Replacement Spiral Balances

Hello! This is a very old style spiral balance that hasn't been made in decades. The good news is that we sell modern hardware that should work just as well.

My top suggestion is the Series 500, along with the 17-012 bracket (sold separately). I've been using these to replace older designs like yours for years and have had a lot of luck. Just note that the diameter of the outer tube is 9/16". You should check to verify that yours is the same.

That's right, you don't count the spiral rod itself. Traditionally you just measure the tube, but since that's not an option here you just want to measure where the tube would be. I personally would go from the top end of the spring to just where the spring ends at the white nylon bearing.

Another way to check length is to go by the glass. Assuming this is a wood window, you can measure the height of the visible glass and add 3" for the bottom sash or 1" for the top sash.

So, for example, if the visible glass is 20" high on the bottom sash, you'd want a 23" long balance. 

Hope that makes sense! Keep in mind this is only a rule for wood windows, but it's a reliable one.

It's not uncommon for top and bottom sashes of equal size to have different length balances, but in your case the difference is pretty extreme. I'm not sure what the reason may be for that, but my philosophy is not to mess with the original specs too much if I can help it. If those sizes had been working well all these years then it's a good idea to stick with it.

Looking at your tape measure, I think 31" and 21" would be the play in each case. Your balances actually look to be a little longer in each case, but only incrementally. Spiral balances do have a bit of leeway in that sense and rounding down to the previous inch is totally fine. In a worst case scenario, you can always drill a new mounting hole a little lower in the track to make up the difference, but that's rarely necessary in my experience.