Im surprise there isn’t one of these threads already that's stickied
here since Honda uses some weird sizes.
Found this while searching for my seat mounting bolts size.
May not be all the sizes so feel free to add or correct there are some sizes wrong…Most pertain to civics though but I guess it might be for all Hondas.
M6-1.0 --- common (most of our 10mm head bolts)
M8-1.25 -- common (probably most of our 12mm head bolts)
M10-1.25 - some headbolts) (probably most of our 14mm head bolts)
M11x1.5 -- some headbolts)
M12x1.0 -- flywheel bolts + shift fork ball spring bolts)
M12-1.25 - common (probably most of our 17mm head bolts)
M12-1.5 -- lugnuts)
M14-1.25 - crank bolt?)
M14-1.5 -- oil pan drain plug. 19mm head bolt that connects rear trans bracket to trans
M20x1.0 -- 10mm allen bolt
M20x1.5 (oil filter threads????)
M22x??? d-series countershaft nut
M28x1.5 - 14mm allen bolt
Flywheel bolts (B and D the same, dont know about H and K): M12 x 1.0
Pressure Plate bolts (same b and d dont know about h and k): M8 x 1.25
Oil pan/Trans drain plug: M14 x 1.5
Trans case bolts that hold that little ball bearing in place with spring: M12 x 1.0 (oddly enough this is a hard tap to find, and timesert hasnt even made an insert for it yet so dont screw this one up)
Oil Pressure Sensor (back of block): 1/8 - 28BSP
Bumper screw/bolts: M6 x 1.0
Crank Bolt: M14 x 1.25
14mm Allen Bolt: M28 x 1.5
10mm Allen Bolt: M20 x 1.0
19mm bolt that connects rear trans bracket to trans: M14 x 1.5
D-series head stud thread: M10x1.25
B-series head stud thread: M11x1.5
Also, if it's an unusual thread, like the oil filter for example, Please put it like this
M20x1.5 (oil filter threads)
M12 x 1.25 - rear inner seat rail bolt
M10x1.5 - Shifter (for all you poor saps that need a locknut for your
Front LCA Bolts:
Subframe flange bolt: 14x1.5mm
Bushing bracket flange bolt: 14x1.5mm
Bushing nut: 14x1.5mm
Shock fork lower bolt: 12x1.25mm
Shock fork upper bolt: 10x1.25mm
Swaybar endlink nuts: 8x1.25mm
Swaybar bushing bolts: 8x1.25mm
M18X1.5 O2 Sensor Bung
How big are the bolts that hold your radius rod to the LCA?
A. M12x1.25, same as all of the other 17mm head suspension bolts.
Says it in the suspension diagram. Any Honda suspension bolt with
a 17mm head is a M12x1.25. The rear trailing arm bushingbolts are
the same thread size and pitch.