Need advice- petcock screws

hondadreamca77 · Post by **hondadreamca77** » Sun Oct 14, 2012 8:12 pm

Need some advice here. I've read the petcock screw posting on this site and it recommends 6m x9 x25mm. Last nite I went to Lowes and using the thread gauge mine appears to be 5m not 6. I only have one screw left as I had drill them all out and it is bent at that. Knowing the nuts are welded inside the tank I am not going to take any risk buggering this up. Did any of the 305 dreams use 5m?

Thanks

Snakeoil · Post by **Snakeoil** » Sun Oct 14, 2012 8:25 pm

Screws are cheap. Buy one of each and try them using your fingers.

If there is still junk in the threads in the tank threads, cut axial slots in a screw and it will let the crud move into the slot, similar to the chips with a thread tap.

regards,
Rob

G-Man · Post by **G-Man** » Mon Oct 15, 2012 1:36 am

M5 x 0.9mm pitch sounds right. These are JIS threads. M6 is the same pitch in both JIS and ISO Metric.

Here are the comparisons for reference....

Thread size- newISO - oldJIS
3mm 0.5 0.6
4mm 0.7 0.75
5mm 0.8 0.9
6mm 1.0 1.0
8mm 1.25 1.0
10mm 1.5 1.25
12mm 1.75 1.5

G