The joke among guys is if your car is making a strange or irritating noise, turn the radio up. But there are some noises you just shouldn't ignore, and the whine coming from the pump area of the 4R70W Ford overdrive transmission in our ex-Santa Barbara County Sheriff's '03 Crown Victoria would surely leave us stranded by the roadside if we took that advice. We were expecting a bad stator bearing in the torque converter but decided to have the whole transmission gone through just to be safe. Good thing, too. It was a mess in there. If you want to see what lots of hard miles do to any transmission, follow along as Leo Glassbrenner, owner of Remac Transmissions in San Dimas, California, performs a transmission rebuild on our severely worn 4R70W Ford overdrive transmission to severe duty specs. Chevy and Chrysler guys, read along. Even if you don't speak Ford, there is transmission rebuild information in this article that applies to any modern, electronically controlled transmission. What's A 4R70W? The 4R70W Ford Overdrive Transmission is an updated version of Ford's long-running AOD transmission that first appeared in the '80s. The nomenclature breaks down like this: 4 - Four forward speeds R - Rear-wheel drive 70 - Torque rating x 10 (will hold 700 lb-ft) Note: This rating is based on torque converter multiplication. It won't stand up to an engine that makes 700 lb-ft at the crank. W - Wide ratio Compare the gear ratios and you can see why the 4R earned its W designation. All 4Rs have the same gear ratios, by the way. There is no such thing as a non-W 4R70. Ford Overdrive Transmission Applications '93 to '98 Lincoln Mark VIII '96 to '04 Ford Mustang '94 to '97 Ford Thunderbird, Mercury Cougar '95 to '04 Ford Crown Victoria, Mercury Grand Marquis '93 to '04 Lincoln Town Car '93 to '03 Ford F-series trucks '97 to '04 Ford Expedition '96 to '01 Ford Explorer, Mercury Mountaineer Gear Ratio Chart 4R70W AOD First 2.84:1 2.40:1 Second 1.63:1 1.47:1 Third 1.00:1 1.00:1 Fourth 0.78:1 0.67:1 We pulled the transmission from the car ourselves and dropped it off at Remac. Glassbrenner called us after it had been disassembled to break the news: It was a mess. First of all, the oil pump rotor had worn a deep groove into the pump housing and would need to be replaced. We pulled the transmission from the car ourselves and dropped it off at Remac. Glassbrenne The friction discs of the forward clutch were nearly worn smooth. Second gear had been slipping, as evidenced by the blue spots on the steel rings, indicating that the whole assembly had overheated. In addition, our direct clutches and overdrive band were toast. The seals around the reverse band apply servo were also shot, explaining the annoying driveline shudder when reversing at low speeds. Second gear had been slipping, as evidenced by the blue spots on the steel rings, indicati Adding insult to injury, the sealing rings on the tailshaft wore deep grooves in the transmission case. To fix this, we either needed to resleeve the case or junk it for a new one. Adding insult to injury, the sealing rings on the tailshaft wore deep grooves in the trans We did discover the source of the mysterious bellhousing noise and were relieved to see that we weren't too far off with our diagnosis. One of the torque converter fins had snapped off and become lodged against the stator. We did discover the source of the mysterious bellhousing noise and were relieved to see th That scratching sound coming from the bellhousing was the fin slowly (and imprecisely) machining away our stator. That scratching sound coming from the bellhousing was the fin slowly (and imprecisely) mac 1 | 2 | 3 | » | View Full Article By John McGann Enjoyed this Post? Subscribe to our RSS Feed, or use your favorite social media to recommend us to friends and colleagues!