Thread type model 8

[kayaker]

Hi Guys I've tried in vain to ascertain the thread type in the engine side covers on my model 8 1960, I would have thought they would have been UNC ? I need to put a couple of helicoils in, the bolts that are in it may not be the correct ones so I don't want to measure them.
any help gratefully received.

Ian

[Ozmadman]

I have a 1960 model 8 and I am pretty sure from memory they are 1/4" BSF. They didn't use any coarse threaded bolts on these bikes such as Whitworth and UNC is too new to be used on this model. They only used BSF and BSC ( a fine cycle thread) but as it is going into an ally casing it has to be BSF. You can buy the genuine type slot headed screws

[Janet]

I have a 1960 model 8 and I am pretty sure from memory they are 1/4" BSF.

My memory's not so good so hang on a minute and I'll go to my upstairs workshop and dig out a spare screw from my G2.

patter, patter, patter

Now I'll go outside to the man cave and find a selection of nuts from NelLiE that fit it. patter, patter, patter

patter, patter, patter

gasp, gasp I'm getting too old for all this running up and down.

Right, NelLiE's parts list confirms Paul's memory and it is, indeed ¼" BSF.

[Ozmadman]

Ha, ha !! like it.. you can eat a Mars bar now with all those calories you have burnt off..

[kayaker]

many thanks guys, BSF would appear to be too fine for aluminium, probably why a couple are dodgy so I suppose I have options now with helicoil wouldn't be standard I know but more effective,
Cant for the life of me understand if they didn't have UNC then why not whitworth.
Hey Ho decision time

ps I have a Stannah stairlift for sale

[SPRIDDLER]

ps I have a Stannah stairlift for sale

I'd be interested if it's the latest 'TURBO' model so that I can get to the top of the stairs before I've forgotten why I've gone up there.

[Ozmadman]

Keep it BSF if you can as BSF helicoils/kits are still easily available

[Andy51]

Ian, don't know anything about lightweights, but 1/4 in threads in alloy in heavyweights are Whitworth (20 tpi). 1/4 BSF is 26 tpi, same tpi as as BSC, but different flank angle of 55 deg; the two should not be interchanged because of the different angles. Andy

[Janet]

At least we agree, Paul. We're both wrong.
I suppose I should dig out my thread gauges and check properly.

What a pity the parts lists don't say what they are.

[clanger9]

26tpi on my 1966 Model 14 (using a thread gauge). Looks like 1/4" BSF to me...