Hopefully someone will know - I've got a bunch of M7 caliper (assembly) bolts and have found what I believe to be the correct ones for my Late Front /4 calipers ... but the ones I have left over that should be for the rears don't look right to me.

The issue is that when installed they don't "peak" out the ends like on other calipers (much less have room for a hex nut). I don't believe they necessarily use a hex nut but the end of these bolts seem too far from the openings on the back side, quite a ways from it actually.

Thought I'd check by looking at a set of early rear calipers that I have but (to my surprise) those use a Ribe bolt system that actually have a recess machined for the round head of the Ribe bolt (so I can not use these bolts with my Late rear calipers) AND also those include a hex bolt on the back side! So, that makes the
short Hex bolts for the later calipers seem even less appropriate.

Any one got length dimensions for those LATE rear calipers? .. or can confirm that the short (much recessed) bolts are right? thx.


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Rear calipers use M7x45 and M7x50 bolts. Late fronts use M7x48 and M7x60.

While the bolts appear too short, they’re just fine. Rule of thumb on thread engagement in steel is 1xdiameter. In aluminum, 2x diameter…cast iron acts more like aluminum than it does like heat treated steel, so I like to see 2x diameter. Look at the width of an M7 nut…it’s about 7mm. 8mm nut…right about 8mm. In the cast iron late calipers, even though 2 of the bolts could be longer, you’ve still got about 4 diameters of engagement, which is more than sufficient.

Perfect, thanks!

Yep those are the ones I have left, and also thanks for the explanation too.. nice to no the why's.


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