[C38] Transmission

Mon May 14 18:24:46 EDT 2012

Steve: Right on. Prop always bangs in when put in gear.

Dick
----- Original Message ----- 
From: "Steve Smolinske" <SSmolinske at rainierrubber.com>
To: <tdtron at earthlink.net>; "Catalina 38 Listserve"
<listserve at catalina38.org>
Sent: Monday, May 14, 2012 6:16 PM
Subject: Re: [C38] Transmission

> Third source of the clunk can be a feathering prop opening when the boat
> is put into gear.
>
>
> -----Original Message-----
> From: listserve-bounces at catalina38.org
> [mailto:listserve-bounces at catalina38.org] On Behalf Of
> tdtron at earthlink.net
> Sent: Monday, May 14, 2012 12:47 PM
> To: Catalina 38 forum
> Subject: Re: [C38] Transmission
>
> Hello Larry,
>
> I'm no expert on transmissions but I may have some answers for you
> anyway.
>
> The "clunk" you refer to is usually caused by two things. The Hurth
> transmission uses a spiral input shaft with matching driven plate that
> allows the torque of the shaft to engage the drive plates like a nut on
> a bolt.  The rotation of the input shaft actually tightens up the drive
> plates when you shift gears.  This is how our transmissions shift so
> easily when a manual transmission car or truck will have a pressure
> plate and throwout bearing and clutch pedal which we don't have.  The
> reasons cars and trucks don't use spiral input shafts like our boats do
> is because you can't "slip the clutch" with our systems, our systems are
> either totally engaged or totally disengaged so they won't work on
> street vehicles.
>
> Another source of a clunk sound is the slack in the gears which
> increases from wear.  All of these components with slack combine to
> cause the clunk but with a good flex plate, this clunk sound should not
> be a problem.
>
> As regards to the "sweet spot" your technician was telling you about, it
> is the truth.  Every engine has resonant vibrations that are more
> pronounced at certain RPMs and less at others.  Having only three
> cylinders compounds the problem as does being diesel.  Idling is much
> more detrimental than motoring but low speed in either case increases
> gear chatter and wear.
> Sometimes speeding up or slowing down  will reduce but not eliminate the
> resonant vibrations.
>
> I replaced my Universal flywheel flex plate with the PYI unit and my
> engine was noticeably quieter and smoother at all speeds.  Another
> extremely important benefit of the PYI flex plate is that the engine
> will continue to drive the transmission even if the flex plate fails,
> unlike the steel springs Universal unit.  The PYI shaft coupler also
> offers this same benefit of positive engagement even with cushion
> failure.  I replace both my flex plate and shaft coupler and it was like
> I had re-powered to a smoother engine with more cylinders.  The results
> were nothing short of incredible.
>
> Universal flex plates have a history of fatigue failure of the cushion
> springs which can break like glass after they fatigue leaving your
> engine without thrust.  All of those pieces of the steel springs have no
> where to go but around and around inside the bell housing causing havoc
> to your aluminum bell housing, starter pinion, flywheel and ring gear.
>
> PYI claims their synthetic material isn't prone to fatigue but even if
> the cushion material ever did fail, you would still have thrust in both
> forward and reverse because the metal dogs are captive with the
> synthetic material acting as a cushion between the steel dogs but if the
> cushion material somehow magically disappeared, the dogs would still
> propel the boat.
>
> One problem I did have with the PYI flex plate was that when I tried to
> install it I couldn't get all of the flywheel bolts started without
> slightly filing the plate holes with a small rat tail file to help get
> the bolts started.  I don't know if the bolt pattern irregularity was
> from the flywheel,  the PYI flex plate, or both but the amount of
> material I had to remove was only a thousandths or two of an inch so
> there was no balance or concentric alignment problem.
>
> I know money doesn't grow on trees and PYI flex plates and shaft
> couplers aren't cheap but the PYI upgrades were some of the best
> improvements I ever made to my boat.  With the upgrades we could idle
> back to our slip with almost no vibration or noise  and sometimes I
> thought the engine had died because it had become so quiet and smooth.
>
> Tom Troncalli
>
>
>
>
> > [Original Message]
> > From: Larry Malmberg <Larrypi at roadrunner.com>
> > To: Catalina 38 Listserve <listserve at catalina38.org>
> > Date: 5/14/2012 12:28:52 PM
> > Subject: [C38] Transmission
> >
> > A very special Thank You to Jay Sorensen for coming through with a
> > used transmission.  Picked it up Sunday and am taking it to the shop
> > today.  A quick question though regarding transmissions.  Does every
> > one with a
> Hurth
> > transmission get that "clunk" when you put it into gear?  Also, the
> > transmission guy tells me that there is a "sweet spot" for engine rpm
> > when idling, this so called sweet spot causes less wear on the damper
> > and
> gears,
> > what's your experience with this?  My idle is set at about 900 rpm
> > which apparently is a bit too low?  I'm told the damper was worn from
> > "engine chatter" as well as a few of the gears, the engine chatter is
> > apparently from the idle being set too low.
> >
> >
> >
> >
> >
> > Best regards,
> >
> > Larry Malmberg
> >
> > 7231 Boulder Avenue Suite 507
> > Highland, CA 92346 PI 15211
> > Telephone  909-208-1847
> > FAX           909-991-7568
> >
> > E Mail  Larrypi at roadrunner.com
> >
> >
> >
> > ?
> > Life is short, Break the rules, Forgive quickly, Kiss slowly, Love
> > truly, Laugh uncontrollably, And never regret anything that made you
> smile..
> > ?
> > "The American Indians found out what happens when? you don't control
> > immigration"
> >
> >
> > "Life is not a journey to the grave with the intention of arriving
> > safely
> in
> > a pretty and well preserved body, but rather to skid in broadside,
> > thoroughly used up, totally worn out, and loudly proclaiming; WOW-- 
> > What a Ride!"
> >
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