Splitting the 4HP20 in Half
Preparation
Using the hoist to help, lay be gearbox rear end down on a soft surface (high density foam is ideal). Now the front clutch is out and the cover is off it will rest very nicely on the cover face. Do take care to avoid any damage to the mating surface and ensure the foam is spotlessly clean. Be prepared for oil spillage.
Ensure the gearbox is in Park.
Remove iin turn all the bolts holding the two halves of the case together, noting the five bolts inside the bellhousing and the two that secure the slinging eye are longer than the rest. keep them in order.
The two havlves of the case are dowelled together. Gently tap around the edges and on convenient lugs until the case halves begin to split apart. NEVER use any levers and take extreme care not to damahe the gasket faces. Once the cases have split as far as freeing the dowels, carefully lift the top off the bottom. It is not too heavy. lay it, upside down on another piece of clean foam.
The oil pump and oil filter are now visible.
This is the other half..
To make this half of the gearbox lighter, the diff can be lifted out. Be careful, it is VERY heavy. Note the dowels and the two shafts in the foreground forming part of the parking pawl mechanism.