10 new Taiwanese made, 70mm long M10-1.25 grade 10.9 hex head bolts arrived yesterday.
I don’t know how long this link will last for U.S. based members, so I will include the product description too so one can copy and paste and easily search.
.M10-1.25 x 70mm Grade 10.9 Hex Cap Screw Bolts Metric Zinc Hardened FINE THREAD.
They measure 9.86mm on the shank/ unthreaded portion.
I pulled out an old RKP baseplate that I think is Paris, or a clone there of. It came with a set of Puaida hub motors and trucks.
Its splined 3/8 kingpin had become wobbly as F, and was retired in the bottom of my box of skate parts.
The unknown grade 3/8” splined wobbly AF kingpin tapped out with the lightest of blows from a lightweight hammer.
It measures 9.51mm on the shank.
I had to grind down the M10’s 17mm hex head to fit inside the baseplate. I went slow as to not overheat, and the water quench never sizzled, so it would seem the hardness and temper is preserved.
The threads would not fit into the receptacle from the bottom, but they would from the top, so I hand threaded it from the top until it got stuck, and then used a 17mm wrench to screw it all the way through. This did not require much force at all.
Then backed it out and was able to thread it in from the bottom till the shank bottomed out on the baseplate receptacle.
I then pulled it into the baseplate using its own threads and some spacers under a new M10-1.25 flange base locknut. This was very cathartic, and seemingly the only thing I did today which went right without fighting.
The bolt was pulled into the baseplate, not requiring too much force on 15mm socket, nor too little. It seated perfectly, and even if it were not prevented from spinning by the ground down sides of hex head, the Nut on top would be unlikely to to so when compressing bushings. It’s tight, but not so tight that the aluminum baseplate could have cracked.
The Flange base M10 -1.25 lockNuts I got are tall and burly.
I did not notice in the product description that they also had some Scotch grip 204 thread locker applied threads. This was the source of much cursing as I has handthreaded a nut on the bolt upto the nylon for grinding, and when I went to remove it was absolutely not going anywhere. Vice grips on ground bolt head and a regular ratchet had no chance. I had to use 1/4 inch impact driver to get it off.
The flanged base of this M10 nut is the same diameter as a tall cone bushing. Since I always flip my roadside cup washers upside down for that extra lean, and because the nut is so thick, and I keep my trucks so loose, I just skipped the cup washer entirely, as I was not able to engage the nylock portion of the nut with the cup washer unless I tightened the trucks far more than I like.
I had removed the Scotch grip 204 thread locker from the M10-1.25 nuts interior threads as that was some serious stuff.
This 3/8 to M10 kingpin swap was easy enough, that I will be swapping all my Kingpins to M10-1.25 Grade 10.9. No Splines to weaken the bolt, no more Wobbly kingpin , and some extra bolt diameter for extra strength and fatigue resistance is win x 3 in my opinion.
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I removed a caliber 2 front truck from my mini kicktail.
Its unsplined Grade 8 king pin was all wobbly, and could be slid out of the baseplate with no tools.
It measures 9.36mm on the unthreaded shank.
I will have to grind the 17mm hex of the M10-1.25 down to fit the Caliber baseplate, And the new M10 kingpin also does not want to hand thread into the caliber baseplate from the top or bottom. so some 400 grit on a 9mm wood dowel will have to get the diameter just wide enough to accept the M10 threads.
I’d like to thank this thread for igniting my fear of broken kingpins and forcing me to do what i could to lessen my personal risk