American bolt thread advice.

[bulltaco]

Hi,
I have an aluminium mounting which came from Surplus Center for mounting a Honda GSX 270 to a Barnes 16gpm pump.
The Honda is no problem, the mounting bolts are metric threads, but could someone tell me please what thread will be used on the pump mounting end of the bracket?. An 8mm bolt begins to go in but is apparently not the right size. Will it be a USA thread?.
(I'm in Scotland).

 

[lone wolf]

Not sure on yours but on mine they are SAE.

 

[mikes mold]

thread pitch

.03937 is one mm so 8mm comes out to be .314 dia with a mm thread pitch. But try 5/16-18 or 5/16-24 dia. 5/16 dia =.3125 dia. They are often confused. On 8mm there is only on pitch 1.25mm. Hope that helps. Mike

 

[bulltaco]

Thanks guys,
I'll raid the hardware shop next time I'm in the big city of Inverness.

 

[RVALUE]

Are sae the odd / special bolts in your stores?

 

[formationrx]

threads

it could just be a bastard size ...... use a pitch gauge ....they are cheap...

 

[camr]

5/16" x 18. The profile is very close to a metric 8 x 1.25. They are easily confused and the results can be ugly.

 

[doug4k]

there is only .005 difference in thread pitch between 5/16-18 and a m8x1.25. an m8 will go in a few pitches before it binds up on the threads. you probably need the 5/16-18. but i would pick up the 5/16-24 also and save a trip to the hardware. you probably could take the unused ones back to the hardware at your convience.:smile2:

 

[bulltaco]

"an m8 will go in a few pitches before it binds up on the threads."

Thanks again.
Absolutely correct about the M8 so 5/16-18 will be the one.
George.