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Nut for Early Dura Ace brake caliper pinch bolt

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Nut for Early Dura Ace brake caliper pinch bolt

Old 03-30-20, 12:18 PM
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Stevensb 
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Nut for Early Dura Ace brake caliper pinch bolt

I bought a brake set on eBay that came to me without either of the nuts for the pinch bolts (bolt on lower left of pic).

I'm trying to determine what size nut will fit.

By my calipers, the threaded portion of the bolt measures 4.85MM or .191 inches in diameter.

If this is a metric threaded bolt then I presume it's an M5 but i don't know about thread pitch, course or fine, etc. as i don't have the appropriate tools.

Or maybe it's not metric?

Anyone able to tell me what nut I need?

TIA.

Cheers.

Brad




Shimano pinch bolt nut by BJ Stevens, on Flickr

I posted in ISO thread last week but didn't get an answer so trying this route. Thanks.
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Old 03-30-20, 12:59 PM
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I can take one off my calipers and go to Ace today after work and let you know, if no else responds by then.
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Old 03-30-20, 01:09 PM
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I'm pretty sure it's just a M5x0.8mm nut. You don't need anything but a ruler to measure thread pitch. Metric thread pitch is just mm per thread, so if you measure 8mm for 10 threads or such, it's 0.8mm per thread.
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Old 03-30-20, 01:18 PM
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It's definitely a garden variety M5 x 0.8 mm nut. The original nut was chromed steel, with a slightly rounded profile on one side. It is exactly the same nut as the two on the QR mechanism in your photo (but not the nut on the pivot or the brake shoes; those are M6 x 1.0 mm).

How do I know this? I'm measuring from a caliper that I have in my hands at the moment. @Stevensb, I sent you a photo of it.
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Old 03-30-20, 02:24 PM
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Problem solved! Thanks all.

Cheers.

Brad
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