Automotive Posts Relating to ‘gears’

AOD Transmission Oil Pump and Piston Assembly

Tuesday, September 13th, 2011

The AOD (for automatic overdrive) is a four-speed automatic transmission with overdrive. Introduced in 1980, it was Ford’s first four-speed automatic overdrive transmission. The 4R70W stands for 4 gears, Rearwheeldrive, 70 stands for the 4th gear ratio, and Wide gear ratio. It has lower 1st and 2nd gear ratios for better take-off acceleration and improved gearset strength.

The AOD was used originally on ’80s and early-’90s Ford, Lincoln, and Mercury products and in the F-series pickups and E-series vans as well. Because the AOD is basically a retooled C-4, many classic car owners have discovered they can substitute this overdrive transmission into their ’60s and ’70s production vehicles relatively easily and reap the benefits of a lower final gear ratio and decreased wear and tear on their vintage small-block V-8 engine. Theres more parts to take off of this but I will do that when the rebuild kit gets here, just to make sure I get the right parts.

How A Differential Works

Sunday, September 4th, 2011

When a car turns a corner, one wheel is on the “inside” of the turn, and the other wheel is on the “outside.” Consequently, the outside wheel has to turn faster than the inside one in order to cover the greater distance in the same amount of time. Because the two wheels are not driven with the same speed, a differential is necessary. A car differential is placed halfway between the driving wheels, on either the front, rear, or both axes (depending on whether it’s a front-wheel drive, rear-wheel drive, or 4-wheel-drive vehicle).