Since Nyroc's site is gone and I've tried about a dozen different springs I thought I'd throw a chart together.
Thanks to Rick Ritter of Ritter Cycle Racing for some of the spring measurements.

Primary Spring Chart

 

awesome meadows and chart. also thank you

 

Cool!

 

The newly revised Aaen clutch tuning book also has a spring chart or two. Aaenperformance.com

 

Good job with the chart,

gives a good reference when people talk colors on these forums.

 

Thanks Kevin, that's alot of usefull info[img]i/expressions/face-icon-small-cool.gif[/img]

 

I tested several manufacturers primary springs on a spring scale today . I had a total of 17 springs ,they were all brand new .

My readings may vary from the manufacturers , but the whole point of this is to show springs relations to each other . My scale is repeatable to a variance of about 3 pounds , I have checked this by retesting the same spring several times . I do find springs (of the same color code) can vary often by more than that.

I always thought an EPI red and a polaris white were identical . The two springs appear to be the same , and maybe they are , I may have gotten a wimpy white spring . I tested several EPI reds and they all tested close together , the polaris white is just a little lower .

My scale is not a high quality certified scale , I am using a common bathroom scale in my press with a tool I made to hold the spring and allow me to compress it while I read the calibrations on the side . The poundage may be off but the tests are repeatable with in the variances I have previously mentioned .

I put this list together so at least we can all see how these things measure on the same day , on the same tester . I hope this helps you all in tuning your clutches .

Color 2.5" 2.25" 2.0" 1.75" 1.5" 1.25"
Polaris blue/green 5 24 46 66 90 117
Dalton plain/white 13 30 47 65 86 105
Dalton blue 3 26 52 81 111 145
Polaris white 34 52 72 93 116 140
EPI red 37 57 76 97 118 140
Dalton black/white 39 57 77 100 122 144
Polaris green 43 61 78 96 116 140
Dalton black/orange53 71 88 106 125 150
Aaen green 54 73 91 112 130 154
EPI orange 79 91 102 118 130 145
HPD plain 32 65 102 145 185 235
Polaris orange 72 92 115 141 166 196
HPD red/yellow 118 139 161 187 214 243
HPD red 135 162 183 206 229 253
Dalton Black/red/white147 177 204 234 267 298
HPD violet 153 179 206 229 252 281
EPI maroon 199 228 245 277 303 330

 

Here is a question I have had on these type of clutches from the get go. Why are they not rated in rpms when coupled with weights? Comet has a chart for some of their torque converters that tells you with the blue springs and whatever weight, engagement is lets say 1800rpm and full shift is lets say 4000rpm. This way you can pick when it engages and is at full shift by what the rpm profile of the motor is. Does the Aaen book do this?

 

Thanks for the info, guys. Information such as this is invaluable to us on the forums.