Measuring my rotors, irons and housings
 

Hi guys,

I'm actually measuring all my internal parts to know if they are reusable.

Bought a straight edge, feeler gauges, dial indicator set (with magnet)... And I just saw at TurboRX7.com > Criteria For Replacement of Rotary Engine Parts that I need much more.

Vernier caliper
Micrometer 25-50mm
Micrometer 50-75mm
Micrometer 75-100mm
Inside micrometer 25-50mm
Inside micrometer 50-75mm
Bar limit gauge (TKK special tool No. 49 0839 165, MMA No. 4908 39 1650)
V-Blocks

Why I never saw these tools on the forum? Do you guys really use these to rebuild your engines?

Be honest, please.

Thanks!

Hmmm...

I thought it was a pretty easy question to answer...

I used all those besides the bar limit gauge and inside micrometers. I used t-gauges and regular micrometers instead of the inside ones.

Im no expert though, I just watched the dvds and read on the forum.

You don't need all that but it would be nice to have. Feeler gauges, straight edge, micrometer, dial indicator with magnet are a must. Buy a digital caliper from harbor freight. They also have Digital micrometers. Those tools work fine.

The first time I use parts (new or used) I do give them the full measuring regime as per factory manual. What a pain.

I borrow the big outside mics and inside mics when I have to do this (bring parts and notepad to mics instead of other way around and people are more willing to loan their use).

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For a regular rebuild using the same parts it is more of a visual inspection and measuring the parts that can wear, warp or become loose.

Then, for the rotating assembly I do only measure the e-shaft run-out with v-blocks and dial indicator.

I do a visual on the e-shaft journals and bearings.
If the bearings are good there isn't a problem with journal or bearing.
If the e-shaft journals aren't perfect I toss it because they are dime a dozen.

If I replace bearings I always use the largest size available or competition bearing/size and flap down the high spots after pressing them in.

So, I avoid the inside and outside mic use there.

I measure side housing step wear with the dial ind mic and flatness with the bar and feeler gauge.

I measure all seals and seal grooves as per manual.
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So far this hasn't bitten me in the butt; however, these are engines that I am racing and are failing catastrophically from some peripheral component failure or other. I am not building engines to drive 200,000 miles.

Brand new engine will always be best value for that use, but kind of a waste if you know the engine will die from some engine peripheral component failing.

Thank you guys. Where did you get that bar limit gauge BLUE_TII? Just went to NAPA and Mazda and they can't find it.

Oh, I never ordered that from Mazda- but that is where I would get one.

I use a new Mazda corner seal and make sure it can pop up back with spring behind it, but has no side to side wiggle when all the way down and very little wiggle when halfway in the bore.

I have "adjusted" the corner seal bore when I wanted to re-use damaged (not worn out) rotors with a hammer and file (and then fix the side seal slot). That is a real pain!

At IRP we measure everything. Most of the measurements you will be making are in thousandths of an inch so you need good quality instruments that are properly maintained and calibrated. Most of out calipers and micrometers are Mitituyo. Out feeler gauges are Snapon. Our rotor files are manufactured buy Grubet. We also have a large amount of oem SST tools. This is one area where cheap tools won't cut it in my opinion. If you are doing this just once it may not be cost effective for you to buy all the necessary tools to do a proper build and may be cheaper to have a professional do it. You really shouldn't be re-using any internal seal, spring, gasket, or bearing in my opinion. Even if they are within spec for wear you can't measure the countless heat cycles they went through.

Well thanks but I ordered all the tools now, except the bar limit gauge. The gauge is over $600 at the dealership. What's your alternatives to measure the corner seals slots?

given the condition of most of the motors i see coming in i am not surprised that many rebuilders don't either possess or use the proper spread of measurement tools.

if you are either re-building your own rotary or a shop doing multiple engines you will need to either buy or borrow certain tools.

4 accurate digital micrometers are essential.

i see very little mention of width measurement of rotor housings. this is the first item on my CPR 6 page specification sheet that is generated from every incoming and outgoing (built) motor. it is also worth noting that rotor housings are sold in the classifieds apparently without any thought as to width.

as housings heat cycle throughout their life the unusual heat dispersion (cold at the top, hot near the bottom) impact the aluminum. if the width of the housing at certain points grows to .0024 or more the housing will tend to displace the coolant seals and you will be back to calling your engine builder.

approximately 10% of the housings i see fail. you need an accurate 3 to 4 inch micrometer.

in addition you will be using it to spec the rotor thrust width and relate it to the housing width to calculate rotor clearance.

a 2 to 3 inch micrometer is essential for crank journals and reads the rotor bearing off an inside bore gauge.

a 1 to 2 inch reads similarly re main journals.

a 0 to 1 reads the thrust bearing spacer for endplay.

a dial indicator reads endplay.

apex seal to groove clearance generally sucks on used motors... generally at .004 plus in the center of the apex seal groove and around .006 on the outer sections.

you have only three options if you are going to build a proper motor. a new(er) rotor w proper spec grooves, mill to 3 mm (20th century tech like a dial phone) or fit a Goopy .004 over standard sized 2 mm seal. in order to do this you will need to invest 2 to 3 hours filing the groove and the corner seal slot.

and you will end up w .002 clearance:)

just scratching the surface but the overall message is you can build a motor in a very short time or spend lots of time.

both will look the same until you turn the key.

Howard

That's because most "builders" neglect to take the time to inspect and measure everything as it is supposed to be. Here we have an entire cabinet dedicated for tools just to measure and clearance motors. And then people wonder how they are doing rebuilds for $1500 when parts alone cost more than that.