73 4 speed with auto trans relays

[2Forty]

I bought a 73 4 speed and correcting some wiring issues found all the automatic transmission relays still in place. I doubt the previous owner swapped in a 4 speed after looking at the wiring issues. My question is: Did Datsun produce 4 speed cars with automatic transmission relays in place. I was told by the PO that the first owner was the wife of a Datsun dealership owner. If so, why buy an automatic and convert it?

[Walter Moore]

The first owner may not have done the conversion. Who knows what has been done to your car in the past 39 years? Can you even be sure how many different people have owned the car?

The issue is less "Why was this done?" than "How do I make this work correctly?"

Are the relays causing a problem?

[EScanlon]

To my knowledge the relays for an AT tranny are not utilized by a manual tranny 4 or 5 speed.

The two main ones that I can recall: the Ignition Temp Advance Relay (Not the actual name, but a description) which switches the points ground, and the Seat Belt Interlock Relay, which senses whether the car is Parked or in Neutral. The MT would only need the one for Neutral (and maybe not even that if you don't care for it.)

If the car runs and operates properly I would surmise that the tranny swap was done properly and not worry about the relays being there or not.

An AT Dash Wiring Harness has an additional wire that an MT harness does... the Kick Down Switch wire. The rear harness is the same for both and the Engine Harness, as you've discovered, has the relays for the AT but you can ignore them. Other than that you the Engine bay harness is the same for either tranny.

As far as to why buying an AT to convert... well the AT's as a group, seem to have survived better than the MT's which have been getting "run hard" (IMO). As a result it is much easier to find a good condition Z as an original AT and convert it, than finding a manual tranny Z in equivalent condition. I'm not saying it doesn't happen, just that for the most part the AT's have been driven less strenuously and as a result have survived in better condition.

Some people will intentionally buy the AT and then convert the car and then... run it hard... and others won't.

FWIW

E