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infernosg
infernosg Reader
4/7/22 12:33 p.m.

Got this buttoned up a couple weeks ago. I've only run the car twice: once to bleed the cooling system, which didn't involve moving the car, and then to drive to the gas station to fill it up. No obvious leaks, funny smells or unusual noises. Oil pressure with the new setup seems to top out at just over 100 psi indicated. Even when the oil temperature hit 200F pressure was ~85 psi at 3000 RPM (this was observed while bleeding the cooling system). So I'm calling this endeavor a success. Still wish I could have gotten a larger capacity, baffled oil pan but since none are currently available, oh well.

Next event is this weekend! One-day HPDE with the WDCR SCCA at Dominion Raceway on the 9th. Other than the oil system refresh the brakes have been bled and everything given a quick inspection so we're good to go. I'm excited to learn the "correct" line around Dominion after having done several Track Nights there with less direction. Also, there have been some repairs done to the track so I'm excited for a smoother surface. After that it's time for something a little different as I'll be attending the Deal's Gap Rotary Rally for the first time since 2019. It'll be good to meet up with some old friends again.

The only other news is after a two year hiatus my full annual bonus has returned so I was able to splurge on some more goodies for the RX7. A couple more items to bring the tech in the car up to the current decade...

infernosg
infernosg Reader
4/11/22 12:07 p.m.

Dominion HPDE has come and gone with no major issues. The new oiling system seemed to work fine. Dominion is a shorter, tighter track and I'm in 2nd gear for maybe half the lap, so despite ambient temperatures around 60F I still saw maximum oil temperatures around 210F. Oil pressure was ~90 psi and considering maximum engine speeds were 8000-8500 RPM I'm considering the change a success.

I signed up for Saturday-only HPDE. It makes it easier for SWMBO to agree to let me do these things 8+ times a year if I'm not gone all weekend. Single day meant I got four 20-25 minutes sessions. They cut our second session ten minutes short (for lunch, I'm told). Fortunately, the event was MUCH smaller than the NASA weekends I'm used to, so they were able to bake in more time for our third session. ~30 minutes is definitely the longest I've ever been out on track at speed. My arms and legs are feeling it today. An endurance racer, I'm not. While I didn't set a new PB my lines were much better and more importantly, more consistent. Faster lap times will come with more confidence.

Speaking of confidence, something that had been bothering me at VIR, and again at Dominion, was the car's brake balance. I didn't remember having this issue at VIR last October but it was very easy to lock up the rears with moderate brake pressure. I installed a new set of HP+ pads before this season and had assumed this was partially the cause. To combat this, at the advise of my instructor at Dominion, I started dialing up the compression/rebound stiffness (single-adjustable dampers) to try to limit the forward weight transfer under braking. Two clicks stiffer front and rear yielded better results during the second session but it was still easier than I remember to lock the rears. Over lunch I re-read the instructions/guidelines for my suspension and was reminded that I have 24 levels of adjustment between full soft and full hard. Mine were set 8 from full soft. The guidelines for track use say start in the middle and adjust up/down as needed. I'm pretty sure I followed this guidance when I installed these last year and ended up going up two clicks from the starting point since the car felt "floaty" through esses compared to the old setup. So I would have been 14 clicks from full soft last year. I can only assume during my nut/bolt check before this season I backed them to full soft and then cranked them back up to confirm their position. Only I forgot these coilovers have 24 levels of adjustability unlike my old ones, which had 16. I cranked the front and rears up to 14 and immediately noticed a difference. I put down my fastest lap times of the day during the third session. Now I need to refamiliarize myself with the braking threshold.

The only "issue" I had was a broken throttle return spring during the 3rd session. It wasn't a huge deal since I have three: a torsion spring on the throttle body and two linear springs on the bell crank to assist. It was one of the linear springs that broke. I had this happen last year during a Track Night at VIR. It's not really noticeable driving at pace but it can cause the engine to hang between shifts and in the worst case, get stuck at a certain speed. The latter only happens at lower speeds; usually 2000 RPM or lower. The linear springs were added to help close the throttle plates because the torsion spring alone isn't strong enough. I've had this issue with two different throttle bodies from EFI Hardware despite using their "heavy" torsion springs. I don't think it's a cable issue as I've used two different throttle cables and experienced the same issue. I've even cleaned them thoroughly and lubricated with stuff for bicycle cables. Throttle position returns cleanly to 0% with the engine off so I'm assuming engine vacuum/airflow is somehow pulling the plates open slightly. I was able to rig up something for the 4th session but that ended up breaking as well.

infernosg
infernosg Reader
4/12/22 11:51 a.m.

Forgot to bring this up in the last post. I think I might be now exceeding the capabilities of the HP+ pads. I know they're intended to be an autocross pad but they've worked well for me over the past couple of years as a track day/night pad that sees limited street use. After the longer 30 minute session I found my rear pads like this:

Whatever coating/covering Hawk uses is clearly melted and has separated from the pads. It appears I overheated the pads. I didn't notice any obvious fade on track and I've yet to pull the pads to look for glazing. At the advice of my instructor I'm starting to look at dedicated track pads. The goal is something that will last a full season, which is 8-10 weekends a year, that has similar characteristics to the HP+ but with more temperature capability. Sessions are in the 10-30 minutes range. Speed varies from 40-130 mi/hr. "Race" weight is 2500-2700 lb depending on fuel level and who's in it. Power is in the 250 hp range. I don't have any significant aero. I rarely drive the car on the street except for fuel runs, tuning/troubleshooting and the occasional car show/meet. It seems I should be looking at entry-level/light duty track use or endurance pads:

Hawk DTC-60 or ER-1

Carbotech XP-8 or RP2

G Loc R8 or R14

Raybestos ST43 or ST45

Porterfield R4 or R4-E

I know there are others I'm forgetting. I'm most familiar with Hawk's lineup but I'm open to other brands. Most likely it'll come down to price.

infernosg
infernosg Reader
5/11/22 2:41 p.m.

So it's been 4 weeks since the last update. Not really much happened in the meantime except DGRR. It's a different kind of event than my usual track days but it gave me an excuse/reason to detail the car. This was also the first year I trailored the car down instead of driving it. More expensive but definitely the right choice. The rotary rally was a bit more subdued than years past but I still had fun meeting up with friends I haven't seen in three years. Driving the Cherohala Skyway and Tail of the Dragon was kind of a mixed bag. I got a couple good runs in but was frequently plagued by other motorists. I understand, public roads, not a racetrack, etc. but I rarely go more than 10 mi/hr over the speed limit and there are plenty of pull-offs to let faster vehicles go by. I did this myself many times. I was also having intermittent problems with my MAP sensor. Coming down the Cherohala Skyway one time it would randomly bounce between actual engine vacuum and atmospheric pressure. This would cause the ECU to dump fuel into the engine as it was thinking I was at WOT when in reality I was at light-to-medium throttle at best. This only seemed to happen after long periods of deep vacuum like one does coming down a mountain. After stopping for lunch at the bottom I played with the sensor but didn't see anything obviously wrong. Unplugged it, made sure nothing was out of the ordinary and plugged it back in, and didn't have any issues for the rest of the weekend. So I'm not sure if there's an issue with the sensor or somehow the altitude change was causing it. Regardless, I grabbed a new one after the event that I'll be installing before my next HPDE. Since this is becoming a wall of test let's break it up with some photos. Here's a quick shot at te Scenic Overlook at the top of the Skyway (6000 ft):

The hood is up because the car runs hot in these conditions (low speed, high RPM). I think it's funny the car runs cooler on the track than it does on public roads. And some shots from the Saturday car show. First is the "RotorRossa"

I'm pretty sure this started out life as a Berkley. Powered by a 12A with a DCOE carb. I'm not even sure what this next thing was:

Some kind of wild sandrail/dunebuggy thing powered by a turbo 13B. The thing had a massive turbo, eight injectors and was all EFI courtesy of Haltech. Not sure I'd ever want to drive it as the fuel tank was up high hanging out past the rear wheels (the chrome thing in the photo above). If anyone is curious what a side-ported 4 rotor with a massive turbo looks like look no further:

Apparently I neglected to take a shot of the entire car (probably too many people around) but this FD sounded absolutely mental. According to the builders it's "street legal" and the owner wanted to use it for 1/2 and full mile top speed runs. Some other highlights include this very cool RX2 racecar:

And this pretty clean 20B Cosmo:

I really want to own one of these some day and is one of the few cars I'd consider selling my SA for. I just like the idea of having a big, comfy cruiser the whole family could ride in. I think these cars, with the OEM body kit, a slight drop and some tasteful wheels look amazing. I managed to pick up honors for best FC (second generation):

There wasn't a huge turnout of this body style but I'm always flattered by the compliments this car gets. The big turbo cars always seem to get all the attention and everyone is always surprised when I show them my car is still N/A.

I'm hoping I'll be able to make it again next year. If so, I've already made up my mind that I'm bring the first gen. I think it's just better suited to this kind of event than the FC and I think a lot of people would appreciate seeing a clean, stock SA.

Jumping back to the MAP sensor for a bit, I'm now wondering if it was the reason the car was running poorly a while back before the last Dominion HPDE. I was on my way to fill up the car when I got stuck moving behind a slow moving construction vehicle. I didn't look at the MAP value but the feeling and situations were similar - going downhill under heavy vacuum for a while followed by the car generally running like crap. I assumed it was just the car running low on fuel (light was on) because once I filled up it didn't happen again. I had another, similar situation when I was playing with ECU grounds. Without going into detail I tried something different with the ECU grounds based on Haltech's recommendations for the Elite since I had to make some compromises as I'm still using my original Platinum Sport wiring harness. I assumed the poor running was the result of moving grounds around because the car was running very rich but again, I didn't note the MAP value. Only difference that time was no extended driving in deep vacuum. It definitely seems like something wonky is going on with the MAP sensor. I'm hoping it's just a dying sensor as I do have a replacement. I'm not intimately familiar with how they work but is it normal for them to lose all resistance (i.e. always output 5V) when bad?

In other news I'm still waiting on my new dash (Haltech IC7) and wideband controller kit. I guess the chop shortage has hit the aftermarket ECU industry as well since both of these are backordered. The last update was an expected 5/20 ship date so we'll see. I really want to upgrade to the newer and faster LSU 4.9 sensors and free up inputs with the CAN setup and running fuel level directly to the display. My goal of DWB is getting closer. I've also started looking at PWM-controlled, brushless cooling fans. My current fan suffered some damage when my trigger wheel exploded at VIR last October. While it appears to be working fine (just the shroud is broken in places) I'm worried Tech might take exception with it at some events. I have open PWM outputs available from my ECU and I like the idea of "soft starts" and being able to control fan speed based on engine temperature. Been looking at 16" fans from SPAL and DeltaPAG. I haven't heard of the latter until recently but they're advertising slightly more flow, less current draw and with a slightly lower price point than the SPALs. They even have a 18" version (my core is ~18" x 20").

Up next is a one-day HPDE with the SCCA at Dominion again on the 21st. Need to bleed the brakes, install the new MAP sensor and give the car a quick wash before re-applying my numbers and I'm good to go. After that I've signed up to run with NASA at Summit Point the end of June. For that I ended up signing up for HPDE2 since 1 was full. I asked if I could register for 2 given my experience and they agreed.

wvumtnbkr
wvumtnbkr PowerDork
5/11/22 3:17 p.m.
infernosg said:

Forgot to bring this up in the last post. I think I might be now exceeding the capabilities of the HP+ pads. I know they're intended to be an autocross pad but they've worked well for me over the past couple of years as a track day/night pad that sees limited street use. After the longer 30 minute session I found my rear pads like this:

Whatever coating/covering Hawk uses is clearly melted and has separated from the pads. It appears I overheated the pads. I didn't notice any obvious fade on track and I've yet to pull the pads to look for glazing. At the advice of my instructor I'm starting to look at dedicated track pads. The goal is something that will last a full season, which is 8-10 weekends a year, that has similar characteristics to the HP+ but with more temperature capability. Sessions are in the 10-30 minutes range. Speed varies from 40-130 mi/hr. "Race" weight is 2500-2700 lb depending on fuel level and who's in it. Power is in the 250 hp range. I don't have any significant aero. I rarely drive the car on the street except for fuel runs, tuning/troubleshooting and the occasional car show/meet. It seems I should be looking at entry-level/light duty track use or endurance pads:

Hawk DTC-60 or ER-1

Carbotech XP-8 or RP2

G Loc R8 or R14

Raybestos ST43 or ST45

Porterfield R4 or R4-E

I know there are others I'm forgetting. I'm most familiar with Hawk's lineup but I'm open to other brands. Most likely it'll come down to price.

We run hp+ on the rear of our endurance racing rx7 with a v6 swap.  That coating is just paint and usually burns off.  

We run hp+ in the rear, because anything more aggressive and the rears lock.  A lot!

We run hawk blue or er1 on the front.

AMiataCalledSteve
AMiataCalledSteve New Reader
5/11/22 3:30 p.m.

Wow, an amazing collection of cars on some great driving roads. I haven't actually driven the Dragon myself, but there's all sorts of great routes in the NC mountains. I'm glad there are so many rotary enthusiasts in such an eclectic assortment of cars, it's always cool to see something out of the ordinary.

infernosg
infernosg Reader
5/12/22 10:06 a.m.

In reply to wvumtnbkr :

That's pretty much what the guys at Hawk recommended once they got back to me - stick with the HP+ until I start to notice some fade then jump to a full-fledged track pad in the front like the ER1 or DTC60. The guys at G-Loc recommended a similar route but suggested I jump to track pads front and rear: R10 up front and R6 in the rear. I will say stiffening up the fronts has helped significantly but I don't think it's going to eliminate early lockup in the rear completely so the need for a less aggressive rear pad or adjustable brake bias is clear.

infernosg
infernosg Reader
5/12/22 10:09 a.m.

In reply to AMiataCalledSteve :

DGRR always brings out some interesting vehicles. There was also an original NSU Spider there but apparently I neglected to photograph it. Some people really like to push it on the Dragon but I get my fill of aggressive driving on track so I usually just take it easy. That's why I think I'll take the first gen next year. It's a much better "weekend driver" car than the FC even though the latter always gets lots of attention.

wvumtnbkr
wvumtnbkr PowerDork
5/12/22 1:23 p.m.
infernosg said:

In reply to wvumtnbkr :

That's pretty much what the guys at Hawk recommended once they got back to me - stick with the HP+ until I start to notice some fade then jump to a full-fledged track pad in the front like the ER1 or DTC60. The guys at G-Loc recommended a similar route but suggested I jump to track pads front and rear: R10 up front and R6 in the rear. I will say stiffening up the fronts has helped significantly but I don't think it's going to eliminate early lockup in the rear completely so the need for a less aggressive rear pad or adjustable brake bias is clear.

What front pads are you running?  

 

The 2nd gen rx7 absolutely requires a less aggressive pad in the rear (for track work) from my experience.  (I've owned 8 of them).

 

If you are running stock type pads or hp + in the front, then yep!  The hp+ are gonna lock up in the rear.

 

Hawk black is not a bad step up for the front if running hp+ in the rear, however, a full on race pad up front will ensure no rear lockups.

infernosg
infernosg Reader
5/13/22 11:02 a.m.

In reply to wvumtnbkr :

Running HP+ in the front as well. The plan is to just deal with these pads for this year/season since they're still relatively new. Only 3 events on them so far. If I do happen to get significantly faster and fade and/or lock up becomes a real issue I'll upgrade. I've been sitting on a new set of rotors while I figure out what to do with pads. My biggest concern about going up to race pads, be it Black, Blue, DTC60, etc., is being able to properly bed them in. Internet wisdom says they'll need much more heat in them than I'll be able to generate while driving irresponsibly on back roads. I really don't want to have to waste a HPDE session.

Sonic
Sonic UberDork
5/13/22 11:31 a.m.

You can get enough heat in track pads to bed them in on the street.  I did it recently on our Mazda3 with Raybestos ST45, 10 quick runs from 60-10 back to back gets them hot enough.   Would recommend strongly the ST43 for your use, they are excellent.  Easy to modulate, zero rotor wear, we usually get 3+ endurance races of life. 

infernosg
infernosg Reader
5/13/22 2:10 p.m.

In reply to Sonic :

Good to know. I have a good number of nearby rural country roads where I can easily hit 60 mi/hr without having to worry about potential law enforcement issues. Getting 10 runs in quick succession could be a challenge though.

I've read nothing but good things about the ST43. I just didn't see an obvious, lower friction track-specific option from Raybestos for the rear. ST31, maybe? Nothing says I have to run pads from the same manufacturer front + rear, though. Assuming I stick with tracking the car I can see this being a multi-year experiment. Hawk this year, G-Loc next year, Raybestos after that, etc. For now HPDE is fulfilling enough so I imagine I'll get at least a season (8-10 weekend events) out of each set.

dannyp84
dannyp84 Reader
5/24/22 9:59 a.m.

What I wouldn't give for that RX-2! Infernosg when you were setting up your car were you able to find definitive information on which Mazda ring & pinions interchange with the n/a FC? I just picked up a '91 vert and the gear ratios seem awfully long for an n/a rotary.. even with 4.1 gears.

infernosg
infernosg Reader
5/24/22 1:02 p.m.

In reply to dannyp84 :

The easiest answer is any ring and pinion set from a naturally-aspirated 2nd generation car is interchangeable. They only offered 3 ratios from the factory: 3.909 (automatic convertible), 4.100 (everything else except GTUs) and 4.300 (GTUs - that's the trim, not the plural of GTU). Mazda Motorsports used to sell some shorter ratios. A 4.7x or 4.8x and a 5.1x set. NLA. The ring gear diameter is actually the same later FBs and Miatas. The issue is the pinion gear. For a while you could get the shorter ratios by taking a Miata ring and pinion set, the stock RX7 pinion gear, cutting off the ends of both pinion gears and welding the Miata gear to the RX7 shaft. It doesn't look like anyone is offering that service anymore.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
5/24/22 1:20 p.m.

FWIW, all autos got the 3.91, not just convertibles.

Sonic
Sonic UberDork
5/24/22 1:42 p.m.

In reply to infernosg :

We use Porterfield R4E pads in the rear with ST43 up front to get the balance you're looking for.  Bonus that they are cheaper too.  They seem to wear a little more quickly but are just as rotor friendly as the ST43.  

infernosg
infernosg Reader
5/24/22 1:44 p.m.

Unfortunately, I killed the car at Dominion this past Saturday. Despite temperatures nearing 100F the car was running well and I was already running at my fastest pace from back in April. Let's start with a quick picture of happier times.

Clear, sunny day. A little hot but there's a steady breeze in the paddock. What could go wrong? After the second session we took a break for lunch so I headed up to the nearest gas station for a bite and to top off the fuel. On the way there I noticed the car sounded strange and was running poorly. Felt like a constant misfire. I thought I felt something during the session while accelerating out of the last corner onto the front straight but I didn't notice the car driving any differently at speed. The miss didn't go away after lunch so back at the track I pulled both leading spark plugs and cranked over the engine. I was getting three solid puffs from each rotor but knowing I can't reliably spin the engine fast enough by hand I started asking around for a compression tester. Fortunately, I found one and a willing helper to crank the car over while I watched the gage. With the rotary engine and this tool I'm just looking for three even pulses while I hold the Schrader Valve open. Start with the front. Helper cranks the engine with the throttle wide open. 60 psi, 60 psi, 60 psi, etc. Good. Yes, that seems low but you don't get accurate compression numbers from a rotary with standard compression tester. On to the rear. 60 psi, 30 psi, 30 psi, 60 psi, 30 psi, 30 psi, etc. CRAP! Low compression on two faces usually means a bad apex seal. Even though the car still starts and runs alright I don't risk further damage and call it. Event over after 2/4 sessions.

Back at home I get the car into the garage and decide to reconfirm the test at the track. With SWMBO as the helper I get the same results. DAMN! I've got a couple hours before I need to return the trailer to U-Haul so I dive right in. First let's look at those plugs. These are factory RX8 plugs about a year old and maybe 1500 miles on them.

Wait, what's going on with the leading plug for the front rotor? Let's take a closer look.

There's no electrode! That would explain why the car was running like crap pulling it off the trailer and into the garage. The front rotor was firing on the trailing plug only (about 15 degrees later). Now I don't remember seeing this at the track when I pulled the plugs. Did I miss it? Did I get the plugs swapped around and this was in the rear? A broken electrode going through the engine could certainly trash a ceramic apex seal. So many questions! Unfortunately, I don't think this is the root cause. As I was playing with the other leading plug its electrode also fell off! I've never seen anything like this but I did find some comments online from RX8 owners who track their cars with similar experiences. Still not sure of the failure mode here. Plugs get too hot?

Over the next hour or so I get most of the engine peripherals off. Need to stop and return the trailer and SWMBO wants to go out to east. Maybe sushi will make me feel better. Thus ended Saturday. Sundays chores took up most of the next day but I was still able to drain the oil and coolant and get down to the bare engine. Since there's wasn't enough time left to prepare to pull the engine I decided to bust out the USB borescope and shove it in the rear exhaust port while I slowly turned the engine. Hopefully I'd see something obvious and I could get an initial impression on the condition of the rotor and housings. Here's shots of all three apex seals.

I also took a ~3 minute video but I'm not sure how to upload it here. Oddly, all three look pretty good from what I can see. Even the rotor and housings look pretty good. This makes sense since the engine still turned over easily and without any weird sounds. Usually a broken ceramic seals means instant death for the rotor, the rotor housing and both adjacent side housings. Not the case here. There might be some wear in the center but comparing it to the front rotor doesn't show much of a difference. I think it may be slightly more wear in the center from where the seal rubs over the spark plug area. That's a known hot spot. If that's the case I'm incredibly fortunate nothing broke.

Yesterday I dug the engine hoist and stand out of storage and assembled them. After that things escalated quickly.

If given an unobstructed day I could go from running car to completely disassembled engine in a day. Well, maybe, assuming the flywheel nut cooperates. That usually takes some penetrating fluid, maybe some heat and lots of pounding and swearing to break loose. Here is where I stand as of last night.

Water pump, clutch, engine mounts, etc. have been removed. Basically down to the short block. Next step is to flip it over and pull the oil pan. Then off comes the front cover and underlying assembly. Then I get to tackle the flywheel nut before finally pulling all the tension studs, which allows me to de-stack the engine. I'm hoping to have everything down to individual pieces in the next couple days so I can spend the long weekend cleaning and inspecting everything. I'm signed up for HPDE with NASA at Summit Point 6/25-26 and I'm really hoping I can have this back together and running by then.

fidelity101
fidelity101 UberDork
5/24/22 2:24 p.m.

apex seals intact? and the plot thickens...

dannyp84
dannyp84 Reader
5/24/22 3:04 p.m.

Would a single corner seal failure cause a compression reading like that? Also is it a possibility that one of the seals is just stuck down against the spring, like compressed when it shouldn't be? I remember reading that one of the issues with the RX-8s not starting when they were otherwise healthy motors was that the apex seals would sink down into the groove of the rotor and not create enough compression till you cranked the starter forever or used some ATF to simulate compression till the engine fired and the seals slipped back in place, but this could all be rumor. 

Fingers crossed that when you unstack, both the housings are still in good shape and that spark plug electrode blew out the exhaust without scraping things up. Also, I didn't realize you had ceramic seals, the champagne of apex seals. 

infernosg
infernosg Reader
5/25/22 1:05 p.m.

In reply to dannyp84 :

Failed corner seal and/or corner seal spring is one of the theories. Another is a failed apex seal spring. Both would cause low but not zero compression across two faces like I'm seeing. I don't think anything is stuck that would un-stick itself without disassembly, though. I had the car running a few times and even gave it a few revs and nothing changed. Either of these theories proven correct would be awesome.

infernosg
infernosg Reader
5/25/22 1:15 p.m.

Made a little more progress last night. I managed to get the flywheel nut off without much fuss for once. Usually it takes me a couple days soaking it in penetrating fluid and beating on it. Some Kroil and a little bit of heat does wonders, I suppose. I've got the engine down to the bare keg. The next step is to start cracking the tension studs loose.

I figured this was a good point to stop and get myself reorganized. I have limited work space in the garage and at this point I had parts and hardware all over the place and my bench was a mess. So rather than start disassembling the engine I started cleaning various bits and organizing them into bags. In the pictures above you can see I've also started scraping old RTV off various surfaces. I figure it's easier to do this now when it's one piece instead of 6. I've got a few more things to clean up and organize but I should be able to open the engine tonight. Hoping to finally find the root cause!

WondrousBread
WondrousBread New Reader
5/25/22 1:18 p.m.

Sorry to hear about the engine. That spark plug failure is interesting though. I'll stay away from Rx8 plugs; the Rx7 ones just have the center electrode.

 

I also took a previous engine apart with a similar failure - slight high spot on the apex seals, all seals present and looked okay otherwise, but the compression test showed 80-10-80-10-80-10. Never did figure out what caused that.

infernosg
infernosg Reader
5/26/22 11:52 a.m.

WE HAVE ROOT CAUSE!

More on that in a bit. Time was limited last night so I only managed to pull the rear side housing and look at the rear face of the rear rotor.

Turns out, that was enough. See it in the picture above? Let's take a look at that top-right corner seal.

That doesn't seem right. Compare to the other two, which look like this:

Let's grab the springs and take a look.

Can you guess which spring went with which corner seal? So crushed corner seal spring it is! I'm not sure what causes this and more importantly, why it happened to only one spring. To flatten a spring you need it to yield in compression. Usually through a combination of force and heat. This almost looks like creep. An effect where something exposed to elevated temperatures over time can plastically deform despite stresses below yield. So the good news I know what went wrong. The bad news is I don't know what caused this so I can't address it in the future. This will be especially important if I find the corresponding spring on the front of the rear rotor is also crushed.

Also took some time to inspect the rear side housing.

Other than being dirty it looks good. The lapping marks are still present and I don't feel anything with my fingernail. The one thing I did find that slightly concerns me is the rear stationary gear bearing. I can see copper on a small area near the rear.

No discernable grooves or wear that I can feel and nothing looks flaked off. I don't have the proper tool to measure the ID of the bearing to check the clearance between it and the eccentric shaft, though. I kinda want to use as is and send it. Bad idea?

Teardown will continue tonight. I need to come up with a method to keep all the seals organized since I plan on reusing them all and I want them to go back in the same places.

dannyp84
dannyp84 Reader
5/26/22 2:12 p.m.

At least no damage to the housings or irons! I'd be curious as to whether some carbon build up was creating a hot spot at that corner damaging the spring or something. I'd be curious to ask Logan at Defined whether he's seen that before. Maybe have a look around for the tool to measure your bearing ID, just to avoid taking the motor apart again in the near future.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
5/26/22 6:11 p.m.

Heat kills them.

My corner seal springs always look like that after a while.  I would double check the apex seals to verify none cracked or warped, just to be safe.

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