Mudguard eyelet bolts - imperial thread size

[Gunk]

Would anyone know the size of bolt which is used to thread into the frame and forks to secure the mudguard stays? It's a 1962 Claud Butler, my LBS suggests tapping it out to take a generic metric bolt, but I'd rather replace them.

 

[wafter]

Might be worth measuring its ID and trying to get an idea of the thread pitch by measuring the thickness of the material and counting the threads at within that hole depth? Imperial stuff can often be a bit of a nightmare but I'm 100% with you in keeping it original if possible

 

[Gunk]

I have got the original bolts, but they have a flat slotted head (which are difficult to tighten) and as I'm adding a pannier rack the rear bolts need to be slightly deeper.

 

[carpenter]

I just checked my 1950's Carpenter and a m5 hex head bolt fits with no problems.

I bought a set of these about a year ago - stainless, seems to last well and cheap:

https://www.sealantsandtoolsdirect....steel_hex_socket_cap_screws_40552_P30096.html

 

[biggs682]

Why not use a smaller diameter metric but and bolt

 

[Gunk]

Why not use a smaller diameter metric but and bolt

That is an option, feels like a slight bodge though.

 

[Gunk]

I just checked my 1950's Carpenter and a m5 hex head bolt fits with no problems.

I bought a set of these about a year ago - stainless, seems to last well and cheap:

https://www.sealantsandtoolsdirect....steel_hex_socket_cap_screws_40552_P30096.html

I tried one of those and it doesn't quite run freely in the thread, Ideally I would like to replace them with the correct bolts but with a standard bolt head so it's easier to tighten them.

 

[biggs682]

That is an option, feels like a slight bodge though.

How can that be a bodge !!!!

 

[Gunk]

How can that be a bodge !!!!

Because the eyelet is threaded my inner fussiness means I want to use the correct bolts.

 

[Gunk]

I might have found the answer, looks like they are 10-32 UNF

 

[Gunk]

I've ordered 2x 1/2" for the front and 2x 3/4" for the rear, only a couple of quid, I'll update this post once they arrive.

 

[wafter]

I might have found the answer, looks like they are 10-32 UNF

Nice work - didn't realise you had the original bolt and in that case it should just be a (relatively) straighforward process of measuring its OD and ascertaining it's thread pitch - which I imagine is what you've already done. Good luck getting it sorted

 

[biggs682]

Because the eyelet is threaded my inner fussiness means I want to use the correct bolts.

But now you are using new bolts of a different design so surely that is also a bodge !!

 

[roley poley]

if you get yourself one of these

its an 8 sided thread restoring file by pickavant and you can refurb old threads on original bits there are vids on YouTube of them in action

 

[figbat]

But now you are using new bolts of a different design so surely that is also a bodge !!

To be fair, a single bolt that fits the threaded hole will not protrude inboard of the frame and present potential clearance issues like a nut would.