Hannah in VA --

Resolder your OD relay (properly) and it'll outlast your brick. The relay assembly is a sound design -- it's the crummy automated soldering process that causes the problem.

And if you must manually disengage OD with your design, keep in mind that you can do some serious damage if OD is inadvertently engaged in reverse.

And don't EVER loan your car to someone to drive -- that person might forget to manually disengage......
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Don Foster (near Cape Cod, MA)

Hey Chitty Chitty -

The 4th gear sensor on the tranny connects the red wire from the relay terminal #85 to ground. I can't tell if the ground allows the relay to engage, or causes it to disengage.

But, surely there's a way to keep that 4th gear switch in the circuit to avoid having the OD engaged in other than 4th gear.

I rigged up a system from an OD relay from an AW70 to work in a M46 car, and did have the OD engaged in reverse, one time. The loading on the tranny can be damaging.

Good Luck,

Bob

:>)

Some of us are dying to know. What... could be more reliable than a Bosch or Hella wave-soldered relay circuit in a plastic box?? (bit of sarcasm here)

Seriously, were you disenchanted with the timing characteristics and debouncing of the push-button latch or just the poor soldering?
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Art Benstein near Baltimore