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Solutions to the Raptor Clutch
Issues
Of all the primary components on the extremely popular ThunderTigre
Raptor, only the stock Muffler causes more problems than the
somewhat poorly designed clutch. Especially under hard use the
stock clucthes fail far too often with far too little use. HHI/Quick
has finally got the new hi-carbon clutches shipped to us and
we'll be offering these at the best prices to help solve the
problem. But the REAL solution is even cheaper. (Our thanks to
Michael Prewitt's web posts for convincing us that we were on
the right track here. His page at www2.starnet.com/mprewitt/clutchrepair.html)
Look at the difference between the Raptor flywheel and the
Kalt Baron flywheel below. (The Kalt is a similar but much less
failure prone system)
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| As you can see, the Kalt flywheel
is releived so that the shoes (the parts of the one-pc clutch
that throws out under centrifugal force) do NOT rub or chatter
against the flywheel. The Raptor flywheel has no such releif. |
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| Again, note in the above photos the way the Raptor
shoes are fitted against the flywheel vs. the Kalt design. |
| At right is the flywheel from
our store Raptor (Ellen's) after only 6 tanks of fuel! Note how
much rubbing has already obviously taken place. We have absolutely
no doubt that this much friction and side load are the biggest
reasons for premature clutch failures. (As you can see below,
the actual Ace clutches are not that different from the Kalts.
But the elongated holes on the Kalt spread the stress and are
probably a better design.) |
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| One solution - as done by Mike and others - is
to file or machine the Ace flywheel to have shoe clearance as
per the Kalt. But as of today there's another solution that is
almost as cheap and will solve the problem. It's a simple stainless
steel shim than fits between the clutch and the flywheel to raise
the clutch about 30 thou above the flywheel. In effect this makes
the flywheel identical to the Kalt unit. In the photo at below
right you see the installed unit - now the shoes can not rub
against the flywheel. It took us about 10 minutes to install
(including removing the the engine from the heli and taking several
of these photos. ) |
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