Mountune MMT6 Gearbox Service & Upgrade for Ford Focus ST & RS

MMT6 Gearbox Service & Upgrade Information

Our Ford MMT6 Gearbox service and upgrade for Focus ST and RS transmissions replace the fragile factory components with our upgraded synchros and countershaft bearing.

Upon receiving your used MMT6 gearbox from your Focus RS or ST our experienced technicians will conduct a full teardown of your transmission, and perform a motorsport-grade cleaning of your gearbox and components.

We then inspect each gear, synchro, shift fork, bearing, and shaft to ensure serviceability prior to reassembly. If any parts are found to be worn or damaged and not serviceable, we will contact you and provide a quote to replace the necessary components.

Your gearbox will then be professionally rebuilt in-house with our upgraded carbon-lined synchros and steel-caged bearings ensuring accurate selection when going through the gears, even under hard acceleration.

The transmission will then be shipped back to you fully assembled and ready to install.

Applicable Models:

MMT6 Gearbox Upgrade Standard Features

After the MMT6 Service & Upgrade your Ford Focus RS/ST gearbox transmission will arrive at your doorstep fully assembled and ready to install, meticulously rebuilt by our experienced in-house motorsport technicians. Benefit from their expertise and enjoy a hassle-free installation experience, knowing your gearbox is optimized for ultimate performance. 


We replace your factory plastic-sleeved bearings with our high-performance steel-caged bearings. These bearings deliver the strength and resilience required for relentless racing performance. 


Shift gears with extraordinary precision and lightning-fast speed. Our carbon-lined steel synchros replace the MMT6's factory brass synchros, ensuring seamless gear changes that give you the edge on the track. 

MMT6 Gearbox Upgrade Optional Features

Optional upgrades include the mountune quick shifter and WPC surface treatment, delivering even smoother, more precise shifts and a further reduction in gear wear. Upgrading to a Quaife ATB differential, you'll also be able to enjoy unbeatable traction and control on any race track. 

    MMT6 Gearbox Service & Upgrade Crate Shipping Service Option

    We make shipping your gearbox to us easy. For a one-time fee of $240, we offer a 3-way shipping service.

    With this option, you will be sent a heavy-duty shipping container with a return label back to our facility. Simply place your gearbox (dry and free of any fluids) in the container and send it back to us via UPS.

    Once we have completed your service we will package up your newly upgraded transmission and ship it back to you at no additional cost. Please note, this option applies to the lower 48 United States only.

    Shop now - Choose your platform

    MMT6 Gearbox Service & Upgrade - Focus RS

    Product Code: 6000-GL-RS
    Starting from $2,163.00

    MMT6 Gearbox Service & Upgrade - Focus ST

    Product Code: 6000-GL-ST
    Starting from $1,998.00


    Frequently Asked Questions (FAQ's)

    How long does the MMT6 Service & Upgrade take to complete?

    Once we have received your MMT6 transmission, the entire process from start to finish takes approximately 1-2 weeks to complete.

    Please note, that there may be circumstances that may delay this process including (but not limited to) sourcing and replacing unserviceable gears/components or parts shortages and backorders beyond our control.

    Does mountune offer removal/installation of gearboxes?

    At this time we do not offer any removal or installation services.

    How do I get my gearbox to mountune once it has been uninstalled?

    We offer an easy 3-way shipping option for $199 that covers all shipping costs from start to finish. First, we will send you a heavy-duty shipping container to ship your gearbox (dry and free of any fluids) to us using an included return label. Once the service has been completed we will ship your upgraded MMT6 transmission back to you for installation. Please note this option is only available to the lower 48 United States only.

    If you would prefer to drop it off in person we are available to accept gearboxes during regular business hours Monday through Friday from 9:00 am to 5:00 pm at our Carson, California motorsport engineering and development facility located at 1000 East Carson Street, Carson, CA 90745.

    What happens if you find damaged or worn parts that are not included or replaced in the normal MMT6 Service?

    We inspect all gears, synchros, shift forks, bearings, and shafts during the rebuild process. If any parts are found to be worn or damaged and not serviceable, we will contact you and provide a quote to source and replace the parts. Mountune will not reassemble a gearbox with worn parts that we believe may cause the gearbox not to function correctly. If you decide not to continue with the rebuild process, you will be refunded the original invoice amount less a $700.00 inspection and service fee.

    In the case that your MMT6 gearbox is not serviceable, we do offer all new gearboxes with many of the same features included in the MMT6 gearbox service.
    Click here for pricing and details on mountune MMT6 Stage 1 transmissions

    Is there a break-in procedure for the rebuilt gearbox?

    We highly recommend taking the following precautions for at least the first 500 miles:

    • Use proper GL4 or similar shockproof gear oil. Our preferred transmission fluid is MOTUL MULTI Dual Clutch Transmission Fluid (DCTF) for superior lubrication and performance.
    • Allow a minimum of 20 minutes of running time to warm up the gear oil.
    • No flat foot shifting.
    • Avoid making rapid gear changes.
    • Make sure you are using a dual-mass flywheel or clutch with a sprung hub.
    • Avoid high-rpm drag race style launches and starts.
    • Make sure you know how to correctly operate a manual transmission.

    What transmission fluid does mountune recommend?

    We highly recommend using Motul Multi-DCTF Dual Clutch Transmission Fluid in our Stage 1 gearbox transmissions for the best performance. It will require two-1L bottles which can be purchased here:

    [ Shop for Motul Multi-DCTF ]

    What is WPC gear and shaft treatment?

    The WPC process is unrivaled in treating engine parts and other surfaces that have contact points of friction. WPC is superior because it is not a coating; it is a permanent surface treatment that reduces friction. Its unique micro-dimple formation pattern greatly reduces friction and is unmatched by conventional methods of surface treatment.

    What is a Quaife ATB Differential upgrade?

    A direct replacement for the standard front Ford open differential, the Quaife ATB differential transforms your car's performance maximizing traction and improving cornering. Unlike a conventional plate-style limited slip differential, the Quaife differential relies on gears rather than clutch plates for its operation. That means it is much smoother in operation and never locks harshly with a set pre-load of wheel slip across the driven axle. Instead, the Quaife differential automatically biases the torque away from the spinning wheel, across the axle to a constantly varying degree.

    Does the rebuilt gearbox include a warranty or guarantee?

    Mountune MMT6 Rebuilt and Upgraded Transmissions come with a 6-month (starting from the date of product delivery) warranty against defects in parts or workmanship. This warranty is limited to the repair of the transmission by Mountune LLC only and does not cover installation or removal labor, shipping, or the cost of any other expenses incurred. Damage due to racing, abuse, or bad driving habits is not covered under this warranty.

    Is my gearbox stronger than the original gearbox after servicing by Mountune?

    No, your gearbox is not stronger than the original gearbox after servicing. We do not replace the original gears or any other primary component with anything other than factory-grade components and therefore would have the same rating as the original gearbox. The upgraded synchros offer improved shifting and longer life than the original components but can still fail when subjected to poor driving habits and abuse.

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