EthansDad
01-05-2012, 08:10 AM
Last year, I did some testing for a number of torque springs to capture the force they produce to make it easier for folks to choose a spring. This year, folks asked, "what about fade" or how do I know which spring will last (keep its force) under race conditions?".
I came up with a test to introduce fade into springs from heating them, and tested a whole lot of springs before and after heating with the results listed below.
A big thanks to Rich @ Hetrick, Justin @ MAX RPM and Marc at Hot Quads for providing some springs to torture (er, test).
full results found here (easier to read):
Spring Testing Results (https://docs.google.com/spreadsheet/ccc?key=0Av3_8nTLRJqTdGpMUWFxSVZIMjBCREEtYzRaN3V1Y 3c)
some background on the data:
-each spring has an initial force (at rest, bike idling), a final force (fully shifted out) and a rate which is basically how much the force changed over 1 inch of compression. the chart lists all these numbers (before and after fade) - you can use them to pick a spring that is close to what you have now, or a bit more/less to test with tuning
-rate (or change in force in lbs over an inch) is really how quick/slow the bike will shift out and in my book, the #1 factor for performance differences when testing springs. I can clutch the bike different (heavier/lighter rollers) to deal with a bigger initial force, but once its overcome, its up to the rate to how its going to shift out.
-initial force -this is the force in lbs that the spring produces when its compressed to 1.75 inches, which is exactly what it is when in the CVT's rear pulley BEFORE any shifting happens. As I've said before, I really don't like the term 1000, 1500, 2000 for springs. from now on, I will refer to them by their initial force. you can see from the data a 1000rpm spring = (about) 60lbs, a 1500 spring = 80bs, and a 2000 spring = about 90-100 lbs.
-how the testing was done - same as last year, can search on forum and see full "how its done" info. for fade, I won't go into boring details, unless you ask, but I promise you, I did a lot of pre-testing/research on how to do it, the test was successful in introducing heat and compression related "fade" (similar to race conditions), and all springs got exactly the same treatment. what I can't promise is your springs will only fade X% in a race, but the fade I got should be a good indicator as to how well a spring holds up, which is what I was after.
how to use the data:
-can start by looking on the big graphic/chart at the bottom. look at a spring you know/use, then look for other springs with similar "heights" on the chart - they will be close to what you have now - just a bit firmer/softer. taller = firmer, shorter = softer.
-can next look at the numbers - I'd start by looking at rate, then initial force to match up, or figure out which spring is just a bit more/less than what I currently run and put that on my list to try in the bike.
-keep in mind, just a few lbs - like 3-5lbs can make a very BIG performance difference. that is basically the difference between holeshots and bog city. you'll notice on the softer springs, losing just 2lbs is a big deal, while on the firmer springs, they may loose 8-9 lbs. that is why I put the loss/fade in terms of percent % so its easier to see how they hold up.
-an interesting note, you can see some springs loose force differently. some loose more initial force, some loose more final force. they all shrink, some a little, some quite a bit.
all comments that help improve the testing/data welcome. I didn't have to make this public you know :-)
Big Spring Chart:
https://lh5.googleusercontent.com/-jaCHgCOD2u8/TwW7V8L0EfI/AAAAAAAAANI/m8p8CSmOVyE/s800/spring%252520chart.JPG
Spring Measurements:
https://lh3.googleusercontent.com/-BQoGRCNdTAk/TwW7dNztNsI/AAAAAAAAANU/-fzHqD3zsZk/s800/spring%252520numbers.JPG
I came up with a test to introduce fade into springs from heating them, and tested a whole lot of springs before and after heating with the results listed below.
A big thanks to Rich @ Hetrick, Justin @ MAX RPM and Marc at Hot Quads for providing some springs to torture (er, test).
full results found here (easier to read):
Spring Testing Results (https://docs.google.com/spreadsheet/ccc?key=0Av3_8nTLRJqTdGpMUWFxSVZIMjBCREEtYzRaN3V1Y 3c)
some background on the data:
-each spring has an initial force (at rest, bike idling), a final force (fully shifted out) and a rate which is basically how much the force changed over 1 inch of compression. the chart lists all these numbers (before and after fade) - you can use them to pick a spring that is close to what you have now, or a bit more/less to test with tuning
-rate (or change in force in lbs over an inch) is really how quick/slow the bike will shift out and in my book, the #1 factor for performance differences when testing springs. I can clutch the bike different (heavier/lighter rollers) to deal with a bigger initial force, but once its overcome, its up to the rate to how its going to shift out.
-initial force -this is the force in lbs that the spring produces when its compressed to 1.75 inches, which is exactly what it is when in the CVT's rear pulley BEFORE any shifting happens. As I've said before, I really don't like the term 1000, 1500, 2000 for springs. from now on, I will refer to them by their initial force. you can see from the data a 1000rpm spring = (about) 60lbs, a 1500 spring = 80bs, and a 2000 spring = about 90-100 lbs.
-how the testing was done - same as last year, can search on forum and see full "how its done" info. for fade, I won't go into boring details, unless you ask, but I promise you, I did a lot of pre-testing/research on how to do it, the test was successful in introducing heat and compression related "fade" (similar to race conditions), and all springs got exactly the same treatment. what I can't promise is your springs will only fade X% in a race, but the fade I got should be a good indicator as to how well a spring holds up, which is what I was after.
how to use the data:
-can start by looking on the big graphic/chart at the bottom. look at a spring you know/use, then look for other springs with similar "heights" on the chart - they will be close to what you have now - just a bit firmer/softer. taller = firmer, shorter = softer.
-can next look at the numbers - I'd start by looking at rate, then initial force to match up, or figure out which spring is just a bit more/less than what I currently run and put that on my list to try in the bike.
-keep in mind, just a few lbs - like 3-5lbs can make a very BIG performance difference. that is basically the difference between holeshots and bog city. you'll notice on the softer springs, losing just 2lbs is a big deal, while on the firmer springs, they may loose 8-9 lbs. that is why I put the loss/fade in terms of percent % so its easier to see how they hold up.
-an interesting note, you can see some springs loose force differently. some loose more initial force, some loose more final force. they all shrink, some a little, some quite a bit.
all comments that help improve the testing/data welcome. I didn't have to make this public you know :-)
Big Spring Chart:
https://lh5.googleusercontent.com/-jaCHgCOD2u8/TwW7V8L0EfI/AAAAAAAAANI/m8p8CSmOVyE/s800/spring%252520chart.JPG
Spring Measurements:
https://lh3.googleusercontent.com/-BQoGRCNdTAk/TwW7dNztNsI/AAAAAAAAANU/-fzHqD3zsZk/s800/spring%252520numbers.JPG