Your vehicle is a system comprised of various parts that all work in tandem. Like in all systems, there are major and “minor” parts. One of your vehicle’s major components is the transmission, which is responsible for the way your car moves.
In some instances, a bad transmission can prevent your vehicle from working. The functionality of your vehicle’s transmission is significantly affected by the transmission mounts. So it is imperative that you know the symptoms of a bad transmission mount.
A lot of vehicle owners do not fully appreciate the significance of the bad transmission mount. You probably got here because you typed in the search query “what happens when you have a bad transmission mount” or something related.
If that’s you, you are in for a treat because this article will focus on the significance of a transmission mount and how you can tell when your transmission mount is bad.
What is a Transmission Mount?
A transmission mount is a component that securely connects your transmission to the vehicle’s frame or subframe. It can be compared to a cushioned bracket that holds your transmission in place while absorbing vibrations during operation.
The mount serves two main purposes: it keeps the transmission properly positioned so it can transfer power to the wheels, and it dampens the vibrations that naturally occur as the transmission operates.
Without a functioning mount, your transmission would shake excessively and potentially damage surrounding components.
Transmission mounts are different from motor mounts (also called engine mounts), which hold the engine in place.
While both types of mounts have similar functions and can cause vibrations when they fail, transmission mounts specifically support the transmission end of the drivetrain.
Most vehicles use rubber transmission mounts, which consist of a metal bracket with rubber cushioning material. The rubber acts as a shock absorber, soaking up normal vibrations while providing solid support.
Some higher-end vehicles use hydraulic mounts, which contain fluid-filled chambers for even better vibration dampening.
Your car typically has one or two transmission mounts, depending on the vehicle design. Under normal driving conditions, these mounts can last anywhere from 60,000 to 120,000 miles (or more).
However, factors like aggressive driving, extreme temperatures, and oil leaks can shorten their lifespan as the rubber material naturally degrades over time.
The Function of a Transmission Mount
A transmission mount does what you think it does; it mounts the transmission to the vehicle frame.
The frame is the only component on your vehicle strong enough handle all the weight from your engine and transmission, and mount holds it in place so it won’t shift around while you drive.
Sounds simple enough, but if it is not working properly, you will run into a ton of different problems.
Symptoms of Bad Transmission Mount
When a transmission mount starts to fail, your car will give you several warning signs. Here are the most common symptoms, starting with what you’re most likely to notice first.
#1. Excessive Vibration.
By far the most common sign of a bad transmission mount is increased shaking and vibration throughout the vehicle (not just the steering wheel). It’s usually most noticeable when idling in drive with your foot on the brake, such as when stopped at a traffic light.
When the mount fails, the transmission can no longer dampen its natural vibrations effectively, creating noticeable shaking that travels through the vehicle’s frame into the cabin. The vibrations often get worse during acceleration from a complete stop.
You may notice the steering wheel shaking, gear shifter vibrating, or feel vibrations through your seat. Unlike tire-related vibrations, transmission mount vibrations are usually most pronounced when stationary but in gear.
#2. Clunking or Banging Noises.
A failing transmission mount often produces distinct clunking or banging sounds, especially during acceleration or when coming to a stop. This happens because the transmission is no longer properly secured and moves around more than it should.
You’ll typically hear these sounds coming from underneath the vehicle, particularly when accelerating from a stop, going over bumps, or during hard braking.
In automatic transmissions, you might also hear these noises when the transmission shifts between gears under load.
The sounds usually start as occasional light taps but progressively get louder and more frequent as the mount deteriorates.
While these noises often correlate with acceleration and deceleration, they can sometimes be mistaken for exhaust system rattles or other undercar noises. If you’re unsure of the source, a professional inspection is recommended.
#3. Rough Shifting.
While automatic transmissions handle gear changes without driver input, a bad transmission mount can still affect shift quality.
When the transmission isn’t properly supported, it can move slightly during gear changes, creating a harsh or jerky shifting sensation.
Shifts may feel more abrupt than usual, and there might be a slight delay before the transmission engages into gear when shifting from park to drive.
This happens because the unstable transmission position affects the alignment and can transmit additional movement into the cabin, making shifts feel rougher even though the transmission’s mechanical operation is still functioning correctly.
The roughness is usually most noticeable during the first few shifts when the transmission is cold, or when accelerating moderately to highway speeds.
#4. Transmission Movement.
With a severely worn transmission mount, you may actually see the transmission moving when you look under the hood. This is more common in front-wheel-drive vehicles where part of the transmission is visible in the engine bay.
This excessive movement isn’t always easy to spot just by looking under the hood (especially on many modern vehicles where the transmission isn’t fully visible).
In some front-wheel-drive vehicles where part of the transmission is accessible, you might notice some movement.
To safely check for this, have someone rev the engine while you observe the transmission area (or have a mechanic inspect from underneath the vehicle where it’s usually more noticeable).
A properly mounted transmission should remain relatively stationary with only minor movement. Excessive movement indicates a failed mount.
Sometimes this movement is more obvious when shifting from park to drive or reverse, as the transmission will lurch more dramatically than normal. Be extra careful when attempting to view this.
#5. Increased Road Noise.
A bad transmission mount can lead to increased noise levels inside the cabin, as the mount no longer effectively isolates transmission vibrations and sounds.
Normal road noise may seem louder than usual, and some drivers report hearing more mechanical sounds from the drivetrain.
This happens because vibrations that should be absorbed by the mount are instead transmitted through the vehicle’s frame directly into the passenger compartment. The increased noise is often most noticeable at highway speeds or during acceleration.
Pay attention to any changes in your vehicle’s normal sound profile, especially if accompanied by other symptoms on this list.
#6. Dashboard/Interior Vibrations.
When transmission mounts fail, the increased vibrations will usually make their way into the vehicle’s interior components. Your dashboard may rattle (especially around the air vents or radio area) and the center console may also shake a bit more than usual.
These interior vibrations are usually most noticeable when idling in gear or during low-speed acceleration.
Unlike vibrations caused by engine mounts, transmission mount vibrations tend to be more pronounced when the vehicle is in gear rather than in park or neutral.
If you notice that the gear shifter seems to shake on its own or items in your cup holders are rattling, these could be signs of transmission mount failure.
Diagnosing a Bad Transmission Mount
Step 1: Inspect the Transmission Mounts Visually.
Begin the diagnostic process by visually inspecting the transmission mounts for any apparent damage, cracks, or excessive wear.
Safely lift the vehicle using a jack and secure it on jack stands to gain access to the undercarriage. Locate the transmission mounts, which are typically situated near the front and rear of the transmission.
Examine each mount closely, looking for signs of deterioration, such as:
- Rubber that appears cracked, torn, or separated from the metal
- Broken or missing bolts
- Deformed or bent metal brackets
If any visible damage is detected, the affected transmission mount will likely need to be replaced.
Step 2: Check for Excessive Movement.
With the vehicle still securely lifted, have an assistant start the engine while you observe the transmission from underneath. Ask the assistant to shift through the gears, including reverse, while the vehicle is stationary.
Watch for any excessive movement or shifting of the transmission as the gears are engaged. The transmission should remain relatively stable, with only minimal movement.
If you notice significant jerking, shifting, or swaying of the transmission, it indicates that one or more mounts may be failing and no longer effectively securing the transmission in place.
Step 3: Perform the Pry Bar Test.
To further assess the condition of the transmission mounts, conduct the pry bar test. With the engine off and the vehicle securely lifted, place a pry bar between the transmission and the frame or cross member.
Apply moderate pressure to the pry bar, attempting to move the transmission in various directions.
A transmission with healthy mounts should resist movement and feel firmly in place. If the transmission moves excessively or feels loose, it suggests worn or damaged mounts that may require replacement.
Step 4: Conduct a Road Test.
If the visual inspection and pry bar test do not provide conclusive evidence of a bad transmission mount, perform a road test to assess the vehicle’s behavior under real-world driving conditions.
During the road test, pay attention to the following:
- Vibrations felt through the steering wheel, floorboard, or seat, especially during acceleration or deceleration
- Clunking or banging noises when shifting gears or engaging the clutch
- Difficulty shifting gears or the transmission popping out of gear
- Unusual transmission noises or increased noise levels
- Delayed or sluggish acceleration response
If any of these symptoms are present during the road test, it further indicates the likelihood of a bad transmission mount.
Step 5: Use a Diagnostic Scanner.
Connect a diagnostic scanner to the vehicle’s OBD-II port to check for any transmission-related trouble codes. While a bad transmission mount may not directly trigger a specific code, it can lead to issues that cause the check engine light to illuminate.
Scan for codes such as:
- P0700-P0799: Transmission-related codes
- P1700-P1799: Transmission control module (TCM) codes
- P2700-P2799: Transmission output shaft speed sensor codes
If any relevant codes are detected, investigate the issue further and consider how a failing transmission mount may be contributing to the problem.
Step 6: Consult a Professional.
If the above steps indicate a potential issue with the transmission mounts, it is advisable to consult a professional mechanic or transmission specialist for a more thorough evaluation.
They can confirm the diagnosis and recommend the most appropriate course of action, whether it involves replacing the mounts or addressing any underlying issues.
How to Check Transmission Mount?
Sometimes your vehicle might not even show any signs that the transmission mount is bad, so you should regularly check the vehicle to avoid dealing with unexpected transmission mount issues.
This is because knowing how to check your vehicle’s transmission mount can save you from having to deal with problems with your vehicle. Here’s how to check engine mounts:
#1. Listen For Knocking Sounds.
Listen for a knocking sound when the engine is turned on or off. You could also hear a knocking sound whenever there is an engine load change. If you also notice that the engine tilts a lot when you rev the engine, then the chances are high that the transmission is bad.
#2. Look Under the Vehicle.
Jack up the vehicle until you can go underneath easily. Once you are under the vehicle, closely inspect the transmission mounts for loose brackets or loose/missing bolts.
Loose brackets and missing bolts might not necessarily require replacements as you could fasten or replace the bolts.
While under the vehicle, check to see if you can find collapsed or rotted rubber or if the transmission mount has broken or is separated.
It would help if you also looked out for cracks in the rubber. If you notice cracks or a collapse or rotting of the rubber on your vehicle’s transmission mount, you should prepare to replace it for a visual presentation.
How to Replace a Transmission Mount?
If your vehicle has shown some or all the transmission mount symptoms associated with a bad transmission mount, your best bet would be to replace it. There are two ways to do that.
The first would be to get it done by an auto mechanic. However, since transmission mount replacement cost is often on the high side, many folks opt for the second option: the DIY approach.
To get your vehicle’s transmission mount replaced by an auto mechanic, all you need do is to run an internet search with the entry “engine mount replacement near me.” That should help you get in touch with seasoned mechanics near you.
On the other hand, if you opt for the DIY approach, then you would need the quality mechanic tools required to change motor mounts:
- A breaker bar
- Wrenches
- Different sizes of extensions
- A hammer
- A pry bars
- A flat-head screwdriver
- Jack Stands
- A jack(preferably a bottle jack)
- A block of wood
How long does it take to replace motor mounts? Not very long, especially when you have gotten the hang of it. Once you have the required tools in your toolbox, you can then proceed to replace the bad transmission mount. Here’s how:
#1. Locate the Bad Transmission Mount.
To do this, park your vehicle on a flat, hard surface because it prevents the vehicle from rolling away when you are working on it. Locate the mount and then spray the bolts on the mount with penetrating fluid.
Allow it to seep into the bolts for a few minutes before you loosen the bottom bolts using a breaker bar and short extensions. To loosen the top bolt on the amount, you might need to improvise using two wrenches.
To do this, put the open end of the second wrench in the closed end of the wrench you are using to loosen the bolt. You will get something like an extended wrench that will provide more reach and torque.
#2. Jack Up The Vehicle.
The next step would be to use the jack, and the jack stands to raise the vehicle high enough for you to get underneath it easily. But you need to know how to support the engine when replacing the motor mount.
Pay attention to where you put the jack. Look for a solid piece of the transmission that wouldn’t get damaged by the jack’s pressure. The best place to situate the jack would be an area that does not have a seal.
Once you have found one, fit the wooden blocks on the transmission, then jack up the vehicle slightly to remove pressure from the mount. This way, you can remove the already loosened bolts from the transmission mount.
When you have done that, jack up the vehicle a little bit more so that you can easily remove the transmission mount.
#3. Replace the Transmission Mount.
Remove the mount from the bracket that it is attached to by removing the bolts at the bottom of the bracket.
You then replace it with the new mount but ensure that it is a good fit. Before you apply the bolts, you might want to apply some thread lockers on the bolts before tightening them as hard as you can.
To install the new transmission mount, slide it into position on the vehicle using a hammer and screwdriver to nudge it in.
You might experience some difficulty as the new mount will be slightly taller, but you should avoid using force, or you risk damaging the transmission mount. Jack up the vehicle a bit so that the mount is well aligned before fitting in the bolts and fastening them.
After this has been done, lower the vehicle before you torque the bolts using a torque wrench or the extended wrench from earlier on. You can follow this guide for a visual presentation.
So at this point, you have probably asked yourself the question should I replace all motor mounts? Well, you might actually, because in most cases, once one of the mounts fails, the other mounts are close to going bad too.
Transmission Mount Replacement Cost
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Most transmission mount replacements at an independent mechanic will cost between $250 to $550, including parts and labor. The wide price range depends on your vehicle’s make, model, and how difficult the mount is to access.
Labor typically accounts for the majority of the cost, ranging from $200 to $400. Some transmission mounts are relatively easy to reach and can be replaced in about an hour, while others require removing surrounding components or partially lowering the transmission for access.
The mount itself usually costs between $50 to $150. Basic rubber mounts for common vehicles like Honda Civics or Toyota Camrys are on the lower end, while luxury vehicles or trucks with larger transmissions often require more expensive mounts.
Factors Affecting Price
Vehicle type plays a major role in replacement cost. Front-wheel-drive cars typically have more accessible mounts compared to rear-wheel-drive vehicles where the mount may be located underneath the car.
Dealership prices tend to run $100 to $200 higher than independent shops, with total costs often reaching $400 to $700.
However, dealerships use original equipment parts, may offer warranties on their work, and have manufacturer-specific training that most auto repair shops don’t.
If multiple mounts need replacement simultaneously, expect to pay for additional parts but labor costs shouldn’t be double since the mechanic is already working in the same area.
FAQs.
Q: Is it okay to drive with a broken transmission mount?
No. It is not recommended to drive with a bad transmission mount. A broken transmission mount can cause your transmission to not be properly in position, and this can cause damage to the drive shafts or cables.
If it’s really bad, it can even cause your transmission to fall into the ground, depending on the car model.
Q: Can a bad transmission mount affect shifting?
A bad transmission mount can certainly affect shifting. If your transmission mount is bad and the transmission is not fixed in the correct position, it can cause tension in the shift linkage, driveshaft or wirings which can affect the shifting performance.
Q: Can I replace a bad transmission mount myself?
Replacing a bad transmission mount can be tricky and dangerous if you don’t have the right knowledge.
To remove the transmission mount, you will need a floor jack to hold the transmission in a fixed position when replacing the transmission bracket. Otherwise, it may fall down.
Final Words
As a vehicle owner, you must be able to recognize the symptoms of a bad transmission mount. This is because while your vehicle’s transmission mounts may not be the biggest or the most expensive part of the vehicle, it is essential to have a great driving experience.
The transmission mount is meant to prevent vibrations and overcome the torque which the engine generates while running.
So what happens when you have a bad transmission mount? Once the transmission fails, the vehicle’s performance is adversely affected, and over time severe engine damage might occur.
Your ability to identify these symptoms will save you a lot of repair costs and enable you to get the most from your vehicle in the long run.