Identify replacement window springs : SWISCO.com

Handy Person from Seattle

Feb 8, 2026 9:47 am

I'm trying to replace the springs on an aluminum window. The plastic piece over the spring is 29-7/8" x 3/8". Thanks for any help.
-Ryan

3 user uploaded images

4 Replies

Casey from SWISCO

Feb 9, 2026 11:43 am

Hello,

We don't carry spiral balances that have the bottom bracket built in like yours. Our best option would be the (3/8") S400-30 spiral balance for non-tilt windows, which commonly uses the 17-031 mounting bracket. Review the specifications to see if you could use these parts to replace your original hardware. Thank you!

How to measure the length of the Series 400 spiral balance

Alternate image for 17-031

Handy Person from Seattle

Feb 25, 2026 7:16 pm

Thanks for the help. Can you tell me how that bracket attaches to the bottom of the window and the spring? On my window the aluminum frame is just folded over the 90 degree "L" shaped part in my photo.

Casey from SWISCO

Feb 26, 2026 8:05 am

Sure, you can see how the bracket and balance spiral attach in our guide below.

Guide: How to adjust a spiral balance on a non-tilt window