The acculmulators in a trans. help to absorb the harshness of the shift by softening to application of the clutches/bands. They do this by "accumulating" fluid against a spring in a small chamber. This slows the application of the clutches/bands making for a softer shift.
The spring pressure works backwards against what you would think. A softer spring makes for a firmer shift since the accumulator compresses quickly and full pressure is applied to the clutches/bands sooner. A stiffer spring makes for a softer shift since it takes longer to compress and full pressure is reached more slowly.
Most of the manual valve bodies will remove the accumulator spring entirely which makes for a tire barking shift all the time but it's really tough on drivetrain parts.
A forum community dedicated to Ford Mustang owners and enthusiasts. Come join the discussion about performance, production numbers, VIN decoders, modifications, troubleshooting, power adders, DIY tutorials, and more!