I am currently in the process of restoring a vintage Tsunoda Grand Prix bike, and have replaced the caliper brakes with new ones, however there is a part on the brakes which is made of plastic and I would like to replace, but I cannot figure out what it is called. It sandwiches the caliper spring in between itself and the calipers, any help would be greatly appreciated. Unfortunately I cannot post a picture of the part as this is my first post on here.

Thank you, Ben

What make and model of calipers are you using?

Saccon Alloy Caliper Brakes, sadly no specific model number or name, hope this helps, thanks.

https://www.saccon.it/index.php?area...e=126&lingua=1

https://www.saccon.it/public/brochur..._bike_2017.pdf

This is one of those parts that doesn't have a name, as it is typically an integral part of the pivot/mountng bolt. I'd refer to it as the spring retention flange. I've never seen one that was a separate part in plastic but if the pivot/mounting bolt was splined or keyed. it would be possible. Link to OP's picture: https://www.bikeforums.net/g/album/15039420

Ah, pictures certainly make it easier to visualize. I too have never seen one that was not part of the pivot mounting bolt. The picture of a caliper from the Saccon web site sure looks like it was metal, not plastic. Perhaps the OP is referring to a plastic bushing that isolates the brake arm from the pivot.

I agree. If that part is plastic you want new brakes. Does the part go in front of the notched cylinder that hold so the spring and the first caliper arm? If so, any plastic, brass, or bronze washer that fits should work.