Jump to content

The Thread on Soundproofing the CX60


Recommended Posts

It is well acknowledged that the CX60 has a significant deficiency in terms of insulation and soundproofing. In my perspective, the presence of road noise and tyre roar significantly detracts from the overall pleasant atmosphere inside the vehicle interior. This is particularly disappointing considering the car's designation as a 'luxury' model. However, it is worth noting that these issues can be readily and inexpensively resolved.

There are several methods for incorporating soundproofing, with a diverse range of materials. Certain individuals use the technique of deadening, followed by the incorporation of absorbent materials, while others choose for the utilisation of heavy mass substances, such as thick rubber sheets. I wanted an element that might introduce a degree of sophistication, without overtly manifesting itself or necessitating any alterations to carpets, panels, clips, and similar components.

Kindly provide your own soundproofing techniques for the CX60 in this discussion, accompanied with relevant visual documentation.

I used the 'Stage 1' methodology in my research.

The doors and bonnet are equipped with a 2.5mm Killmat material, providing a coverage of 90%.

The installation of a 2mm layer of Killmat, together with an additional 2.5mm layer, in the boot and rear wheel wells/arches is being considered.

In all, I used a whole box, amounting to an approximate expenditure of £65, and contributed an additional mass of around 7kg.

Link to comment
Share on other sites

The observed impact is noteworthy, as the vehicle now exhibits a significant reduction in audible noise, with just minimal sounds emanating from the front wheels and engine. The next project will include addressing the front wheel wells and the gearbox tunnel/bulkhead. It is worth noting that owners of plug-in hybrid electric vehicles (PHEVs) may not find it necessary to address the bulkhead, since the noise generated by the 4-cylinder engine is comparatively less pronounced than that of the 6-cylinder engine.

The photographs captured do not adequately depict the completed state of the subject due to suboptimal photography. Their primary purpose is to provide a general impression or concept rather than a comprehensive representation.

Unfortunately, there are no photographs available depicting the doors in question. However, it is worth noting that the Mazda Technical Service Bulletin (TSB) insulation was removed and replaced with Killmat, which now covers around 90% of the doors. As a result, the doors have gained a substantial amount of weight, comparable to that of Bentley vehicles. The Mazda Technical Service Bulletin (TSB) primarily aimed to mitigate the occurrence of door flex and the resulting tinny sound. While it did achieve this objective to some degree, the overall efficiency of sound insulation was contingent upon factors such as the application technique used by the dealer technician, the quantity of material utilised, and the specific grade employed. The nature of the work exhibits significant variability. Mazda has recently implemented the inclusion of two minuscule 1mm sheets inside the doors, aimed at mitigating the inherent flexion originating from the manufacturing process. However, this modification has shown to have little impact on the overall effectiveness of sound insulation.

A noticeable improvement in the reduction of road noise is seen in the doors, as the sound of passing automobiles or traffic is no longer audible from the inside.

The visual representation bears resemblance to this.


The subsequent region under consideration was the boot floor. There are many reasons why it might be considered aesthetically unpleasing.

(This pertains to a Diesel vehicle; however, the configuration of the PHEV boot floor may change, thereby requiring adjustments according on individual circumstances.)

One must consider the surrounding regions where the storage bin is located. If these areas are covered, it may result in a little increase in floor height, depending on the thickness of the material used. This may potentially lead to an irregular appearance and cause the floor to exhibit rocking and vibration, which may be undesirable for those with obsessive-compulsive tendencies. By using my chosen method, I achieved a 90% efficacy rate while maintaining a seamless appearance and avoiding any potential complications.

Mazda has included a cost-effective and somewhat ineffective spray sound deadener in this vehicle. In contrast, my previous PHEV model lacked such a feature and instead had exposed metal surfaces. Consequently, I choose to address this issue selectively rather than completely removing the sound deadener. One is able to audibly perceive a distressing metallic resonance while tapping various areas of the boot. When the Killmat is included, the resulting sound is characterised by a distinct and substantial "thud." The improvement is significant.

Regrettably, I neglected to get a photograph of the completed state of the subject in question, since further additions were made subsequent to the aforementioned photographs being taken.


The most prominent observation is to the absence of sound insulation inside the rear wheel arches, namely in the arch and rear quarter. A little quantity of lightweight foam material is used to prevent friction between the carpeted cover and the painted surface, hence serving as the only purpose of its application. When tapped, the arches produce a sound reminiscent of a tin can. The excessive noise generated by the tyres of the CX60, a vehicle with a rear wheel bias, may be attributed to its design characteristics. I made an effort to include a substantial amount of Killmat, however it proved challenging without extensively deconstructing the material. If I were to do the task once again, it is likely that I would be able to handle a greater workload, especially if I were to enlist the assistance of a someone with diminutive hands.

Following that, the next item to be discussed was the bonnet.

The presence of support welds on the second layer necessitates the use of cut-out portions rather than full sheets for installation.


The use of this technology significantly reduced the auditory emissions of the engine in external environments, as well as inside the cabin. Consequently, it effectively eliminated any higher frequency sounds, resulting in a much deeper and more sophisticated auditory experience. However, it is important to remember that this modification does result in a reduction of the pleasing auditory experience produced by the inline-6 engine. Therefore, it is advised to proceed with caution.

It is important to acknowledge that the installation of insulation in the automobile results in a redistribution of noise, causing a notable increase in noise emanating from the front tyre wells. Consequently, it becomes necessary to do this insulation procedure at some point in order to achieve noise equilibrium.

The audio quality of the stereo has significantly improved, with the subwoofer producing a satisfying bass sound. Additionally, there is no longer a need to increase the volume when driving on the motorway in order to mask the noise generated by the tyres.

In general, the cabin exhibits a heightened perception of tranquilly, resulting in reduced fatigue during extended journeys. Moreover, its level of refinement has a striking resemblance to that of the Q5 and X5 models.

One notable advantage is that the panels may be seamlessly concealed, making them imperceptible when reinstalled. I believe that the £65 I have invested in enhancing this vehicle is the most advantageous expenditure.

The following list presents forthcoming employment opportunities, with updates to be provided in subsequent posts.

1. The matter under consideration pertains to the optimal approach for addressing the front wheel arches. Specifically, the options being weighed include augmenting the arch liner with more material, while taking into account any concerns about the adequacy of the clips for subsequent reinstallation.


Alternatively, the object might be placed in the wheel well as seen in the illustration below. The present occupation seems to be more favourable; nonetheless, there is a worry over the ingress of water into the butyl, which may result in its detachment or the accumulation of moisture, possibly leading to future complications. I want to pursue the second option, using butyl roof flashing tape as a means to effectively seal the edges.

The bulkhead and gearbox tunnel are two integral components of a vehicle's structure. The bulkhead serves as a partition between the engine compartment and the passenger cabin, providing structural support and ensuring the safety of occupants. It also helps to reduce noise and vibrations from the engine. On the other hand

The inclusion of this feature may not be seen necessary for the Plug-in Hybrid Electric Vehicle (PHEV), unless one finds the audible sound produced by the electric vehicle (EV) to be bothersome. However, it should be noted that the 6-cylinder engine does emit a distinct engine sound that may become fatiguing under congested traffic situations and extended journeys. Additionally, the transmission's abrupt noise upon starting the vehicle can be perceived as awkward or uncomfortable.

This would include the removal of the seats, centre console, and maybe some components of the dashboard. Undertaking this task is of considerable magnitude, and I have reservations about its potential for success. Consequently, should I want to proceed, this will be the ultimate stage in the process.

An alternative approach is the incorporation of sound-absorbing material into the many crevices located behind the dashboard. This method may be executed with relative ease, however with caution to avoid obstructing any ventilation openings, while also ensuring the selected material has fire-resistant properties.

Given the presence of a sunroof, the available roof area for soundproofing is limited. Consequently, I want to include a few layers of butyl material at the rear section, followed by the addition of a couple of panes of the aforementioned substance. Individuals who do not own a sunroof are recommended to coat the whole roof, since it is comparable to a container made of tin.

The tailboard will be lowered, allowing for the installation of Kilmat in certain areas.

Additional resources pertaining to the concept of 'quiet'

One example of all-season tyres equipped with noise cancelling technology is the Pirelli Scorpion All Season PCNS. These tyres were specifically developed for use in vehicles manufactured by Jaguar Land Rover. Several other companies provide their own proprietary noise cancelling technology; nevertheless, the availability of the specific tyre size is quite limited.


Link to comment
Share on other sites

The video I saw was intriguing as it highlighted Mercedes' use of a diverse array of materials with varying densities to effectively attenuate and impede the transmission of sound inside their automobiles. Attempting to do this task without access to a laboratory would involve a significant amount of trial and error. However, the Killmat, despite its considerable weight, effectively fulfils its intended purpose, although at the cost of increased weight.

According to the information I discovered, Mazda has implemented little soundproofing measures in the CX60 model.


Link to comment
Share on other sites

The manner in which the door card must be removed renders it susceptible to potential breaking from above, but the process is rather straightforward provided one has the requisite knowledge. The time-consuming aspect lies in the laborious process of extracting the internal systems.

Individuals who own early vehicle identification numbers (VINs) who have not yet had the door insulation technical service bulletin (TSB) installed may consider requesting their dealer to use the Killmat, provided by the customer, and to extend the coverage on the doors. Although it may involve an additional expense beyond Mazda's payment for the Technical Service Bulletin (TSB), the benefits derived from this investment are significant.

Link to comment
Share on other sites

The task was executed with great proficiency.Additionally, I am interested in engaging in sound insulation measures. However, I have some reservations since I just discovered that alubutyl does not possess the automobile manufacturer's approval for use inside the engine compartment, namely below the hood.

Link to comment
Share on other sites

The task was executed with great proficiency.Additionally, I am interested in engaging in sound insulation measures. However, I have some reservations since I have discovered that alubutyl is not authorised by the automobile manufacturer for use in the engine compartment (located under the hood).

Link to comment
Share on other sites

The soundproofing of my CX-60, manufactured in September 2023, is insufficient. Following my test drive in a demonstration vehicle, I conveyed to the sales manager my preference for purchasing a car that had superior soundproofing capabilities. He made a promise to rectify the issue. Subsequently, with the arrival of my vehicle, it was determined that there was no need for more soundproofing. It seems that Mazda has implemented an upgrade to enhance their product.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...