518 TRANS OD/LU WIRING AND SWITCHES
I have had a good look at the various solutions to wiring the overdrive. I think I have come up with something new that solves the issue of switching in and out of overdrive around the speed of actuation. Others have used a time delay relay but this will allow instant switching.
Circuit for overdrive only. Lockup controlled by manifold pressure switch.
The relay has 2 separate sets of contacts. There are 2 pressure switches. One determines speed (pressure) at which overdrive comes in. The other determines when it releases. When the transmission reaches the lower pressure the switch applies power to the higher pressure switch. Nothing happens. When the pressure increases enough to operate the higher pressure switch the relay operates and switches in the overdrive but it also bypasses the high pressure switch. The relay will then remain on until the pressure falls enough to switch off the lower pressure switch.
If adjustable switches such as those from PATC are used it will be possible to have a decent hysteresis with about 5lbs difference between on and off.
I can't try this out until the car comes back from having some metalwork done but I reckon it looks promising.
Please let me know what you think.
I have had a good look at the various solutions to wiring the overdrive. I think I have come up with something new that solves the issue of switching in and out of overdrive around the speed of actuation. Others have used a time delay relay but this will allow instant switching.
Circuit for overdrive only. Lockup controlled by manifold pressure switch.
The relay has 2 separate sets of contacts. There are 2 pressure switches. One determines speed (pressure) at which overdrive comes in. The other determines when it releases. When the transmission reaches the lower pressure the switch applies power to the higher pressure switch. Nothing happens. When the pressure increases enough to operate the higher pressure switch the relay operates and switches in the overdrive but it also bypasses the high pressure switch. The relay will then remain on until the pressure falls enough to switch off the lower pressure switch.
If adjustable switches such as those from PATC are used it will be possible to have a decent hysteresis with about 5lbs difference between on and off.
I can't try this out until the car comes back from having some metalwork done but I reckon it looks promising.
Please let me know what you think.
