TR2/3/3A TR-3A Gas filler cap

[Arrow]

All three of my TR-3 have the gas cap that once through the body has a threaded female that screws up against the underside of the body panel. This inturns goes into the rubber tube that goes to the tank neck. My daughter gave me, for my birthday a new cap but it is not threaded on the bottom and appears like the rubber tube hooks directly to it. Moss sells both types. I assume the threaded is original application. Did Triumph also use the non-threaded and when? What are pros and cons? Tom

 

[TR3driver]

There were at least 3 different types used by the factory. I think the one with no threads at all and the hose goes straight on was very late, at least after TS60k and maybe later than that. Same as TR4.

The early one was as you describe, then there was a third type in the middle that had threads but only a big nut and washer under the body panel.

 

[vivdownunder]

The one piece cap was introduced at TS60001, and was evolutionary, being cheaper to make and quicker to fit on the assembly line.

If replacing the two piece cap, you need the correct rubber grommet which acts as the water seal between the new cap neck and the rear scuttle.

Unless it's reasonably new, it's also worth replacing the rubber connector tube too. Really tighten the lower hose clamp or fuel can seep between the connector tube and the tank nozzle, causing cabin fuel smells when the wet weather gear is on.

Viv.