ocscully
Member
First let me say that the following information applies only to the New Clutch supplied by Grubee and bicycle-engines.com for the Honda 4G drives and and as a replacement clutch for the Type II & III Gearboxs. This new clutch has alot to like in the way of improvements over the older design clutch, but it has one major flaw, as supplied from Grubee/bicycle-engines its stall speed/engagement rpm is dangeriously low. Far worse that the old style clutch. At first I tried drilling lightening holes but the change was insignificant. (first photo below) Then I started looking into changing the springs. The clutch uses three small compression springs to control/set the stall speed/engagement. (second photo below) To start with I needed to determine the dimensions and spring rate of the original springs so I could find and purchase springs that would fit and had a higher spring rate. The original springs are .520in. OD X .780in. Long. and I determined the spring rate to be 40lbs/in. I found a set of 47lbs/in. springs at a local industrial hardware store and tried them out in the lightened clutch. The result was better (the motor no longer died when I came to a stop) but still the clutch was to grabby at idle and still took off like a jack rabbit when first started. The local store didn't have any springs that would fit stronger than the 47lbs ones so I tracked down a local spring mfg. (LA) Century Spring Corp. They had several springs in their catalog that seemed like they might fit my needs. So I made a trip to LA to buy more Springs. I figured I needed and additional 10lbs-15lbs of spring rate. I ended up buying a set of 57lbs/in. and a set of 60lbs/in. springs. The 57lbs springs work well in the lightened clutch and the 60lbs work well in the clutch without the lightening holes. The Last two photos below show the various springs from top and side views. From left to right they are 40lbs/in. stock springs, 47lbs/in., 57lbs/in., and 60lbs/in.
ocscully
ocscully
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