1. When cross drilling is another hole drilled through the rotor journal in addition to the factory one that goes right through.

2. On my e-shaft the front main journal (for stationary gear bearing) the oil hole goes right through but on the rear it only goes half way through - why?

3. Can you lighten an e-shaft?

4. In my book 'Mazda Rotary performance handbook' (pretty lame) it has a section in the back outlining how to build a 12App with factory parts. One of which is a e-shaft that has "to reduce the likelihood of bearing seizure the rear half of the rear main journal machined 20 thou smaller in diameter" - What the heck!? How does this prevent bearing failure?

Cheers

 

That gives u a considerable thicker layer of oil between the journal and bearing.

 

Yeah, prevents metal on metal contact *when* things start flexing around.... although 20 thou seems a bit EXTREME... the most I've heard of was an additional thousandth of clearance, not .020"... .020" to my thinking wouldn't be clearance, it would be rattling around in the bearing and a major source of pressure bleed-off, if the engine builds pressure at *all*!

I haven't heard of anyone crossdrilling E-shafts, I thought that was just one of my dumb ideas from the boinger world that I'd apply to rotaries. What you do is take the existing oil hole and drill it though to the other side of the E-shaft. Then deburr, *maybe* add a little chamfer, and clean all the shavings and swarf out thoroughly.

Can you lighten an E-shaft?


He says 1/2lb per journal.

 

Yeah sorry its not 20 thou its 20 (then that weird 'U' symbol) which apparently is 0.02mm.

 

That funny looking U is a "mu" and it symbolizes microns, one million of a meter, so yepper 20 mu is .02mm.

Now check this out... (For our SAE/Imperial measuring friends) One micron is a thousandth of a millimeter, yes? And there are 25.4 millimeters to the inch. Therefore there are 25.4 microns to the thousandth of an inch. So .02mm (20 mu) is slightly less than one thousandth of an inch.

That much can be "machined" away with an abrasive, like fine sandpaper or emery cloth.

 

I get 5 thousandths of an inch.

.02/10 = .002 cms (convert to cms)
.002*2.54 = .00508

Not too sure if im right though.

 

I get 5 thousandths of an inch.

.02/10 = .002 cms (convert to cms)
.002*2.54 = .00508 (convert to inchs)

Not too sure if im right though.

 

25.4 microns per thousandth of an inch

20 microns is smaller than 25.4, so we know the end result will be less than .001".

20 / 25.4 is .7874... of a thousandth. Rounding to numbers we can use in the real world with measuring tools that are commonly available: eight ten-thousandths (.0008").

Converting to inches, you have to divide, not multiply. Dividing gives the same result.

 

OK, 1 thousandth, anyway has anyone tried it?

Back to cross drilling - its pretty common from my understanding. My e-shaft oil holes already go all the way through, is this not standard??

 

20mu = 0.0007874 of an inch?

matt

 

Rounds up to 1 thousandth (.001").

Has anyone tried it? RB recommends increasing bearing clearances by - get this - .001", so it's done on both sides of the big puddle.

The oil holes on *my* E-shafts (12A) do not go through all the way.