Primary case screw set for 1968 MklV Spitfire

[Mickygee]

Hi about to order a new set of screws for the primary cover. My bike is a 1968, but is a hybrid originally manufactured in 1967, with the Y extension on the frame and engine number.

Do I order pre (BSF) or post (UNC) 1968 screw sets, as I believe they changed thread at this time ?

Thanks

[Mickygee]

Or does it really matter as thread form so close ?

[cornishbob]

i'd say NEVER mix-n-match NEVER EVER NEVER

[DAVE BRADY]

Hi,

Use the timing side screws as a guide.

Dave.

[cornishbob]

order one of each from ebay
check first to come. if they fit YIPPEEE. if they dont start a return 'not as described
the second one should fit if they dint start a return for them

if neither fit sell the bike and join a monestry

[V500]

Or does it really matter as thread form so close ?

BSF and UNC aren't remotely similar. 1/4 Whit and UNC are close though.

[cornishbob]

i learnt to my cost about whitworth and unc.
i used, because they were there, whitworth to fix a disc to an old front wheel before embarking on a long journey.
luckily i had a toolkit as the whitworths were rattling loose. that 5 degrees made all the difference to the fitment

[Allan G]

68 models still use bsc/BSF threads. Unified threads didn't start until 69.