Signs of a Faulty Transmission Mount and How to Replace It

Technical

Jun 23rd, 2020

Signs of a Faulty Transmission Mount and How to Replace It

All cars, like their users, get sick as they age or operate at peak efficiency for the whole duration of their lives. Driving styles, road conditions, or general wear-and-tear can cause parts, the transmission mounts included, to die a slow death themselves. First, it would be helpful to know a little more about transmission mounts before attempting a replacement. 

Transmission mounts are round metal sections that help the transmission remain in place and use elastic squares to keep the vehicle from vibrating and shaking while at the same time running at optimum levels. It is logical then, that failing transmission mounts will manifest themselves in vibrating or rattling like the incessant coughing of an ailing patient. 

What Are the Signs of a Failing Transmission Mount?

Shaking

Because a failing transmission mount causes your vehicle to clatter harshly while you accelerate it, the car will feel like it lugs heavy equipment in its trunk. Your immediate step once you detect this noise should be to stop driving and have the car checked for faulty transmission mounts.

The second sign of a weary mount would be general vibration and disturbance, which is often in conjunction with the noise. As you may have already noticed, when one thing goes wrong with your vehicle, others follow in quick succession. One issue spreads and covers everything from the base to the core. Hence, it is crucial to detect and treat the problem as soon as you can, before it metastasises, so to speak.

Again, wear-and-tear of the transmission mounts is common but something that should not be ignored. Continuing to drive the car in this instance might break the transmission, get detached and tumble from the vehicle. This increases the difficulty and cost of fixing the issue.  

Expanded engine driveshaft distortion 

Mounts help settle and bolster the principal motor driveshaft, which is an augmentation of the motor driving rod that goes through the transmission and associates with the back vehicle pivot. When the transmission itself breaks due to nonfunctional mounts, then the issue expands in manifold ways because the performance of the car will be affected. 

This loss of strength prompts expanded motor driveshaft vibration and disturbance, which is transmitted into the traveller vehicle compartment. This condition can cause a deafening noise at unusually high speeds. 

Transmission misalignment 

Internal issues are equally detectable from the outside once the condition escalates out of proportions. One sign, then, is that the transmission lodging itself misaligns and becomes visible from the outside when one crawls under the vehicle. Transmission mounts help keep a transmission adjusted appropriately corresponding to the motor and the motor driveshaft.

Transmission housing damage 

Another example of the noticeable damage caused by a messed-up mount, which can be "felt" from the outside, perhaps, is housing damage. The mount may stick around and appear to be in perfect condition and not cause any damage to the vehicle. Not for long, though. Vehicle transmissions are major mechanical parts that require critical help to balance out appropriately.

What Can You Do about a Bad Transmission Mount?

You can either replace the mounts yourself or get a mechanic to do it for you. Transmission mounts on most local cars will be standardised; hence, unless your vehicle is rare or exotic, you may want to do it yourself. 

However, the tradeoff is that you may not be technically adept, and DIY-repairing may even cost you more. The choice is yours, but it would be advisable to completely know your transmission type and owners’ manuals, before attempting this general guide. 

Types of Mounts

FWD transmission mounts

On FWD transmissions, where one expects to find transversely-mounted motors, there are right and left motor/transmission mounts and a third mount above or underneath to triangulate the structure. 

“Dynamic” mounts

Also, some late-model vehicles have electronically-controlled "dynamic" mounts that can adjust the firmness of the mount to counterbalance the noise at different motor speeds and loads.

Owners who are replacing a motor, transmission or grip ought to consistently examine the entirety of the motor/transmission mounts and remove any that are severely eroded. Replacing just one may cause the transmission to remain misaligned and cause uneven erosion overtime. Hence, it is generally recommended to replace all transmission mounts in the event of a singular faulty one. 

RWD transmission mounts

On rear-wheel drive vehicles, there is generally a couple of engine mounts on each side of the motor to help the motor and a solitary mount under the rear of the transmission. 

The difference in fixing mounts in these three types is in the ordering or sequence in which they exist in the transmission. The rest of the process is similarly applicable, however. 

How to Replace a Transmission Mount

The process for the three types is fairly similar. 

Stage 1: 

Gradually raise the jack with the goal that the transmission is lifted somewhat from the cross-axle.

Stage 2: 

Slide another transmission mount onto the cross-part. Gradually lower the jack, ensuring the mounting openings in the metal tabs on the mount line up to the threaded gaps in the transmission and the cross-axle. 

Stage 3: 

Remove the jolts and fix them with a customisable wrench with clockwise turns.

Like any other vehicular parts that are constantly in motion, mounts crumble with age and mileage, so it's not extraordinary to discover at least one broken or fallen mount in high-mileage vehicles. If one mount has fizzled out to the end of its life, odds are the others are close to the furthest limit of their life as well, so they should be replaced as a whole so that you don’t have to access the transmission housing repeatedly.

A Smart Way to Search for Replacement Parts

Are you searching for transmission mounts, or maybe a high-quality genuine transmission? Finding one that matches your car's requirements can take up so much time, we know. Worry not because CarPart offers a smart way to search for parts nationwide, and this service is FREE! 

Send us a request for parts here to get quotes from the best auto parts sellers and wreckers nearest you, wherever you are in Australia!


By Ahmed Humayun