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Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

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Old 12-21-10, 12:23 AM   #1
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Braze-on size differences??

Yep, I'm a newbie. My technical question has to do with the BUILD of my FRAME, so I believe this to be the best section to post in. Please correct me if I'm wrong.

I'm trying to mount a rear rack on my late 70s Centurion frame. The braze-ons next to the rear drop-outs don't seem to be compatible with the screws that came with the package. My questions is: are these braze-ons created with different thicknesses??

The details:
The screws are too short to fit the frame's braze-on, plus the thickness of the rear rack. There's only a nub of the screw left to thread a hex nut on the back side - not nearly enough to get it to lock. My easy fix might just require a trip to the hardware store. My frame is late 70s, made in Japan ... My bike research is in line with my research on 60s and 70s Japanese-made guitars (another hobby) - everything is unique to that specific time and place. The braze-ons have threading in them, and I'm not sure if I could find longer screws with that same size and threading. Or should I forgo the hex nuts and just let gravity and the outward tension of the rack do the work? (The rack rails fit inside of the frame, so outward tension helps my cause.

FYI, I'm putting a child seat on top of the rack, so I'm very concerned about it's fortitude.

I do eventually want to build frames - I have some general welding and metalwork experience under my belt. That dream is a little ways off yet. Knowing stuff like this will definitely be beneficial down the road, regardless of whether or not I get a straight answer.

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Old 12-21-10, 12:34 AM   #2
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I usually don't use a nut for threaded holes, perhaps a little blue Loctite. M5 is the most common threaded hole size in my experience.
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Old 12-21-10, 01:51 AM   #3
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yes, every dropout is different as far as the thickness of the eyelets is concerned. I don't use nuts on a threaded eyelet. I've never used locktite there either but if you are concerned, it's not a bad idea. I have seen bolts come loose, but I would think you would have excessive rattling before there was a real problem. You can certainly get longer bolts. Ace hardware seems to be the best local source, it's a 5mm bolt. The big box stores have them too, the bolts on my commuter came from Lowes. I just bought a lifetime supply of fender/rack bolts from McMaster Carr.
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