Mazdaspeed Forums - JBR Motor Mounts

Introduction

James Barone Racing is a relatively new name to the Mazda aftermarket. Jamie has been making quality products for the Mazda market since September 2009. Today, we will be reviewing a full set of his 80a durometer motor mounts for the Mazdaspeed 3 (Gen 1 and Gen 2). Since there has already been a MSF review done on the CP-E mounts, this review will only have limited coverage of the installation process. In addition to the installation tutorial in the existing MSF review, very thorough instructions are available here at the JBR support website:

Support : James Barone Racing, Custom Fabrication

The main goal of this review is to show the reader how the successive installation of the JBR RMM, TMM, and then the PMM affect the performance, drivability, and ride comfort of their car. This review was written to answer the common questions that people have about how their car will be affected by upgrading the three different kinds of Mazdaspeed 3 motor mounts.

Technical Background

There are three Mazdaspeed 3 motor mounts: the Rear Motor Mount (RMM), Transmission Motor Mount (TMM), and Passenger Motor Mount (PMM). This section will cover the design of the physical dimensions and materials that make up the mount bushings, and the importance of engine mount placement. The TMM and PMM are commonly collectively referred to as the side mounts. It is important to note that these two side mounts are the load-bearing mounts. When at rest, the engine sits on these two side mounts. This is why the engine does not need to be supported when doing a RMM install. Here is a picture of roughly where the stock side mounts are located:

http://www.mazdaspeedforum.org/forum/pics...WithMounts.png

When the engine is turning, the rotation of the crankshaft induces a circular rotational force (as seen in the picture above) that rocks the engine back and forth in place toward the front and back of the car when the rotation of the crankshaft accelerates and decelerates. The side motor mounts are designed to support the weight of the engine pushing downward and the horizontal forces exerted by the rotational force of the crankshaft. The placement of the PMM at the top of the rotational arc and the TMM at the bottom of the rotational arc allow the isolation of the circular forces generated by the crankshaft to a single horizontal plane at these strategic locations. These forces are shown in the following pictures, which are taken as if the camera were aimed from the driverâ€™s side while the mount was installed:

http://www.mazdaspeedforum.org/forum/pics...-PMMforces.png

http://www.mazdaspeedforum.org/forum/pics...-TMMforces.png

This gives absorption points to deaden the rotational forces generated by the crankshaft at both the top and bottom of the arc it traverses. The bushings of the stock side motor mounts were designed to deaden forces in both a vertical and horizontal direction, so this is why they are both shaped in a roughly conical shape:

http://www.mazdaspeedforum.org/forum/pics...4-PMMlower.jpg

http://www.mazdaspeedforum.org/forum/pics...5-PMMupper.jpg

http://www.mazdaspeedforum.org/forum/pics...s06-TMMtop.jpg

This conical shape is designed to only be secured (attached to the frame of the car) on one side of the bushing (with the weight of the engine pushing on this point), with the other side of the bushing swinging loosely to absorb engine vibration and rotational energy in both a vertical and horizontal direction. The advantage of this complex bushing geometry is that it allows for the absorption of both horizontal and vertical forces, but its disadvantage is that it allows more deflection, and does not age as well as a more standard bushing design. This differs from the RMM, which is designed to deal with only the horizontal rotational forces, which are roughly parallel to the ground at the point where the RMM is mounted. Remember: the stock motor mounts were designed with daily driving comfort as a high priority, so that is why Mazda has used rubber bushings with complex conical bushings and extra cutouts to allow for added comfort while driving and idling. The follow picture shows the JBR 88a dogbone RMM, but its bushing orientation is the same as the stock RMM:

http://www.mazdaspeedforum.org/forum/pics...-RMMforces.png

A common change that aftermarket mounts make to the OEM design is to make the mount bushings solid (as opposed to having the weird cutouts that the OEM RMM and TMM have) to increase the hardness of the bushing material. The durometer of the bushing gives a measure of the hardness of the material. The harder the material, the more force it is able to absorb for a given amount of deflection (and the more uncomfortable it is for the ride quality). Aftermarket mounts also commonly change the hardness (durometer) of the specific blend of polyurethane or rubber that they use to achieve different levels of performance vs comfort that fit the needs of their users. Generally, the better the mount performs, the more the ride comfort will suffer. (Sorry, no free lunch here…)

The physical dimensions of the bushing also play a large role in the performance and comfortable characteristics of the mount. A bushing with a small diameter will put a lot more stress on the bushing material, whereas a larger bushing will have much more bushing material to absorb the force applied by the engine. This means that all things equal, a large bushing does not need to be as hard as a smaller bushing to maintain the same deflection with the same applied force. Additionally, a larger bushing (of appropriate hardness) eats up more high frequency (low amplitude) vibration while still providing good deadening against large movements than a smaller bushing. These performance and comfort advantages are why JBR uses some of the largest bushings available on the market.

[multipage=The Mounts]
The Mounts

The JBR mounts are constructed from a combination of billet aluminum and steel. Jamie chose bushings that are made using 70a, 80a, and 88a durometer polyurethane. The 70a and 80a bushings are a much larger diameter (~2.75” ID and ~3” OD) than the 88a durometer bushings (~2.00” ID and ~2.25” OD). As mentioned in the previous section, these 70a and 80a bushings are some of the largest available on the aftermarket today.

JBR Rear Motor Mount:

http://www.mazdaspeedforum.org/forum/pics...-RMMbillet.jpg

The JBR RMM is made from billet T6-6061 aluminum, and is of extremely solid construction. This is a very solid mount that should last a very long time. The entire mount is coated with a signature black wrinkled powder coat, which is done in house at JBR. The available bushing durometers are: 70a, 80a, and 88a. The 88a bushing is available only in a dogbone design with a smaller bushing diameter:

http://www.mazdaspeedforum.org/forum/pics...RMMdogbone.jpg

JBR Transmission Motor Mount:

http://www.mazdaspeedforum.org/forum/pics...10-TMMside.jpg

The JBR TMM is made from .188 steel, and is made with 0.250” plates for the top and bottom plates with a solid 2.00” tall steel perch. This piece is also very solidly built, and should have no problems. The entire mount is powder coated black. Available bushing diameters are: 70a, 80a, 88a.

JBR Passenger Motor Mount:

http://www.mazdaspeedforum.org/forum/pics...11-PMMside.jpg

The JBR PMM has a welded steel support and a billet T6-6061 aluminum piece containing the bushing. This mount comes preassembled with the pictured bolt impacted into place. DO NOT ATTEMPT TO DISASSEMBLE! The steel support is powder coated black, and the billet aluminum piece is coated with the signature JBR wrinkled black powder coat. Available bushing durometers are: 70a and 80a.

[multipage=The Test]
The Test

Review Car Setup:

Before we begin, here are the relevant power and suspension mods in the car used for this review. This should put the performance remarks and video samples into more perspective:

-Cobb AP (custom-tuned at ~18psi)
-Cobb SRI + Inlet
-Cobb FMIC
-Cobb TBE (DP+CBE)
-CP-E HPFP
-Cobb BPV
-Cobb Springs
-Bilstein Sport Shocks
-Ford XT-M5-QS Transmission Fluid
-70,000 miles on the odometer

The Terminology:

Before talking about the performance and ride comfort of the JBR mounts, letâ€™s define the different aspects of “performance” and “comfort” that will be referred to in this review (these are just the terminology used for this review, and not necessarily the “official” wording):

Engine Slop - is the excessive rotation of engine when you change from acceleration to deceleration (and vice versa). This “slop” manifests itself in the uneven lurch you feel in the car as you accelerate and decelerate when the engine rocks back and forth because the motor mounts allow an excessive amount of engine movement. This movement causes wheel hop, reduces throttle response, causes noticeable hiccups in power delivery any time you change between acceleration and deceleration, and makes shifting sloppier. Even with stiffest of aftermarket mounts, you will always be able to feel some amount of engine slop during shifts and going on and off throttle. However, aftermarket mounts will provide significantly better performance over the stock motor mounts.

Wheel hop is the loud banging you get when launching hard with the stock mounts as your wheels bounce up and down due to the excessive engine movement that the stock mounts allow. This problem will worsen over time as your mounts get softer from wear, and can be greatly improved with the use of aftermarket engine mounts. Wheel hop can pretty easily be eliminated with 1 or more aftermarket mounts at stock to fully-bolted power levels, but once a big turbo is used, even a full set of aftermarket mounts cannot guarantee the complete elimination of wheel hop.

Throttle Response - is how quickly and smoothly the car reacts to throttle input. With stock mounts, a noticeable pause and or hiccup will occur when apply throttle after shifting or engine braking. This problem will worsen over time as your mounts get softer from wear, and can be greatly improved with the use of aftermarket engine mounts.

Cabin Vibration - is shaking that can be felt in the cabin of the car that is being transferred from the engine bay. In the context of this review, it is caused by the stiffer mounts, and affects the ride comfort of the car. Remember, nothing comes for free, so you must be willing to accept some level of added vibration in order to gain the performance improvements that come with aftermarket mounts.

Cabin Noise - is the added noise heard in the cabin that is transferred from the engine bay. In the context of this review, it is caused by the stiffer mounts, and affects the ride comfort of the car. Once again, nothing comes for free, so you must be willing to accept some level of added noise in order to gain the performance improvements that come with aftermarket mounts.

Ride Comfort - generically covers both cabin vibration and noise. Both of these factors will affect how comfortable your car rides. Notice that I left out the “harshness” part of NVH, because I felt that rolls right into vibration.

The Procedure:

Each one of JBRâ€™s mounts was installed and individually broken in to find out how each successive mount affected the performance and comfort of the car. The following order was used: RMM->TMM->PMM. After each mount was installed and broken in, videos were taken of startup and low/medium/high speed conditions to give the reader a better view of what the cabin of the car sounds like.

[multipage=RMM Tested]
Rear Motor Mount Test:

The JBR rear motor mount installation was very straightforward. Please refer to the JBR support page for a very thorough set of installation instructions:

http://jamesbaroneracing.com/support...structions.pdf

Here is a picture comparing it with a CP-E Stage 1 75a RMM:

http://www.mazdaspeedforum.org/forum/pics...2-RMMvsCPE.jpg

As you can see, the JBR bushing is a very large diameter.

Performance:

The JBR 80a RMM provided about the same improvement over stock as the CP-E Stage 1 75a RMM in the performance categories of wheel hop, throttle response, and engine slop. Wheel hop all but disappeared on hard launches and shifting. Pretty much all the wheel hop I normally got from hard launches with the OEM RMM had been converted to wheel spin. In this scenario, wheel spin is far preferable to wheel hop, because wheel hop is more detrimental to overall performance and more damaging to the car.

A good amount of engine slop was reduced from the stock RMM, resulting in significantly better shifting and throttle response when compared to the stock RMM. Despite the improvement, there is still a noticeable amount of engine slop from the side mounts. Depending on the age of your side mounts, this remaining engine slop will vary in intensity. My OEM side mounts were definitely worn, so I would say that the RMM reduced roughly 30% of the total engine slop I felt while using all OEM motor mounts.

Comfort:

The JBR 80a RMM feels about as comfortable at idle as the CPE Stage 1 75a RMM. When the air conditioner turns on, you will be able to feel a bit of added vibration, but it is relatively small. One thing that will be noticeable is that a bit more vibration can be felt in the car when engaging the clutch and while accelerating slowly at about 1,500 rpm to 2,500 rpm. None of these added vibrations are terribly noticeable after break in and there is not really a noticeable increase in cabin noise. This means that the vast majority of MSF users should have no problems with this mount.

The following videos will give a better idea of how the cabin of the car sounds after the RMM was installed: (Please note that only an idle video taken right after installation is available right now due to some lost files during the review. The review car is coming up on a clutch replacement, so a full set of videos will be made with the JBR RMM (with over 2000 miles) + OEM side motor mounts before that happens.)

CPE 75A Stage 1 RMM with OEM Side Mounts - Start Up:

http://www.youtube.com/watch?v=9HxaS3GWcRs

JBR 80A RMM with OEM Side Mounts - First Start Up:

http://www.youtube.com/watch?v=5Do0YegDcVQ

Coming Soon: Fully Broken In JBR 80A RMM with OEM Side Mounts - Start Up, Low, Medium, and High Speed.

Cost:

The JBR 80a durometer billet RMM costs $125 if purchased alone. Discounts can be had if purchased as a full set with the PMM and TMM ($455), but even at the base price, this mount is still pretty competitively priced when compared to similar quality billet solutions from other companies.

Overall Analysis:

The JBR billet RMM is a very high quality piece that provides solid improvements to wheel hop, engine slop, and throttle response at the cost of very little ride comfort degradation. These improvements help a lot to smooth out shifting and better put down power. Since this is such a cheap and easy modification with so few drawbacks, this should be the one no-brainer upgrade that every MSFer should be doing when they start modding their Mazdaspeed 3. The only choice necessary is whether you should go with the 70a, 80a, or 88a durometer bushing. As tested in this review, the 80a is quite a comfortable choice for a significant improvement in performance, so if youâ€™re ultra sensitive to vibration, you can consider getting the 70a. Otherwise, if youâ€™re willing to deal with a bit more vibration and noise, you should be considering the 88a durometer dogbone RMM.

[multipage=TMM Tested]
Transmission Motor Mount Test:

The JBR transmission motor mount installation took a bit longer than the RMM, but as long as you have a good breaker bar or a pipe to throw over the handle of your ratchet, you should be able to knock this out without too much trouble. Please refer to the JBR support page for a very thorough set of installation instructions:

http://jamesbaroneracing.com/support...structions.pdf

Here are a few pictures of the JBR TMM:

Included parts:

http://www.mazdaspeedforum.org/forum/pics...3-TMMparts.png

Partially assembled:

http://www.mazdaspeedforum.org/forum/pics...Massembled.png

It is important to note that the way the bushing of this mount is arranged isolates the engine movement to the horizontal direction shown in the first TMM picture above. The restrictor plates, shown at the ends of the bolt, limit the vertical motion of the TMM to the thickness of the bushing lips as seen above with the shown arrows. This helps to guarantee that the engine can only move in one direction, but is done so at the cost of the mountâ€™s ability to handle vertical vibrations. Unfortunately, it is difficult to orient bushing of this geometry without having to choose between being able to deaden vertical or horizontal forces, so JBR chose to concentrate on deadening horizontal forces to protect against the worst of the rotational forces generated by the crankshaft. This protects the cabin from the worst of the engine vibrations, but allows transmission noise to enter instead.

Performance:

Initially, the JBR 80a durometer TMM, brought a large amount of improvement to the remaining engine slop, but this reduced noticeably after about 500 miles of break in. Due to the worn nature of the OEM PMM, it is likely that the added stress from having two stiffer aftermarket mounts caused the remaining OEM mount to allow a lot more movement on the passenger side than it was originally designed to allow. This meant that throttle response and shift quality were initially greatly improved, but degraded down to just being moderately improved after break in was completed. Please note that this degradation in overall performance is not reflective of a weakness in the JBR TMM, but more reflective of mismatched side motor mount. The side mounts are meant to balance each other out, so having a lopsided setup with the JBR TMM and OEM PMM was not a good idea.

Overall, this mount definitely yielded a noticeable improvement, but you could definitely tell that leaving the PMM stock was keeping the JBR TMM from realizing its true potential. Upgrading both side mounts at the same time is a much better idea than doing them one at a time.

Comfort:

Even during the break in period, the JBR 80a durometer TMM only resulted in a pretty minor amount of added cabin vibrations. A small amount of added vibration was felt at higher rpms, but this added vibration was still relatively minor. The main thing that was very noticeable was the added transmission noise during idle and when revving the engine. At idle, you can definitely hear transmission chatter when the clutch is out. This chatter improved a bit after the break in, but still was very noticeable with the clutch out. With the clutch in, it completely goes away, but this does mean that you will definitely notice this while waiting at a light with the clutch out. Normal radio volume should block out this chatter, though, so it is not necessarily a big deal. Also, a lot more synchro whine can be heard when accelerating. This high-pitched whine can definitely be heard over the sound of the engine, but whether it bothers the driver is a completely subjective thing. When I first heard the added synchro whine, it actually sounded a lot like a supercharger to my ears, so you will have to listen to the audio in the following videos to decide for yourself if these noises are going to matter to you personally:

JBR 80A RMM and TMM with OEM PMM Mount - Start Up:

http://www.youtube.com/watch?v=XXrTz0fge0g

JBR 80A RMM and TMM with OEM PMM Mount - Low Speed:

http://www.youtube.com/watch?v=w7HgIn1R2cc

Cost:

The JBR 80a durometer TMM costs $185 if purchased alone. Discounts can be had if purchased as a side mount set with the PMM ($350), or as a full set with the PMM and RMM ($455). Even at the base price, this mount is still pretty competitively priced, since there are not many well-built TMM solutions available.

Overall Analysis:

The JBR TMM mount provided strong improvements in engine slop and throttle response initially, but leaving the PMM stock probably led to the PMM to move a lot more when all the added stress was concentrated on it. The real issue is that the uneven mount stiffness between the TMM and PMM causes too much force to be concentrated on the PMM for it to hold steady, so it ends up moving around a lot more than it was intended to move. Modders should carefully view the above videos to decide if they are willing to deal with the added transmission noise at idle and during acceleration before making their decision to upgrade their TMM. For performance and durability reasons, this upgrade should be made in conjunction with the JBR PMM.

[multipage=PMM Tested]
Passenger Motor Mount Test:

The JBR passenger motor mount installation should be about as easy as the RMM (if not easier). Please refer to the JBR support page for a very thorough set of installation instructions:

http://jamesbaroneracing.com/support...structions.pdf

Here is an installed picture of the JBR PMM:

http://www.mazdaspeedforum.org/forum/pics...Minstalled.jpg

Here are a few pictures comparing the JBR PMM with the OEM PMM:

http://www.mazdaspeedforum.org/forum/pics...MsideVsOEM.jpg

http://www.mazdaspeedforum.org/forum/pics...MMtopVsOEM.png

An important detail to note is that like the JBR TMM, the bushing is designed to only allow motion in the horizontal direction, as pictured above. Like the TMM, this means that very little vertical motion is allowed with this mount, which translates to a fair amount of added cabin vibrations and noise.

Performance:

The addition of the JBR 80a durometer PMM to the JBR 80a durometer TMM made a huge improvement to the remaining engine slop. This highlighted just how much the OEM PMM was moving around. Even after 700 miles of break in, the combined improvement of the JBR mounts probably added up to roughly 70% (30% for the RMM and 40% for the combined PMM and TMM) of the engine slop that was originally present with a full set of OEM motor mounts. This leads to a huge improvement in engine slop, throttle response, and shift quality. With this full set of engine mounts, the car literally feels like a whole new animal. It is so much more responsive than before, and does not suffer from the noticeable engine slop and hesitation that the OEM side motor mounts were causing after 70,000 miles. Remember, your mileage may vary based on how worn your OEM side mounts are, but itâ€™s only a matter of time before your OEM mounts need to be replaced.

Comfort:

The addition of the PMM has a much larger effect on ride comfort than the TMM. Since the PMM does not allow very much vertical movement, this means that any vertical vibrations caused by the engine translates into vibrations and noise in the cabin of the car. At idle, the cabin vibrations are virtually the same as with just the RMM and TMM, but once the engine starts revving up, the vibrations really start to get noisy and cause some moderate buzzing from the dash. This is likely why many people report a change in the exhaust note with the installation of a JBR PMM. Just remember that is probably completely unnoticeable from the exterior of the car.

The level of cabin vibration and noise improved a bit with 700 miles of break in, and I am told that a little more improvement can be expected by roughly 2,000 miles, but the bottom line is that there will always be a noticeable amount of added noise and vibration caused by the addition of the PMM. You will have to decide for yourself if it is enough to keep you from upgrading. The following videos show how the car sounds at idle, acceleration from a stop, slow cruise, and highway cruise. Compare them with the previous videos in this review to get an idea of how much more vibration and noise you will be dealing with:

JBR 80A RMM, TMM, and PMM Mount - Start Up:

http://www.youtube.com/watch?v=BogJWcPVpto

JBR 80A RMM, TMM, and PMM Mount - Low Speed:

http://www.youtube.com/watch?v=3XaCZjv9vXE

JBR 80A RMM, TMM, and PMM Mount - Medium Speed:

http://www.youtube.com/watch?v=Wi8wwr66nXU

JBR 80A RMM, TMM, and PMM Mount - 70 mph Cruise Speed:

http://www.youtube.com/watch?v=21ARlzwpkG4

Cost:

The JBR 80a durometer PMM costs $185 if purchased alone. Discounts can be had if purchased as a side mount set with the TMM ($350), or as a full set with the TMM and RMM ($455). Even at the base price, this mount is still pretty competitively priced, since there are not many well-built PMM solutions available.

Overall Analysis:

Of these mounts, the JBR PMM will probably be the hardest decision for most modders to make. The improvement to engine slop and throttle response is very large when combined with the JBR TMM, but the added noise and vibration cannot be ignored as a big factor in many peopleâ€™s decisions. Those who use their cars as daily drivers will have to very carefully examine the videos included with this review and decide for themselves if they are willing to take the hit in ride comfort to gain the performance improvements that these side mounts give over the stock mounts. Those who use their cars for road racing, autocross, or the drag strip would be out of their minds NOT to upgrade to these side mounts, because they offer a huge improvement over the stock mounts without becoming stupidly harsh. For me, personally, even though the noise and vibration are probably close to the edge of whatâ€™s comfortable for me on a daily basis, the performance improvements to engine slop were so big that I could never imagine changing back to the stock side mounts. Let me say this again for emphasis: the car drives like a whole new animal with these side mounts! The added responsiveness makes the car so much more fun to drive, and I am more than happy to ignore the drawbacks for the smile it puts on my face when I mash down on the fun pedal and get an almost-instantaneous response from the car!

[multipage=Conclusion]
Conclusion

The JBR motor mounts have shown themselves to be very solid performers for the Mazdaspeed 3. Jamieâ€™s large 70a/80a durometer polyurethane bushings provide a good combination of performance and comfort with a price tag that should meet the needs of the vast majority of the MSF community. The JBR RMM (pick your durometer) is an upgrade that pretty much the entire community should be considering. The JBR TMM and PMM provide a huge improvement over the stock side mounts, but will require each individually to carefully evaluate the videos found in this review to decide whether they can deal with the added noise and/or vibration on a daily basis. The performance improvements are very impressive, but the increased cabin noise and vibration will require a personal choice between fun and comfort.

The Mazdaspeed 3â€™s motor mounts are made to work together to hold the engine in place while allowing for a limited amount of movement to deaden the vibrations and rotation forces generated by the engine while accelerating and decelerating. It is important to remember that strengthening one mount means putting more stress on other mounts. Upgrading the RMM allows the added stress to be put evenly on the OEM side motor mounts. This will put increased wear on the side mounts, but by doing so evenly, they should last longer than if you made an uneven upgrade like RMM + TMM or RMM + PMM. Putting all the added stress on the OEM TMM or PMM alone will cause the affected mount to wear out much more quickly, and will just leave you with a lot more engine slop than you should have. This is why I would recommend either getting the RMM, the side mount package, or the full set of RMM + TMM + PMM when upgrading. Buying only the RMM should leave you a decent amount of mileage on the OEM side motor mounts before needing to upgrade. Getting only a RMM and a TMM or RMM (RMM + TMM or RMM + PMM) will probably cause your remaining mount to wear out very quickly and force you to upgrade the last mount anyway. The OEM motor mounts were never designed to perform the way that much of the MSF community wants, so itâ€™s only a matter of time before needing to upgrade to an aftermarket mount. As we have seen, the JBR mounts are a great option to consider when the time comes to replace your stock motor mounts.

A special thanks goes out to James Barone for sending us a set of his excellent motor mounts to review, and to superskaterxes for helping me with the PMM when I didnâ€™t have a place to do the install.