In article , Roger Long
wrote:

Just skimmed it.

I think he's right but he's talking about something different than the
couplings faces being true and square to the shaft. If you have a
true running shaft pulled out of line by the engine moving on the
mounts or not being perfectly aimed towards the strut, that's one
thing and probably not a big issues as he says. If the engine is
trying to wave the far end of the shaft in a circle under the same
circumstances, I think you are going to have some noise.

I'd agree with you. What I don't understand, though, is why, *ever*,
you wouldn't have flange faces that weren't at right angles to the
shaft(s) to within extremely close tolerances. But then I'm a
fitter/machinist amongst other things and have a couple of lathes about
the place. Facing a flange off square is a 30 second job. Boring it to
a close sliding fit on a shaft, not much longer.

The whole issue of small boat drive trains strikes me as something that
shoulda been left in the ark. If I ever get my shed finished so I can
move onto the boat, I'm planning on mounting my engine/trans with a CV
joint between it and the shaft. This will require a thrust bearing on
the end of the shaft, but so what. I can mount the engine pretty much
wherever I want, on soft vibration reducing mounts, and forget about
drive train misalignment. We're only talking 30 HP or so. My tractor
PTO handles way more than that reliably. No thrust loads there of
course, hence the need for a thrust bearing on the shaft.

I can't understand why drive systems are hard coupled other than it's
cheap to do the first time and any subsequent maint probs aren't coming
home to the builder.

PDW

Bill Kearney wrote:

Heh, a friend of mine used to say "I hope the man that invented Liquid
Wrench died peacefully in his sleep at a ripe old age". Saved our asses
more than a few times as gear heads on his old Chevy.

Forget Liquid Wrench. Use PBlaster. Nothing finer. Kroil is o.k.
but PBlaster has worked wonders for me.

Evan Gatehouse

Roger Long wrote:
Skip Gundlach" wrote

However, I'm baffled, given your prior assertions, that you don't
eliminate the issue by using a solid spacer, as I'm, based on your
scholarly treatise on the subject, going to do.


Good point and touched on in a reply above. Worth expanding on.

I was reporting what the most knowledgeable driveline people I've met
told me. Looking at better pictures of the unit at the link that Evan
sent, I find it a bit harder to understand why they feel that way. My
discussions with them involved engines of 35 times the horsepower
which may bear significantly on the issue.

I still think my boat (and yours) would end up smoother with a solid
coupling and everything trued up as I recommend you do but it is
acceptably smooth to me now. I wouldn't at this stage of refit and
finances, pay for a spacer and all the other machining just to make it
a little quieter. I'll probably do all that before I head off to
Newfoundland in a few years but my priority now is to not find myself
sinking because the stuffing box hose let got while also avoiding
divorce because of the bills. Either would probably result in loss of
the boat.


By the way, in my business we really like Lo-Rez mounts / couplings as
they are considerably softer (and thus transmit less vibration) than
rubber or elastomer mounts and couplings. And we use them on 5000 HP
tugs all the time.

I also have a wicked clearance issue that makes packing the stuffing
box almost impossible and would much rather invest in the proper
length shaft than a spacer. One thing prompting this is the discovery
that there is only room for one hose clamp on the stern tube. I think
it's long enough but someone lapped the glass on top too much and
covered up part of it. I think I can cut that back but I'll need a
new hose to get enough length for the second hose clamp. Sliding the
hose back enough to pull the coupling bolts is not an option.

Having a similar situation on my last boat you have my sympathy.
Getting the packing out of the stuffing box required the use of a fish
hook that had been straightend out and held with some needle nose vise
grips.

Evan Gatehouse

Bill Kearney writes:

Heh, a friend of mine used to say "I hope the man that invented Liquid
Wrench died peacefully in his sleep at a ripe old age".

He must have died with a guilty conscience, seeing as how Liquid Wrench is
essentially overpriced kerosene.

Richard J Kinch wrote:
Bill Kearney writes:


Heh, a friend of mine used to say "I hope the man that invented Liquid
Wrench died peacefully in his sleep at a ripe old age".


He must have died with a guilty conscience, seeing as how Liquid Wrench is
essentially overpriced kerosene.

Why should he feel "guilty" about that?

Actually, Liquid Wrench is not listed as having kerosene by the
National Institute of Health, though I'm sure its pretty close. Many
STP products, however, are almost entirely kerosene.

Jeff writes:

Actually, Liquid Wrench is not listed as having kerosene by the
National Institute of Health, though I'm sure its pretty close.

Different names for the same thing.

I got the coupling separated. The gear flange attachments on these
small Drivesavers appear to be molded in studs. The nuts on them were
thoroughly rounded and buggered up when the unit was installed so it
probably isn't coming off the gear unless the engine comes out of the
boat.

Picture here and more info he

Http://home.maine.rr.com/rlma/Strider0605.htm#Latest

--

Roger Long