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Mountune USA

Ford MMT6 Gearbox Transmission Service and Upgrade - Focus RS

Ford MMT6 Gearbox Transmission Service and Upgrade - Focus RS

SKU: 6000-GL-RS

Regular price $2,163.00
Regular price $1,964.00 Sale price $2,163.00
Sale Sold out
Gear Treatment
Shipping Option
Having issues shifting smoothly through the gears? Our Ford MMT6 Gearbox service and upgrade replaces all the fragile standard synchros with our carbon-lined heavy-duty components along with all new upgraded bearings. This ensures accurate selection when going through the gears, even under hard acceleration. A full teardown, motorsport grade cleaning, and inspection are performed before re-assembly making sure your gearbox is more reliable and performs better than new.

Shipping your gearbox to us is easy. We send you a heavy-duty shipping container with a return label. Simply place your gearbox in the container and send it back to us for upgrading. Select this $199.00 option when checking out. This option applies to the lower 48 United States only.

Add an optional Quaife ATB Differential or WPC Gear treatment for maximum performance.
  • Faster, more accurate shifting
  • Upgraded components and bearings
  • Optional Quaife ATB
  • Optional WPC Gear Treatment

2016-2018 Focus RS

* Note - Prices quoted include parts and labor for gearbox only and do not include removal or installation of gearbox in car or shipping of gearbox to and from Mountune. Contact us for full vehicle service prices.

Frequently Asked Questions (FAQ) MMT6 Gearbox Service & Upgrade

1. Does mountune offer removal/installation of gearboxes?
At this time we do not offer any removal or installation services.

2. How do I get my gearbox to mountune once it's out?
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 to us in 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.

3. 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.

4. 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 improves 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.

Click here to learn more about Quaife ATB Differentials

5. 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 $500.00 shipping and crating fee and $200.00 inspection 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

6. Is there a break-in procedure for the rebuilt and serviced 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 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.

7. Does the MMT6 Service from Mountune LLC (USA) include a warranty or guarantee?
In general and because we cannot control the environment the part or assembly is used in, Mountune competition and/or performance parts carry no warranty including MMT6 Gearbox rebuilds and service. Mountune LLC shall not be liable for direct, indirect, incidental or consequential damage or injury to persons or property that might be claimed as result from the installation or improper installation and failure of part, including claims for delay, loss of profits or labor. There are no warranties expressed or implied.

8. 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 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.

Return Policy

You have 7 calendar days to return an item from the date you received it. To be eligible for a return, your item must be unused and in the same condition that you received it. Your item must be in the original packaging. Your item needs to have the receipt or proof of purchase. Some exclusions apply.

For additional details see our Return & Refund Policy.

Installation Guides

To see all available installation and break-in instructions, click here.

Disclaimers & Legal

This part has been designed and is intended for off-highway application only. Installation of this part on a vehicle that is driven on public roads may violate U.S. and Canadian laws and regulations relating to emission requirements and motor vehicle safety standards.

Click Here for emissions compliance information.

California Residents Prop 65 Information
California’s Proposition 65 entitles California consumers to special warnings for products that contain chemicals known to the state of California to cause cancer and birth defects or other reproductive harm if those products expose consumers to such chemicals above certain threshold levels. This product can expose you to chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

For more information visit

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