There aren't any "good" caps available. The cheap copycats are all you can buy. The only two brands I've ever seen are Motorad and Gates and its obvious that they are identical and made by the same manufacturer. You have to make do with the junk being offered.
I don't necessarily think that the spring specs are wrong. They just get stuck and don't work. In my case, the cap worked for a while and then didn't.
