If you've been following along with Ron Burgundy, our '87 Fox Mustang project car, you might be wondering how the stock, zillion-mile drivetrain is putting up with 555 lb-ft of torque at the wheels from the Hellion Turbo and endless smokey donuts and street thrashing. We were wondering as well, until the transmission decided to take a few moments between shifts. After we added a set of Mickey Thompson P275/50R15 ET Street radials to get the car to hook, the stock AOD failed completely. A quick yell across the hall to KJ Jones of 5.0 Mustang and Super Fords magazine was all the research we needed to get dialed into one of Performance Automatic's (PA) 4R70W overdrives for the car. The transmission first appeared in the '94 Mustang and is similar to the original AOD that came with the earlier 5.0L Mustangs, except that shifting and converter lockup are controlled by the computer. In addition to the overdrive, the PA transmission has a forward manual valvebody, a lockup converter, electronic overdrive control, and a transbrake. Inside, the Fox Mustang trans has improved parts in place of any stock ones that might fail. The basics such as Raybestos clutches and high-performance bands are included, along with Ford-specific updates like a hardened stub (input) shaft and drum. The transmission has been track-tested on cars making more than 1,000 hp. Fox Mustang Parts Description PN Price 4R70W PA45102M-50 $3,995.00 5.0 Fox Mustang 1987 2,000.00 Autolite spark plugs (8) 24 12.00 Ford MAF lightning plug 1U2Z-14S411-AY 47.38 FRPP 90mm MAF FMS-M-12579-L54 189.95 Hellion street-heat turbo kit N/A 3,999.00 Hellion MAF adapter and hose kit N/A 100.00 (est.) NAPA oil filter 1085 4.36 Precision Industries 91?2-inch torque converter N/A 1,600.00 Trick Flow fuel pump TFS-25002 124.95 Summit high-flow, 42-pound injectors SUM-240042 339.95 Valvoline Dex/Mec MaxLife ATF 31.45 Valvoline NextGen motor oil 10W30 15.47 Total $12,428.06 This is the 4R70W from PA that was factory equipment in the '94 to '04 Mustang GT. In 2005, Ford switched to the 5R55 five-speed and the 6R80 six-speed. The "W" stands for wide ratio, meaning the ratios are 2.84, 1.55, 1.00, and 0.70 instead of 2.40, 1.47, 1.00, and 0.667 on the AOD or non-W 4R70. This is the 4R70W from PA that was factory equipment in the '94 to '04 Mustang GT. In 2005 Grant Peterson grabbed the factory speedometer gear from the fried AOD and used it to connect the cable on the new transmission. The 4R70W can be used with a mechanical or electronic speedometer. Grant Peterson grabbed the factory speedometer gear from the fried AOD and used it to conn On the left is the stock 12-inch converter, and on the right is the 9-1/2-inch-high, stall-speed, lockup converter from Precision Industries. PA recommends this multi-disc lockup converter with transbrake applications because it has anti-ballooning plates and overall indestructibleness. At the track, the converter is unlocked in First and can be locked in Second and Drive to load the engine and the turbo for better track times. On the left is the stock 12-inch converter, and on the right is the 9-1/2-inch-high, stall Here is a tech tip: Always add a quart of transmission fluid to the converter and lube the snout before you install it. To ensure it is seated in the pump, the converter needs to be 3/4 to 1 inch below the face of the bellhousing. Here is a tech tip: Always add a quart of transmission fluid to the converter and lube the We tried to use as many of the stock pieces as possible for the install. Here, we replaced the housing bolts with studs to mount the factory shifter bracket. We tried to use as many of the stock pieces as possible for the install. Here, we replaced Here you can see the factory shifter bracket in place (arrow). we had to grind down a mounting boss to get it to fit. we recommend an aftermarket shifter to solve this problem if you have the extra dough. Here you can see the factory shifter bracket in place (arrow). we had to grind down a moun The 4R70W is slightly longer than the AOD it replaces and required us to move the crossmember toward the rear of the car. Fortunately, the bushing was welded in instead of being integral, so we cut the welds off with a die grinder. The 4R70W is slightly longer than the AOD it replaces and required us to move the crossmem To move the crossmember back, we slid the bushing forward as far as it would go. Once it was reinstalled, we were able to bolt the transmission to the factory mount. To move the crossmember back, we slid the bushing forward as far as it would go. Once it w We also had to notch the crossmember for the factory shifter cable and pan clearance on both sides. We also had to notch the crossmember for the factory shifter cable and pan clearance on bo Wires for the transbrake, overdrive, and lockup converter are self explanatory. Twelve volts activate them. Wires for the transbrake, overdrive, and lockup converter are self explanatory. Twelve vol We replaced the ashtray with this handmade aluminum panel. The lower two switches control the lockup converter and the overdrive, and the big red button is for launching off the transbrake. We replaced the ashtray with this handmade aluminum panel. The lower two switches control We added 5 quarts of transmission fluid, started the engine, and checked the level in Park. The beauty of the transbrake in the 4R70W is that it allows the Mustang to launch like a standard-transmission car and shift like an automatic. The overdrive and lockup make the car driveable on the street. We added 5 quarts of transmission fluid, started the engine, and checked the level in Park SOURCES Trick Flow Specialties 1248 Southeast Avenue Tallmadge OH 44278 330-630-1555 www.trickflow.com Valvoline PO Box 14000 Lexington KY 40512 800-832-6825 www.valvoline.com Precision Industries 120 Independence Dr. Whiteville TN 38075 731-254-0055 www.converter.com Hellion Power Systems 2735 Della Rd. SW Albuquerque NM 87105 505-873-4670 www.hellionpowersystems.com Performance Automatic 8174 Beechcraft Ave. Gaithersburg MD 20879 301-963-8078 www.performanceautomatic.com Autolite 39 Old Ridgebury Road Danbury CT 06810 800-890-2075 www.autolite.com Ford Racing Performance Parts 15021 Commerce Drive S Suite 200 Dearborn MI 48120 800-FOR-D788 www.fordracingparts.com By Douglas R. Glad Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!