WIndwo balance and shoe

The company that made your coil spring balance system has gone out of business. May I have the width and thickness of your pivot shoe? I'd also like to see the pivot bar from your sash, which goes in the pivot shoe. I will then recommend a replacement.

The pivot shoe you can use with your pivot bar is our 15-180. The coil are Series 152 springs. You will need to get the stamped spring weight number from the old springs when ordering. You can use the 15-150D double coil spring support as a replacement, as well.

You might have S152-7 springs, using them in a tandem, but that would be for a sash weighing around 28 lb. Are you able to weigh your sash and confirm?

Ah, perfect. I'm glad you weighed your sash, our S152-7 would be far too heavy. There are a couple options ahead of you. Basically, you want to divide the sash weight among how many springs you have. Since you have an 18 pound sash and 4 springs, you'd ideally want a spring that carries 4.5 pounds.

The bad news is, no such Series 152 spring is made. The closest we have is the S152-4, four of which could carry 16 pounds, and the S152-5, four of which can carry 20 pounds. The S152-5 is probably the better bet, but it may be too strong. You may ultimately want to consider just two S152-9 springs, two of which comfortably carry an 18 pound sash. You would use one on each side.