I have had my '64 dodge dart for a couple years, and it recently developed a habit of not starting. I put the key in and nothing, the engine doesn't even turn over. This doesn't happen every time, and after a couple of tries it usually starts. The car's in gear, and my starter relay seems fine, if a little dirty. Would a good cleaning help the connection, or could it be something more serious??

I am pretty certain it is your neutral safety switch. Next time it happens, try putting the gear selector in N and then shift to D or R and back to N (try both). If that helps it start then either your shift linkage is misadjusted, or your n.s. switch is going bad. You can disconnect the n.s. wire from the trans (only wire under there - near where gear shift linkage enters trans case) and ground it too, which will disable the n.s. function (just remember not to start the car with the car in gear!).

Lou

_________________
Home of Slant6-powered fun machines since 1988

This can be as simple as dirty battery terminals (posts). Pull-off the cables and clean the connection to see if that fixes the problem.
DD

I have pretty much the same problem...I've found that on my '72 Duster, if I turn the key to the "ON" position, run the gear selector down to 1st then slam it back up into park it'll start(figured that out one day when I was short on patience). Another alternative until you find the source of the problem, turn the key to the "ON" position and throw a screw-driver across the starter solenoid...if you've never done this before, be careful, if you touch the wrong 2 posts together you get a lot of sparks and the screw-driver will almost arc-weld itself to the posts. (these are not solutions to your problem, only "band-aids" until you can get the problem figured out)

-Don

This sounds like the shifter linkage needs to be readjusted to make sure the neutral safety switch is "triggered" when the selector is in the Park and position Neutral. The Duster (mechanical linkage) is easer to adjust then the 64 Dart. (cable linkage)

With the Dart, you will need to remove the bolt from the multi-hole wheel, where the cable goes into the transmission, then try a few new positions. ( mark your current location)
You can get this adjustment "dead-on" if you drop the trans pan (messy job) so you can see and carefully align the linkage trigger to the safety switch. (the little arrow pointer(s) on the linkage "comb")
The best way to test to see if this is the problem, is to ground-out the wire that goes to the neutral safety switch., The starter should energize every time, even if you have the car in gear.
DD

I'm definitely not a mechanic, but I had this problem once with my 65 Dart.

The usual tricks didn't work -- cleaning terminals and bypassing the neutral safety switch and such.

Bit the bullet and took it to a shop. Diagnosis: damaged teeth on the starter gear so sometimes it starts and sometimes not.

Been starting for 5 years after replacing the starter.