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cghstang_chris
cghstang_chris Dork
1/25/21 9:06 a.m.

So, which car for the RXNC?

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
1/25/21 9:08 a.m.

I have done this a few times before when cross-pollinating intake manifold flavors and it works just fine.  First, a pair of self tapping screws to make me feel better.

Then, a whole tube of Quiksteel gets kneaded together and globbed into place.

Then we let that sit, and go hit a raccoon on I-90 and berk up the Volvo.  More on that later.

Then go and work on the engine some more.

Thoroughly dried, stick intake gasket on to make sure you did apply enough stinky Play-Doh.

File flat and mark gasket edge...

 

Remove excess, stick gasket on, and marvel at your craftsmanship!

 

Then clean it all off, and I like to paint intake manifolds white, because of something David Vizard wrote a ways back.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
1/25/21 12:49 p.m.
cghstang_chris said:

So, which car for the RXNC?

Whichever one is running at the time?

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
2/16/21 6:37 p.m.

 

Well, that would be why the car was shaking so bad.

dannyp84
dannyp84 None
2/17/21 2:57 p.m.

In reply to Pete. (l33t FS) :

Is this the car with the FC subframe and steering rack?

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
2/17/21 4:39 p.m.

In reply to dannyp84 :

The black one is.  The 12A is for the red car, which is mostly stock and is intended to stay that way.

dannyp84
dannyp84 New Reader
2/18/21 9:08 a.m.

In reply to Pete. (l33t FS) :

I remember reading somewhere that you regretted doing the FC subframe, so I've avoided doing that on my fb (especially because I've amassed a small hoard of 4x110mm wheels) but I can't remember what you didn't like about it. This chassis doesn't much like lots of changes in suspension components/ride height from what I can tell..

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
2/19/21 7:48 p.m.

In reply to dannyp84 :

It's a double edged sword.  I don't regret doing the swap because my power steering box was developing issues, and they are incredibly rare (only available as an OPTION on '84-85 GSL and GSL-SE) and I was also going through strut housings at an alarming rate due to bending the spindles.  The FC spindles are massively beefier.

Knowing now what I know, and having the resources I have now, I'd have thrown a quickener on a manual box, put Mazda 3 ball joints in the FB control arms, and used the FC uprights/struts with FB suspension.  I may just do this anyway, I have all the bits to do it.

 

I DO regret the swap because..... It's complex.  The FB rear roll center is fairly high.  When I did the 9", I moved the Watts pivot (the roll center) 40mm lower, so that it is on-center for axle centerline.  I also had to move it quite a bit even more offset to the right, which introduced more handling problems and I really want to pitch it all for a Panhard... BUT ANYWAY.  Roll center high in back.  The SA/FB front suspension has nice loooong control arms, so the roll center height doesn't move all that much.

 

The FC has really short control arms.  They need to be, because the rack has to be wide to clear the engine, and so to keep bumpsteer from being crazy the control arm pivots also have to be really far apart.  So the arms are fairly short.  This makes the roll center height move around a lot.  This is not a huge problem for the FC because the rear roll center is also fairly low and moves around a lot, but they move around in concert with each other, so it is all nice and harmonious.

 

When you put the FC front on the FB rear, you get disharmony.  When I first did the swap, I did a low Panhard at the same time, and I found that I needed to run 250lb springs in the front to get the same handling feel as 175lb springs with the original suspension and Watts in the back.  It still never felt "good", just "acceptable".  Driving my '81 feels like a breath of fresh air because it's not scary on pavement.  The '84....  It does not carve corners.  It does straight lines and then you hack into a different direction and you never feel good driving at more than about 7/10ths.  It's okay on loose dirt because loose dirt is so forgiving.

dannyp84
dannyp84 New Reader
2/22/21 9:25 a.m.

In reply to Pete. (l33t FS) :

That makes sense, my control arms had worn ball joints so I went with the t3 adjustable control arms with the snap ring style ball joint because i was told that pressing in new joints to the old control arms often warps the hole and they don't fit as snug as they should.. the t3 arms are regrettable because they're not actually adjustable on the car unless you unbolt them from the subframe. My car is arguably too low, which means the 4 link arms in the rear hit the wheel wells/body, but the upside to this is that the rear end doesn't really do anything spooky mid-corner because it can't move much, though I do worry a little about my pinion angle.

Is a panhard technically a step backward compared to the watts link, if the factory watts link was actually equal length arms? I was always told that the watts in the fb was a strange design and that the 4 link arms should've all been equal length, but I'm still learning as I go..

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
2/22/21 11:05 a.m.

In reply to dannyp84 :

I'd unlower the car unless you want to deal with body damage soon.  The rear 4 link bind gets worse when you make the car lower.  Combine that with removing the rear sway bar, and you will rip the upper mounts off of the body.

Suspension parts designed by people who are interested in handling do not lower the rear. Due to spring sag, they usually make the car higher.

 

T3 does not make any good suspension parts for the RX-7.  Everything they sell is either the suspension equivalent of 5" exhaust tips and double wiper blades (harmless but pointless) or it actively makes handling, performance, and longevity worse.

 

The issue with the Watts is that it is too high.  It needs to be that high for clearance reasons and also so it is not fighting the roll center defined by the angled upper control arms.  A Panhard is better because you can put it at whatever height you want it, but you really need to remove the upper suspension arms for a 3 link to be able to exploit this.  Otherwise you just have a too high Panhard instead of a too high Watts,

dannyp84
dannyp84 New Reader
2/22/21 2:10 p.m.

So the secret to a good FB is to leave it stock? Also I tend to feel the same about a lot of the T3 products, I've actually sent some of them back after I opened the packages and wasn't happy with what I saw. I should've gone with the adjustable mazdatrix control arms. I have some time to sort out the suspension while my 12a irons get ported.  Also, what is the advantage of a white intake manifold?

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
2/22/21 4:53 p.m.

In reply to dannyp84 :

Well, not so much "leave it stock", but don't move the ride height so much.  The better drop-in springs are 50-80% stiffer in front and 0-10% softer in rear, but leave ride height fairly stock.

 

If you lower it, you have to make the front extremely stiff to compensate for the rear suspension wanting to move like a swing axle Corvair, following the adage of a suspension can do no wrong if it is not allowed to move.  Flip side is, it can do no right, either.

 

The cars are getting into a weird place.  They are not raced much anymore, so there are no good parts available.  And good ones are becoming $10k-15k examples, and up.

 

A lot of why I want to keep the '81 unmodified.  Everything done to it is bolt on.  Interestingly, it has 250lb front and 150lb rear coilovers, which I also had settled on as decent, with the stock 4 link/Watts.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
2/23/21 4:55 p.m.

While waffling about whether to V8 swap the black car and stop rallycrossing it, or just finally put an "engineering freeze" order on the car, I accidentally bought a pair of new GSL-SE rotor housings.  Oops?

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/21/21 3:19 p.m.

One month to first event.  Haven't been updating because due to weather and an injury, I had not been spending much time in the garage.  Weather is getting better and I can stand and walk a bit without life sucking.  I do have a huge backlog of pics but for now...

 

Replaced all of the vacuum hoses in the solenoid rack, new water pump, found an air pump that isn't locked up, looked FOREVER to find the A/C drive pulley, etc etc etc.

One thing that was funny.  I pulled the distributor (original one to the car) out of the sick 13B in the car and just popped it into the 12A to plug the hole.  Turns out I accidentally stabbed it in the correct orientation!

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/21/21 8:01 p.m.

Here we go again...

 

Were it not for wanting to repair the MOP lines on the engine stand, the new engine would be in tonight.  But the hoses I bought are just a touch too large, I either need different hoses or some tiny full-circle clamps.

Also need to remember to buy some oil filters, a pair of radiator hoses, remember to bring home a jug of oil (I bought a case of six gallons last summer and keep them at work), and hopefully the Nikki carb I bought on eBay last week shows up like tracking suggested.  I need a lot of solenoids and a TPS.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/22/21 9:03 p.m.

 

and then an hour later...

What was fun was after I was putting the bellhousing bolts in after remarkably not much fight getting the two together, then having one of those Thoughts.  "Did I put the dowels in the engine?"

 

Sigh.

Back apart, yep they were there...

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/28/21 12:20 a.m.

A/C idle up solenoid, dashpot, and TPS from eBay carb installed.

 

 

The TPS was a trick because I also needed the linkage on the carb for it.  Well, apparently there was a running change and the '81 has an 8mm throttle shaft while the junk carb necked down to 6mm.  Had to drill out a bronze bushing, which was a trick.

No choke linkage, because that all was either damaged or nonfunctional on the junk carb (garburetor?)

 

And so:

 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/28/21 8:27 p.m.

Well, it runs, technically.

And technically runs is the best kind of runs!

 

..

 

Wait, no it's not.

 

It would not run except on carb cleaner, since I am apparently out of starting fluid, and then it'd die.  Plugs would foul massively.  Did a lot of the rotary-unflood crank with plugs out, heat up plugs with a torch, add oil and combustibles, cha-cha.   No joy.  And apparently my battery charger is a POS and doesn't actually maintain batteries once charged, so the battery kept dying.  Drove off to the Autozone next to where I work to order new, actually-for-the-application spark plugs instead of the ancient heat range 10 plugs I had scrounged from the POS13B, which sucked an hour and a half of time, but I needed that time to recharge the battery, so why not?

Trying again, with freshly torched plugs, starts on carb cleaner, won't stay running.  Verified that the spark plugs were actually getting spark.  Something clicked: "Maybe the fuel in the tank isn't fuel anymore, you drove this car only once, for like a week, in late 2019".  That isn't long enough for fuel to go bad!  But, hey, it's cheap to test.  So I grabbed about six or seven feet of hose off of the roll of 5/16" that I'd bought a while back and extended the fuel line at the firewall to a new position into a 5 gallon container.  (I was gifted a whole bunch of them from someone who needs to buy VP race fuel for his heavily tuned New Beetle)  I can't tell good from bad by odor, but the fuel is coming out clearish-green, when it previously had a definite blue tint thanks to all the 2 stroke oil.

Sigh.

In a kind of "history doesn't repeat but it does rhyme" moment, I pumped the fuel out of the tank while I set to work removing the top of the carb so I could sop out the fuel from the bowls.  It is significantly more difficult to take the top off of a Nikki 4-barrel carb than it is a Dell'Orto DHLA, but what needs to be done needs to be done.  Not to say that it is crazy hard, just that the Dell is really REALLY easy.  Drove 10 gallons of suspected bad fuel a half hour to work to dump off in the waste oil tank.  Found out while I was there that my next week will involve transmission R&R on a 2.0t Jetta.  Drove back to the Batcave, stopping along the way to add 14 gallons of 93 to teh R and 5 gallons to one of the now-empty fuel containers.

 

It runs!  Sort of.  Technically.  It only runs off of the accelerator pump shot.  It won't stay running long enough for me to not have to constantly mind the accelerator pedal.  Something's mucked up with the carburetor, and I dread having to disassemble it again to the point that saying "fark it, I'm up to my eyeballs in debt anyway" and throwing $1100 or whatever at Racing Beat for one of their Holley setups sounds like a good idea, even though I HATE Holleys and I know from experience that their Holleys need a lot of work to make good fuel economy. 

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/29/21 7:53 p.m.

New plugs of the correct species made no difference.  Oh well, I needed them anyway.

Unplugged the fuel pump fuse, ran the engine as long as I could on the fuel in the carb, popped the top off and then popped the main body of the carb off.  No compressed air in the Batcave, so I used brake cleaner to verify that various passages were not plugged.  Nothing was plugged, no gaskets torn.  Spraying into the idle air bleeds would shoot brake cleaner out of the main jets, proof that the idle circuit is able to pass fuel from the main circuit.  Put it back together, and yes, still no run unless you feed it fuel with the accelerator pump.

 

I'm starting to think I merely have a vacuum leak.  I SHOULDN'T, but I'm running out of things to try.  Next step is to remove the air control valve and replace it with a blockoff plate.  I thought I'd plugged all passages to the ACV with JB Weld, but anything's possible, and it's foolish to assume.

j_tso
j_tso GRM+ Memberand Reader
3/30/21 7:58 a.m.

didn't want to derail the tie rod thread, were these the johnny joints you were referring to there? 

I'm doing a GSL-SE axle swap and thought about using them to replace the Watt's links, the 34 degrees of movement look like a good idea, but making a pair of links would be more than twice the cost of new OEM links from the dealer.  

sevenracer
sevenracer Reader
3/30/21 9:52 a.m.

Don't know if it helps you, but I probably have another stock carb if you need one. Not sure of year, and condition, but let me know if you are interested,  I can dig it out and send pics.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/31/21 3:56 p.m.

In reply to j_tso :

I don't think they would be a good idea.  The bushings only work rotationally, so there is no real need for articulation.  Further, since the bellcrank mounts the bushings in single shear, you may not WANT bushings that can articulate.

 

plus, I don't think they make any small enough to work.

 

Use stock links, put a heat shield on the bellcrank end of the upper link (exhaust heat kills it), call it good enough.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/31/21 4:01 p.m.

Speaking of bad ideas, this showed up today.

 

 

9" Track-Locks are weird.  There is only room for clutch packs on one side, and the clutch packs have their own separate splines to grab the left side axle.

 

I am remembering vaguely that all 9" diffs take the same length axles except for one type, that needs axles 1/2" longer or shorter.  I hope this ain't it.  Time to research...

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
3/31/21 6:35 p.m.

Also.

 

Left arm is sore, so I did not start working on pulling the rearend apart, which sucks even with two fully functional arms.  I did at least get the battery charged enough to turn the car around, so I can start pulling it apart tomorrow or Friday after work.

It's supposed to snow later this week, and I really don't feel like tracking mud into the garage, so I at least got it turned around.

Boy howdy, the steering sucks when you can't put much force through one of your shoulders...

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
4/2/21 10:38 p.m.

Lots of shivers, and THANKS WORLD FOR THE 20 DEGREE WEATHER.

It's my fault; I put my garage heater away last weekend.

 

Fighting the shivers and cold and urge to curl up under about six blankets with a mug of hot soup (don't ask, it just seems to make sense) I went out, centered the car so I could pull the axles, jacked the car, made some reference marks on the link mounts, drained the gear oil, pulled the axles, and did some thinking and figuring.

Axle bearings are definitely both bad, they're indexing.  Axle seals are also leaking, as there was a pile of gear oil between the seals and the bearings.  Probably should replace the seals, but the probability is high that I'll just mangle those ones when I install them, so I'm biased towards leaving well enough alone at this point.

 

Did a lot of eyeballing, figuring, measuring, seeing what bits I had on hand, more measuring, holding up OE parts to see how far I've deviated, eyeballed some more, etc.  I think I have an Idea.

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