On Sat, 14 Feb 2004 21:12:53 GMT, Jim Kelly wrote:

Yes, the transmission is bolted to a bell housing on the engine so that it
sits at the same angle as the engine. The prop shaft also assumes this angle
since it is direct coupled to the transmission. This is what is referred to
as a "straight inboard". On many newer boats of this size, the engine is
mounted backward with the front of the engine close to the transom. A V-drive
is then used to connect the engine to the prop shaft. On this type of
installation, the engine is not angled as in the straight application since
the prop shaft angle is accommodated by the angled "V" drive design.

Hah!! See, learn something new every day.

Thanks for the info Jim.

Later,

Tom
S. Woodstock, CT
----------

"Fisherman are born honest, but they get
over it." - Ed Zern

Anytime, Tom.
One other source of a clunk would be the dampener. This is a metal plate with a
splined hub in the center. The plate bolts to the flywheel and the transmission
input shaft slides into the hub. The dampener contains springs which absorb
torsional vibration. If the springs are damaged or if the bolts are loose, you may
get a clunk.

Short Wave Sportfishing wrote:

On Sat, 14 Feb 2004 21:12:53 GMT, Jim Kelly wrote:

Yes, the transmission is bolted to a bell housing on the engine so that it
sits at the same angle as the engine. The prop shaft also assumes this angle
since it is direct coupled to the transmission. This is what is referred to
as a "straight inboard". On many newer boats of this size, the engine is
mounted backward with the front of the engine close to the transom. A V-drive
is then used to connect the engine to the prop shaft. On this type of
installation, the engine is not angled as in the straight application since
the prop shaft angle is accommodated by the angled "V" drive design.

Hah!! See, learn something new every day.

Thanks for the info Jim.

Later,

Tom
S. Woodstock, CT
----------

"Fisherman are born honest, but they get
over it." - Ed Zern

Thanks, WaIIy, I like your answer the best of all, so far! It's certainly
the easiest!

====

Charles T. Low
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www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"WaIIy" wrote in message
...

I have two 1989 BG Velvet Drives in the "V" configuration. They "clunk"
although it is a very light clunk, much as you describe.
No problems so far.

Jim,

Your several message in this thread so far are much appreciated. I'm not
exactly visualizing everything just yet, but then I have no idea what these
things look like inside. (How do you?) Spool valves, pumps, relief valves,
heat exchangers, front adapter, clutches and reverse clutches, hydraulic
circuits - but I do find it all very intriguing!

Testing pressure - as in screw a manometer of some type into the 3/8 plug
hole? A manometer of _what_ type? Prob'y easier to ask mechanic to do it for
me.

When I had a new shaft made a few seasons back, it was built twice (at a
machine shop) because mechanic wasn't happy with tolerances first time.
Finally got it to 4/1000, I think, and then 7/1000 installed but this was
out of the water. Mechanic said that was a little over tolerance, but that
it all slid together so effortlessly that he considered that a very good
sign, and opined that fiddling with it further would probably not be
advantageous. Sort of "the enemy of 'good' is 'perfect'" philosophy. Anyway,
it seems fine - there was minimal perceptible vibration with the original
shaft, same now. I've had my hand on the stuffing box while someone else
piloted the boat, up on plane (16 knots - whee!!!), and it's as smooth as
silk (if that means anything).

Thanks again.

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Jim Kelly" wrote in message
...
...
When you move the selector to forward or reverse, the spool valve directs
the
fluid to the proper clutch. There should be at least 120 PSI present at
the
spool valve in all selector positions. The internal pump is actually
capable of
much higher pressure but it is regulated by a relief valve built into the
end of
the spool valve. The relief valve directs fluid to the heat exchanger.
There
are test ports for checking the pressure. Remove the 3/8 plug on the top
of the
case next to the port leading out to the heat exchanger. Warm and idling
you
should read at least 120 PSI in all selector positions.

To check reverse pressure, there is a smaller plug either next to the 3/8
plug
or on the front adapter on the top of the case depending on the vintage
(some
models have both plugs in which case you can use either). Warm and idling
in
reverse, you should again read a minimum of 120 PSI. This verifies that
the
reverse clutches in the front of the transmission are receiving full apply
pressure.

There is no separate test port for forward apply pressure since the
hydraulic
circuit for forward is through the center of the shafts and not the case
as it
is in reverse. If you have the specified pressure at the 3/8 test port
while in
forward, it is pretty safe to assume that the forward clutches are
receiving
full apply pressure due to the design of the circuit.

Tom,

As others have already explained, this is a straight-shaft inboard setup,
pretty standard, I think, and it is not horizontal. You can see a photo at
www.ctlow.ca/Trojan26/Rudder2001.JPG, from my Ksenia page (address below).
No U-joints, and no "shock absorbers" - the shock is absorbed by the water!

I think it would be more efficient if it were horizontal, and on some
displacement hulls (a few) it is, but on a planing hull I think it just has
to angle down. Building a casing below the hull to contain a CV joint which
would then allow the shaft to run horizontally would not be
"hydrodynamically" efficient either, I don't think - might as well have an
I/O - pros and cons! I do depend heavily on trim tabs to maintain attitude
when on plane. ("Slow" plane, which is all this boat does!)

The cutlass bearing referred to elsewhere is in the housing at the bottom of
the strut in the photo referred to above. The prop shaft is stabilized by it
and by the passage through the hull and then at the transmission. Apparently
very long shafts require extra supports, but for most of us that's a typical
arrangement. If the shaft were misaligned with the tranny, or just not
straight enough, then that would cause vibration and premature wear of all
sorts of things (I guess), but not the behaviour I'm describing. At least,
not directly.

I have, by the way, checked the prop, by hand, but it seems absolutely
solid.

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Short Wave Sportfishing" wrote in message
...

It just occured to me - does the drive train have U-joints? If so,
then that's the most likely cluprit.

Good luck.

Later,

Tom
S. Woodstock, CT

On Sun, 15 Feb 2004 16:53:37 -0500, "Charles T. Low"
wrote:

Tom,

As others have already explained, this is a straight-shaft inboard setup,
pretty standard, I think, and it is not horizontal. You can see a photo at
www.ctlow.ca/Trojan26/Rudder2001.JPG, from my Ksenia page (address below).
No U-joints, and no "shock absorbers" - the shock is absorbed by the water!

Twelve boats in my life, all outboards. I'm seriously thinking about
converting the '68 Chris*Craft Corsair to an outboard - I did rebuild
a "stringer" type drive and I have two Buick V-6s, one of which has
been rebuilt, but I'm not at all comfortable with that setup.

All of which has nothing to do with your drive system. :)

Well, as long as you are happy with it, that's all that's necessary.

Good luck.

Later,

Tom
S. Woodstock, CT
----------

"Fisherman are born honest, but they get
over it." - Ed Zern

Charles,
Velvet Drives are relatively simple transmissions. I have rebuilt several.
The parts are readily available and comparatively inexpensive. The only special
tool required is a snap ring pliers for Eaton type rings. These rings have no
holes in them so standard snap ring pliers won't work. The coupling nut will
have to be removed and installed with an impact wrench but, if you do not have
one, you can get this done at any automotive repair shop. A good source for
rebuild kits and parts is Transmission Marine in Ft. Lauderdale. Anyone with
average mechanical skills should be capable of rebuilding these units.

A simple dial type pressure gauge can be used for checking the pressures. It
should have a range of at least 160 psi. You can buy one from industrial supply
houses like Grangier for less than $10.

"Charles T. Low" wrote:

Jim,

Your several message in this thread so far are much appreciated. I'm not
exactly visualizing everything just yet, but then I have no idea what these
things look like inside. (How do you?) Spool valves, pumps, relief valves,
heat exchangers, front adapter, clutches and reverse clutches, hydraulic
circuits - but I do find it all very intriguing!

Testing pressure - as in screw a manometer of some type into the 3/8 plug
hole? A manometer of _what_ type? Prob'y easier to ask mechanic to do it for
me.

When I had a new shaft made a few seasons back, it was built twice (at a
machine shop) because mechanic wasn't happy with tolerances first time.
Finally got it to 4/1000, I think, and then 7/1000 installed but this was
out of the water. Mechanic said that was a little over tolerance, but that
it all slid together so effortlessly that he considered that a very good
sign, and opined that fiddling with it further would probably not be
advantageous. Sort of "the enemy of 'good' is 'perfect'" philosophy. Anyway,
it seems fine - there was minimal perceptible vibration with the original
shaft, same now. I've had my hand on the stuffing box while someone else
piloted the boat, up on plane (16 knots - whee!!!), and it's as smooth as
silk (if that means anything).

Thanks again.

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

"Jim Kelly" wrote in message
...
...
When you move the selector to forward or reverse, the spool valve directs
the
fluid to the proper clutch. There should be at least 120 PSI present at
the
spool valve in all selector positions. The internal pump is actually
capable of
much higher pressure but it is regulated by a relief valve built into the
end of
the spool valve. The relief valve directs fluid to the heat exchanger.
There
are test ports for checking the pressure. Remove the 3/8 plug on the top
of the
case next to the port leading out to the heat exchanger. Warm and idling
you
should read at least 120 PSI in all selector positions.

To check reverse pressure, there is a smaller plug either next to the 3/8
plug
or on the front adapter on the top of the case depending on the vintage
(some
models have both plugs in which case you can use either). Warm and idling
in
reverse, you should again read a minimum of 120 PSI. This verifies that
the
reverse clutches in the front of the transmission are receiving full apply
pressure.

There is no separate test port for forward apply pressure since the
hydraulic
circuit for forward is through the center of the shafts and not the case
as it
is in reverse. If you have the specified pressure at the 3/8 test port
while in
forward, it is pretty safe to assume that the forward clutches are
receiving
full apply pressure due to the design of the circuit.

"Charles T. Low" wrote in message ...
I've had my 1978 Trojan 26 for three seasons now, and can't for the life of
me decide for sure whether the transmission has always done this or not. My
mechanic thinks it's OK. The AT lubricant is full and looks crystal clear to
the naked eye, and I do change it (rarely). It's a Borg-Warner Velvet Drive,
original with the boat, to my knowledge.

When put into gear, there is a slight pause, a fraction of a second only,
but easily visible that the prop tranny/shaft does not start turning
immediately - then it catches and away it goes. (Idling just above 600 rpm
indicated.) It does so with a very soft audible clunk, and I seem to
remember it being noiseless when "new" (to me).

I have shifted it into gear at above idle speed, very infrequently, count on
one hand, etc., because I'm kind of clumsy. Other than that, I can't think
of anything that might be considered abusive.

It is still so much smoother than the Bravo II I/O I used to own, which
itself was so much smoother than the Alpha 1 before that. Passengers have
never noticed or commented - it's quite a subtle clunk. I think I may just
be listening too hard.

What is normal behaviour for these transmissions? Thanks.

====

Charles T. Low
- remove "UN"
www.boatdocking.com/BDPhoto.html - Photo Contest
www.boatdocking.com
www.ctlow.ca/Trojan26 - my boat

====

It's your low idle speed that's causing the noise, BW's make noise at
low RPM's. Your idle should be up around 700 to 750 RPM's. Your
hearing either back lash, or the clutch pack. Crank the idle back up
where it belongs before you really damage the gears.

"Charles T. Low" wrote in message
. ..

When put into gear, there is a slight pause, a fraction of a second only,
but easily visible that the prop tranny/shaft does not start turning
immediately - then it catches and away it goes. (Idling just above 600 rpm
indicated.) It does so with a very soft audible clunk, and I seem to
remember it being noiseless when "new" (to me).


Sounds like normal operation to me!

The transmission operates on hydraulic pressure. When you put it "in gear",
you are moving a valve that routes the output of the oil pump (operated off
the input shaft) so that the clutch plates get "squeezed". As with any
clutch, it is designed to engage smoothly, so that the clutch plates slip
just a bit before grabbing hold. When the clutch plates are new the motion
required by the diaphragm would be much less then when it has worn some.
Add in an oil pump that may have lost a little bit of idle speed pressure
and it might take slightly longer for the clutch to operate.

I wouldn't worry about the delay or the clunk. If you are concerned about
the transmission, pay attention to how it works under heavy load
(acceleration). If you ever detect any amount of slip, schedule a rebuild
ASAP.

Rod

posible that the flexplate is worn or broken. similar to a clutch disc on a
manual transmission, it has springs arranged in a circle that if broken or
lost strength might give an extra clunky sound. It is what couples the
engine crankshaft to the velvet drive input shaft. This is separate, not a
part of the transmission.
My own velvet drives are fairly quiet. And the fractional second delay is
normal.

"Rod McInnis" wrote in message
...

"Charles T. Low" wrote in message
. ..

When put into gear, there is a slight pause, a fraction of a second
only,
but easily visible that the prop tranny/shaft does not start turning
immediately - then it catches and away it goes. (Idling just above 600
rpm
indicated.) It does so with a very soft audible clunk, and I seem to
remember it being noiseless when "new" (to me).


Sounds like normal operation to me!

The transmission operates on hydraulic pressure. When you put it "in
gear",
you are moving a valve that routes the output of the oil pump (operated
off
the input shaft) so that the clutch plates get "squeezed". As with any
clutch, it is designed to engage smoothly, so that the clutch plates slip
just a bit before grabbing hold. When the clutch plates are new the
motion
required by the diaphragm would be much less then when it has worn some.
Add in an oil pump that may have lost a little bit of idle speed pressure
and it might take slightly longer for the clutch to operate.

I wouldn't worry about the delay or the clunk. If you are concerned about
the transmission, pay attention to how it works under heavy load
(acceleration). If you ever detect any amount of slip, schedule a rebuild
ASAP.

Rod