Motard & the vertically challenged

[tls25rs]

My link didn't work out so good but if you search fastenal for M12 and DIN7991 you'll find a ton of options. Not too many for M12 Fine thread.

[xxaarraa]

Did you choose the M12X1.5 thread pitch for a reason? Typically M12 standard hardware is a 1.75 pitch.

Had you tapped the frame to the M12X1.75 pitch then you could have found any number of DIN7991 (flush top/countersink) hardware

Not that these bolts are going to see a ton of stress in the axial direction but chasing the imperial thread bolt with the M12X1.5 die took a good amount of the material off of the bolt threads. You may consider installing some type of insert, helicoil, timesert etc. into the frame at the M12X1.75 pitch and then buying new bolts.

Wow, good to know tls. I chose 12x1.5 because the allen bolt I got at fastenal was a 12. And the lowest pitch in my tap and die set for a 12 was 1.5. I could have gone 1.75 but didn't know the details you mention. Weirdly, the stock Aprilia bolt was a 12x1.25 (big bolt but super fine pitch?). My tap and die only had 1.25 pitch for a 10 bolt and lowest for a 12 bolt was 1.5.

If I wanted to go to 12x1.75, couldn't I just retap with the 1.75? Why would I need an insert for a bigger pitch?

[tls25rs]

Why would I need an insert for a bigger pitch?

The reason I suggested the insert:

Installing the insert will oversize the current hole past where there is already material removed for the current threads. This will allow you to tap fresh material for the insert as opposed to tapping already tapped material, which will have overlapping threads some thinner than they should be, and winding up with a threaded hole with reduced strength in the threads. Similar to what has happened when running the die over the bolt you have in there. Once the insert is installed properly the threaded hole will typically be stronger than a hole just tapped into the raw material.


Not too sure why Aprilia would have used the super fine thread pitch on their stock hardware. Possibly increased strength due to more threads for a given material thickness Main reason I suggested the 1.75 pitch is the availability of hardware.

There is a shop in Wakefield MA Metric Screw & Tool - all metric supplier that is a go to place for this type of thing as well.

[xxaarraa]

The reason I suggested the insert:

Installing the insert will oversize the current hole past where there is already material removed for the current threads. This will allow you to tap fresh material for the insert as opposed to tapping already tapped material, which will have overlapping threads some thinner than they should be, and winding up with a threaded hole with reduced strength in the threads. Similar to what has happened when running the die over the bolt you have in there. Once the insert is installed properly the threaded hole will typically be stronger than a hole just tapped into the raw material.


Not too sure why Aprilia would have used the super fine thread pitch on their stock hardware. Possibly increased strength due to more threads for a given material thickness Main reason I suggested the 1.75 pitch is the availability of hardware.

There is a shop in Wakefield MA Metric Screw & Tool - all metric supplier that is a go to place for this type of thing as well.

Wow, I learned something new today. Thanks for this, I did not know the science behind tap & die.

Good to know on availability of hardware too. I tapped two extra fastenal bolts to 12x1.5 while I was at it to throw in the trackday spare hardware box, but it's the same situation - retapped the imperial when insert would have been better. I'll keep your suggestion in mind, thanks.

[Garandman]

BTW, probably no motard but there is a lengthy "shortpants" thread on Advrider.