Bolts - mudguard stay to fork end

From the top of my head, 1/4" x 26tpi. Originally studs and nuts rather than bolts (or even set screws). If starting from scratch, I would be tempted to go non-standard and use 1/4" whitworth into the alloy leg. That's me doomed to be burned as a heretic!

I think Gordon is right re cycle thread, as 62 was before AMC changed things, most threads in ally were whitworth but cycle would not vibrate loose so easily and as this is not an item that would be undone regularly I would go for bolts as fitted to my 99 ,with a tiny drop of threadlock!..

Hi all,

I had to have my sliders welded so we can drill and thread for new bolts to the mudguard stays. The bolts that came with the forks were wrong and mismatched, the threads in the sliders were trashed. The part number for the bolts, shown in the NOC shop, is 18854 but are out of stock. Since I'm not in the UK, shipping costs for four bolts would be horrendous, can anyone tell me what these bolts are? Size and thread? Knowing that I can, hopefully, find them elsewhere. It would be nice to use the original size/thread bolts.

thanks!

Bruce

hello early ones are 1/4 whitworth have fun your anna j

In my humble opinion, I should go for UNC 1/4", as they can be more easily obtained in some less developed countries than the UK. When I studied mechanical engineering we where told to use coarse threads in aluminium alloys. The .2 mm head size difference should probably not give any problems?Living in a metric country, I have quite a lot of problems with my Nortons where previous owners has replaced nuts and bolts with metric threads.

Mike

Mikael is right. Whitworth was used because it is better to have a coarse thread in a relatively soft alloy to avoid stripping. Personally I would use either a 1/4" whitworth stud and matching nuts, or a 1/4" Whitworth or UNC machine screw ("Bolt"). In one of my rebuilds the rusty stud snapped off so I drilled it out and retapped - using 1/4" studding rather than messing about with Whitworthon the innerend and BSF or Cycle the outer end. It isn't worth the bother as no-one will see it!

Mikael is right. Whitworth was used because it is better to have a coarse thread in a relatively soft alloy to avoid stripping. Personally I would use either a 1/4" whitworth stud and matching nuts, or a 1/4" Whitworth or UNC machine screw ("Bolt"). In one of my rebuilds the rusty stud snapped off so I drilled it out and retapped - using 1/4" studding rather than messing about with Whitworthon the innerend and BSF or Cycle the outer end. It isn't worth the bother as no-one will see it!

Well Hello Now Whitworth has been standard tread size around the world for well over 100 years now so this will still be avalible now and for a long time too come And my advice is if this been made with a whitworth tread size then replace it with a whitworth tread size , you can now make your own if you get the right tooling like a good tap and die set from Rga tools there are lot of tutorials on you tube on making you own nuts and bolts and you have some fun doing it too!

yours Anna J

Just found i have a similar problem on the 67 Atlas, one side appears to be 1/4 cycle or UNF while the other side is whit or UNC, Be nice to know what they were orriginally , thinking AMC so UNF ??.

Previously Bruce Mitchell wrote:

Previously Gordon Johnston wrote:

From the top of my head, 1/4" x 26tpi. Originally studs and nuts rather than bolts (or even set screws). If starting from scratch, I would be tempted to go non-standard and use 1/4" whitworth into the alloy leg. That's me doomed to be burned as a heretic!

Thanks! The bike is a '62 99SS and the parts book claims bolts not studs.

Cheers!

Hello - Your 99SS fork slider bottom fixings, to the mudguard stays, would have been 5/16 inch X 26 tpi (BSC) bolts with a reduced hex head size ( same as 1/4 inch BSW ). The top mountings for the mudguard U-bracket would have been 1/4 inch X 26 tpi ( BSC ) double threaded studs. The threads changed to UNC formats when the Commando was introduced. Will Horgan at Stainless Classics stocks these items.

Good Luck. Howard