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Mark,
I agree. I am not certain how you would
hold it flat while you weld it. It might try to warp.
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mark Steitle
Sent: Saturday, July 16, 2011
12:53 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Flex
Plate Failure - Improvements
Bill,
TIG welding out near the ring gear would create one incredibly strong
assembly. BTW, it weighs a mere 6.8#.
Mark
On Sat, Jul 16, 2011 at 11:24 AM, Bill
Bradburry <bbradburry@bellsouth.net>
wrote:
Regardless of the method used, you will discover that those teeth
are hard! And there are many of them!
I also think you will need to spot weld or something the two plates
together so that they become one in order for this to work. Especially since
the rubber bushings allow the bolts to wiggle? side to side, putting opposite
forces on the two plates.
Bill B
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]
On Behalf Of Kelly Troyer
Sent: Saturday, July 16, 2011
12:06 PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Flex
Plate Failure - Improvements
In
the interest of maintaining flexplate balance I would probably rig up some way
to grind the ring gear tooth bevel
with a tool post grinder perhaps either on the lathe
or milling machine..........I would bet
your friend Bob D. could come up with a method
to do this...................<:)
Kelly Troyer
"DYKE DELTA
JD2" (Eventually)
"13B ROTARY"_ Engine
"RWS"_RD1C/EC2/EM2
"MISTRAL"_Backplate/Oil Manifold
"TURBONETICS"_TO4E50 Turbo
From: Mark Steitle <msteitle@gmail.com>
To: Rotary
motors in aircraft <flyrotary@lancaironline.net>
Sent: Saturday, July 16, 2011 9:04
AM
Subject: [FlyRotary] Re: Flex
Plate Failure - Improvements
Bill,
That's a good point. The 20B
flexplate, which appears to be the same as the Renesis, has a small bevel on
the engine side of each tooth, 180* opposite of the 13B flexplate. My
thought is that this could be duplicated using a dremmel or die grinder.
Mark S.
On Sat, Jul 16, 2011 at 8:39 AM, Bill Bradburry <bbradburry@bellsouth.net>
wrote:
The RX-8 flywheel/flexplate is designed to
have the starter gear enter from the front as related to the engine. The
RX-7 has the starter entering from the rear as related to the engine. As
a result the RX-8 flywheel will not work with the RX-7 starter.
That is my opinion as I remember the layout. I am willing to stand
corrected by more knowledgeable folks.
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]
On Behalf Of Tracy
Sent: Friday, July 15, 2011 2:41
PM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Flex
Plate Failure - Improvements
I'm still in analysis mode on this myself.
So far the possibilities are:
1. The flex plate may have been warped when installed ( I bought several
that were) I think the standard should be close to zero runout or wobble
on the flexplate in view of this failure.
2. The flexplate could have had cracks when installed (I also
bought several that had cracks and they were not visible unless you looked
closely)
3. The dang things (RX-7 flexplates) are not strong enough for boosted
13Bs or 20Bs.
I do NOT think the problem is fore & aft travel of the input shaft.
The RD-1x drives have had thrust bearings from day one. There is no
thrust load at all on the damper, flexplate or crankshaft imposed by the
drive. This was not the case with the Ross drive I used at first.
I have over 1000 hours on the same flexplate on my NA 13B. I have only 55
hours on the 20B. But I'll be checking both. I did inspect
both flexplates VERY carefully before installing.
If I found that a change were necessary, I would consider two possibilities.
1. Use a modified aluminum racing flywheel used with an auto
counterweight. (Or possibly a lightweight steel one if there is such a
thing)
2. Use an RX-8 flexplate with an adapter plate made of aluminum or steel
sheet to go between the flexplate and damper. The RX-8 version looks
stronger than the RX-7. I briefly studied this when good RX-7 flexplates were
getting hard to find. I did not develop a formal procedure for doing
this but it looked like it would be pretty easy. Anybody with spare time
out there want to take a closer look? Hint: The damper bolt
pattern would be offset 45 degrees from the RX-8 torque converter bolt pattern.
Tracy Crook, RWS
Bill summed up what I’ve been thinking the
last few days. I’m not changing anything until Tracy makes a recommendation. It could be
fore and aft movement on the shaft, flex plate out of round, worn rubber
isolators or a combination of all these items. We may need a scheduled
maintenance plan to replace items like the rubber isolators or other items that
wear and loosen tolerances.
I will however be inspecting for
this problem before most flights.
(playing with fiberglass again)
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]
On Behalf Of Bill Bradburry
Sent: Friday, July 15, 2011 10:03
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Re: Ok Here
are the important flywheel measurements
I can’t help but think that you may be
fixing something that is not broken. I realize that the flexplate came
apart on your plane, but that doesn’t mean that the flexplate is the cause of
the problem. That flexplate holds up quite well in the car with a heavy
torque converter attached to it. Think of the forces when a car under
heavy acceleration changes gear! As long as the forces are along the plane of
the plate it is very strong. Not so much in the forward/rearward
directions. In fact that would cause metal fatigue and cause it to break
just like yours did. I think that what ever is causing the endplay is
what you should be looking at. I suspect that if you check out the
transmission on the car you will find that the endplay of the input shaft is
controlled by thrust bearings or some such device. Lynn may know the answer to this??
That msg from Al Wick really resonates
with me. Tracy
had to install a thrust bearing to prevent the drive shaft from hitting the
bottom of the pilot bearing and causing an eccentric shaft failure on the
engine. Maybe you now need to add a cage similar to what Al was
discussing that will trap the shaft end play completely. That, to me,
makes more sense than adding a bigger flywheel. If you strengthen the
weak spot, you will then discover where the next weakest spot is because that
will be the next failure!
This is a real opportunity for you and the
rest of us with the same drive. Please study this a little more before
you begin the fix!
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]
On Behalf Of David Leonard
Sent: Friday, July 15, 2011 12:42
AM
To: Rotary
motors in aircraft
Subject: [FlyRotary] Ok Here are
the important flywheel measurements
I finally got to the hangar and measured
out my S5 turbo flywheel and the remains of my S5 flexplate. The results
are very encouraging, even as good as the possibly could be to make the swap,
but I only had ten min at the hangar before I had to leave to pick up my
daughter from daycare, so they are one try and slightly sloppy... I make no
guarantees. The height measurements of the flex plate were particularly
suspect because, well, mine is all warped and broken.
Ring Gear Diameter - Perfect
fit. As we suspected, same size, same tooth spacing.
Ring Gear Fore-Aft Placement - As
measured from the underside of the big nut. (for all further reference, aft
means aft in the CAR). The flex plate puts the aft side of the ring gear
1.290 inches from the front of the big nut. The flywheel puts it 0.913.
So the flex plate puts the ring gear (appx) 0.377 in. further aft. This
is actually fortuitous because it just so happens that the ring gear thickness
is .365 ... So all we have to do to fix the discrepancy is
weld and extra ring gears onto to the flywheel ring gear and there will be
teeth that the starter can reach:(bottom of the page.. the cost $80)
http://mazdatrix.com/flywheel.htm
It may also be possible to fix the discrepancy by changing the starter... will
look into that.
Damper Plate Placement - On the
flywheel, the mounting surface is proud (or aft) of the ring gear. On the
flex plate, the mounting surface is recessed (or forward) from the ring gear.
And it all pretty much works out. That position on the flywheel will vary
somewhat depending on which flywheel you have and how much wear you have on the
clutch slip surface. But on my (I assume well-worn) flywheel the placement was
0.965 while the flex plate was 0.950. Pretty damn close and given
measurement error it might me meant to be right on. Or, any difference
could be made up by trimming down the spline on the damper plate or removing or
adding spacers between the two.
So in my mind, a flywheel is the way to go. Stout, easy to get, pick your
weight, only mods seem to be drilling the mounting holes and welding on a second
gear ring.
--
David Leonard
Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net
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