Does anyone know of a source for a U-bolt - preferably stainless - that with nuts could fit around a 30.7mm / 1.21" OD motor mount and within a 55.3mm / 2.18" ID body tube?
I did a search here and checked on many vendors' sites, but tuned up nothing definitive. I suppose the parameters are a little obscure.
Standard 1-3/8" won't likely work without shimming or grinding on the nuts. It's 1.375" ID, which is good, but add a half diameter of each 1/4" leg to get the center to center, and it's 1.625". Then the maximum OD (the distance between opposite points of a hexagon being 1.54x the distance between opposite flats - Edit: whoops, that should "1.154x," i.e., 2/(3^(1/2))) of the 7/16" heads of the matching bolts should be about 0.674", and adding half that to each side makes 2.3" total.
Likewise the standard 1-1/4" won't work, since 1.25" plus 0.25" minus 0.674" is too small.
(If my math is correct.)
If all else fails, the 1-3/8" size will work if the bolts are epoxied on and then any protruding bolt peaks are ground off before the centering ring is glued in or if alternatively, the bolts are each shimmed (or simply lucky) so that the flats are to the outside of the tube, but if anyone knows of something that would work without having to worry about such adjustments - and possibly something lighter with a tighter bend (since a quick link is a lot smaller than the 1" pipe for which the parts I'm looking at are intended), I'd be grateful to know it.
BT-70 is an elegant size, but it is often a harsh mistress when compared to BT-80 or to the minimalist constraints of smaller tubes.
Edit to add, I realized seconds after posting that the inside of the 1-3/8 is going to be a problem too, being only 0.95" at the points of the bolts and at 1.1875, even the flats will need to be ground to fit around the motor mount.
Has anyone had success simply epoxying u-bolt threads without nuts?
Edit again, for math!
I did a search here and checked on many vendors' sites, but tuned up nothing definitive. I suppose the parameters are a little obscure.
Standard 1-3/8" won't likely work without shimming or grinding on the nuts. It's 1.375" ID, which is good, but add a half diameter of each 1/4" leg to get the center to center, and it's 1.625". Then the maximum OD (the distance between opposite points of a hexagon being 1.54x the distance between opposite flats - Edit: whoops, that should "1.154x," i.e., 2/(3^(1/2))) of the 7/16" heads of the matching bolts should be about 0.674", and adding half that to each side makes 2.3" total.
Likewise the standard 1-1/4" won't work, since 1.25" plus 0.25" minus 0.674" is too small.
(If my math is correct.)
If all else fails, the 1-3/8" size will work if the bolts are epoxied on and then any protruding bolt peaks are ground off before the centering ring is glued in or if alternatively, the bolts are each shimmed (or simply lucky) so that the flats are to the outside of the tube, but if anyone knows of something that would work without having to worry about such adjustments - and possibly something lighter with a tighter bend (since a quick link is a lot smaller than the 1" pipe for which the parts I'm looking at are intended), I'd be grateful to know it.
BT-70 is an elegant size, but it is often a harsh mistress when compared to BT-80 or to the minimalist constraints of smaller tubes.
Edit to add, I realized seconds after posting that the inside of the 1-3/8 is going to be a problem too, being only 0.95" at the points of the bolts and at 1.1875, even the flats will need to be ground to fit around the motor mount.
Has anyone had success simply epoxying u-bolt threads without nuts?
Edit again, for math!
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