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Paul,

My understanding (Leon, Lynn, jump right in) is that so long as the rotors and counterweights are matched you are OK. The flex plate has much less mass than the manual transmission flywheel (like 1-2 lbs vs 30 lbs). I have an 86 eccentric shaft in my 91 turbo block so it appears that you are Ok there as well. The triangular shaped item in the Ross drive contains the spline shaft that the shaft from the gear box is driven by. The flex plate is bolted to the eccentric shaft by the infamous large "Flywheel Nut". The triangular shape thing with the springs is bolted to the flex plate. I think the springs were viewed by Lou Ross as the "dampner" but of course springs do not dampen. Never had any problem with that part of the Ross drive. The regular flex plate measure 12 7/8" dia (as best I recall), the smaller on is right at 12" dia. A Ross drive could have either one. Where it makes a difference is how your starter would/would not align with the flywheel teeth. If your Ross uses the smaller flex plate then a regular one may not work for you - you may be stuck with the smaller one. However, some of the Ross drives had considerable adjustment of the starter - so it may still work. You'll just have to trial fit to see.

Ed A

----- Original Message -----

From: Paul

To: Rotary motors in aircraft

Sent: Sunday, January 23, 2005 10:09 AM

Subject: [FlyRotary] Re: flex plate

Thanks, Ed. I have to admit that I am still not certain that I understand everything I need to know about the flex plates, etc. Here is my scenario....I have a street ported 4 port turbo block that I am building up with NA rotors and housings. The rotors and housings are coming from an engine I just acquired that is from a car that had a standard transmission. I'm assuming I can use the rotors, eccentric shaft, and counterweights...but can I use this flywheel? Or do I need a flywheel and counterweights that were specifically made for an automatic? Or are we saying that that little triangular shaped item with the springs in it is the flex plate and can be mounted on any flywheel? Sorry for the barrage of questions.....I just don't have quite enough information to ask intelligent questions yet. Thanks for trying to educate me. Paul Conner

----- Original Message -----

From: Ed Anderson

To: Rotary motors in aircraft

Sent: Saturday, January 22, 2005 6:47 AM

Subject: [FlyRotary] Re: flex plate

I had a Ross drive that used the smaller flexplates - almost 1" smaller in diameter than the 13B. I almost used it as an alignment for the starter position when I modified Tracy's Mounting plate for my Plugs Up installation - fortunately before cutting metal I measure the flex plate on a 13B sitting in my shop and found it was 1" larger in diameter.

Ed Anderson

----- Original Message -----

From: Kelly Troyer

To: Rotary motors in aircraft

Sent: Friday, January 21, 2005 11:37 PM

Subject: [FlyRotary] Re: flex plate

OK Paul, I have been out of town so may be late with this info !! Ross

used the flexplates from the 12A to 1973 and  (some 1974) top mounted

starter rotary engines until they became hard to find....Then they started

making them from aluminum and adding a ring gear for the starter !! These

flexplates are smaller in diameter than the later ones......FWIW

--
Kelly Troyer
Dyke Delta/13B/RD1C/EC2

> > > On Mon, 17 Jan 2005 09:44:03 -0600
> > > "Paul" wrote:
> > >
> > >> OK....I am going to openly display my ignorance here....I had my
> > >Ross > PSRU off only one time, when I had the thrust bearing mod
> > >done. I > simply reinstalled it opposite of how I took it off. That
> > >was some > time ago, and I can't recall what it looked like where it
> > >mated to the > flywheel. Did the Ross also use an auto flex plate?
> > >I remember the > shaft was splined. That's about all I recall. I am
> > >asking this, > because I have purchased a set of street ported 4-port
> > >plates to which > I will add a set of NA rotors and housings to build
> > >up a complete > engine so I will les! sen my "downtime" by hopefully
> > >swapping engines on > a weekend. I would like to have this new engine
> > >ready to bolt on and > run. I'm assuming that the stock, cast iron
> > >flywheel I have if from > a standard transmission RX7. Are the
> > >automatic and standard flywheels > different, or do you just add an
> > >automatic transmission flex plate to > the cast iron flywheel I
> > >already have? Just when I thought I had > everything figured out, I
> > >start reading new posts about flex > plates....
> > >> Thanks in advance for any and all replies/suggestions. Paul,
> > >> what the heck is a flexplate, Conner

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