Measuring Contra Spring Tension

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Wheelman-111
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Measuring Contra Spring Tension

Post by Wheelman-111 »

Greetings:

Contra springs tend to lose their Spunk with time. What I needed to do today was determine how much spunk my blue Malossi had left.
F7MalossiTai+2K.jpg
F7MalossiTai+2K.jpg (163.06 KiB) Viewed 9142 times
The Venerable Baka-san correctly pointed out that the Wheelman method of assessing spring tension (Just squeezing the pulleys together using formidable Wheel-Thumbs...) was not accurate. So I set about determining a slightly more Scientific method. Enter the Counselor bathroom scale, and a pair of half-inch sockets. The height of the sockets is pretty close to the compressed dimension of the spring in the rear pulley assembly.
F7SpringGauge.jpg
F7SpringGauge.jpg (132.07 KiB) Viewed 9141 times
I just leaned on the bathroom scale until it just kissed the sockets, noting the numbers on the scale.

The result? The red Tai spring read 135, confirming its stiffness. The result was repeatable to within a couple of pounds over several trials for all 3 springs. The yellow read 110 pounds at the same compression distance. And my now-retired, short Malossi "+2000"? Only 90 pounds. This would explain why the revs on early Flash 7 were still so low despite only 27 grams of variator load. If I could've found my stock Honda spring, I would have tested it just for comparison. Since this is now on the record, it'll be interesting to re-test the same yellow Tai spring using the same method the next time I dismantle the rear pulleys.
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
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Wheelman-111
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Re: Measuring Contra Spring Tension

Post by Wheelman-111 »

Greetings:

Both the Elite and my new Reflex manuals specify a service limit for an uncompressed spring - nothing about measuring the compressed tension in Honda-land. Anyway, we're dealing with the Aftermarket. Springs from Asia and Italy will obviously have different specs to produce the performance characteristics we seek.
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
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