
Originally Posted by
patch697
Im no wizz with auto's but I've plaid with a few in my day (Not a Patrol one though).
From what I know & learned from playing with Hi performance Holdens, Fords & Chryslers mostly, You don't always need a new Valve body to upgrade your auto with say a mild to medium shift kit Stage 1 or 2.
Some shift kit require some modifications be made to the valve body but these are usually a simple hole enlargement here or there & maybe a spring change in one or more of the valves themselves.
A lot of the modifications are in the separation plate that goes between the valve body & the transmission body itself & the modified plate normally comes with the kit or a list of instruction for the modifications that need to be done to your existing plate.
All these mods are designed to increase fluid flow & increase pressure to improve the auto's gear shifting ability & the added pressure improves its ability to hold more firmly whilst in gear to minimize slippage.
Most all STD auto transmissions are only designed to work with the power output of there intened power plants & when faced with a sizable increase of power (ie a modified engine) they begin to fail.
Shift kits are normally a quite effective way to overcome this problem on a small medium scale power increase & as long as the trans is beefy enough. (which a Patrol one generally is) will produce a good result.
Outside of this, more internal modifications are generally required.