Pete. (l33t FS)
Pete. (l33t FS) MegaDork
9/23/21 4:56 p.m.

On today's episode...

 

Wheel bearing in teh R, which is more of a pain than it should be, which is why it has been screaming for five or seven thousand miles, and extracted the rear U joint from the shortened driveshaft I acquired from gpb a long while ago, to install in the '81's driveshaft.

I have never seen a U joint do that.  Joint got loose after the I-96 rallycross, had a small amount of play it didn't have before.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
9/25/21 9:03 p.m.

Purple crack has arrived.

 

Not for that car.  Not for that one either.

TurnerX19
TurnerX19 UltraDork
9/26/21 10:37 a.m.

Gee, I have seen hundreds of Ujoints pound their inner races like that. Every MGB or Volvo 140 would look like that if you got to them before they ate their way through the cups, and sometimes the yoke too. Soft metallurgy and too few rollers combined with vigorous drivers.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
9/27/21 12:51 p.m.

In reply to TurnerX19 :

Every loose U joint I have ever seen had powdered rollers.  So this was a new one on me.

 

Today I learned that 255/40-13 Hoosier A7s berking suck.  Two of them had beads torn down to the reinforcing cables.  I know this is not something I did, because when I exposed them, they were very rusty.

So out of eight tires, I scrapped two that were corded and I have two with good tread but unsafe beads.  Lovely.  Oh well, I am pretty sure I have four good-ish ones, and that is plenty for my purposes.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
9/27/21 6:35 p.m.

Find the mistake!

 

cghstang_chris
cghstang_chris Dork
9/27/21 6:52 p.m.

No ratchet strap ?

EvanB
EvanB MegaDork
9/27/21 6:57 p.m.

You put a single pipe to a muffler with two inlets?

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
9/27/21 8:47 p.m.

That is the original muffler that I'd repacked.

 

Mistake was that I'd wanted to stick the flex piece at a horizontal part above the axle.  When making the bends forward from the muffler over the axle, I got a little carried away. and went "ooh, I can just use most of this 180 to turn right over the axle and point down at a good place for the Y pipe".  Oops.

Also, when making the exit from the front flange, I went "ooh! Straight shot and it fits!" without considering that I needed room to put a socket on all three bolts.  Oops. 

In my defense, I am using 1 7/8" tubing whereas the original Racing Beat (whatever Italian company they contracted out to) was 1 3/4" thickwall pipe, and I had to open the holes up quite a bit to get a spigot fit with the pipes.

More on that in a bit.

GasTungstenArc
GasTungstenArc New Reader
9/28/21 7:08 a.m.

Pete, I am curious about where the tubing bits came from.  It looks to me like you started with a new flange, and the tubes off the flange heading to the muffler appear to be new chromed pipes.  

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
9/28/21 8:38 a.m.

In reply to GasTungstenArc :

Scavenged flange from muffler, and 304 stainless mandrel bends from Summit.  16 gauge

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/3/21 9:58 a.m.

 

I'm not panicking, you're panicking.

 

Alternator is a POS.  It doesn't surpass 12v with the fans on even at 2500rpm.  Stock one is going back on.

Low speed fans are noisy.  Can run on the other circuit for "low" but this is troubling.

Brake booster seems to be dying.  I have a "spare", spare meaning the rusty one I took from the '81 that may or may not be leaky.  No time for a manual conversion.

I don't like the noises the rearend makes but I can't do much about that.

Need to paint the white bumper black, modify for trailer hitch, and install.

 

Was having soooooo many problems welding up the new muffler that I don't trust that it won't just outright fail.

 

I still have time to bounce to the PR car.  But it needs some cosmetic attention to be PR legal (lighting and radio antenna, mainly), need to finish the trailer wiring so tires can be hauled, and also it is really slow and runs hot.  Plus, I want to stay in MR because I was called out in the SportsCar "Who will win?" article, and not showing up with that car would be just rude.

 

"Lightened"? "Just enough power"? "Well sorted"?? 

I am banking on my ability to accelerate out of corners and carry the speed through straights, and... um... wing it in the corners.  I figure I have almost double Dozeman's power, while only having almost double the weight.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/3/21 5:59 p.m.

I forgot the other big problem on the black car: the tach doesn't work.

Now, I have bad experience with messing around with tachs on Megasquirted Mazdas immediately before the championship.  But, nothing ventured nothing gained, and I sort of have a backup car, so I persevered with some testing and think I have a solution that doesn't involve buying more stuff.  Or extensive rewiring.

 

Speaking of backup car.  I acquired an antenna for it.  Installing the antenna requires removing the right taillight, along with baked-on painter's tape covering the hole.  While trying to remove the taillight, the lens popped off.

That is the reflector/color lens behind the lens.  I guess this might be why people don't seem to see my turn signal?

Fortunately, the same parts run that netted me a white rear bumper and a fuel tank for the '81 also got me a collection of taillights.  After MUCH cleaning of the shell where decades of red clay had caked in the taillight area, one new light is in.

I'm gonna do the other one.  The brake lights and turn signal actually shine off of the garage door 2' away on the right side now, they don't on the left...

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/4/21 9:35 p.m.

Left my electric hacking tools at work, so today I focused on the brakes.  Car has FC front end on it, and by happenstance the FB (and 1980) calipers bolt up to the FC hangers.  So, years back, when I needed a caliper in an emergency, I slapped an FB caliper on the left front.

260k mile old pads from 1988 are basically granite at this point, so I bought new pads a couple years ago.  Turns out that there is one more critical difference: FC calipers are about 2-2.1 inches wide inside, FB are only about 1.8-1.9.  The FB caliper would not fit over the new pads. 

One difference between the '81 and '84 is that the '81 has new pads all around, and its brakes are phenomenal, so today the Plan was to put in the new pads, filing down the ones going to the left front as necessary.  The plan lasted exactly long enough to meet the enemy: Piston on FC caliper is seized and rusted.  Hmm. Tried opening the bleeder and it just snapped off. 

What would Batman do?  Order new ones of course.  This would also alleviate the need to file about 1/8" of pad away.  New problem:  None available.  Can't get new calipers anywhere.  I can get a left, but not a right.

Also, I am not Batman.  What can Pete do?

Found two FB calipers in the stuff pile.  Right front had a clean piston and the bleeder opened.  Lots and lots and lots of filing later, I got it to slide over the pads.  Pads have to be filed down from over .600" thick to just about .500", even with cheating by pulling the shims off a lot of material needs to come off.  Outboard pad needs more removed than inboard pad, too.

On to the left side.  Filed down a third pad to get the caliper to slide over.  Inspected the piston, and while it does move easily when pumping the brakes, it's also rusty enough that I don't feel comfortable graunching the rust past the seal, so on to the left caliper from the pile.  Its bleeder opens but the piston is seized.

At this point it was 9:30 and I was beat, so I get to rebuild a caliper at work tomorrow...

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/9/21 7:34 a.m.
Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/9/21 2:53 p.m.

This week was just lovely.  Ended up trying to dismantle three or four different calipers to try to find a good piston for the one right caliper I have with a bleeder that opens.  After getting to be way too good at reassembling calipers without compressed air available, then it was time to bleed the brakes.

Absolutely nothing happening.  Went so far as to pull the reservoir off of the master cylinder to make sure the inlet port was not plugged.  While poking around looking for ideas, I found my Mityvac brake bleeder setup.

It isn't in the instructions, but you can turn a Mityvac into a pressure bleeder if you put the hose to the canister on the pump outlet.  Some Teflon tape on the bleeder threads, and I reverse bled both front calipers, which forces air out of the master cylinder.  And it worked!

On to the tach not working.  I have noticed that the tach, besides turning spastic over 7000rpm, could also be made to jump by spiking the throttle. So I think EMI from the tower of ignition coils that the tach input had to go past had something to do with it.  Brought my laptop from home on Tuesday, and after some experimentation with test mode, I verified that I could make the tach work with the fidle circuit.  And so on Wednesday...

1000 ohm resistor between tach input and 12V.  I figured this was by far the cleanest way to do it.

Pull tach lead out from through the firewall, route to right side of car, zap zap shrink shrink...

 

aaand.... the tach didn't work.  *sigh*  At least I didn't brick the MS2.

 

Once home, I checked my latest tune and noted that I did not have the tach output enabled. D'oh!  Took laptop home on Thursday, turned that function on, and it works.  Took car to Dragway 42 last night for WOT pulls and found that the tach does not bounce anymore.  Win!

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/9/21 4:58 p.m.

apparently the shop welder is junk now, too.

 

I noticed that my peak RPM intake manifold pressure was higher than in 2015.  I am using the same everything except muffler.  I think the new muffler may be restricting power, so the repacked one definitely is going on.

 

Also the car is a half second and 8mph slower in the quarter mile.  I would like to blame my suspiscion that 42 is slightly uphill, but that is too much for that to account.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/9/21 11:21 p.m.

Well..... It's a lot quieter.

 

But, annoyingly, the stainless chamber style muffler actually seems to flow more air at idle and WOT.  The old perf-core muffler definitely flows more air at part throttle.  Also much MUCH quieter.  I can't hear the exhaust at all at 70mph.

 

But look at the datalog histograms.  This was last night driving home from 42:

And this was tonight with the same tune and the new old muffler. 

Patrick (Forum Supporter)
Patrick (Forum Supporter) MegaDork
10/10/21 8:07 a.m.

So what did it run

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/10/21 9:30 a.m.

In reply to Patrick (Forum Supporter) :

Pathetic @ slow.

I think my third run was a 14.18 at 98.  With the previous incarnation of this engine, and the Mazda rear with 4.78 gears, I had run a 13.6 at 106.  Currently have 4.87 gears in the 9" so this is pretty comparable.  Was going through the traps at 9500 in 3rd.  Not sure that I can believe that the 9" is sucking that much more power.

 

Looking over prior datalogs, noted that I used to have the engine running a lot leaner at WOT.  With the tune that I had on my first run, the engine went from 12:1 to 10:1 air:fuel over 9000 and it just laid right over like someone corked the tailpipe, so I might gain some more oomph from leaning it out a bit. 

'Course, I was HOPING that putting the perf core muffler back on would flow more air, so the engine would run leaner, and I wouldn't have to retune.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/12/21 9:26 p.m.

Have been driving the '81 all week, because I have all winter to drive the Volvo.

 

Also.

For the first time in... a lot... an intact, correct-ish colored rear bumper is installed.

It's not the same color.  RX-7 has some name like metallic charcoal, Duplicolor is something mica.  Close enough.  Doesn't look horrible.

Work continues.

I asked Red Bull for sponsorship, but they sent a form letter saying they had current obligations regarding some sort of karts or something.

j_tso
j_tso HalfDork
10/12/21 9:55 p.m.

the dark grey is Tornado Silver™

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/13/21 10:23 a.m.

Pretty sure the car is H1 (Sparkling Black) while the Duplicolor that I bought was... not.  I bought it because it was the only blackish metallic in the store, coincidentally it was Mazda.  Had mica in the name...

dannyp84
dannyp84 Reader
10/13/21 10:47 a.m.

I've been happy with the borla universal mufflers for my 12a, I run one right beneath the passenger floor and one at the tail of the car, they don't seem to be too restrictive and they hold up to rotary heat. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/13/21 5:15 p.m.

Thought I heard detonation at the top of 3rd gear at the dragstrip.  Must have been something hitting something.

Definitely heard detonation accelerating with a cold engine this morning on the way to work.  Ignition timing was 13 degrees initial, which means just under 40 degrees total.  Eeeeep.

Set it back down to 25 degrees total, using a different timing light.  Distributor must be worn, this translates to 0 degrees initial.  Unless somehow I have a GSL-SE distributor.  Anyway, it idles like a bridge port now and not I Put a Spell On You.

 

in a previous life, I'd noted no power change between 22 and 26 degrees, so I ran it at 26 because that made for better fuel economy.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
10/13/21 8:37 p.m.

Oh it runs SWEETLY now!  It sings.

 

Bumper is officially Dupli-Color's version of Graphite Mica.

 

What is interesting is that H1 is not listed as an '84 color by anyone I quickly searched.  My '84 was built in September '83 and it had the three month only 3.933 rear gear.  It also had big axles, putting to rest the idea that the 3.933 cars had small axle rears.

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