Today's Message Index:
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1. 02:16 PM - Re: N601EZ is running with a Saturn in tow. (Don Walker)
2. 05:48 PM - Investigating vibration! (Bill Morelli)
Message 1
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| Subject: | Re: N601EZ is running with a Saturn in tow. |
Seal-Send-Time: Fri, 7 May 2004 16:13:45 -0500
--> Stratus-List message posted by: "Don Walker" <d3dw@msn.com>
Likewise, my light stays on until about 1800 rpm and the voltage shows 12.4. When
the light goes off, the voltmeter jumps to 14.
My bearings used to be warm. Since I put in the grease fitting on the upper hub,
they stay cool to the touch. Don Walker HDS
----- Original Message -----
From: Bill Morelli
To: stratus-list@matronics.com
Sent: Thursday, May 06, 2004 9:39 PM
Subject: RE: Stratus-List: N601EZ is running with a Saturn in tow.
--> Stratus-List message posted by: "Bill Morelli" <billvt@together.net>
Larry,
My redrive assembly gets hot. I believe it's just heat from the engine
being transferred to the redrive and not the bearings heating up. Mine gets
hot to the touch but not so hot that you can't leave you hand on it.
> I notice that the redrive bearings are very warm to the touch and the
belt is 1/8"
> deflection at 20 lbs.
>
> Has anyone ever found the bearings to be cool while driving
> a prop or do they all get hot when running?
My volt meter (analog) on my panel shows close to 14 volts when the
alternator light is off. When I start my engine, the alt light stays on
until I get the rpm up around 2000 then the light goes off. The volts jump
from just over 12 volts to closer to 14 volts. Once the light goes off, it
stays off at even at low rpm. This having to run the engine up to 2000 to
get the alt light off has been seen by other Stratus owners in the past.
> My EIS Volts says the alternator is doing 12.4 at 1800
> rpms but I'm not sure what it should be reading at this point.
Bill
Message 2
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| Subject: | Investigating vibration! |
pts rule name description
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--> Stratus-List message posted by: "Bill Morelli" <billvt@together.net>
Stratus guys,
As I think I mentioned before, in an attempt to reduce my vibration to the
minimum, I decided to do three things.
1 - Adjust belt tension / tracking
2 - Synchronize the bing carbs
3 - Have the prop dynamically balanced
During flight, I have a very pronounced vibration at 3500 rpm. I have a
vertical card compass mounted on my glare shield. It is mounted on a piece
of foam for shock mounting. Turns out that the compass is a great vibration
indicator. I usually fly my downwind leg at 4000 rpm and all is smooth
(cruise at 4400 - 4800 is also smooth). I then pull back to 3000 for base
and final and that is also smooth. But if I run at 3500 anytime, that
compass starts shaking like a Hula Girl!!
Anyway, in order to try and determine if it is all prop or spinner or
redrive or engine - today I pulled the prop and ran the engine.
With the prop off and the engine running, the vertical card compass does
not shake at any RPM. I tried from idle all the way up to 4800 and no
shake. So at first glance, it seems as though my problem is in the prop /
spinner.
I then added a more sensitive vibration indicator. I took a long ty-wrap
and taped it to the top of one of the bing air cleaners so it was sticking
straight up in the air. Ran the engine up again and found that this
indicator is indeed more sensitive than the shaking compass. The ty-wrap
oscillates a bit at idle. As RPM is increased, it smoothes out the starts
to vibrate a bit from 2400 to 3000. Then it smoothes out again all the way
up to 4800.
I then checked the belt tension with a spring scale and ruler after all was
nice and warm. I had a bit over 1/8" of deflection. My belt also had ben
tracking close to the back flange of the lower pulley so I adjusted the
tracking and tension. Got the belt more centered and the tension to the
1/8" at 20 pound spec Stratus call for. I found out that tweaking the
tracking the running it to see where the belt tracks was much easier that
mucking with the Stratus depth gauge.
One thing you notice right away is that as tension is increased more noise
(whining) comes from the redrive bearings. This is something you would
never notice with the prop on (too much noise) but it is very obvious with
the prop off.
Now my vibration (a small amount) only seems to occur at around 3000 rpm
and a bit at idle.
I'm hoping that adjusting the carbs (which I will do tomorrow) will help
the idle vibration.
Another thing worth noting is that even though the redrive housing gets
pretty warm (hot but you can still keep your hand on it), the rear bearing
does not get very warm at all. The redrive is apparently heating up because
it is bolted to the engine not because the bearing is heating. Something
else that I had forgotten about since I had not run this engine up without
the prop for a long time is how much that little EA-81 screams at 4800 rpm.
The question I have about dynamic balancing is. It is my understanding that
the dynamic balance is done at the cruise RPM and since I don't have a
vibration at cruise (4400 - 4800) will my vibration at 3500 be taken care
of if it is indeed the prop?
I would like to thank Kelly Meiste for kindly sending me his carb sync
vacuum gauge setup.
Regards,
Bill
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