Spare tyre bobbin thread pitch?

[The Veg]

Anybody know the thread pitch of the bobbin in the floor of the boot of a Plus 2 that holds down the spare tyre? Manual gives diametre and length but not pitch, and none of the common bolts I have are threading into it even though the threads look OK.

[mbell]

1/4 unc if memory serves me right.

The bolt decoder should confirm unc v unf, but bobbins are almost always unc.

[Ianashdown]

I just checked my S2 Elan. It should be 5/16 UNC I think, but that doesn’t thread in, nor does UNF or M8.

Mystery Lotus thread?

Ian

[mbell]

Part manual lists it as "XUCB0520". I think that decodes to hex head, 5/16" diameter, 1.25" length and course thread bolt.

So i was wrong and Ian correct.

Probably not uncommon for the thread to fill up with gunk or be damaged. So probably wise to run a thread cleaner tool through it first. Worse case should be easy to helicoil it.

[alanr]

The spare wheel bobbin on my +2 is definitely 5/16'' UNC.

Alan