HELP: Lost Shimano CX77 Disc Caliper Cable Fixing Bolt and Nut

[ColonelJLloyd]

The cable pinch bolt assembly in this CX77 caliper consists of:

• A bolt
• A washer
• A thin, square nut that is inserted within the caliper body where the awl is pointing in the photo below.

Am I SOL? I know if this was a TRP caliper I'd talk to a human on the phone that could sort out what I need. Anyone know if the number here might be helpful? FWIW, these calipers were bought second hand last year.

Untitled by ColonelJLloyd, on Flickr

[sales guy]

Shimano doesn't offer it. Neither does Q,

I looked and they show it on the blow up, but there is no part available for replacement.

Now, its a pretty standard thing. Just an M6x 1.0 bolt. The washer and nut, same thing. Go to your local hardware store and find them there. The nut part, you might have to grind down if it's too thick to fit the gap. But a local Ace Hardware is your best bet.

[ColonelJLloyd]

BS that they don't offer it.

I get that the threading is standard. But, a ~2mm thick, square nut is not. Grinding down a 4mm thick nut doesn't sound easy with my limited equipment. How long would that take with a palm sander and 60 grit? Hmm.

[cp43]

I bet that nut and washer are the same, or very similar on caliper rim brakes. Might be worth checking at your LBS for broken calipers that you could pull those parts from.

Good luck!

Chris

[dddd]

The anchor nut is M6x1 and is not 2mm thick, more like 3,5mm thick since such bolts are given a solid "reef" at installation.

I quickly found one such "thin" hex nut in my M6 NUTS drawer, it was from an old barrel adjuster of some sort I believe.

Absent any source of exact replacement parts, the challenge here is determining the dimensions of the needed nut. Perhaps you could start by probing the cavity with a 3mm hex key to estimate the needed thickness.

A bench grinder is very useful and would be the normal way to modify a standard hex nut into submission, but a belt-sander would also make very short work of this.

Even a vise and sharp file should be fully up to the duty of modifying a standard-thickness M6 hex nut in ten minutes or so.

[ColonelJLloyd]

Really appreciate the feedback.

dddd: yes, a 3mm hex key fit in the slot.

I sorted through the loose hardware bin and found an M6 nut that is 2.86mm thick. I used a Dremel cut off disc to square it off to just under 8mm. I also cut down an M6 bolt and there we have it. This caliper/bike will be going on a bikepacking trip next weekend so I made a second spare nut using a Presta valve nut because you never know.

Untitled by ColonelJLloyd, on Flickr

Untitled by ColonelJLloyd, on Flickr

Untitled by ColonelJLloyd, on Flickr

Untitled by ColonelJLloyd, on Flickr

[dddd]

Good job, looks like a solid fix.

Yikes, my Presta nuts don't seem to be even made out of steel, so if it's needed I would apply torque most carefully to that spare that you made.

[ColonelJLloyd]

I have dozens of Presta nuts around as I almost never put them on after installing a tire. They're not all created equal as some are thicker, some are harder steel, some aren't quite flat but have the shallow base of a dome to nestle into the rim hole. But, as far as I can tell they are all steel. Most are a low grade, relatively soft alloy I imagine. For sure I would be judicious with torque if I had to utilize one.

Right now the caliper is in service and working great. It replaced BB7 ok my friend's Fargo; big improvement in setup and modulation.