old hexcentrics and stoppers ... best way to repair/refurbish?

I have a whole set of old (pre 1985, not sure how pre) hexes and some stoppers. Most of the hexes are threaded with 10.5?mm rope, I assume static. The smaller ones are threaded with something around 8 or 9 mm.

I plan on cutting the rope out and replacing it. Should I use the same diameter rope or can I get away with 7mm nylon cord, double fishermans? Will it be a problem that 7mm doesn't fill the holes in the hex? The guy at REI thought I should replace with same diameter rope to avoid friction of the 7mm moving through. What do you think?

As far as the stoppers, are they safe to use? Should they be rewired? Does Black Diamond do this?

Thanks for your input/help!

As long as you know the history (no long drops or hard falls) passive metal protection should last forever. I would rethread them with a high breaking strength cord like Blue Water 8mm Accessory Cord . Threading hexes you need something that is very strong. Look for anything Dyneema or with a breaking streingth of 14kn or more. The double fisherman's is a great low impact knot but it still reduces the breaking strength of the cord by 30%.

Hope that helps!

Don't use dyneema. Use perlon cord. It stretches and helps
take some of the force on falls, unlike spectra or dyneema.
Lasts longer, and takes knots better also. I always used the
suggested diameter cord for each of my hexes/stoppers, still do.
I'm sure if you check the BD site they'll have recommendations
for what sizes.

useful info here:

mountainproject.com/v/climb…

Sorry Steve, you are right, dyneema and spectra are wrong. Perlon is the way to go for sure. I found a great site with some specs on the durability (strength after 200 bending cycles) and strength when tied in a knot or anchor. It compares perlon, spectra and tech cord. Check it Out