spring rate calculator

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Has anyone looked into this? I'm trying to figure out the best way of lowering my car, with 145# miata springs, and cutting coils crossed my mind, but I don't want to blindly start chopping off things I can't put back.

I found this online calculator, but I don't know wether I should believe anything it says or not, has anyone else tried it? I'm going to measure some springs I have laying around tomorrow and see what it says, but if you want to give it a shot let me know what you think of it..

http://www.proshocks.com/calcs/coilsprate.htm

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messing around, here's some results from that calculator..

2002 MT Kia Rio front springs

.445" wire diameter
4" OD
7 active coils
175# spring rate


99-00 Racing Beat Mazda Miata Lowering Springs (pn54018)
.460" Wire diameter
4.25" OD
6 active coils
193# Spring Rate

1994 Aspire Rear Spring
.375 wire diameter
3.9 OD
7 active coils
90# springs

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Just did another spring, a front aspire spring. This calculator is touchy, the measurements have to be exact for the wire diameter.

2002 MT Kia Rio front springs
.445" wire diameter
4" OD
7 active coils
175# spring rate


99-00 Racing Beat Mazda Miata Lowering Springs (pn54018 )
.460" Wire diameter
4.25" OD
6 active coils
193# Spring Rate

1994 MTX Aspire Rear Spring
.375 wire diameter
3.9 OD
7 active coils
90# springs

1997 ATX Aspire Front Spring
.406 Wire Diameter
4.125 OD
7 active coils
106# springs

[FB71]

calculator looks accurate. Aspire springs are 110# front 90# rear, IIRC.

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Adding a new spring to the list. I am hoping one day one of you peoples will attempt this too! This is a front festiva spring..



2002 MT Kia Rio front springs
.445" wire diameter
4" OD
7 active coils
175# spring rate


99-00 Racing Beat Mazda Miata Lowering Springs (pn54018 )
.460" Wire diameter
4.25" OD
6 active coils
193# Spring Rate

1994 MTX Aspire Rear Spring
.375 wire diameter
3.9 OD
7 active coils
90# springs

1997 ATX Aspire Front Spring
.406 Wire Diameter
4.125 OD
7 active coils
106# springs

1993 MTX Ford Festiva Spring
.402" Wire Diameter
4.25" OD
6 active coils
107# Springs




I don't know why the measurements came up so different from aspire to festiva, but they did, and it still came out close enough to assume they're pretty much the same spring. I also redid measurements on a 2001 Rio spring, it's basically the same as the 02 spring I was doing, but there's really 7 1/2 active coils so the spring rate is in the vicinity of 160-175# .....looking for other measurements from other members!

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I haven't measured a rear festy spring yet I guess? This is looking good tho, I bet the rear 5 door avella spring will come in around 130lbs and would be perfect for the rear end of a Festiva. The 150lb. Miata springs are definitely too stiff for a daily driver.

the spring on the right is the rear spring for the 94 5 door pride. the one on the left is a stock 3 door festiva spring. all dimensions are the same except that the wire diameter for the 5 door spring is 1/2 mm larger in diameter (10mm). when plugged into a simple online spring rate calculator the 5 door spring is almost 25% higher force for each inch of compression. (97 lbs./in. vs 121 lbs./in.). part# KK153 28 011. $25.45. still available as of 10/2013.