Pivot Shoe & Coil Balances

Thanks for posting. It's difficult for me to make out your pivot shoe in these photos. Does your pivot shoe look like our 15-180? The identity of the pivot shoe determines the identity of the coil balances needed. If you have the 15-180, then you need our Series 190 Coil Springs. Let us know if you have any further questions.

If your sash weighs 17.8 lbs, then it would best to use a S190-440 (4 lbs of support) and S190-540 (5 lbs of support) on each side of the sash. This will equal 9 lbs of support on each side of the sash, for a total of 18 lbs of support. the difference between 18 lbs and 17.8 lbs shouldn't make a difference.