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Have you ever wondered if it’s possible to upgrade your C6 transmission to meet modern-day expectations in terms of toughness and performance? Yes, it is likely because experts have done it. You can revamp – or purchase a C6 performance transmission – rebuilt to handle anything you throw at it. Bear in mind that the C6 was built to provide long-term durability. As a result, it came to the fore in the powerful Ford trucks of the ’70s and high-performance Mustangs and sedans. This means you will get more than decent results if you upgrade your C6 transmission to meet modern-day standards. However, you may need to fish out some powerful components that will help take your C6 a little further to ensure you enjoy the best horsepower. Here’s what you need to know about the C6 transmission and a few upgrade tips you should consider.

Overview of the C6 Transmission

The Ford C6 transmission is the Ford Motor Company’s brainchild and prevailed from 1966 to 1996. It is a beefy 3-speed, heavy-duty automatic transmission heavily marketed as the SelectShift Cruise-O-Matic by Ford. This automatic transmission had a 30-year service life, after which Ford released it to give room for the modern overdrive versions of the company’s extensive transmission line-up. The C6 automatic transmission is somewhat lighter and has a less complex build than its predecessors. As a result, it offers less power loss and greater torque capacity, especially compared to its immediate predecessor’s MX transmission. The design of the MX transmission fooled many users, but the C6 achieved enormous capabilities with its more petite build.

Moreover, the C6 automatic transmission is simpatico to the Borg-Warner flexible shift band. The primary goal of making the C6 compatible with the adjustable shift band was to boost its durability and service life significantly. Despite the delivery of this purely mechanical – i.e., zero electronic controls –automatic transmission, it has a downside worth noting. First, it is beefy, meaning it weighs quite a lot. This causes valuable horsepower to be lost to turn the pieces and parts. However, this is gradually changing due to the possibility of merging customized components with specified C6 parts and particular pieces of the modern-day 4R100 electronic-overdrive sibling. The outcome is a powerful transmission unit capable of withstanding any abuse while negating the power-robbing pickles of the original C6 automatic transmission design.

C6 Transmission Gear Ratios and Vehicle Compatability

The stock C6 transmission from the factory features the following gear ratio:

  • First gear = 2.40:1
  • Second gear = 1.40:1
  • Third gear = 1:1

A brand-new wide-ratio gearset is installed, which offers a numerically more excellent gear ratio viz:

  • First gear = 2.72:1
  • Second gear = 1.54:1
  • Third gear = 1:1

This higher first gear is of much assistance with heavier vehicles since it makes the rear gear behave larger without unnecessarily boosting the highway cruising rpm. Some of the vehicles with the C6 automatic transmission include:

  • 1964 — 1970 Ford Fairlane
  • 1966 — 1974 Ford Galaxie
  • 1966 — 1980 Ford LTD
  • 1966 — 1979 Ford Thunderbird
  • 1966 — 1979 Ford Ranchero
  • 1966 — 1969 Ford Mercury Comet
  • 1966 — 1979 Ford Lincoln
  • 1966 — 1972 Ford Mercury Meteor
  • 1967 — 1996 Ford F-Series
  • 1967 — 1973 Ford Mustang
  • 1967 — 1978 Ford Mercury Cougar
  • 1968 — 1976 Ford Torino
  • 1977 Ford Mustang Cobra II

Therefore, upgrading your C6 automatic transmission should be part of your plans if you own any of these classic vehicles. Thus, it is essential to equip your C6 to combat common transmission problems.

C6 Transmission Upgrade Tips and Tech

Nothing should dampen the joy of driving a classic car on modern roads or cruising around town. But you can only guarantee this when you upgrade your C6. Therefore, here are a few tips that will come in handy when upgrading your C6 automatic transmission:

Modify the Parking Pawl Gear

Several small details of the C6 automatic transmission can be upgraded. This includes the modified parking pawl gear. In addition, it can be machined down such that it fits a needle-bearing assembly rather than a thrust washer. When the parking pawl gear accelerates, it pushes outward. This is entirely satisfactory until you ease off the gas pedal and go to deceleration. Switching to a needle bearing keeps the case from getting worked over on deceleration. At this point, the input shaft exerts lots of pressure on the housing. Modified parking pawls prevent severe damage from the strains that deceleration causes.

Replace the Planetary Gearset With a Stronger Counterpart

The First and Reverse planetary gearset in a C6 automatic transmission feature a 3- or 4-pinion unit. Each of these is constructed with aluminum. This is replaced with a 6-pinion, super heavy-duty steel planetary gear set. The extra pinions help to efficiently disperse the load since the steel material is more robust than its aluminum counterpart.

Work on the Lincoln Drum

The Lincoln drum refers to the Third-gear/direct drum featuring a higher snap-ring groove. This groove gives room for the installation of more clutches. A factory-fitted Lincoln drum uses four clutches, while the other third-gear drums only have three clutches. However, you can fit up to 6 brand-new high-performance clutches within the Lincoln drum for an enhanced grip.

Upgrade the Valve Body

You can get experts to upgrade the valve body, which allows for manual action (reverse and forward) or automatic shifting. In addition, you may require a valve body shift kit that promises to give firmer shifts to do away with annoying issues like clutch chatter, band failure, and a premature clutch. Drag racers can also install a trans-brake while settling for a deeper oil pan (optional) or using thicker high-performance bands.

Work on the Aftermarket Clutches

You can do away with stock clutches and go for less thick but highly durable aftermarket options. For example, stock clutches are usually 0.0080 inches wide. But you can find aftermarket options that are not thicker than 0.0065 inches.

Shifting Into High Gear

These are just a few tips you should consider and follow for upgrading your beloved C6 automatic transmission. This exercise ensures your transmission attains the level of performance its modern-day counterparts are accomplishing. The C6 automatic transmission already has a pretty solid foundation; all you need to do is to work on the suggested areas, and you’ll be good to go!

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