Thanks, Ron
I quickly wrote Mike and he wrote back. I think his response worth showing here.
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Generally speaking, the lighter the weights, the more RPMs required to overcome the spring tension in the main spring behind your clutch.
The combination of the springs and weights work together to regulate how quickly the RPMs spool up, and how fast it transitions from the low gear ratio to high (closed to fully open). Changing to lighter weights vs stock tunes the engine to have a faster rev up of RPMs at lower speeds, which gets you into the motor’s high torque range (for more power) at a lower speed than before. Lighter weights can raise the top speed RPMs outside of the engine’s optimal torque range and result in less overall engine power at higher speeds.
Heavier than stock weights will have a more subdued low end, but more responsive mid/high speed range. This is because the lower RPMs required to overcome the clutch main spring tension keep the engine in the high torque RPM band at higher velocities. However, they can be more sluggish during initial acceleration and hill climbing than stock (or lighter) weights.
In both examples, the farther up or down from the stock weights, the more exacerbated the results. Dr Pulley recommends going 10-15% lighter for most applications (most people are looking for a more spry low end for in-town driving and general peppiness), In your case, I would recommend getting the 32g weights. They should perform similar to (if not slightly better) on your low end power, and improve that midrange. You’ll likely have slightly lower overall RPMs, which would help with the fuel economy as well. 30g would also work, and give a bit more to the low speed power, too.
You can find the weights on our site here:
https://www.buggypartsnw.com/index.php/dr-pulley-slider-weight-30x20-for-bmw-c600-c650gt.html
Regards,
Michael Baird
Owner - Buggy Parts NW
503-860-7250
[email protected]
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Stock roller weights are 33g if I have it right.
I guess that the Dr. Pulley slider weights engage earlier than roller weights of the same mass and lock up earlier.
I found this to be good info.
Thanks Ron