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It is well known that the stock rear motor mount on the Focus ST is a weak link. Custom Performance Engineering, Inc. has chosen to think outside the box on this and come up with a completely new design. To do this, cp-e™ carefully studied the layout of the stock Focus ST rear motor mount. Immediately after removing the rear mount it was decided that a better design could be achieved.
The way the Ford Ecoboost engine mount system works is that the two side mounts provide a rotational mounting point and the bottom of the engine is free to swing like a pendulum if just these two mounts are installed without a lower engine mount. Now, if you take the stock engine mount and put it in place with its horizontally mounted bushing and you apply some power, it will help stop the engine from swinging but you are now stressing the bushing in two directions. These types of bushing are not really meant for this and they are unable to prevent the engine from forcing the mount to slam into the frame.
So cp-e™ came up with a way to stress the bushing in only one direction. By remaking both pieces of the rear engine mount cp-e™ was able to mount the bushing vertically so that the pendulum effect of the engine is stretching or pushing in only one direction. This also increases the durability of the engine mount substantially. Orienting the bushing in a way that allows it to be compressed properly has allowed us to create a mount that provides a stiffer system without using an overly stiff bushing.
cp-e™ goes a step further using EPDM, a sort of rubber bushing. Urethane begins to fail at temperatures as low as 200°F and generally the mounts need a higher durometer rated bushing in order for the bushing to hold together. Our rear motor mount is a perfect example of when not to use urethane. The mount bolts directly to the transmission, transferring a large amount of heat to the mount and the bushing. EPDM holds up to this heat, and doesn’t begin to break down and fail. EPDM also carries a higher density than urethane, so the bushing can have a lower durometer rating while keeping a high reliability. Why is that good? Higher durometer ratings provide more vibrations through the vehicle and to the cabin, raising the NVH (noise, vibration, & harshness) value within the cabin.
To create this mount two blocks of aluminum, starting at 17.1 lbs are slowly whittled down over the course of a couple of hours in our CNC machine to a final weight of 2.17 lbs. This process takes a lot of time but was necessary to give the benefits that this mount has to offer. Once the pieces are machined, the bushing is installed, and secured in place by the retaining ring. From here, the mount takes its final step to the cleaning and packaging department.
Through initial testing our mount has shown to eliminate the factory ‘bang’, and the included wheel hop while providing a low durometer bushing in order to keep the in cabin vibrations low. It is to be expected that vibrations will be added in some points of the driving experience, but this effect comes solely from stiffening up the engine mounting system.
| Model | Year(s) |
|---|---|
SKU:RFM-R157208521+35
SKU:LR-1234-1114GT
