Tales from the Batcave (RX-7, rallycross, misc. stuff content)

So.  I had an interesting Saturday leading up to the rallycross, which is really deserving of its own thread.  Call it an object lesson in humility.  For now, I learned some important lessons regarding tuning and realized the true cause of some of the hot or cold issues I'd been having.  But on the bright side, the engine stayed below 190 on the highway despite the high temps, so the lower nose is helping shovel air through the radiator.

Sunday, I'm following Evan and his trailered Miata to the event.  We get on 270, going about 55mph.  55 is kind of an unhappy speed for my driveline, but not awful.  The road is syncopatedly lumpy, though, and it's matching some resonant frequency in my car/trailer equation.  I'm watching my tires getting airborne maybe twice a second, like they're on a trampoline.  Then I start to hear a squeak with every bounce, and visions of the trailer tongue separating from the rest start filling my head, and I say berk it, I know where I'm going, and haul ass past Evan.  Everything smooths out at.. uh... over 70.

Turns out I didn't know where I was going.  Evan went down I-71, I went further around 270 to meet Route 23.  Oh well, I guess I know where I am going?

Halfway down 23, I'm pulling away from a traffic light and think, huh, seems like the exhaust is a little louder.  Then on the next upshift the muffler falls off.  I don't hear too much scraping, and it's not like I can do anything anyway, so I press on.  Eventually I come across a plaza with a Rural King and an auto parts store, so I pull off to find that they were not open at 8am on a Sunday.  I take advantage of the stop and check out the damage: the muffler is still on its rear hangers, the tips are levered against the bumper.  Ratchet strap the front of the muffler so it can't hit anything and keep truckin'.  Hey, at least I'd identified the squeak, it was the pipe failing.

At the rallycross.  Much to Josh's relief, the helmet mount for my GoPro broke while I was running to Ed's WRX for a ride along on the parade lap.  I gridded my car last so I could get enough time to run to my trailer and get the suction cup mount.

Verified that there were no locals to annoy and that sound regulations were not in place.  We are go.  Sorry, corner workers,  Once again back is the incredible

Car feels... good.  The lack of midrange torque sucks, to be sure, but with the 4.44 gears I could use 1st a little more, and this engine defintely pulls like a freight train over 7000rpm.  But the steering and front suspension!  The front end has good bite and it doesn't seem to wallow in a hole when cornering and hitting a bump.  I'd love to have played with shock adjustments but the screwdriver that I used to have in the glovebox was missing.  As it is, it feels like I can get away with more bite in the rear now that the front is working.   After four runs, I heard a funky rattle, and saw that the remaining exhaust hanger fell off.  8 feet of heavy wall exhaust was hanging off the engine.  I opted for a bogey time instead of risking the rest of the exhaust.

On lunch, I stole a washer from under my strut tower and reinforced the single-shear exhaust hanger, and went in for five more runs.  Competiton got the better of me   Gave Orion a ride in the car for my first afternoon run, since he'd never rode in the car before (after how many years???).  After the flick-turn at the bottom the hill, all the way up around the corner to the first F.U. slalom, I had the throttle pinned and the car sideways.  Never could do that before.  So, of course, on my second run (this is the "throwing horns" video linked above) I tried it again, and as it turns out the car accelerates a lot harder with only one person in it and I ended up going way screwed up through the slalom.  My fastest runs were taken with less throttle and more neat driving, which is not as fun and also not as easily controllable, so for my last couple runs I went into full BTTW mode again.  Which bit me in the ass on my penultimate run, when I found a slick spot in the final sweeping corner and nearly looped it and/or missed the finish gate altogether.

Not quite enough.  BUT I do know that I'm on to something, the stockport is not the end of the world competitiveness-wise, and I can probably pick up some more speed if I got the rearend to grip more so I could really throw it into corners.  John W. might find and remove the cone magnet in his Miata, though. 

Then it was a quick (ha!) limp back to Evan's to try to weld the muffler back together enough to make it the rest of the way home.  I left his place at about 8pm.  I got home at around 1am.  I had to nap a couple times along the way because I was simply dead tired.  There was no way in hell I was going to make it to the Batcave to collect teh R before getting home, so I opted to just drop the trailer in the backyard and drive the RX-7 to work on Monday.

Monday.  Woke up late for work, hauled all the ass going in to work - speedo was reading 90, which is a lie, but also an indicator of driveshaft speed, and did I mention that I have the pinion angle set so that everything is happy when towing a trailer, but it gets a little unhappy when unloaded?  But it didn't shake too badly so, hell, we got to go to work.

During lunch, went to order a new muffler from Racing Beat.  Still on mega-backorder???  I called Mazdatrix, and spoke with The Man himself, Dave Lemon, who answered the phone because everyone else was busy.  Yes, they have an '81-82 Power Pulse muffler in stock.  They even will ship to a different address from the billing address now!  I gave him my billing info and, $430 later, a muffler was placed into UPS's clutches.

On the way home, it felt like the world ended after a 2-3 shift.  Any acceleration at all felt like the car was going to disassemble itself.  At this point I was only barely more conscious than your run-of-the-mill zombie, so I had two options:

1. Limp the car home, leave extra early for work since I couldn't go over 50mph, and cross fingers that I actually made it there, or

2. Limp the car home, hook up the trailer, drive 30 minutes to the garage, switch cars, drive back home, fall asleep standing up in the kitchen

I opted for the second option.  I really had no motivation to do anything but sleep, but I did reach under the car and wiggle the U-joints.  Tight.  Crap.  This means either the trans exploded (no big) or the rearend is coming apart (big).   I did think the pinion bearing sounded a little different... but there was no discernible play.

Tuesday, woke up REALLY late for work, went straight home after.

Wednesday, spent quality time on the RX-7.  Checked over all the welds in the floor and on the rearend for any surprise pinion angle changes.  Everything seemed okay.  No large puddle of fluid under the trans, either, which was a good sign I suppose.  Saw that the muffler was starting to come apart again, felt relieved that I didn't just waste a crapton of money on a muffler I didn't quite need yet.  Grabbed the U-joints again, all is fine.  Grabbed the front driveshaft yoke...

Yep, broke a cap.  That'll do it.

Now, if you notice, the U joints are staked in.  Nonreplaceable.  On Thursday, I checked out car-part and 83-85 RX-7 driveshafts are not all that common anymore.  I can go to Michigan or PA for one, it looks like.

Dorman makes one, for $350, but they are apparently built to suit, and I'd get it roughly when I would need to be in Ross County again. Plus, $350.

I went to call a local driveshaft shop to see what they could do, figuring if they also made the driveshaft a half inch shorter I could move the rearend forward where it is supposed to be... but they JUST closed down for a move and won't reopen until June.

One more option: I could try to replace the U joint myself.  This is nontrivial since the cups must be precisely located to prevent vibration.  I have driven rebuilt driveshafts that shook horribly, and don't want that to happen.  But it looks like it will be my only choice for a while.

Also, hey, learning experience.

Today:

I got a box.

Interestingly, it doesn't collect before the inlet anymore.  Not sure if this is good, bad, or indifferent.  It is also made of thickwall stainless instead of thickwall mild.

Since everybody decided to watch John Wick, I decided to work on the RX-7.

Driveshaft is still a head scratcher.  The new muffler is still safely in its box where it probably won't break.  So, let's attack the mess of rear floor that I loosely bodged together nine years ago and promptly ignored.

That's the fuel pump connector.  That looks.... ugly.  And the two housings are melted together.  Maybe this is part of my fuel pump overheating problem.

Anyway, back to the floor.

The upper deck is basically broken where the two chunks of angle iron welded to it.  All this has to go.  I cut the angle iron and then levered out the booger-welded 26 gauge sheet that sort of filled the gap

Did some more trimming of waste, and marked up a straight line from the link mount...

Then did what I should have done in 2010 and made a 16 gauge sheet to go from here to there.

Welding to Mazda Mystery Steel with flux core wire well and truly sucks.  I really need to get a gas bottle.

Total time spent, just over two hours, including partially disassembling the rear suspension.

I feel dirty.  Here's what I did yesterday.

Aaaand...

REALLY need to get the fuel tank situation sorted for the '81 so I am not tempted to borrow parts from it like this.

Took a super rare and impossible to replace RX-7 part today and sliced it up with a grinder.

It's all because I realized Leon's in my class now and I need to step up my game.

Don't get too intimidated. I will probably get NO practice in the car before the event. I have been running FWD all these years and have no real RWD experience in RX. Just getting it assembled and all working in time is going to be a challenge. You've got a lot of time in that RX7 and so it's going to be at least sorted out. I am hoping for wet events as that should slow down Brianne and help me with the weight distribution advantage.

In reply to RallyCaddy :

All maybe true, but you have a lot more fabricating talent and resources than I could ever hope to have.  And my car is definitely not "static"... it goes through regular suspension and drivetrain changes as I alternately chase some issue I think it has, or need to engineer my way around a part that is too difficult to source.  And I think I have driven it four times in the last three years, the rest of the time was spent driving the S40 or the S60 or other peoples' cars (front, rear  or all wheel drive)

My car does have a something like 47/53 distribution, more if I remember to fill the fuel tank before the event.

New U joint was the wrong one for the driveshaft, so that is a total nonstarter.  Really annoyed.  But I did have a productive day at Evan's place using his grinder and welder, at least.

Volvo is setting a P0throttlebody.  Lovely.

(It's been throwing the cat code for a couple months, now, I will probably fix with a 3" downpipe)

Henderson doesn't rebuild driveshafts, they make new ones.  If I will have one made, I'll swap that Mazdafied flange for a strap type one and move the rearend back forward.  For now, I will see if a 79-82 U-joint will fit.

Started on side 2. I cut out the ugliness and realized that I needed to make way for the Watts to clear.  So, I yanked the wheels and popped the springs out...

Realized that the planned geometry change as well as the 3/8" axle setback I have meant the back needs to be adjusted as well.

I measured, I trimmed, I laid in some more 16 gauge and marked it for cutting, and decided to go home early because I feel a cold coming on and I got really fatigued, fast.  What I did not do is take more pictures...

Whatever sort throat/mucus generation device I have acquired is sapping my energy hard.

Still managed to cut the other side panel and start welding it into place before saying berk it, time to go home and sleep.  Have pre-work meeting tomorrow, need to get in extra early.

Terry at Henderson builds whatever i bring him, especially when i tell him I need it cheap for a challenge car.  Used yokes, used tubes, etc. unless they changed policy since last year, but every time i see him he takes care of me.  It probably helps that I asked for stickers to put on the racecars.

In reply to Patrick :

Good to know.

However, the part that I normally ruin on driveshafts is the yoke.  They don't like spinning very fast in the tailhousing bushing.  Back inna day when IMSA used a lot of OE parts, Mazda Motorsports (or whatever they were called back then) had a hardened steel yoke and a roller or needle bearing setup to replace the bushing.  It also required that you weld up the housing and bore it to a larger diameter.  Of course, all this was expensive and is now NLA anyway, so I've resigned myself to treating the driveshaft as a wear item.

For now, I do have one driveshaft left, but it's only temporary because the yoke is thoroughly trashed from being driven for a few months in a trans that had 40-grit gear oil due to shattering third gear.  You can see the diameter variations from five feet away.  But, it's not completely broken, and I'm out of time and money.  (Well, not OUT of money, but the Volvo is telling me that it is due for a throttle body, and I should rebuild the PCV system, and replace the timing belt, and and and...)

Stopped at Tractor Supply for some more sheetmetal, hacked and wheezed and generally felt like the R5-D4 unit that Owen Lars picked up (google it).

It is okay, I have seven whole days to.. um... E36 M3.

K24-7400 has arrived.  VIRB X still on the way.

Both sides welded in fully, then got a notice that the National Tour conference call was in a half hour.

Kurwa.

Rush home, etc. On conf call now...

Currently on tea with honey and lemon.

"Vodka with some black pepper: Vodka is slav miracle sure for almost anything, including forgetting unnecessary things like last night for example.  Take pepper, put in vodka, take shot, kill everything inside you, and boom: no more sickness"

Today's episode brought to you by finding a Tractor Supply (oddly enough about five minutes from Patrick) that actually had argon bottles in stock.  $120 later, I got a Hobart prefilled 20cu-ft unit that will probably last me two or three years.  Also brought to you by uamee - IL-76 because I am in a hardbass mood.

Actually from yesterday - made the rear fill-in, then spent way too much time boogerwelding it in with flux core.  Headphones hanging from harness bar because they interfere with the welding helmet.

I'm actually surprised that the lake of 2 stroke oil in the spare tire well didn't catch fire.

Today:  Now with 100% more argon/CO2, I went over all of the boogerwelds where I could see light through, then made this little cover pieces for the areas that broke out, and welded them in.  Had a LOT of feeding problems.  I'm using the .6mm wire that came with the welder, and it really sucks.  Loves to kink and when it kinks it kinks in the sheath, so I have to cut it off at the spool and then pull it all back out.

Not pictured:  Redrilling the forward link mount up and forward to complement the up and forward change I'd made at the axle end to clear the raised Watts.  I am hoping this will help keep my drivetrain angles from being so sensitive to ride height.

Cleaned, scuffed, and painted that, then went to work on the $22.50 pair of springs I bought at Summit.  They're for the front of a Jeep, and the description said that they are 136lb-in as is.  I have been keeping an eye out for some 150lb 13" long springs.  Have 175s and they are a touch too stiff, have 125s and they are too soft.  Spring in background is one of the 175s for reference.

Math time!  A coil spring can be thought of as a stack of many, much stiffer springs.  As such, you can back-calculate the rate of each working coil, and then divide that by the number of working coils after you cut it:

So, once cut to length, it will be just about exactly what I already have.  Nevermind.  Hey, they were $22.50, and I might still have a use for them someday.

On to the muffler.  Racing Beat changed suppliers or something, because the new muffler is significantly different.  It no longer collects, so my car will now technically have a true dual exhaust system.  Not sure if that is good, bad, or indifferent.  The resonated tips are huge in diameter as well, which may translate to more noise.  Since they are so large, you can peek in there and see how the muffler is constructed.

It looks like the front half to 2/3rds of the muffler is a perforated core packed type muffler (I believe RB uses/used stainless steel swarf instead of fiberglass), and these two pipes exit into a termination box, and the resonated tips are just the outlet.  Will find out tomorrow how it sounds.

The muffler itself is a lot smaller than the old style one, too.  Weight is about the same, within guesstimation, so even though it is stainless it must be very thick walled stainless.

The left side pipe gets VERY CLOSE to my Watts stud.

I popped the upper link in and jacked the axle up.  The stud got so close that it could easily touch the pipe, but it never actually did touch.

I whacked off about 12mm or so.  I want to leave it long because I still think I want to mount the Watts in double shear, and I do have a pinion support bracket to use as a starting point for a brace. 

Installed the springs, set the car down on the axle, bounced it a bunch, and then set the pinion angle.  I set the pinion angle to exactly the drivetrain angle.  I know this is without a load in the car, but you have to start somewhere.  Then I popped a driveshaft in and measured the driveshaft angle.  For the record, the way the car was jacked up, the pinion and drivetrain are at 1.5 degrees from vertical and the driveshaft is at 1.8 degrees from horizontal.  So there is .3 degrees of U joint angle.

But... remember when I said I'd redrilled the forward pivot?  Now the top of the rearend doesn't come forward as much under compression.  So, now the rearend hits the spare tire well... and also will destroy the metal I just installed, if the suspension compresses that far.

Need to have a think.

Photo dump incoming.  Today was a good day.

Today's episode brought to you by Sabaton - Screaming Eagles.

Went to Summit to acquire some weatherstripping since I couldn't find the scavenged length I'd been saving for this moment for the past few years.

Then found out that my floor hole is almost exactly 24" long, which makes it difficult to make a cover plate out of a 12x24" piece if you want flanged sides.  Made do as best as I could with flat Vise-Grips (Sheetmetal brake?  Not in this garage!) and kind sorta welded the flange lips where it was slotted for bends and corners, set some paint on it, and went back to attacking the clearance issue.  Off come the wheels, jack the car off the axle and onto the chassis, remove the springs again, jack axle all the way up again...

That is with the axle all the way up.  Next, I unbolted the driveshaft (again) to see how much plunge is remaining.

I figured screw it, if the axle ever comes up this high then the body is going to be flexing and contorting anyway, so I measured the plunge at 7mm and decided to shorten the links 2 turns.  2 turns on 3/4-16 is 2/16ths of an inch per end, or 4/16ths total per link, which is 6.35mm.  After doing this, I measured the gap again and it was still 7mm.  So I went another turn, which brought me back to where I had started axle-placement wise before I lengthened everything because I thought I was bottoming the driveshaft.  OTOH, I had different motor mounts back then, maybe the engine sits more forward now.

What is neat is that the pinion angle was still within a tenth of a degree, after I put the springs back in and set the car on the axle again.  While I had the angle finder out I made sure I didn't accidentally make the links parallel.  Nope, still good.  (8 degree difference, btw)

Strategic bungees are holding the cover down.

Part two: the bumper.  This actually took as much time as the spring/axle/pinion angle hokey pokey because, believe it or not, '81 RX-7 bumpers are shaped differently than '84.

See?  There are many more internal ribs in the '81 bumper.  The Curt trailer hitch uses two of those bolt locations on either side, and one more on each side is kind of in the way, so a total of six bolts need to go.

Grind all the bolt heads off, punch four of them through, drill holes out to 25/64ths to take a 3/8 throughbolt, pick up bumper and dump about a cubic yard of Alabama red clay on the floor.

Thanks, car.

Thought to make sure the license lights worked before I made them inaccessible.  Of course they don't.  Take bumper back off, set on rally tire shaped workbench, remove light housings from bumper...

Mazda what the HELL were you thinking?  The lenses are held in by not only the screws, but also a rubber boot that must be stretched all to heck to remove the lens so you can access the bulb.  Fortunately the 40 year old boots were still pliable enough to not tear.  Not that they actually did anything, as both lenses were packed solid with more Alabama red clay.  Went to the local auto parts store  to find that they closed at 6:30.  Went to the next closest store, which was about 15 minutes further away, and also stocked up on 2 stroke oil since I hate using a card for a $5 purchase.

Right.  Back at the 'cave, lenses cleaned, bulbs in, plug in for testing... one is very sensitive to how you hold the connector.  It's the female terminal on the housing side of the wiring, so I tried to re-spring the terminal with a pick.  Yes, it broke when I touched it.  It had lost its spring tension because it was cracked.  Fortunately I have a bunch of female spade terminals, so I grab my wiring tools, cut the connector off, strip the wire, and notice that I'd cut the wrong one off.

Crap.

Cut, strip, and replace the female one, then tear the garage apart looking for a male terminal I was 99% sure I didn't have anyway.  Ended up cutting a terminal and piece of wire out of a patch harness from something or other and butt connected the two.  Getting really impatient now.  Test on car, yes it works.  Install housings to bumper, pick up bumper and dump another cubic yard of Alabama red clay on the floor.  For extra fun, my trailer tool bag caught a bunch of it.

After mounting the bumper, I then discovered that '81 RX-7 bumper supports are not only different in number, but also location.  The two inner trailer hitch bolts were close enough that I could force the issue, but the outers were over half a diameter out.  Fortunately the 25/64 bit was still in the drill.

And then FINALLY...

What a frickin' ordeal.  Just six bolts and a couple of connectors...

looks like they used an image of you on the scca rallycross fb page

In reply to MrChaos :

I got tired of using my own car for event registration photos so i tried something different.