We probably sound like a broken record to some because we're always singing the praises of Overdrive here at Mustang & Fords. It's indeed one of the most worthwhile conversions of all. If your classic Mustang is an around-town grocery-getter that makes it to an occasional cruise night on the weekends, then a final drive ratio of 1:1 likely doesn't bother you.
On the other hand, if you believe your Mustang was born to run on the open roads, then the addition of Overdrive will convert your classic Ford from a freeway buzz bomb into a quiet, smooth vehicle that can accomplish a 500-mile day with ease. If you've never experienced a classic Mustang with a Fifth gear, you should definitely try out a friend's conversion because it will seem almost miraculous as the transmission slips into Fifth and the tachometer drops from 3,000 rpm to 2,000.
One of the more interesting cars in M&F's stable right now is a '67 T-5 fastback. It's a perfect candidate for a five-speed conversion, as we're reluctant to drive it far from home because of the 1:1 final drive ratio. Just one hour on California's 405 freeway--with the tach pegged at 3,300 rpm trying to keep out in front of the trucks blowing by--gets old fast.
We were about to park the car in the back corner of the garage when Modern Driveline of Caldwell, Idaho, came to our rescue. Modern Driveline is a recognized leader when it comes to classic-Mustang manual-transmission conversions. Owner Bruce Couture has painstakingly engineered the Modern Drive-line T-5 Overdrive kits to install easily and fit right the first time. Only the most reliable components are used in their creation. Join us as we show you how to install one in your car.
The heart of Modern Driveline's...
The heart of Modern Driveline's conversion kit is this brand-new Tremec T-5 Z-trans five-speed gearbox. The First through Fifth gear ratios are 2.95, 1.94, 1.34, 1:1, and 0.63. The transmission also features double moly hardening on the Second and Third gear as well as the countershaft. This transmission is rated to handle 330 lb-ft of torque.
We used Modern Driveline's...
We used Modern Driveline's optional kit that features a capacity of 450 hp. It upgrades the project with a Kevlar clutch kit and a lightened billet flywheel. This photo shows both, as well as the transmission conversion crossmember, transmission mount, speedometer cable, and shift-lever components. At the upper left is the clutch cable, cable-housing support plate, and pedal-conversion bracket. The 450hp kit costs $3,176.35. As our car was originally equipped with a manual transmission, we didn't have to worry about pedals. If you're converting an automatic car, then Modern Driveline has manual transmission pedals for '65-'70 Mustangs, too.
This Quick Time steel bellhousing...
This Quick Time steel bellhousing is also an upgrade from the standard T-5 bellhousing, which is an aluminum casting. The QT piece is far stronger and SFI-certified at 6.1. The QT housing saves 20 pounds of weight when compared to a conventional scattershield. The rings at the bottom of the photo are adapters that allow the bellhousing to be used with several different transmissions. Available at Modern Driveline as PN MD-401-6065, the bellhousing includes a block-off plate and has an over-the-counter price of $430. However, you can add the QT piece for only $112.
Although the new transmission...
Although the new transmission comes with a shifter, we wanted to upgrade to this billet Slick Stik unit (PN MD-82-303-034103). This shifter moves the lever rearward by 1 inch, thus allowing installation without cutting the floor. This shifter is much stronger than the OE part and offers smoother shifting and a shorter throw, at a price of $250.
Modern Driveline's owner Bruce...
Modern Driveline's owner Bruce Couture came to our facility to perform the installation personally. He begins by removing the driveshaft and exhaust system. Here, the original T-10 gearbox is supported by a transmission jack while Couture removes the stock crossmember.
The OE transmission is lowered...
The OE transmission is lowered out of the car. The transmission jack will come in even more handy when it's time to install the new gearbox. Next, the bellhousing, pressure plate, and flywheel were removed. We also pulled the old pilot bushing out of the crankshaft using a puller specifically designed for that purpose.