On the 80 series...its a simple matter of adjusting the Primary Regulator Valve tension on your Valve Body (no tools required). I have NOT looked at the A343F on my 100 series to see if this feature carried over (past '97)..but if it did, the same could be accomplished. Push in on the PRV cap, push up slightly on the flat detent keeper, rotate the cap to the desired position, lower the keeper, done.
The 'purpose'
(do this at your own risk) is to help facilitate firmer clutch engagement across the board without the need to install a trans kit. Faster, more positive shifts (engagement) is an effort to increase the life of the transmission's friction discs (assuming they are still in good condition).
This will NOT appreciably decrease operating temperature...so don't do it for that reason.
The majority of the heat created in the transmission is from the Torque Converter. Anytime the TQ clutch is not locked up...it is creating a lot of heat. This would also be true if friction discs were slipping or a TQ clutch slips. But neither of those last very long when they get that worn.
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