I bought a set of Gran Compe NGC450b brakes a couple years back for $30, thinking they were pretty cool looking and for the price, and gee wiz ball bearing pivots, I could not go wrong. (below picture not mine)
I did not know what I was getting myself into. I quickly realized they were really short-reach - short enough that the only bike of mine they'd work on was my Vitus 979. So I put them on there. Yes, these brakes are shiny, and yeah, the braking power is good, but the noise they make, my god!!
Others on the Cycling UK forums mentioned this too. Also, everything down to the pads and straddle cable is proprietary, and I only had enough hardware to set up one brake. Naturally, I took them apart. The bearings inside are tiny! It is no wonder they squeal. They can be forced out of alignment with minimal pressure.
They sit on a little stepped post, 6mm on the outside and m5x8 threaded on the inside. Each bearing is 4mm thick, but they ride in a 7mm deep hole in the brake arm. So I thought to myself, why not add a second bearing in each brake arm? That should stabilize things! The bearings are readily available, part number MR126-ZZ. I bought ten of them for $9.
The only thing I had to make was a set of new bolts. These were somewhat difficult to machine. It starts out simple, with an M5x0.8 thread, but then there has to be a 6mm shoulder for the bearing, the bolt head has to be relieved so that it doesn't foul the outer race or seal, and everything has to be pretty concentric and fit tightly. I was able to do it on the good old Hardinge HLV-H lathe at work, before things got locked up for the virus thing.
I also machined a m6x1.0 stud on the other end, for eventual mounting of a rack. More on that rack thing later.
Finally, of course, the proprietary pads can be changed out for normal ones if pad mounting hardware is swapped for stuff from a Mafac or CLB racer.
With these modifications (after about 10 hours of work), the brakes work really well, and are quiet!
I also made a straddle cable. I soldered a little brass donut that I filed out of an old spoke nipple onto a short length of road brake cable, including the pear-shaped cable end. This way, like the original, there is a little handle to grab to quickly un-slot the cable from the brake arms on one side. I used Harris Stay-Brite 8, which is 6% silver, so I can solder with a soldering iron. The cable was 100mm long, so I couldn't use a MAFAC Competition straddle cable, which is 113mm.
Phew. Much ado about nothing, and throwing good money after bad. But coming up next, a silly little placeholder rack.