Can You Weld a Cracked Gearbox? Here’s What You Need to Know

If you find a crack in your gearbox, it can be worrying. The gearbox is an important part of a vehicle; if it gets cracked, it is a big problem.
Before you rush to purchase a new gearbox, you might think, “Can I weld the crack?”

The answer isn’t just “Yes” or “No”. Welding can be a good idea, but it has both good and bad sides. Today we discuss the pros, cons, and alternatives of welding to fix your gearbox, and when you should get help from a professional.

Why Does a Gearbox Crack?

First, we have to understand what causes a gearbox to crack. By knowing the root cause, we can make a quicker decision.

Wear and Tear: Over time, gearboxes undergo a lot of stress when subjected to load and high speed.

Impact Damage: When you hit a big pothole or have a small accident, your car can get more damage than you believe. Usually, the gearbox is well-protected by the car body, but even then, it can get damaged.

You may not observe damage right away, but the force from the hit can cause cracks that affect the working of the gearbox. That’s why checking your car after a hard impact is important.

Poor Maintenance: Many people don’t regularly maintain their vehicles. Changing gear oil and regular servicing can reduce issues like overheating or other problems that could cause cracks.

Manufacturing Defects: This is very rare, but some vehicles come with manufacturing defects, like small air cavities or minor flaws. Over time, these issues can develop into cracks due to regular load and vibration.

Can You Really Weld a Cracked Gearbox?

Welding a cracked gearbox is a tough decision, that depends on several factors, such as the material, nature of the crack, and overall condition of the gearbox.

To determine if welding is a feasible solution, it’s important to consider the following factors:

1. Material Considerations

Different metals react differently when welding:

Aluminum Gearboxes:

Aluminium is a commonly used metal in gearboxes because it is lightweight and strong.

However, welding aluminium is challenging because it heats up and cools down very quickly. If not done correctly, this can cause the part to change shape or crack. To avoid these problems, the welding process needs to be managed very precisely.

TIG welding is most commonly used for welding aluminium parts, because it provides proper control over the heat, making it easier to avoid distorting or cracking.

Cast Iron Gearboxes:

Cast iron gearboxes are durable but they are very brittle, welding them is also a difficult process.

Cast iron requires preheating to prevent further cracking during the welding process.

This process involves stick welding with specific rods and careful cooling after the weld, to avoid additional stress on the metal.

2. Crack Characteristics

Whether welding is feasible depends on the type and location of the crack.

Type of Crack: Surface or minor cracks are easier to weld when compared to deep or structural cracks.

Surface cracks may be repaired effectively with welding, while deep cracks can reduce the gearbox’s strength and require more extensive repair methods.

Location of Crack:

Cracks near critical areas such as mounting points or bearing seats are more challenging. These areas experience high stress, and welding might not provide the necessary strength to it.

Cracks in these locations may need different repair processes or even replacement of the gearbox.

3. Overall Condition of the Gearbox

The overall condition of the gearbox helps us to decide if welding is a good idea or not:

Age and Wear:

If your vehicle is new or the gearbox is in good condition then you can fix cracks with the welding.

If the gearbox is old and has many problems or is worn out with multiple issues, replacing it with a new gearbox is the best option, as welding may only provide a short-term fix.

Previous Repairs:

If the gearbox has been previously repaired or it has multiple cracks, then welding might not be effective. A gearbox with extensive damage may require a complete rebuild or replacement.

The Pros and Cons of Welding a Cracked Gearbox

Pros:

• Cost-Effective: Welding is usually a cheaper option than replacing the entire gearbox, particularly if the crack is small and easy to weld. In some minor cases, you can even weld it yourself.
• Faster Fix: Welding can get you back on the road faster than waiting for a new part or a complete gearbox to arrive. For outdated vehicles, it is very difficult to find original parts.
• Keeps Original Parts: If you have a classic or rare car, welding allows you to keep the original gearbox, which may be hard to replace. The manufacturer of the vehicle may have stopped producing new parts.

Cons:

• Structural Integrity: Welding can weaken the material, especially if it’s not done correctly. This can cause another crack after some time.
• Risk of Warping: The heat from welding can distort the gearbox housing, leading to misalignment and affecting the vehicle’s performance.
• Temporary Fix: After welding the crack, if the root cause isn’t addressed, the crack may reappear or spread, damaging the gearbox again.

Alternative Solutions to Welding a Gearbox

If welding sounds too risky, don’t worry—there are other ways to fix a cracked gearbox.

Epoxy Repair

For small cracks, you can use a special type of glue called Metal epoxy. This is easy to apply and inexpensive, suitable for minor cracks not for large or deep cracks and is not as strong as welding.

Gearbox Rebuilding

Rebuilding means taking apart the gearbox from your vehicle, and then checking each part, and replacing the damaged part. This is a more thorough fix compared to welding and it can make the gearbox work like a new one.

Replacement

Sometimes, the best option is to simply get a new or refurbished gearbox. This means replacing the old gearbox with a new one. It’s often the most reliable long-term solution, especially if the gearbox is significantly damaged or old.

How Long Does a Gearbox Last?

Gearboxes usually last for 90,000 to 120,000 miles or 7 to 10 years. Good maintenance helps them last longer. If your gearbox is old, you should consider replacing it with a new one. Welding a crack can help, but after some time, you may encounter new cracks.

Should You Weld It Yourself or Get a Professional?

When deciding whether to weld a cracked gearbox yourself or hire a professional, consider these points:

1. Skill and Experience

• Doing It Yourself: Welding a gearbox can be tough, especially if it’s made of aluminium or cast iron. If you don’t have experience with these metals or welding methods, you might end up causing more damage. Welding requires precise skills to get a good outcome.
• Hiring a Professional: A professional has the experience and tools needed to fix that crack correctly. They know how to handle different types of metal and avoid common mistakes, like warping or further cracking.

2. Tools and Equipment

• Doing It Yourself: Proper welding requires specific tools and equipment like welding machines, clamps, angle grinders etc, which are expensive and complicated to use. If you are not familiar with how to use them, the welding job might not turn out well.
• Hiring a Professional: Professionals have the right tools and know how to use them effectively. They also know how to prepare the gearbox properly and ensure a strong weld.

3. Cost

• Doing It Yourself: Welding it yourself might seem cheaper, but if the repair is not done well, you could end up spending more to fix additional damage or get it redone by a professional, which increases the cost.
• Hiring a Professional: While hiring a professional might cost more upfront, it can save you money in the long run by ensuring a high-quality repair that prevents further problems.

How can I teach myself to weld?

Cost of Welding a Cracked Gearbox

When considering welding a cracked gearbox, it’s important to understand the costs involved:

1. Cost of Welding Services

• Professional Fees: Hiring a professional welder generally costs between $150 and $500. The price can vary based on the size and location of the crack, and gearbox material is also one of the main things. For instance, welding aluminium might be more expensive due to the specialized techniques required.
• Material Costs: Additional costs for welding materials, such as specialized rods or fillers, generally range from $30 to $100. The actual amount depends on the type and quantity of materials needed.

2. Preparation and Additional Work

• Preparation Costs: Preparing the gearbox for welding, including cleaning and maybe disassembling it, will add $50 to $150 to the total cost. Proper preparation can ensure better welding work.
• Post-Welding Costs: After welding, you should need a budget for reassembly, testing, or painting to protect the repaired area. These costs can range from $50 to $150, depending on the complexity of the work required.

3. Comparing Costs

• DIY Welding: If you choose to weld the gearbox yourself, you’ll need to purchase or rent welding equipment and tools. The cost of a basic welding setup can range from $200 to $600, while welding materials might add another $30 to $100. We have to keep in mind that this does not include potential costs for fixing mistakes or additional damage.
• Professional Welding: While hiring a professional is typically more expensive, with total costs often ranging from $250 to $850, it usually provides a higher quality and more reliable repair. This can be a cost-effective option in the long run, as it reduces the risk of further repairs or replacements.

In total, fixing a cracked gearbox could cost between $400 and $900, depending on your location.

How to Avoid Gearbox Cracks in the Future

• Regular Maintenance: Regularly changing the gear oil and inspecting the gearbox will help minimize the risk of failure.
• Fix Small Issues Early: If you hear strange noises or notice your car isn’t running smoothly, address the problem early to prevent bigger issues.
• Drive Carefully: Avoid overloading your vehicle or driving roughly.

Frequently Asked Questions:

1) What is the best type of welding for a cracked gearbox?

TIG [Tungsten Inert Gas] welding is the best option for welding Gearboxes, especially when made from aluminium, MIG welding is another option, but it has less precision.

2) Can all cracks in a gearbox be fixed by welding?

Not all cracks can be fixed with the help of welding. If the crack is large or affects the structural integrity of the gearbox, it might be safer and more effective to replace the damaged part or the entire gearbox.

3) Should I weld a cracked gearbox if it’s old?

NO, welding an old gearbox is not a long-term solution, after some time new cracks can appear. It is recommended to replace it.

4) Should I replace the cracked part or the entire gearbox?

If the crack is limited to one part of the gearbox, you can replace just that section. However, if the crack is big or affects multiple areas, replacing the entire gearbox is a better option.

Conclusion

Yes, you can weld a cracked gearbox, but it is not always the best solution. Welding is a cheaper and faster option, but it can also reduce the strength of the gearbox or cause warping due to high temperatures. For large cracks, replacing the part or the entire gearbox may be a better option. If you decide to weld, make sure someone does it with the right tools and skills to avoid further damage.

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