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Silencer mounting bolt

Posted: Mon Aug 06, 2018 12:16 pm
by MalcW
Hi

Does anyone know the bolt and thread size for the silencer mounting bolt on a 1960 heavyweight - the one that goes into the back of the pillion footrest? The thread in the frame on mine seems dodgy on one side and I'm sure the bolts are not original. I'd like to run a tap down it to see if it helps.

Cheers,

Malc

Re: Silencer mounting bolt

Posted: Mon Aug 06, 2018 12:23 pm
by Rob Harknett
You should see in your parts list its 000347, (old pt. no. STd 347 ) Used for years pre & post war on many parts on the bike. Old pats lists give sizes STD 347 1 5/8" long 1/4 x 26 TPI cycle thread. You will find most fittings are cycle thread.

Re: Silencer mounting bolt

Posted: Mon Aug 06, 2018 1:01 pm
by MalcW
Thanks Rob.

Re: Silencer mounting bolt

Posted: Mon Aug 06, 2018 2:07 pm
by Mick D
Hi

As far as I know the fixing you refer to should actually be stud part number 016768, which is a 5/16" stud with a 26 TPI thread to take the silencer retaining nut. I can't find my old one to measure but I would expect the thread to the frame to be either 5/16" UNF, (24 TPI), or 5/16" BSC, (26 TPI).

I sourced my stud from Steve at AMC Classic Spares, he may be able to advise of which, (as Club spares don't appear to list the part).

Regards Mick

Re: Silencer mounting bolt

Posted: Mon Aug 06, 2018 3:21 pm
by MalcW
I must say that the idea of a stud seems preferable, as it can be securely fitted. Then a nut and washer can be threadlocked in place.

Thanks,

Malc

Re: Silencer mounting bolt

Posted: Mon Aug 06, 2018 4:25 pm
by Rob Harknett
Mick D wrote:Hi

As far as I know the fixing you refer to should actually be stud part number 016768, which is a 5/16" stud with a 26 TPI thread to take the silencer retaining nut. I can't find my old one to measure but I would expect the thread to the frame to be either 5/16" UNF, (24 TPI), or 5/16" BSC, (26 TPI).

I sourced my stud from Steve at AMC Classic Spares, he may be able to advise of which, (as Club spares don't appear to list the part).

Regards Mick
I though that was a long bolt Mick, so took another look & enlarged the parts list. 000347 was silencer clamping bolt. 01768 is silencer fixing stud. Its in 54 parts book as being for oil tank and air filter fixing. 1 1/8" x 5/16" 26 TPI. By 1960 it seems also for silencer. So you may find the part number could have several different descriptions as to what it fits.