Does anyone know the procedure for internal engine component balancing, like t
he rotors look simple enough, just a rotating piece, what would be a recomended speed in rpm for the rotor for a proper balance, then the counter weights locked on the E-shaft what would bob weight number be , 100%-70%or maybe 50% of the rotor weight, does anyone know here, or am I just wasting time on internal balancing maybe its not worth the effort. RON

 

For everyday street use, not worth it.
I would say its only necessary when you are constantly hugging the 10000rpm

 

OMg I need this answered to I try it but with no avail. Here is all the info I gathered. It is in the second gen tech section so it might look a little wierd Like I am talking to myself.lol.


Ok today at work we pretty much had the day off so I had my friend bring me back to the house and grab some engine parts. For those who odnt know I work at a engine machine shop. Well considering most of my stuff is about useless, I figures I would try balancing the rotating assembly including the flywheel. Well I had it all put up like it suppost to be run on the machine for balancing. I started up the machine and it appears that the stock parts from the factory are way out of balance. I tried it with and without the flywheel. And yes I did have the counter wieghts on.

Ok so my first question is what would be the best way to balance out the assembly. Taking wieght off of the rotors to make them the same wieght. But then I would come to the issue of the counter wieghts. How would I go about changing there wieght to balance things out.

Now you are probably thinking well if you work at a machine shop you should know how to do this. instead of just rauuning the e-shaft i put on the rotors and countershafts and gave them a whirl on the machine. Now most of the time we just run the crank on the balancer and then make all of the rods and pistons the same wieght.

So has anyone tried this. And what were your experinces. Am I going about this in the right way. Like I said noone at the shop has tried to balance a rotory so were basically just trying different methods. Also the equipment is a little old we dont have anything that is computer controlled. Thanks for your help.

Now for my run of who will be the one with the best answer. Hmmm Im thinking either ted or Icemark may have the answer hidden away somewhere.


Well a good idea would be to acquire matching rotors. THey are stamped, i forget where atm, with letter designations. If you get a matching letter pair then you wont have to balance them that much. and as far as the rest of the assembly...I think its been covered once or thrice.


Well thats the part that got me. THey do match up. They are S4 rotors and Ill have to go look at the number but they are way out. They dont have anychips or anything like that to make them that way but they are way out. I have it all written down at the shop. I Am thinking that may have come that way from the factory but I am sure they would be as bad as they were.


WEll i have been looking for a link to some more info but cant find anything. But I am also thinking about were would be the best place to remove wieght from the rotor. But then that also got me thinking about the wieght of all the seals and springs. I wonder if that would affect the balance at all. Maybe I should fully assemble the rotors with all seals and springs ect and then try to balance them.

Any information on this subject would be greatly apprectiated

Well I think that I am thinking to much now on this subject. Now If a spinning rotor has three different sides and are on opposing side of the e-shaft then this would make 3 different wieghts at different points in time. So then that would make a total of six different wieght points. Now for the engine to be in total balance by this therory then each one of the sides of the front rotor would have to be the exact wieght of the opposite side of the rear rotor. Thus making the rotors in complete balance with each other in there rotations. But there is a problem with this theory I do not know of a way to balance the different sides of a rotor individually.

So far is any of this making any sense other than to myself. Its kinda like that orbiting theory. Were an objects center is always in balance. But the objects from its center even though connected are not in balance with each other it will cause a disturbance. This is were my theory on this is dirived from. I think it makes sense. So here is bacically what I would have to do to make a perfectly in balance rotor.

Find a way to measure the wieght of the rotor in thrids much like cutting it into 3 pieces and measuring them. But without accually cutting them. Compare the wieght of the 3rds with the other rotor and find the lowest wieght withing the 6 3rds of the 3 rotors. Then remove enough from all the other pieces to were each one of the pieces is the exact wieht. This would also include apex seals springs and ect.. AS for the flywheel were most of the imbalance is occured it would be balanced much like a tire. Rotating it at higher speed to see were there is more or less wieght and have it machined to be in perfect balance. Thus eleminating alot of vibration in the rotating assembly reducing wear in the engine. And possibly making more power.

But for the Counter wieghts I am not sure about them at this point, the way I have explained it you might be able to run without the counterwieght thus creating less rotating mass and more gains on the top end.

Well I am Sorry if none of this made sense. I am just wanting to try all of these Ideas in my head all of a sudden. Feel free to post your comments thoughts flames

Hmm Ddub did just bring up a good point about the counter wieghts that I had over looked. the rear is used to position the flywheel. Now the best way to have the engine in balance in the way I depicted would be to have the rear counter wieght were it needs to be. But on the opposite end of the e-shaft have a counterwieght of the exact same wieght. Ok lets say that the rear conterwieght is sitting on top of the e-shaft(remember this is just to get a point across) then I would have to make a counterwieght of the exact same wieght that would sit on the bottom of the e-shaft on the front. This would act like cancelling wavelengths. Thus the rear counterwieght could position the flywheel but would not be part of the eqation for the balance of the rotating assembly.

Any comment or questions, gripes, bitches, or anything like that

I'm rebuilding a motor and also work in a machine shop. I want to lighten my rotors by machining like RB and other people do. I have asked about balancing (RB) and they said they use a "Propriatary Formula" to calculate the wheight of the rotor "Including oil wheight". They would not tell me how to calculate my balnce wheight in proportion to my counter-wheight. I would be very interested in any information that could help me in this matter.

FC, this is good head candy. I believe there might advantages to balancing. Even a basically stock motor. When I took my '89NA apart, I was surprised how differant the rotors looked. One was smooth and the other had grooves like it didn't go through a finishing operation. I know the previous owner and am sure it is the stock motor.

Ok correct me if I am wrong here somebody. But you were talking aboutthe oil in side the rotors right. Well I am pretty sure a liquid spinning balances its self out by pressing up against the side of the rotor. But hey I am not even sure if there is oil in the center of the rotor or not while it is running.

If there is it would be like taking and swirling water in a pitcher if you spin the water fat enought it moves to the oputside and is in balance. because the force is being distributed evenly. But hey I never did take physics in school. I took bilogy instead. So all of the stuff I know is basically from my head and a couple of physics books I have read.

Oil sloshes around in the rotor. It is not always constant. That is where the secret is.

Point, flat, point, flat; the rotor is not shaped like a pitcher. Think!

Yeah but the inside of it would basicaly be the same. Oh damn I just thought about something. And you are right. It would be very unbalanced because the oil would go into one oiont and then not beable to flow evenly between the other because of cintrifigul force. Ya not spelled right I know. I have benn looking at this more and more but I need more info on the workings of the internals of a rotor.

I told you what I know. If you can get more information on what percentage of the rotor wheight, including oil, that balancers use please tell me!
If anyone else can help me get this info, speak up.

And thats all i got so far. Hope it wasnt a waste of bandwidth.

Alex Saunders

 

??? try contacting Paul Yaw (Yawpower.com I think) or someone like that who is helpful to the rotary community and not just trying to make a buck??

I seem to remember reading someones detailed description of balancing the rotating assembly. Maybe No Pistons forum or another of the more technical forums?

Also, I remember besides the rotating balance issues in the rotary the combustion pressures should be balanced as well.

To do this one should measure from the bottom tip of the rotor (apex seal groove) as viewed from the front of engine to the beginning of the combustion chamber (rotor depression). This length and shape should all be machined to the same (shortest length) on all rotors and it would be a good idea to CC all the rotor depressions as well.

 

People Who Balance:

Paul Yaw
Daryl Drummond
CLR
Rodger Mandenville
Downing
MazdaTrix
Racing Beat

SDJ has closed up shop for a while (Although parts are still available)

 

If the engine is being rebuilt, the $200 is worth it in my opinion, especially if the rotors are new. One of my friends was a doubter also until he drove my car and had it done on the second rebuild of his engine.

 

OMG its only $200. Hell if you have counted all the hours I have spent getting know where at the shop I am probably up to like 4500$. Oh well I guess I learned something. Dont waste your time let someone waste theres for the same reason you wanted to.

But back to the issue at hand. Does the balancing inclue the flywheel. just wondering. That way Everything in hte rotating assembly from front counter wieght to the flywheel would be balanced.

 

Read up on it from RB...
http://www.racingbeat.com/resultset....rtNumber=11042

 

I read of a Mazda first gen (back before there were any other gens) RX7 that was a factory-backed endurance racer.

Not drag racer, ENDURANCE racer, as in 24-hour races.

Redline: 12,750 RPM. dBA rating: 127 dBA in the cockpit at full throttle.

Since then, I have always wanted a long-lasting high-shrieking and revving rotary motor.

Always been fascinated with high-reving Naturally Aspirated N/A motors.

If it has been done before, it can be done again.

 

If the RB article doesnt do it for ya.. Here is the tech page from Mazdaspeedmotorsports:
http://www.mazdamotorsports.com/weba...ject=balancing

Smilo Yep been done.. still done.. and there are plenty of 10K+ rotaries all over racing still in all generations.. including RX-8s.

 

Yeah. It's a beautiful thing.

 

Okay, so is that it? Fix the dummy weight where the picture shows, and balance it at 720 rpm? The mass of the dummy weight is going to depend on the rotors, right? If you've lightened them, then you need to adjust the dummy weight. What about e-shaft lightening? That doesn't need to be adjusted for, correct? Because the balancing process will show how much extra is needed to be removed from the counterweights.

So I guess the dummy weight is just a ring that goes around the e-shaft lobe. It almost seems too simple...

 

Yep I gather it is really that simple..
I myself have NOT balanced a engine.. but a local guy in St. Pete does them. Turns out he worked for many many years balancing engines with another guy in town who has worlds of time racing at top levels in prototypes etc.
Needless to say.. they fabbed up the bob weights etc.. and made a balancing jig for the whole procedure. And the machinist who made them is REALLY ****. I mean wow.. JUST the guy to have machine things for you.
He did some machining for the 20B in Evilaviators car.. related to the flywheel and rear counterweight.. (3 pound flywheel)

But yes.. I gather its that simple.

 

You know what? I think I might just stick to shipping the parts out to a professional. I wanted to save some money by getting some machines for my business, since no one on island can do any of this and shipping is a big pain in the butt. I also wanted to be able to offer those services to customers. But I'm afraid that I don't know exactly what I'm doing, and the cost of the machinery is a bit high to be ponying up on a "gamble."

 

^ sounds like a rational conclusion to me

 

i still do not understand how dummy weights could replace rotors in balancing since rotors are not fixed on the crankshaft in working engine but also rotating though the gears. this gears connection might eliminate all balancing effort. isnt that true?

 

Well, first you'd have to balance the rotors individually, I'm sure.

Then you replace the rotors with the bobweights, adding a token amount for the oil in the cavities (I theorize that the amount of oil in the cavities is "FULL" and not "half full" or somesuch, and the oil only sloshes out due to overflow from the oil being constantly sprayed in by the oil jets) and the seals on the sides of the rotor. Given that the apex seals and springs are not pulling on the eccentric shaft, but instead are riding against the rotor housing, their weight shouldn't matter any.

This winter, I may scare up some raw materials and make some rotor-balancing fixtures.

 

quick question on the balancing procedure ...

i'm going to get my rotating assembly balanced. i'll be using a lightened flywheel for an SE on my 12A buildup so i can use the clutch off my 13B when it comes out. however, i don't have the 13B front counterweight to go with it. what i want to know is if it matters? since they will be balancing it all anyway, i should be able to get it done with the 12A front counter, no?

thanks.