Retrofit 1980s era window balancers and hardware with newer hardware

A handy person from New Mexico says:
The house we recently purchased has two different eras of tilt windows, half from the mid 80's, the other half from the early 20's. The older windows use a spiral balancer system while the newer ones use the metal coil system. (see picture) Is it possible to retrofit the older windows using a newer coil system? Since the older windows' hardware is in bad shape and needs replaced, I would rather use a newer, easier to open/close system.

The older window's pivot lock shoe has the following dimensions:
1" wide, 2" tall, 3/8" deep.
Spiral balancer is 3/8" diameter.
For the pivot bar, I can use the newer style and modify them to fit the slightly smaller holding channel of the older windows if necessary.
Older windows weigh ~20 lbs

Thank you for your time.

~Experienced handyman
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Tom from SWISCO responded:

I've known some people who were able to use coil balances to replace spiral balances, and vice versa, but its always a risky proposition. There is definitely wiggle room in terms of overall tension but the main problem is just getting the things to fit.

This is especially relevant in your case since your old pivot shoe is 3/8" thick and 1" wide. There are no coil balance-compatible pivot shoes that small. 1/2" is about as thin as these get and that is still way to big to fit in your jamb track.

I hate to say it but I don't think it will be possible in your case. You will probably have to stick with the hardware you're using now. If you were interested in a list of compatible products in our inventory, just let me know and I would be happy to get that together for you.

A handy person from New Mexico says:
I appreciate the response and looks like I will have to go with the older style hardware like you suggest. I have a total of 9 old style windows and I might as well replace all the hardware: pivot bar, spiral balancers, and pivot shoes. If possible, can you send me the part numbers which will replace the existing ones? For the spiral balancers, there isn't a colored tip.

-Experienced handyman.

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Tom from SWISCO responded:

You got it! For the spiral balance setup, I recommend looking at our Series 900 spiral balance, 15-212 pivot shoe, and 26-040 pivot bar. I'm very confident about the balance and pivot bar, but the shoe is just a little different compared to your original. The only significant difference is that ours is 15/16" compared to your 1", so see what you think.

For the coil balance setup, see our 15-199 pivot shoe, Series 160 spring, 15-150D double support, and 26-040 pivot bar. 

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