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New Centax Flyweights (903199) (13/05/2006)
- By:
- Glenn M. Cauley
- Linked to:
- Centax flyweights PTFE machined for .21
Serpent recently released their new 903199 machined flyweights for .21 engines (Centax-2 clutches). This particular set incorporates several new advances and features.
This article describes some of the features of these new flyweights, and what makes them different.
Product Description
http://www.mytsn.com/products/desc.asp?prid=4262
Presenting these newly-machined flyweights for use in your Centax clutch. Different from the original versions, these flyweights have been machined from a solid piece of material, where previously they had been injection moulded. This difference in manufacturing, along with the use of carbon & graphite, results in a denser material that makes the weights harder and therefore longer lasting and able to perform more consistently.
One other thing that makes these flyweights better is the way they pivot, so instead of being a trailing flyweight, these are pushed out at the front (leading flyweight), making for a slightly more aggressive clutch. Each of the 3 flyweights in the set also features a second hole into which you can thread in a setscrew; this further increases the aggression of the clutch as it engages.
Machined vs. Molded
In a molded flyweight the density may not be consistent, rather tending to be harder/denser along the edges and corners. The 903199 flyweights, being machined from a solid piece of material, have uniform hardness/density throughout.
The pivot holes are machined to initially fit slightly snugly on the flywheel pins without undue slop. This is better than having a slip-on or loose fit right away; after the first use the pivot holes will quickly be worn to the proper size.
Trailing vs. Leading
The big difference between the new 903199 flyweights and the original flyweights, is that the new flyweights are "leading" flyweights.
The original flyweights are “trailing” flyweights. That is, the end of the flyweight that moves outward TRAILS the pivot pin as the clutch spins.
The new 903199 flyweights are “leading” flyweights. That is, the end of the flyweight that moves outwards LEADS the pivot pin as the clutch spins.
Leading flyweights react and ‘fly out’ more quickly and aggressively at the same RPM compared to trailing flyweights. So by simply reversing the pivot point on the flyweight, Serpent has given us a slightly more aggressive clutch.
Tunability
Each flyweight has a drilled hole at the end opposite to the pivot hole. This little racers’ trick was adopted by Serpent and factored into the new 903199 flyweights right from the factory.
Lighter (unweighted) flyweights engage later, but have a softer engagement (since more engine RPM is needed to get the same force as with heavy flyweights). By adding a weight (threaded setscrew) into the hole at the far end of the flyweight, the flyweight becomes heavier; it engages earlier and with more force.
(With heavier flyweights, you need more pre-tension force on the spring; this is one of the main reasons why it engages harder.)
Another nice feature is that the top of the hole is chamfered, so that the top of the hole does not “budge up” when you thread in a setscrew.
Unidirectional
Even though it looks like you can install the new 903199 flyweights in several different orientations, the only recommended orientation is as a leading pivoting flyweight.
Wrap-up
I have yet to test these new flyweights in racing applications, but I expect the following:
* unweighted: later engagement, with less force
* weighted: earlier engagement, with more force
I will report back with my findings once I have had a chance to try them out.
Many thanks go to Michael Salven and Rene Cornella for their great advice and knowledge.
Stay tuned for more great things from Serpent!
New 903199 flyweights
Trailing vs. leading
Tuning using weight
Unidirectional flyweights
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