Transmission fill and drain plugs

Hi all,

I decided to change transmission and differential oils in my 67 Duetto myself for the first time. I took out the filler plug first, of course, and then the drain plug. I noticed that washers are not an option with these transmission plugs. So I asked some of my American Alfisti friends, and they told me the plugs were wrong. So I ordered new plugs...Low and behold, I am receiving the same plugs....Here's a pic of what I took out. Are these really what I need, and if so, how on earth are they supposed not to leak? I am hesitant to pump new oil in if I can't be reasonably sure I'm not getting any major leaks.

Thanks,
Peter
Austin, TX, USA

Hi! there: Only a guess, probably way off, but similar with some older machines I've had, possibly? Slightly tapered threads, which never made a perfect oil tight seal, so a few wrap arounds with PTFE tape??:

I'd say they are the wrong plugs. One would not want to install a pipe plug (tapered thread) into an aluminium housing that has a straight thread. There's a pic of a trans drain plug here
that also requires a washer.

I'd say they are the wrong plugs. One would not want to install a pipe plug (tapered thread) into an aluminium housing that has a straight thread. There's a pic of a trans drain plug here that also requires a washer.

Hey Texas
They are the correct plugs, slightly tappered thread as said above.

Originally Posted by Johny5

Hey Texas
They are the correct plugs, slightly tappered thread as said above.

I second that. They are the correct plugs and you will find they seal just fine. Make sure you tighten them to the correct torque.

I think we got there to put texasalfanut's mind at rest, Eh, Chaps?:

Originally Posted by zulu ferret

I think we got there to put texasalfanut's mind at rest, Eh, Chaps?:

I don't know....does anyone actually use these? I must say they did come out of my transmission, and they did not seem to leak, but they were tightened way more than I would ever dare to! And no offense, but I also know that Papajam knows his stuff!! Jim, good to see you here!

Honest....they are the same plugs I had on my last spider and the same ones are on my S4. Also when I put them back in I do not use ptfe tape and there are no leaks ( from the plugs anyway!)

Was common practice over here for years to use that type of taper thread, not just on transmissions, but on sump plugs as well.: They work ok, but you do need a bit of a deft touch when you tighten them, to ensure the torque is about right. Takes me back to the Coventry Climax transaxle transmissions, and many others.:

Stick them back in Peter, they'll be fine: Touch of ptfe on the lower part of the thread as I said previously, helps stop the odd drip or so!

thanks all!!

Changed out the pinion seal on an 89 Spider today and thought to snap these piccies of the plugs. The drain plug, with magnet, is on the left. Note the flange on both plugs for the copper or aluminium sealing washer; a requirement for a straight thread plug. The last pic of the gearbox uses the same type plugs.
I checked a variety of parts books ranging from the mid-1960s Giulia TI to the S4 Spider of the 1990s and although the fill plug part number changed over the years, the drain plugs remained the same and sealing washers are shown for both plugs. However, lacking later model (80s-90s) non-USA market parts books, I can not with any authority verify whether or not non-USA markets cars were fitted with or without straight thread plugs.

Thanks Jim. I have ordered the plugs with flange from centerline as well, and will see whether they fit.