nut to cross thread with the wheel stud. With cars, follow the common size which is 12 mm x 1.25” or 20 mm x 1.5”.
How to Check for Crossed Threads
Noise – Crossed threads have weaker torque, so vibrating equipment with crossed threads are noisier. For vehicles, this means you would hear some rattling because the components have become looser.
Immobile fastener – If you are reinserting a bolt and you can’t go all the way through the socket or hole, chances are that the threads are crossed.
How to Remove Crossed Threads
There are specific tools which can be used to remove crossed threads. Use these tools if you are hard-pressed on removing the bolt without any additional tools.
Lube the bolts – Just to be sure, in case you are removing an old bolt, use lubricant or penetrating fluid to remove it easily. Let it sit for five to ten minutes before starting to remove them. If you can afford it, you can heat the surrounding metal and then melt some wax on it, which will loosen the bolt.
Use screwdrivers – The small turning space of the screw or bolt can increase if you wedge a screwdriver between the bolt head and the hole. Insert the tip of a screwdriver between the hole and the bolt’s head, and apply pressure on the screwdriver. The push of the screwdriver’s tip will increase the mobility of the bolt.
Use Anti-cam out fluid – If you are removing Philips-type screws, or any screw, let a drop of anti-cam out fluid fall on its head. This will provide you with more grip when removing the screw.
If needed, use Locking Pliers – Though there’s a chance you might round off the bolt, using locking pliers is preferred for tough bolts that are either crossed, rounded, or threaded or all at the same time. This will give you the grip you need, as compared to just using flat-jaw pliers and needle nose pliers.
How to Repair Crossed Threads
Repairing crossed threads is no different from repairing stripped threads. You have the following options.
- Rotary Thread Rotary thread is one of the most innovative tools that can give you an ergonomic, versatile, and effective repair option. It’s as easy as three steps which can fix crossed thread bolts in less than a minute or a few minutes. Just apply the right amount of pressure and move from the good threads to the bad threads. Because all inch, metric, and pipe threads have a 60 degree angle, the angle of Rotary thread can be used on any such thread.
- Thread files These are the most straightforward tools to use, but it only works for external threads. Once you have the right size, you just have to sharpen the threads as you would a small saw. For internal threads, you have to use another tool.
- Taps and Dies Use the tap for the internal thread, and the dies for the external thread. Taps can be used to align the internal threads. For dies, however, precision may be an issue. Dies can dig into the bolt threads and cause more damage.
- Thread Plows Thread plows are not ergonomic tools, which will require you to use a lot of room to operate. Poor use of the tool can also cause the workpiece to disengage often.
- Helicoil Well known for its reliability. However, this only works for internal threads. It also is not as straightforward, with many steps along the way. You need to work with a drill, a tap and installation tools.
Cross-threaded bolt will compromise the torque of a joint and weaken its components. When threads are mismatched with one another, this can cause new threads to form. An ergonomic option to fixing crossed threads is to use Rotary thread, which works with inner and outer threads; and can fix every inch, metric, or pipe. Using Rotary thread can help you get more work done, especially if you are keen on how to fix cross-threaded bolts the ergonomic way.