Dura Ace Brake Barrel O-Rings
One of the o-rings on an adjusting barrel of my Dura Ace 7402 brakes cracked in two. I did some measuring and looking around for a replacement. I got a few replacement o-rings 11 mm inside diameter and 3 mm thickness. The attached pictures show the cracked and new rings. The 3mm thickness looks a little thin compared to the original and I should have gotten 3.5 mm or so. Anyone else have a cracked o-ring like this ?? At 20 cents each I bought a lifetime supply and if anybody needs one, drop me a note.
My experience with most automotive type o-rings that I had re-purposed for my bike componentd is that they tend to dry out and crack after just a short time as I think they might be more sensitive to gasses commonly encountered in the environment like Ozone. They last longer in machinery as they are mostly sealed away from these gasses and UV light. I dunno, but has anyone here experienced similar??
Most "O" rings are a form of nitrile. Not all nitrile is the same. There are other compositions, look up O rings in Mc Master-Carr or Grainger for the size you need. Note there are also metric "O" rings, I bought some of those for my Campagnolo adjusters. Silicone ones are often found in Blue...or Red.
Originally Posted by Chombi
The images finally loaded, Look for Silicone.
Green for A/C refrigerant work can be found at well stocked AutoParts Stores. A little more expensive but are high quality.