Is this rotor usable?

[JustJeff]

I bought this and cleaned it up and found what the pics show. Opinions are greatly appreciated

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs929.snc4/74281_1584939177753_1063965498_31517754_577153_n.j pg

http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs576.ash2/149803_1584939337757_1063965498_31517755_6691231_n .jpg

This is my old rotor that I detonated, it seems like it could be in better shape than the one I bought
http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs570.ash2/149201_1584939417759_1063965498_31517756_4587655_n .jpg

[JustJeff]

Seller is replacing the rotor

[rxspeed7]

Good cause I'm pretty sure that is far past the .006" spec for rotor groove clearance.


Zack

[TitaniumTT]

Yeah, that's FUBAR

[JustJeff]

Thanks you guys confirmed what I didn't want to deal with. But the seller is giving me no problems with getting me a replacement.

[rxspeed7]

That's good man. Usually when you cant see a noticeable gap there no good.


Zack

[RETed]

I see no problem using it if clearances are okay, and you're not building a "spec" motor.
You're going to lose a little bit of compression (should be way under 10%, more like 1%), so I doubt you'd feel it (maybe a couple of HP).

The rotor face is machined, so is this a turbo or non-turbo rotor - 9.7 or 9.0?


-Ted

[JustJeff]

I see no problem using it if clearances are okay, and you're not building a "spec" motor.
You're going to lose a little bit of compression (should be way under 10%, more like 1%), so I doubt you'd feel it (maybe a couple of HP).

The rotor face is machined, so is this a turbo or non-turbo rotor - 9.7 or 9.0?


-Ted

It's an 9.0 FD rotor I was going to use it for a S5 13B turbo rebuild. I had considered swapping it into the other housing so that the momentum of the engine would always be pushing the apex seal away from the gap.

I sent the seller a PM with the same pic and he said he'd replace it soon as I got it back to him.

[RETed]

Small cavaet when using FD rotors in an FC 13BT engine...

The FD rotor bearings are different.
I dunno if it's a big deal to you, but the FD rotor bearing groove is deeper than the Kouki FC 13BT rotor bearings.
Also, I think Mazda has like a bazillion different rotor bearing sizes / part numbers for the FD rotor bearing.
The FC3S 13BT rotor bearing only has two - "normal" and "oversized".

Although this should not matter too much for a street motor, but if you're going for big power and or spin over stock redline, this miniscule fact might come into play.

Glad to hear the seller is willing to take care of the problem without much fuss...


-Ted

[JustJeff]

Small cavaet when using FD rotors in an FC 13BT engine...

The FD rotor bearings are different.
I dunno if it's a big deal to you, but the FD rotor bearing groove is deeper than the Kouki FC 13BT rotor bearings.
Also, I think Mazda has like a bazillion different rotor bearing sizes / part numbers for the FD rotor bearing.
The FC3S 13BT rotor bearing only has two - "normal" and "oversized".

Although this should not matter too much for a street motor, but if you're going for big power and or spin over stock redline, this miniscule fact might come into play.

Glad to hear the seller is willing to take care of the problem without much fuss...


-Ted

Thanks Ted, I did not know the bearings were different between the rotors. Though it won't be used for a high HP or RPM engine.

I'm curious on how that damage and gap will effect the actual apex seal. I hadn't considered that it would create compression issues. I had assumed it would effect the apex seals longevity/lifespan. My assumption was that the gap would cause the seal to bend and break...essentially cracking the new seal where the old one detonated. I'd have to think it would be more prone to breaking under detonation on that same spot?

[NoDOHC]

Usability is in the eye of the beholder. If I had the rotor in my hand and I wanted to put an engine together that weekend, I would take a hammer and tap the face of the rotor about 1/8" away from the groove in the place where it was too wide until it was the right width all the way down, then I would use it.

I have done this numerous times with no ill effects at all. A friend who builds more rotaries than I do told me that I could do it, so I gave it a try with great success.

If you are not confident of your machining (or open-die forging) talent, then get a different rotor (as I see you already have).

[RETed]

I've seen worse off rotors than that used in turbo 13B's with no significant problems.

Personally, I wouldn't hesitate to use that rotor (although I'm more of a 8.5:1 junkie :) ) in my engine - take it however you want and standard disclaimers apply here.

Good parts are just getting harder and harder to come by.
The FD is already hitting 15 years old since last production ran.
You tend to get a little looser in your standards when parts start to get harder and harder to find.

The apex seal should have enough support as long as it passes clearances spec.
The apex seal is ductile enough to handle most "normal" combustion loads.
400hp should not be a problem, as long as tuning, fuel, and ignition timing are spot on.
This is assuming at the very least Mazda OEM 2-piece apex seals or better.
Once the motor detonates, all bets are off - you might be a little bit more safety margin from a rotor with better grooves, but IMO it's not that much more than most people think.


-Ted

[JustJeff]

Usability is in the eye of the beholder. If I had the rotor in my hand and I wanted to put an engine together that weekend, I would take a hammer and tap the face of the rotor about 1/8" away from the groove in the place where it was too wide until it was the right width all the way down, then I would use it.

I have done this numerous times with no ill effects at all. A friend who builds more rotaries than I do told me that I could do it, so I gave it a try with great success.

If you are not confident of your machining (or open-die forging) talent, then get a different rotor (as I see you already have).

I'm a little confused but think I'm understanding you. You are saying go 1/8" from the groove and tap it back in?

This is my first rebuild and extensive engine work. I've always been a perfectionist and loose sleep over tiny details. As long as I'm understanding what needs done I'm confident I could get it right...but the idea of taking a hammer to engine parts does seem counterproductive :suspect:

I've seen worse off rotors than that used in turbo 13B's with no significant problems.

Personally, I wouldn't hesitate to use that rotor (although I'm more of a 8.5:1 junkie :) ) in my engine - take it however you want and standard disclaimers apply here.

Good parts are just getting harder and harder to come by.
The FD is already hitting 15 years old since last production ran.
You tend to get a little looser in your standards when parts start to get harder and harder to find.

The apex seal should have enough support as long as it passes clearances spec.
The apex seal is ductile enough to handle most "normal" combustion loads.
400hp should not be a problem, as long as tuning, fuel, and ignition timing are spot on.
This is assuming at the very least Mazda OEM 2-piece apex seals or better.
Once the motor detonates, all bets are off - you might be a little bit more safety margin from a rotor with better grooves, but IMO it's not that much more than most people think.


-Ted

That's an excellent point about the age of parts we are talking about. I had considered that exact thing. Maybe the one I get won't be any better or have other issues the one I have now doesn't have.

I checked clearance on my original rotor. IIRC the difference from the good corner of the apex groove to the bad was like .002 to .003. All I did to test was put corner seals and plugs in with apex seals. First found the feeler that fit the bad corner and slid it towards the good. Then compared that to what I could slid on the good corner.

I did the same for the rotor I bought but for the life of me I can't remember the numbers and didn't write them down. It was better than my old one. I had been planning on checking it again before sending it back. I'll report back once I have those figures.

[JustJeff]

This is assuming at the very least Mazda OEM 2-piece apex seals or better.

I'm a lil confused by the context of this statement. You saying OEM or better apex are good for 400hp. Or that OEM or better in relation to my damaged rotor?

In giving advice about the rotor keep in mind that I'll be using either RA classics or Atkins apex seals. Right now I'm leaning towards RA simply because I've talked to some guys running turbo setups that have been happy with them.

I know OEM are the best choice of the three, but money is an issue. Following the logic I'm going to assume that because I'm not using OEM that adds an extra variable/risk, possibly making the damaged rotor a larger factor? Did I follow that through correctly?

Ted, I thought of something rebuild related, but unrelated to this thread. I'm gonna toss you a PM.

[TitaniumTT]

This is all good info, so post it up as opposed to PM's

As far as the rotors... my feelings, it's obviously damaged, gases are going to get in there and do things that it shouldn't do. The pressures can force the apex seal/corner seal harder into the sealing surfaces than they should and cause accelerated wear... I know someone who tried this by milling gas ports into the rotors. Killed the housings in about 5k from what I understand.

That little imperfection could lead to the seal moving back and forth and wear improperly. Also thinking carbon buildup is going to increase in that area as well.

Regarding the seals... I'm running the RA super seals. When the fuel filter clogged she ran 13.5-13.7 AFR's and 15+psi and detonated for sure. The seals didn't crack, they didn't chip, but they did warp. IMO they saved the engine though.

[rxspeed7]

^I'm totally with you on this. If this is your last hopes for putting the motor together then by all means use it but if you can I know you'd feel better using a rotor you know for sure is good. It's the little things that will always come back and bite you in the ass.

Zack.

P.S. As for me i'm going to be rocking some atkins seals on this motor.

[JustJeff]

This is all good info, so post it up as opposed to PM's

As far as the rotors... my feelings, it's obviously damaged, gases are going to get in there and do things that it shouldn't do. The pressures can force the apex seal/corner seal harder into the sealing surfaces than they should and cause accelerated wear... I know someone who tried this by milling gas ports into the rotors. Killed the housings in about 5k from what I understand.

That little imperfection could lead to the seal moving back and forth and wear improperly. Also thinking carbon buildup is going to increase in that area as well.

Regarding the seals... I'm running the RA super seals. When the fuel filter clogged she ran 13.5-13.7 AFR's and 15+psi and detonated for sure. The seals didn't crack, they didn't chip, but they did warp. IMO they saved the engine though.

I'll create another thread about the PM..make it easier for people to search and find.

You've got good points about added carbon build up in that spot and added wear.

About the detonation...that's what I've read and been told about RA seals. They seem to be more resistant to detonation. I won't be doing Super Seals though. It seems like most of the guys running higher HP and boost are going with the Super Seals. I'm thinking with my mostly stock rebuild and rarely hitting 12psi on my stock turbo I'll be ok with Classics.

I'm curious if you had chatter marks from the Super Seals? IIRC what I read about RA is some chatter marking with the Classics. More chatter marking with the Super Seals.

[TitaniumTT]

I would go for the Super Seals... it only takes one good knock. I would say use the classics in an N/A build, the supers in any boosted engine

Chatter Marks - I didn't have any when I tore that engine apart. I'm also running Idemitsu "fuel lube" being injected through the OMP via the RA OMP adapter and I also run .25oz/gal in the tank. If I'm going to be doing NOTHING but highway driving, I'll knock it in half.

[JustJeff]

I would go for the Super Seals... it only takes one good knock. I would say use the classics in an N/A build, the supers in any boosted engine

Chatter Marks - I didn't have any when I tore that engine apart. I'm also running Idemitsu "fuel lube" being injected through the OMP via the RA OMP adapter and I also run .25oz/gal in the tank. If I'm going to be doing NOTHING but highway driving, I'll knock it in half.

Where did you put the reservoir for the RA adapter? I'm thinking of doing that mod also. I saw a right-up for an FB and the person mounted it to the passenger strut tower. On a turbo I don't think that would be the best location.

[TitaniumTT]

Where the airpump once lived on the FD..... running the REW waterpump.

[RETed]

I'm a lil confused by the context of this statement. You saying OEM or better apex are good for 400hp. Or that OEM or better in relation to my damaged rotor?

Oh boy, this is going to open a big can of worms... :D

I've always advocated the use of Mazda OEM apex seals for anything under 500hp.
They are proven, and other, superior options like "ceramics" are significantly more costly.
I've done a lot of motors with the Mazda OEM apex seals, so I know what they can and cannot do.

Several years ago, they was a proliferation of aftermarket apex seals all touting all kinds of benefits.
Remember Hurley Engineering? Crap. Seals tend to obliterate when pushed moderately. Some people claim these seals did not score housings when they let go, so this was a plus??? *ROLL EYES* You still need to rebuild the motors when seals let go.
Rotary Aviation? I dunno what generation they were on, but the early versions all had problems. Some were too soft. Some were too hard. I've had customer cars who had badly eaten rotor housings prematurely cause of RA seals that were too hard.
(I only kept track of these aftermarket apex seals until about 5 years ago, so some of this info might be outdated.)
It looks like the RA is a little better, but previous experience has left a bad taste in my mouth.
Atkins? Relatively new, but consensus was that you could not use them over 15psi. WTF? I don't like have boost limitations on my motors like that. The relatively low boost level implies these seals are on the softer side.

What I do know as fact...
We sent the Mazda OEM apex seals out for hardness testing, and results were...interesting.
Mazda has long said that their apex seals are electron beam hardened on the leading edge (the edge that contacts the rotor housing).
We found this out to be true.
The leading edge measure to approximately 60C Brinnell hardness.
The "back" side of the apex seal measure to approximately 40C Brinnell hardness.
This expensive treatment of the apex seals were not being done to most of the aftermarket apex seals out there - most aftermarket apex seals were of homogeneous hardness throughout the entire seal.
What does this expensive treatment by Mazda accomplish?
Two things...
1) The leading edge which is exposed to the most abuse (contact with rotor housing and exposure to combustion gases) is more resistant to wear & tear.
2) The back side of the apex seal that sits in the rotor is softer so it doesn't pound the apex seal springs and the rotor groove.
Yes, some of the harder aftermarket apex seals were causing excessive clearances in the rotor apex seal groove over time.
Excessive clearances will cause excessive combustion gas blow-by and, in extreme cases, contact of the rotor apex tips with the rotor housings.

I've had this information posted on my web site for years now:
http://fc3spro.com/TECH/MODS/ENGINE/INTERNAL/ROTORS/apex.htm

I don't have any experience with any of the more expensive options like NRS, Ianetti, or any of those "cermamics".
All of these options are significantly most costly than the Mazda OEM apex seals at around $500 for a set of 6.

Back to the original question...
I set my standard for apex seals with the Mazda OEM units.
Most of the affordable aftermarket apex seals I don't consider equivalent to the Mazda OEM stuff.
Most of the more expensive stuff (which I have zero experience with) is probably better than the Mazda OEM units due to their sheer price tag.


-Ted

[RETed]

As far as the rotors... my feelings, it's obviously damaged, gases are going to get in there and do things that it shouldn't do. The pressures can force the apex seal/corner seal harder into the sealing surfaces than they should and cause accelerated wear... I know someone who tried this by milling gas ports into the rotors. Killed the housings in about 5k from what I understand.

That little imperfection could lead to the seal moving back and forth and wear improperly. Also thinking carbon buildup is going to increase in that area as well.

This is basically the primary reason to worry about clearances.
This is why I mentioned as long as the clearances should be measured.
Pics can sometimes distort dimensions, so it's always prudent to go measure everything yourself.

Side note...
There will always be a little blow-by past the seals.
Anyone who has opened up a high mileage motor (with stock OMP still intact) and checked the rotor apex seal grooves has seen the crap that gets lodged under there.
For the most part, IMO, that carbon build-up is relatively soft.
The apex seal is bouncing up and down in the groove and will most likely just mash all that carbon build-up under it until no more can fit under it.
From my experience, just swapping out the stock OMP with pre-mix greatly reduces the amount of carbon build-up in the engine.
Also, having the fuel mixtures tuned right (not excessively rich) will greatly minimize this carbon build-up also.
At the same time, it's a given that your ignition system be working in top shape to fire off the combustion charge, as misfires are just as bad as a too much fuel.


-Ted

[JustJeff]

Thanks for the posts Ted

I had read your article on apex seals several months ago. In a perfect world I'd go with Mazda seals, BUT I'm already on limited finances from all the bad economy stuff. On top of that I'm trying to get money set aside to start graduate school. I figure now is the perfect time to add some education. There isn't any hiring or moving up going on anyway. Might as well do what I can to pad my resume.

I'll certainly give apex seals some more thought. I suppose I could reuse my pressure plate rather than replace it. Use that money to offset cost between RA and Atkins compared to OEM.

My thoughts on housing wear related to apex seals is that I doubt my housings would be good for another rebuild after this one. So I wasn't as concerned about those. Though I am keeping in mind housing wear and compression.

I hadn't considered wear to the apex groove. I'd like these rotors to last beyond this rebuild.

I took some pics of clearancing my apex grooves. I'll post them up pretty soon.

[JustJeff]

OK...I don't own a dial caliper so this is what I did to compare one corner from the other. Feeler gauges stuck between the apex seal and the groove. I'm sure it's not as accurate as having a dial caliper. But what I was looking for was a comparison from the good end to the bad of the groove.

My old rotor I took to a machine shop and had them measure it. I don't remember the figures and can't find my notes ATM.

I'll be buying a dial caliper tomorrow. The seller seems to be annoyed that I had not measured. I'm annoyed for the obvious reasons.

Bad Corner
http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs467.ash2/74026_1592311122047_1063965498_31528169_3334774_n. jpg

Good Corner
http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs471.ash2/74404_1592311202049_1063965498_31528170_7188106_n. jpg

As a comparison the rotor in my engine when it detonated
Bad Corner
http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs944.snc4/73776_1592310562033_1063965498_31528163_4104138_n. jpg

Good Corner
http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs493.ash2/76679_1592310402029_1063965498_31528161_1422139_n. jpg

[TitaniumTT]

This is basically the primary reason to worry about clearances.
This is why I mentioned as long as the clearances should be measured.
Pics can sometimes distort dimensions, so it's always prudent to go measure everything yourself.

Side note...
There will always be a little blow-by past the seals.
Anyone who has opened up a high mileage motor (with stock OMP still intact) and checked the rotor apex seal grooves has seen the crap that gets lodged under there.
For the most part, IMO, that carbon build-up is relatively soft.
The apex seal is bouncing up and down in the groove and will most likely just mash all that carbon build-up under it until no more can fit under it.
From my experience, just swapping out the stock OMP with pre-mix greatly reduces the amount of carbon build-up in the engine.
Also, having the fuel mixtures tuned right (not excessively rich) will greatly minimize this carbon build-up also.
At the same time, it's a given that your ignition system be working in top shape to fire off the combustion charge, as misfires are just as bad as a too much fuel.


-Ted

I agree 100% Ted, what concerns me though is that a gap like that is going to allow more gasses in there which IMHO will lead to more carbon build-up. Yes the Apex seal moving up and down is going to keep it moving freely, but bad things are more likely to happen due to carbon build up than a rotor without that imperfection. Plus you gotta wonder what happended that caused that and what else was damamged that's not being seen.

As for that carbon, fact of life... I've actually got 2 n/a motors in the shop right now that need to be torn down. One with the OMP, one without. I'll snatch a few pics and post them up. For my engine, even while running spot on (.82L under bull load, .96L cruise) and running idemitsu premix, I was surprised at how much carbon buildup there was in a short amount of time. Granted the buildup was softer and not compacted in there, but I was a little surprised. One more reason I'm going to build my FD around E85.

[RETed]

I agree 100% Ted, what concerns me though is that a gap like that is going to allow more gasses in there which IMHO will lead to more carbon build-up. Yes the Apex seal moving up and down is going to keep it moving freely, but bad things are more likely to happen due to carbon build up than a rotor without that imperfection. Plus you gotta wonder what happended that caused that and what else was damamged that's not being seen.

Ever get to tear down one of those way north of 100k+ mile stock engines still running the stock OMP?
Yes, there is a LOT of carbon under there, but the springs (and seals) all look like they still have full travel (well, not measured, but just an eyeball guesstimate).
I'm talking about side seal springs that are almost welded into place due to so much carbon in the grooves, so when you do pull them out, you swear you're going to snap it into pieces.

I'd figure the premixing has got to help in this case? :D


-Ted

[TitaniumTT]

Ever get to tear down one of those way north of 100k+ mile stock engines still running the stock OMP?
Yes, there is a LOT of carbon under there, but the springs (and seals) all look like they still have full travel (well, not measured, but just an eyeball guesstimate).
I'm talking about side seal springs that are almost welded into place due to so much carbon in the grooves, so when you do pull them out, you swear you're going to snap it into pieces.

I'd figure the premixing has got to help in this case? :D


-Ted

Yup, tore a few down that were north of the 200k mark with the OMP still working and dayum... so yes, I see your point. My concern is, those engines were factory fresh with very tight tolerances when they were first built using all new parts. So, with that gash in there, it's obviously going to let more in than a new rotor. Is it enough gas/carbon to make a difference? I don't know. But it is one of my concerns using that rotor.

On the side seal subject... that's exactely how I lost the first engine after the swap. It was an RE with REW housings. SWEET!!! REBUILT!!!! Comp was 105F/107R so I ran it. The thing lasted 4 hours.... yup... 4 hours before a CARBON LOCKED side seal let loose. I was upping the boost and when the combustion temps/pressures got high enough the seal wanted to move. It couldn't and broke loose wiping out the Apex seals as it went by. Bummer for sure. Upon disassembly it looked like when the engine was "rebuilt" it was just new housings/Apex seals as the carbon buildup on the side seals and oil control rings was out of control yet the exhaust, face of the rotors, were all fairly clean.

Lesson learned.... ALWAYS tear down an unknown engine. It's the only way to know for sure.

[2gslse]

I would think that apex to groove clearance is excessive I checked a set of used rotors and they were .002"-.003"

[NoDOHC]

I think that RETed is correct, that leaner mixes will protect from carbon buildup to a large extent, as will careful selection of engine oil or running premix. I get carbon buildup in my '91 driving around town (where it runs open loop and filthy rich) but it goes away after a long highway cruise (due to closed-loop, stoic fuel mix - or maybe just extended operation). My '86 (which run 16.2:1 AFR (lambda of 1.1) everywhere but WOT) never experiences the carbon-buildup-characteristic knocking that the '91 does (although this may have something to do with the 9ish 7,500 rpm shifts that it experiences everyday on the way to work). My 13,000 mile teardown (which is still a sore subject) indicated very little carbon buildup on the rotors (although they were polished).

[JustJeff]

The numbers are all
FD rotor
.080
.080
.085-.090

What I found after more measuring is that the measurement on the damage varies depending on location along the groove's damage and also how deep I take the reading. Obviously with the damage the edge of the groove angles a bit so that the top is a higher number than the same spot but a touch deeper. At it's worst I found .090. I still haven't looked in my FSM or Haynes, I got home last night and realized I had work to do for this coming work week.

I have the day off tomorrow and am planning to take the rotors to a machine shop. I bought my tool from Harbor Freight and would trust a machine shops tools more.

[TitaniumTT]

The way I measure the grooves is with the Apex seal installed and a feeler gauge. Check out the FSM and report back to us. That will probably give you more of an understanding of the amount of gap. Because you're right, that little bit isn't much for concern, but I bet when you get the seal in place and THEN measure the gap, it'll make more sense.


I'll delete your previous post for you.

[JustJeff]

OK...well it appears I was onto the right idea first time I checked clearance. My first pics are of the feeler gauges on the corners. I put them in angled the top towards the middle as far as they would go. Like I was trying to slide them across the groove.

I checked out the FSM and I think I'll be referring to it more often. My Haynes has a handy page of tolerances but no description on how to go about getting those.

So I've got corner seals and plugs in, apex springs and seals in.

FD rotor on the bad corner
.011-.012-the tip of the feeler barely fits and can't go beyond where the damage is on the edge of the groove.

FD rotor same groove but on the good corner
.005-.006-gets about the same amount of contact...barely fits on the very tip

As far as sliding the feeler gauge all the way to the bottom of the groove. On the corners .002 is the only one that can do that.

I'm probably over thinking this again. But on the corners I can fit the feelers much easier. Probably because my old apex seals are OEM 3-piece. The top half can move a smidge.

With that in mind it seems the groove is within spec...except on the damage. Also the higher clearance is also only at the top where the damage is. The groove isn't uniform. The groove tapers out near the top cause of the damage. Max clearance according to FSM is .059.

[RETed]

Did you change units on us or miss an extra zero?
0.059?
0.059mm?
0.0059"?
:eek:


-Ted

[TitaniumTT]

That's what aI was wondering.....

[JustJeff]

Did you change units on us or miss an extra zero?
0.059?
0.059mm?
0.0059"?
:eek:


-Ted

That's what aI was wondering.....

:lol: Don't read what I wrote, read my mind and what I meant :lol:


FSM max clearance is .0059, but all the other numbers I posted are correct.

But again the thinest feeler gauge that I could slide was .002. That was the thinest feeler I own and moving it was difficult. Once the feeler got closer to the center of the groove it got hard to slide and was likely to tear.

What I noticed on all my rotors both good grooves and bad grooves is that on the corners it was much easier to get thicker feelers in the groove corner but was unable to slide them. Even on the good corners I could get between .005 and .006 into the groove to varying depths. On the damaged FD I just kept going higher and higher with feelers till I couldn't get anything wedged into the groove.

What I found is that the damaged groove isn't uniform. At the bottom of the groove it is consistent with the good grooves. But at the top I have more room as it tapers out due to the damage.

[JustJeff]

Me thinks my perfectionism has overcomplicated this whole process

[TitaniumTT]

No it hasn't. You've got twice the max allowed (per the FSM) clearance at the bad corner.... what does that tell you? It tells me that per the FSM, that rotor is junk.

There have been some great points brought up about reusing them, carbon buildup, reliability, etc etc etc. It's all personal preferance.

Personally.... I wouldn't use that rotor. but that's me. Others said that they have, and have with some degrees of sucess..... It's up to you.

You are forgetting a forth option though........ Get them milled out for 3mm seals.

[JustJeff]

^TTT

My concern regarding the clearance is the difference between the top where the damage is and the bottom where it's same measurement as my good grooves. I don't want to pay shipping back to the seller and have him tell me it's in spec because the bottom of the groove is in spec.

I'm not wanting to go 3mm. I don't live near any rotary shops or machine shops that have any experience with "das wankel" That means shipping two rotors out and back..along with labor costs for milling.

[JustJeff]

Update....seller inspected the returned rotor and has different one on it's way back to me.

[GoopyPerformance]

Hello JustJeff,
Saw your post and photos about your concern with your rotor slots and read through most of the replies on the forum. Here are a few ideas for you and others that have been part of this conversation.

There is obvious damage, but as others have said, you can make it work as many have. However, that damage will contribute to you performing less than optimally.

Agreed, machining to 3mm and using thicker seals can be risky and expensive at best especially given your lack of proximity to machine shop, etc.

What if there were a way to add more material to your slots to fill in the gaps/wear/damage and get your rotors back to factory spec. clearance? That's not really practical, but if there were OVER SIZED APEX SEALS, that would essentially accomplish the same thing ... give you more material to work with.

That is the thinking behind a cost effective solution from Goopy Performance that is inexpensive and requires no special machinery or expertise. Here's how it works.

1. Goopy Performance OVER SIZED APEX SEALS ... for all of the RX-7 Apex Seals that we manufacture. We produce these seals with an additional few thousands of material. So in the example of your 2mm 13B seals instead of being factory stock .115, these seals are .118. By using these seals it is like we just put .003 of new material into your slots.

2. Goopy Performance ROTOR CLEANING KIT ... that includes a high quality flat file that fits into your rotor slots, a .0015 Feeler Gauge (= Factor Clearance), and two stainless steel wire brushes to clean your corner seal slots.

When you try to put the over sized apex seals into the slots they probably will NOT fit, but they will be close. So all that you need to do is CAREFULLY take a few passes with the file on the inside of the slot, keeping the file FLAT and TRUE against the inside walls of the slot and begin to remove some of the rough edges at the top of the slot on both sides.
Do NOT remove too much material at any one time before testing with your new oversized seals again. Probably still doesn't fit but getting closer. Continue to remove material from both sides of the slot and be sure to keep the file FLAT and TRUE against the sides of the slot as you proceed. Remove material along the sides to the full depth of the slot.
Retest and continue to remove old, damaged and excess material until the seals just fit into the slot. Pretty easy, correct?
Now you have another .0015 to go. That is NOT much material so proceed CAUTIOUSLY. Continue to remove material from both sides until you can just fit BOTH the oversized seal PLUS the FEELER GAUGE.
When they together fit perfectly into your slots you now have "FACTORY SPEC" ROTOR CLEARANCES!

No buying new rotors, no machining 3mm slots and hoping your rotors are not ruined, no 3mm seals, no running rotors and apex seals that are way out of spec and leaking compression like and old engine ... just your rotors back to spec!

JustJeff, there is more info. on our web site or feel free to call for assistance.
Reply if you would like contact info., pricing, etc.
Good luck and looking forward to being of help.

Goopy Performance