A50 twin leading shoe nave plate

[Dunc Milne]

Hi on a 8" twin leading shoe on a 1970 A50 royal star what is size of small screws that hold on the nave plate? Thanks

[Spaceman]

I assume you are talking about the gauze air scoop plate in which case it is held on by 3 screws 21-1998 listed as 40 UNC x 11/32.

[Bess]

Hi,
   I  use pt. 21-0650. Which is Number 4 UNC, 40tpi, 5/16"long, pan cross head. Here's two I managed to undo.

Best wishes...

[Bess]

Hi,
     For the nave plate (hub cover plate?) I thought the 1970 model was a push fit with folded tabs. There is a plate that has screws, which is fitted to the A75 they use 4BA 1/4" long.

Best wishes...

[Spaceman]

Just realized my mistake - didn't know the cover on the opposite side of the TLS hub was called a nave plate. Most of the nave plates I've installed required the outer edge to be dimpled in a number of places (eg 4) behind the rim of the hub using a suitable punch to hold it on. It would be easier if suitable tabs were provided but this doesn't seem to be the case on pattern nave plates.

[JulianS]

From the 1970 A75 R3 parts book showing the nave plate and 4ba screws, at 39, as in the post from Bess.

[JulianS]

Sorry here is the page.

[Spaceman]

Interesting difference - my 1970 parts book for the A65/A50 shows no screws for the nave plate and so I assume it is effectively crimped on.

[Bess]

Hi,
    The screwed nave was for the 1968 A65, A75 and Triumph T150 etc.

So at a guess, if the OP's 1970 bike has tappings on the drum its a possibility someone has utilized one, added the tappings for the different nave or all the hubs have tappings.

Best wishes...