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Transmission Rebuild Vs Replace: Which Is Better?

Automatic gearbox transmission on a workbench at a car repair shop

They are the words that no vehicle owner wants to hear: your car needs a new transmission. While this used to be a death knell for most vehicles, the surge in used car prices has left many owners choosing to repair their vehicles instead of getting a replacement. When it comes to fixing a transmission, owners have a couple of options: a rebuild or a replacement. But which is better?

A transmission rebuild is usually a preferred option over a transmission replacement. During a rebuild, the transmission is taken apart, with functional components salvaged and damaged parts swapped for new or refurbished pieces. In addition to keeping your vehicle with its original transmission, a rebuild is often much cheaper than a replacement.

Although a transmission rebuild is the recommended course of action for a transmission in need of serious service, not all transmissions can be rebuilt, and some owners prefer the peace of mind of having a completely new transmission. Keep reading to find out whether a transmission rebuild or replacement is right for you.

Is It Better to Rebuild or Replace a Transmission?

It is usually better to rebuild a transmission, as it will ensure that the vehicle continues operating with the transmission for which it was originally designed.

During a transmission rebuild, the transmission is completely taken apart and put back together, piece by piece. All components that remain in good shape will be cleaned and reinstalled, while those that are worn out will be replaced with new or refurbished components.

Some common components within a typical automatic transmission include seals, valves, gaskets, gears, clutch, bands, torque converter, valve bodies, and flexplates. The condition of all of these components will be assessed during a transmission rebuild.

Although it is usually recommended to rebuild a transmission instead of replacing it, there are some scenarios in which a replacement will be better. Let’s take a look at the pros and cons of rebuilding vs replacing.

Automatic gearbox transmission on a workbench all taken apart with all the internal parts visible

Pros and Cons of Rebuilding a Transmission

There are numerous pros to consider when rebuilding a transmission:

  • It can be a bit more cost-effective since you won’t be purchasing an entirely new transmission
  • A transmission rebuild usually only takes a few days, as opposed to a week or more for a replacement
  • There are more shops capable of doing a transmission rebuild, whereas a replacement is likely only doable for the original manufacturer
  • You will be re-installing the same transmission you know is compatible with your vehicle

On the downside, a transmission rebuild is not always possible. There are some instances in which the damage to the transmission is so significant that you have to start from scratch with a transmission replacement.

In addition, because a transmission rebuild does not replace all components, you run the risk of something else within the transmission wearing out shortly after the rebuild. Even though a part looked good to the technician during the rebuild it still has miles of wear and tears on it, so you may find yourself at the transmission shop sooner after a rebuild than you would like.

Pros and Cons of Replacing a Transmission

There are several different options that may constitute a transmission replacement:

  • The original transmission is completely broken apart, being built back with completely new components. This is sometimes referred to as a “re-manufactured” transmission
  • The damaged transmission is swapped out with a functioning transmission from an identical make and model
  • An entirely new transmission is built specifically for your vehicle (likely only possible when performed by the original manufacturer)

The benefits of a transmission replacement generally involve the peace of mind. Unless you are replacing your damaged transmission with a functioning used one, you have the confidence of knowing that you will be getting a new transmission with no miles on it, built by a technician specializing in the type of transmission your car specifically needs.

The downsides to a replacement are costs, with some replacements costing more than twice as much as a rebuild.

There is also the possibility that your vehicle doesn’t take to the new transmission. While not overly common, there are instances of “lemon” transmissions that go kaput after only a few thousand miles, usually due to errors in the manufacturing process creating a transmission not completely compatible with your vehicle engine.

Auto mechanic inspecting the gearbox automatic transmission that's been removed from the vehicle at a repair shop

8 Signs That Your Transmission Needs Servicing

With a modicum of care, most modern transmissions will last between 100,000 and 150,000 miles. For those owners who regularly have their transmission flushed per factory recommendations (usually every 50,000 miles), it is not uncommon for the transmission to last the entire lifetime of the vehicle.

However, each transmission is different, and there is no set-in-stone odometer reading that will tell you when it is time for a new transmission. Therefore, it is important that you are versed in the following warning signs indicating that your transmission is on its last legs.

1. The Check Engine Light Is On

Although it is highly unlikely an illuminated check engine light is indicating a transmission failure–it is usually triggered by faulty sensors or rich/lean fuel mixtures–seeing the dashboard warning should always make you think a little bit.

Always have a professional technician diagnose a check engine light, and let them know if the light showed up in conjunction with any of the other symptoms on this list.

2. Leaking Fluid

Transmission fluid is one of the most easily recognizable of the numerous fluids your car contains. It is pinkish-red in color and will give off a slightly sweet smell. If you see this on the ground, it is a sign of a transmission leak.

If you cannot identify the color of the fluid, another sign that your transmission is leaking is when you notice a line of fluid as opposed to a puddle. Sometimes, fluid only escapes when you move between gears, so if you see a trail of fluid leading to or from your driveway, it is a likely indication of a transmission leak.

If you suspect a leaking transmission, check the fluid while the vehicle is running. You should see a couple of pink drops fall off the dipstick end of the dipstick. If the dipstick is dry, or the fluid is brown or smells burnt, your transmission is at risk.

Pavement asphalt road with fuel oil and or transmission fluid leaks

3. Burning Smell

A burning smell coming from under the hood could signal a variety of malfunctions. However, friction within the transmission is one of the most likely. If the burning smell is combined with a brownish transmission fluid, get your vehicle to a technician immediately.

4. Strange Noises

Like a burning smell, strange noises are another universal sign of car damage. Humming, whining, or clunking are some of the most common emitted by a faulty transmission, so be on extra high alert if you hear them coming from the area of the transmission (usually directly to one side or the other of the engine).

5. Grinding or Shaking

In a best-case scenario, grinding or shaking when shifting or accelerating is due to worn motor mounts, which will cause your foot to shake when you step on the gas pedal. However, it can also be an indication of a transmission that is operating inefficiently, so get your vehicle examined as soon as possible to pinpoint the exact cause.

6. Difficulty Shifting Gears

As the transmission is designed specifically to switch your vehicle between gears, difficulty shifting is all but a guaranteed symptom of a faulty transmission. Your gear shift may feel stuck, requiring extra effort to move from park into drive, resulting in a massive “thud” when finally successful. Ideally, the new transmission fluid will solve the problem, but you likely have a faulty component that needs to be rebuilt.

7. Slipping Gears

Like difficulty shifting, gear slippage is another surefire indication of transmission trouble. If you are driving along at highway speed and your engine revs through the roof unexpectedly, your transmission has slipped out of the appropriate gear. It will give you the sensation that you have driven over a patch of ice, although no ice is present.

8. Unresponsiveness

Finally, if you shift your car into gear and nothing happens, it is a pretty clear indication that your transmission is shot. Most common when shifting your car from park to drive, a lack of ability to “get it in gear” means that you are looking at a transmission rebuild squarely in the face.

Inside view of an open automatic transmission gearbox with wear and tear visible on the gears

Frequently Asked Questions (FAQ)

Q: Is It More Expensive to Rebuild or Replace a Transmission?

A: As mentioned, it is generally much more cost-effective to rebuild a transmission than replace one, due to the following factors:

  • A rebuilt transmission salvages components in good condition, so there is less material cost
  • It does not take as long to rebuild a transmission than manufacture a new one, so labor costs are reduced
  • There are more shops that specialize in transmission rebuilds, whereas replacements are usually restricted to the original manufacturer

As a very general estimate, the most basic transmission rebuilds for simple transmissions can cost as little as $2,000, with more complex rebuilds approaching $4,000.

On the other hand, transmission replacements will almost always cost over $4,000, with replacements for newer, more complex transmissions approaching $10,000.

For this reason, many owners seriously consider scrapping their vehicle altogether when they get the news that a transmission replacement is their only option for getting back on the road.

Q: Why Is Servicing a Transmission So Expensive?

A: Transmissions are the most complex parts of most vehicles. In fact, it is not really accurate to call them a “part.” They are an entire mechanical system of their own, within the greater mechanical system of the car. The transmission must be functioning and communicating perfectly with your engine to ensure the success of your vehicle.

Due to this complexity, technicians have to completely remove the transmission, take it apart, and get it working as its own system prior to reinstalling it back into the vehicle and syncing it with the engine. It’s not as simple as just removing the faulty part and installing a new one like it is for other areas under the hood, resulting in a higher total cost.

Q: Where Can You Have a Transmission Rebuilt or Replaced?

A: Many general mechanic shops will not be able to rebuild or replace your transmission. They will likely refer you to a specialized transmission shop that employs mechanics specifically trained and experienced in building transmissions. These shops will usually feature “Transmission” in their business title to let you know they do transmission service.

The range of shops that replace transmissions is usually much narrower. In most cases, only the original manufacturer can replace a transmission. For example, if your vehicle is a Ford, you would have to go to a Ford dealer to have a full transmission replacement.

Close up of a mechanic repairing an automatic transmission gearbox with a socket wrench and gloves on

Q: Is Rebuilding a Transmission Always an Option?

A: No, rebuilding a transmission is not always an option.

In cases where damage to the transmission is severe, there may not be enough of the existing transmission to salvage for a rebuild to be successful.

In addition, it is reported to be difficult to rebuild newer, more complex continuously variable (CVT) transmissions.

Q: Is a Transmission Rebuild the Same as a Transmission Repair?

A: There is a misconception that a transmission rebuild is synonymous with a transmission repair. The two procedures are not the same.

A transmission repair is a very simple procedure that can be performed by most general mechanic shops for very minor transmission issues. This may include a transmission flush, transmission fluid replacement, or fixing a leaking transmission pan gasket.

For each of these minor procedures, the transmission does not need to be removed from the vehicle, and no advanced knowledge of transmissions is required to complete the repair.

As previously mentioned, a transmission rebuild involves removing the transmission, breaking it down, and replacing any degraded components.

Conclusion

In most cases, a transmission rebuild is a preferred procedure over a transmission replacement. It is a more affordable process and can help keep your vehicle with the transmission it was originally built with. However, there are some instances in which a rebuild is not possible, making a replacement necessary. Whatever the case, know your vehicle and the signs of transmission failure to help make the most informed decision possible.

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References:

Twin Transmission

Murray’s Auto Clinic, Inc.

Motor Hills

Ralph’s Transmission

Repair, Rebuild, or Replace? Which Transmission Solution Is Right For You?

The Differences Between Automatic and Continuously Variable Transmissions (CVT)

AAMCO Transmissions

AAMCO Keller Blog | Transmission Rebuild VS. Replace

Woodie’s Auto Service & Repair Centers

The Difference Between Transmission Repair, Replacement, and Rebuild – Woodie’s Auto Service and Repair Centers

Christian Brothers Automotive

Transmission Trouble: 10 Warning Signs You Need Repair

Ernest Martynyuk

An automotive enthusiast who's been tinkering with vehicles since I was 15-years old. Repairing automotive electronics has been my main job for over a decade now and have a passion for everything technical regarding cars.

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