Hi All ~



I just wanted to ask anyone experienced with cutting teardrops on the oil passages of the eccentric shaft. I particularly want to know how to determine the size and what bits to use because the e-shaft is really hard to cut and shape. Also, do I polish the teardrop or do I leave it with some texture?



Thanks,

1

Why do you want to do this?

if i understand the concept correctly, it's supposed to aid oil flow between the shaft and bearings.

you mean, since the journal spins in the rotor(bearing) you want to shape the oil passage somehow to improve the flow, right?

is this common somewhere? in the V8-scene or something? i'm just curious

yes, exactly.

well, i had never heard of it on rotaries until relatively recently. however, i did hear about it on piston engines before. i never gave it much thought until i saw it here: http://www.rx7club.com/showthread.php?t=489429



i've since spoken to this gentleman, and he made a compelling case. it took me weeks of on and off thinking about it to understand what i think i now do. add that to the fact that i have a couple of long-term engine projects that i want to get started now that i have the time, albeit sans funding, so i figured i'd throw it out there on this forum and try to gather more insights.

I do it. I copied it off of VW cranks, that came that way from the factory. I cannot say if it helps, hinders, or has no affect at all. It seems like it would help. It is fun to do, and looks cool. Extensive cleaning is required when done.



When in a hurry, I have dropped in a new crank with no mods at all and had the same performance. So that works fine too. Just keep the oil pressure above 100 PSI.



There were some folks who kept killing rotor bearings running stock oil pressure, The built a cooaxial sleeve to fit over the front pulley and measuered oil pressure in the crank, with 75 PSI showing on the gage.



They got 7 PSI. When you scream the engine the column of oil leading into the crank is exposed to a centrifugal load that cancels most of the oil pressure. So, even though you should (in theory) get that all back when the oil leaves the centerline and starts down the run to the rotor bearing, it just falls a bit short.



And therefore, the romance with high oil pressures in a rotary.



On racing cranks in piston engines there is a common practice of addng a slight depression around the oil outlet to the rod journal. This is to allow high pressure oil to be exposed to a larger area on the bearing.

So, at least this part of it works, as nearly all people use it.



Then you look at a Cosworth 4 cylinder crank ( cut from a forged slug ) and it looks like a stock Pinto crank at the oil holes. The rest of the crank looks like a work of art, and not at all like a pinto crank.



So do it, or don't do it. But if you are on the engine a lot, run 100 PSI and there will be few problems.



Lynn E. Hanover

that's just downright frightening!



thanks for the response, Lynn.



yes, i'm planning to run 100 PSI. i'll be using the FC rear regulator. what i was NOT planning to do was shim the front, but i guess now i will.



so ... could you give me some tips on what bits to use to make them? what surface to leave? (i'm thinking polished should be better.) also, how do you decide on what size to make them?

Well,



The VW shapes were very generous, and way wider than the grooves in the bearings. I just try to stay closer to about three times the width of the groove in the bearing. Leading on the main bearing holes and trailing on the rotor bearing holes. Small flame shaped stones work the best. The stone gives a "good enough" finish.



If it is an all out engine, oil the front main bearing with an additional exterior (at least a dash 10) hose.



If it is going to spend a lot of time above 9,000 RPM, an external oil pump (even with a wet sump) is fine.

For constant use above 9,500 RPM then the external dry sump system is a must. Keep oil pressure above 100 PSI for NA engines and many recomend 110 to 115 for turbo engines.



In this picture I have placed a steel tube through the front oiling port to show it's location. The stock plug is drilled out. A hole for a dash 10 boss fitting is tapped. A boss fitting uses a copper "O" ring to seal.

A tapered pipe thread will work, but if over tightened, will crack open the port and ruin the iron.



Lynn E. Hanover

wheew ... https://www.nopistons.com/forums/pub...IR#>/smile.png i'm so glad to hear you say that because after i made my last post last night i went out to the garage and spent a few hours toying with a shaft. yes, the stone worked the best when a carbide bit barely touched it. once i learned the rhythm of how to get the desired shapes, i ended up with some pretty large teardrops, not quite 3 times the width of the groove, but large enough for me to start thinking, "oh **** ... maybe i'm in over my head." https://www.nopistons.com/forums/pub...IR#>/smile.png i ended up sanding the finish down with some 220 grit. i was planning to try something finer today, but if you said the stone was good enough, then i'll probably just leave it as is.



okay Lynn, i don't want to wear out my welcome ... or your patience because , but i have another question. for the ones that oil the main bearings, is it better the bevel the larger edge of the teardrop or should i leave the edge sharp?



PS

just out of curiosity, those VW cranks that you mentioned coming from the factory wth teardrops on the cranks, were they air-cooled engines or water-cooled?



thank you so much for your time and insights.

by the way, that's supposed to be "FD" rear regulator ...

Hey Lynn or diabolical1,

Would it be possible if you can post some pics of this modification? To show us what it looks like. Would be much appreciated.

okay, tonight when i go back to work on it, i'll see if i can snap some shots of mine and post them.

Would it be possible if you can post some pics of this modification? To show us what it looks like. Would be much appreciated.[/i]



The pics of mine in the linked thread not good enough? https://www.nopistons.com/forums/pub...IR#>/smile.png



I already blew that engine (Atkins 2mm seals @15psi ~400RWHP). I found the reason my oil pressure was lower (90-110psi) was my front cover o-ring was pinched; I am going to dowel it this time around.



At 90-110psi oil pressure and 8,500rpm redline on S4 TII rotors there were some slight shiny spots on the outer ends of the bearings.



I am going to fix the oil pressure back up to 130psi (MFR regulator) and hold the redline down to 8,000rpm or 8,500rmp if I balance and lighten the rotors.



Oh, I found why the power was dropping at 7,500rpm. I had the MAP sensor tapped off the primary runner and it was seeing +-4psi fluctuations from dynamic effect. Put the MAP line to the plenum and it pulled smooth and hard to redline.



My porting is staying the same when it goes back together!

hey man,

not sure if i ever thanked you for putting me on with this mod for rotaries, but if not, then thanks.



sounds like balancing issues to me if you saw contact on the outer ends at only 8500 RPM. so i think you're back on track if you're getting it balanced. sorry to hear that the motor went south, but such is the game.



i didn't know you were on this board, too - but i guess it shouldn't be a surprise. https://www.nopistons.com/forums/pub...IR#>/smile.png

My Idea came from big displacement flat 4 cylinder VWs. They have (and aircraft engines have, a tendancy to pound out the center main bearing saddle with both center throws going the same direction, and no counter weights. (Like running a rotary without the counterweights).





My cranks are in engines right now, so I cannot provide pictures.



Damage to corner seal areas and the ends of main bearings shined up is caused by crank flex. It shows up in my engines at the front of the rear main bearing shell first as a shiny area about 1/8" wide at the front end of the bearing. (Not any more) I scrape out that much of the overly and sand off the overly on the front half of the shell with 600 silicone carbide paper in solvent.



The longer crank and heavier rotors of the 13B style engines requires that the rotor width at the apex area be reduced about .012" to .015" per side. It can be a taper, but just a straight cut works fine and takes off some more weight. Use very sharp tooling and debur everything when done. That will get the bearings looking good and the rotors not touching anything. More revs (More than you have been using) are available with lightened rotors and a rebalance. And.......at least 100 PSI of oil pressure.



Lynn E. Hanover

That's helped clearup a confusion with me. I couldn't work out where you tapped the front looking at the other installations.



Thanks



Bill

Unless you have the equipment to do it, I would take the front iron to a machine shop to get that drill and tap operation completed. While the iron is still clamped in place they can flycut the outer (sealing surface) dead flat at 90 degrees to the centerline of the hole. A copper or aluminum "O" ring will be doing the sealing.



Warn them about the frigile bridgebort area lest they crack the bridge while clamping.



Lynn E. Hanover

well, i've been sick for the last few days, but i went out and snapped a couple of shots a few minutes ago.



https://img.photobucket.com/albums/v...s/b2291d6c.jpg

here's another ...



Attachment 20948

by the way, as you can see this shaft is pretty ratty. i went at with a fine emory cloth a few minutes after i took the pics, not much, but just to see if it will get the rust spots off - rather discouraging as some spots don't look like they are coming out. i'll have an earnest go at it after i clean the oil passages, maybe later, maybe tomorrow. still a little weak ...



at any rate, i plan to have ISC Racing polish it for me - probably a dumb question - but do you think that all the spots will come off when they're done?

Polising uses ~400 grit. First you spin it one way with say ~320 then the other way with ~400.



It does not take off much.



Looks very promising though, gonna give it a whirl on my RE

Ive inherited 2 of those adjustible OPR's, Can anyone tell me how much I need to shim the front regulator?

everything i've read says to use 2 washers, but i honestly can't remember if there is a precise measurement (mm or inch) that is required.

According to rb you need to shim it .125". That's what I do.

Brent

Those look fine.



If you cannot feel the marks with your fingernail, just a cleanup will be fine.







Picture is looking at seal tracks through a see through rotor.





Lynn E. Hanover

okay ... i just finished doing the shaft for the engine (a streetport 12A) that i'll be putting together for use while i build the 13B. first off, i noticed that the 13B (an '87) shaft that i snapped the photos of has a slightly different oil passage scheme than the 12A.



the front main has 2 oil passages on the 13B, while the 12A has only 1. does it have something to do with the thermal pellet on the 13B? i'm just curious ...

i can't wait to get the 13B (an '84) out of my car and tear it down to see the shaft on that.



anyway ... the real reason for making this post is to get some direction on how to properly clean the oil passages. i'd love to get some pressurized gasoline (or similar solvent) going through to clean them thoroughly. as you can imagine the metal dust that came from making the teardrops and i simply don't want anything but oil going through when i finally fire the engine. would a local engine builder (no rotary places are local to me) be able to handle it?



i'd love to do it myself, but i have no qualms about having someone else do it as long as it's done right. any instructions or recommendation for professional help is greatly appreciated.

Buy a pickle bucket from Mickey Dees.



Buy a Little Giant fountain pump. Put a length of plastic hose onto the pump outlet.



Place the pump in the pickle bucket. (the pickles have been removed).



Pour in 2 gallons of kerosene.



There you are. A cleaning tank.



Now take the crank to the do it yourself car wash. Wash the car.



Place a floor mat on the floor of the car wash. Use the high pressure nozzle on the oil passages in the crank.



Take it home and use your new cleaning tank and pump.



Blow out all of the passages with compressed air. While wearing eye protection.





Lynn E. Hanover

thanks again, Lynn. will do as soon as i can get my hands on that stuff.

i noticed that the 13B (an '87) shaft that i snapped the photos of has a slightly different oil passage scheme than the 12A.

the front main has 2 oil passages on the 13B, while the 12A has only 1. does it have something to do with the thermal pellet on the 13B?



I believe the 13B simply has a slightly improved oiling system than the 12A. You see, the oil for the front stat gear and rotor bearing comes off the rear oil pressure regulator just like the rear stat gear and rotor bearing, but it must make three more cross drilled 90 degree angles and travel the length of the engine through the dowel pins to get to the front bearings. This causes much more pressure drop than the rear bearing sees and adding one more hole in the e-shaft at the stat gear bearing was Mazda's quick fix to help get oil to the front rotor bearing.



Racers do the quick fix one better by adding another oil hole in the rear rotor for more oil to the rear rotor bearing (just as Mazda did with the front on the 13B) and then running an additional oil line (loop line) from the rear regulator area directly into the front stat gear bearing (through the plugged cross drilled hole already there).

thanks. what you said makes sense to me now.



well, i'm sort of relieved to hear this because my curiosity did not stop at just wanting to know why Mazda did it. i was also thinking if i was going to risk damaging anything if i drilled through the 12A shaft to make it similar to the 13B. hearing you say this makes me want to actually go ahead and try it now.

2 more things ...



1. i just want to confirm ... you did mean rear "main" bearing, right? since there are already 2 holes for the rear rotor bearing.



2. that additional oil loop line that you referred to, is that the same mod that Lynn descibed in post 15? because i think i read about it somewhere else on this board (i'm tempted to say it was a BDC thread, but don't quote me on that). however, i thought it was going way too far for the plans i have.

Ooops! Yes, add another hole for the rear STATIONARY gear bearing when doing a loop line to the front stat gear bearing.

I know i am digging up a very old thread, but would there be a "correct" direction on the tail of the tear drop or does it not matter.

It matters. follow the pic Lynn posted. The tail should be exactly that the tail.

you have to pay attention to the direction of rotation within the respective bearings, mains and rotors, and place the tail accordingly. as stated before, the photos provide a good guide.