Teflon tape? I've never heard of that needing to be used on any sort of oil drain plug. That is just bad manufacturing. Maybe out-source the drain plugs to China, lol. Or maybe they already are? Yikes.

 

Dyna/Softail

Primary cover drain plug for Big Twin Dyna/Softail 5 speed

Attached is a pic of the new style SAE drain plug with an o-ring that replaced the NPT drain plug in 2004. Just as a reference, the outer primary in the picture is a 60506-99A which was updated in 2004 to use the SAE drain plug used on Big Twin Dyna/Softail 5 speeds. In 2006 they went to a 6 speed and they moved the drain plug to the inner primary.

So if you are in the market for a new outer primary for your early model 1999-2005 Big Twin Dyna/Softail, always check to see what type of drain plug that it has. Also in 2004, the derby cover does not have an 0-ring and has been revised to use a gasket.

Hope the pic helps someone and I like that the plug actually has an o-ring and it bottoms out on the case. Yes, I am very familiar with the NPT plug and I always used teflon tape and installed it with a little protruding outside the case and it's true, it does not snug up, so use precaution and install it as recommended in your service manual.

Just as everyone says "Do not over tighten" and as a safety precaution, I always check mine periodically.





SAE Primary drain plug Big Twin Dyna/Softail 5 speed

 

I don't like the idea of Teflon tape on any part of the oiling system. If you've ever taken apart plumbing fittings that were assembled with tape you notice the tape has squished down and there are a lot of small fibers of tape in the threads. The first time you use the tape everything is fine but the second time you take the plug out there is the possibility of those fibers get loose into the oil system and they might plug something up. I think that's why Harley uses pipe dope instead of tape.


Plus I think the seal is accomplished with the o-ring not the threads. I don't think it's a tapered plug the way pipe fittings are.

 

No pipe dope or teflon tape. Not ever. That stuff is for amateurs that think they can mechanic.
Try using the next size smaller o-ring. I've found that the one H-D sells fits loosely and will tear easily because of the loose fit.
You should have to roll it over the threads and it should fit snugly in the groove machined for it.
Lube it so that it doesn't stick and tear and you're golden. No torque wrench necessary, just tighten to a touch past "snug" and you're good to go.