My black forged Piazza

[IZU069]

My Dog, ozfem lives!
Alas your writeup requires a login (and I burned my ozFem ID) but the other was public. Good to see others do what I have suggested for so long - ie, filling of slots with liquid paper etc. It was the flexibility of having 360 slots that I liked - ie, easy to get 12 or 18 slots etc.
But as to the poor sod that did a Magna graft... I so warned against them EXCEPT where a true Cam-CAS was required... some even argued Halls were digital and therefore more accurate than reluctors LOL! (They are all linear!! Their module circuitry makes them digital and that is incorporated in the reluctor's ignitor.)


For symmetrical disks direction won't matter. But any offset slots or individual elongations means direction is critical - ie, "invert" as you suggested. Offsets shouldn't require changing if the dizzy can be rotated to the correct position. And of course the rotor angle must be preserved... (or is it naturally...?)

I agree with your comments re modifying slots. A have seen a few DIY disks and some seem rough as heck. But I may be pedantic (even a rough edged should only affect timing by maybe half a crank degree at most) and only one edge matters - ie, the trailing edge must be clean and properly positioned. (The opticals I have investigated all trigger on trailing edges, hence elongate forward/leading if that is required.)

So Piazza went Delco? Bluddy GM influence. Then again, Delco were touted as masters of all things EFI - they apparently spent $millions in their original research "and did it all".

Incidentally I last looked at a Delco from a VY or similar Commodore. I was aiming for full sequential injection and ignition with wideband O2 for my G200Ws (and mere throttle bodies for G161OHVs), but that was years ago.


I also agree with not using other vehicle tunes if it means across different engine types. (Afterall, traditionally engines got the same tune during production - ie, jet & other carby sizes, exhaust manifold, etc.)
Though with EFI there is more chance of using foreign engines successfully. EG - apparently the standard JE Camira Delco tune is ok for G200Ws, but there are better G200W maps.
EFIs somewhat self tune thanks to O2 sensors (or ionic sensing etc) unlike older vehicles where probably had an individual idle speed & pilot air tune.
The latter reminds me of some old cons resurfaced - eg the old rip-off of putting a resistor in the AFM or MAP sensor lines to richen the mixture - or lean it depending on the site's aim LOL - reappeared but using a voltage regulator instead of the resistor! (Such systems must be in the O2 line; other sensors have no effect.)
But there are those that use 555 timer circuits to avoid replacement of faulty O2 sensors...
And I think of a certain Belletter arguing that Isuzu did not retune for the 4ZC1-t motor, ie from G200W...!
Meanwhile I tout self tuning EMSs - no need for dynos.

You remind me of another reason I like the RG's reluctor sensor - a tough one-piece coil with required magnet and hardware and lower impedance as opposed to older multipiece & multipole reluctors.
They easily provide the current required for older higher impedance systems and any lower voltage should only effect low RPM capability.

[archangel62]

Time for another boring no-photos update.

FRONT SPRINGS:

I've fitted lowered front springs, bit of an experiment but they only cost me $22. Mind you, given the utterly horrible act of changing Piazza front springs, they'll probably be there forever. I'm going to come right out and say it, and I challenge anyone to judge me for it. They're cut springs! Yay! Such quality, you say.

BUT.

I engineered and mathed the shit out of it and know exactly what I'm aiming for. HBL models run 7kg front springs, versus the Aussie ~4.5 or so, and I'm of the strong opinion that the Aussie springs are far too soft, even with decent shocks. I'm an oversteer kind of guy, and sadly my Piazza is not, so I didn't want to go too tough up front either. Target: between 6.5kg and 7kg/mm front rates. I'd also like it to sit level with the rear, eyebrow at around 320-330mm, with maybe 15mm of vertical clearance from tyre to guard. I'm too old to think tucking is cool. Stock springs were a bad candidate, however a trip to U Pull It with some measuring tape came back golden. I believe the ones I ended up with were from an EA Falcon front end. They are almost identical to Piazza front springs, it's seriously uncanny. Here's the numbers:

Piazza spring:
14.7 mm thickness
87.0 mm inner diameter
116.6 mm outer diameter
9.25 active coils estimated
370 mm active coil height estimated
12 total coils including seating
419mm total height uncompressed

Falcon spring:
14.87 mm thickness
90.8 mm inner diameter
120.6 mm outer diameter
8.00 active coils estimated
370 mm active coil height estimated
10 total coils including seating
419 mm total height uncompressed

New front spring (cut Falcon):
14.87 mm thickness
90.8 mm inner diameter
120.6 mm outer diameter
6.5 - 6.75 active coils once loaded (estimate)
320 mm active coil height estimated, uncompressed equivalent total coils including seating
353 mm total height uncompressed
Eyebrow height approx 335mm (not settled yet)
52mm eyebrow drop is 39mm spring drop
Spring effective ratio 1.333
Compressed height estimate 230
Estimated new springs are 6.55kg/mm (386.44 lb/in) and under 1871.53 lb of force
Effectiveness ratio means these feel like 4.37 kg/mm springs in a Macpherson strut car

Process wise, the bottom seat of the Piazza has an indent that's perfect for the bottom of the Falcon spring, but the cut top makes for a poor seating. To combat this I cut almost horizontally across the springs creating a tapered end, and then lopped off halfway along the tapered section where strength would be too poor to be any use. I did this in several sessions to stop the spring getting too hot during the work. If it was too hot to touch, I would stop. It's surprising how much thermal mass they really have, so I have no fear of changing the tempering of the steel. I then painted the cut sections back to a nice original looking gloss black. Although the Falcon springs are only a few millimetres wider and thicker, they are a very tight fit. I suspect any heavy duty (thicker) springs would have similar issues. Coaxing the top section in and seating it correctly was not fun, but once in place and preloaded by the LCA, it has a long seating area and doesn't foul on anything. In brief, it's functional. Both springs were cut and seated identically.

End result: 6.55kg/mm front springs (close to HBL specs) with approx 37mm drop (possibly more pending them settling and actually having the car on a level surface) for $22. Not bad. I looked into buying aftermarket front springs for a long time, but there's now nothing available to order in Australia to my knowledge, and any manufacturers I did contact had no idea how the ride height would end up, so basically it'd be guesswork. I figured if we were playing a guessing game, I may as well guess with cheap wreckers springs, get them right and then have something made to match them. Knowing how horrible a job changing them is, and given how happy I am (so far) with the new springs, I'll probably just leave them be.

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GEARBOX:

Turns out my new gearbox had oil at the bottom of the inspection plate after sitting for a week... only I hadn't put oil in it yet. Sooo, basically this was the first 4Z I built, going back around 5 years now. I didn't realise the flywheel bolts passed through into the sump, since they don't on the G series motors. I didn't put any sealant in the bolts, and with the front of the car up on jack stands it was pushing a lot of oil out through the flywheel bolts. It also explains one of my intermittent bloody oil leaks.

So out came the new gearbox. It only took an hour and a bit, which is pretty good for a Piazza if you ask me, since the tailshaft was just resting in place, centre console was already out, car already on stands and no oil to drain. The clutch and flywheel were oily, but thankfully this is some kind of composite clutch material that shouldn't have soaked it up like my drift car's old organic one did. I spent a good few hours with wax and grease remover, thoroughly cleaning the shit out of it, cleaned the threads and refitted with loctite at the business end, and some non-hardening sealant towards the base of the bolts for good measure. If this leaks I'm setting it on fire! haha

Gearbox is now back in again after a busy day. It still needs oil, a new seal for the speedo cable (not in that order..) and the centre console put back on. While I'm at it I'll mount the boost gauge down by the driver's left knee - legal positioning, and unobtrusive to factory interior of removed.

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ENGINE:

I went to change the rocker shafts and decided digital verniers were in order. Despite the scoring on the old shafts, they weren't actually that undersized, but the alloy rockers sure were. I changed out the rockers and shafts with some wreckers items with significantly less clearance, which will hopefully diminish the truck-like clatter on idle. That's all back together now, thankfully.

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DIFF:

Then it's time to try the LSD I bought from Elky. That's a diff centre, for those playing at home. Years ago I had my factory LSD "shimmed" by a diff guy who basically said it was impossible to get back together with a great deal of shims, but it "wouldn't break away on the bench". In car it's basically an open diff, completely useless. So I bought one from Elky that apparently twins. I've got to say I don't have high hopes, but it's worth a shot before I pursue a more expensive, or alternatively a more welder-based solution. At least I have two diffs to play with now. So anyway, the "good LSD" is on a 4.8? gearset, completely ridiculous. I'm on the fence between swapping it onto my gearset in the optimism that it will work, or just throwing the whole banjo in as is and testing it first. Either way the diff will be changed shortly and I'll take it for a long awaited test drive.

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NEXT UP...

Next fortnight I'll order the Koni Red rear shocks. I've given up on cross-referencing, in brief it's too hard to communicate, and the donor vehicles have different mounting systems. If I was in their warehouse I'm sure I could figure it out, but over the phone it's useless... So I'm shelling out the extra to have them re-valve and shorten their "Piazza" rear shocks to actually suit a Piazza - hot tip, theirs don't. $660 for two shocks is a bit steep, but hopefully the result will be worth it.

Funds pending, I'm going to order a high flow 200PPI 3" catalytic converter from good old eBay, and grab a mandrel bend to fab up a new midpipe. I have a dropsaw and a real decent gas MIG now so I can happily make up exhausts. Currently my 3" dump pipe hits an angled join to the stock midpipe and cat, which eyeballs at around 2". Further down it flares out to maybe a 2.5" rear section. I want to carry on the 3" all the way to the 2.5" system, by which (after the cat) the exhaust should also be a bit cooler and more condensed - or at least, I can't be bothered replacing the whole lot... haha. My dyno tuner and I agree that it's a big restriction at the moment, so I'm keen to get it done and see how much of a difference it makes.

And today's fun fact, turns out my Piazza is running 11psi, not 13, in the dyno runs etc. Better intercooler later...

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AND LAST OF ALL...

The interior is a pond. Water is getting in somewhere, I think above the driver's right knee, possibly other places too. I assumed windscreen rubber but am now also sus of the area under the plastic vents at the back of the bonnet. I've pulled the plastic sections off and am searching for any possible culprits, but the car is undriveable in winter until this is fixed, and it's absolutely ruining the interior too. As soon as it's running I'll be getting the windscreen re-sealed, this needs to be fixed ASAP. On the plus side, our shed should be up by next winter, so this is hopefully the last one the cars will have to weather.

Hopefully pictures of the new ride height soon!

[archangel62]

Gorrammit. I found where the water's getting in. Turns out under the wiper assembly, in the channel beneath the plastic mesh in front of the windscreen, there's a whopping great big rust hole. First inspections missed it because the rusted metal was still "there", just completely porous, being that it had the structural integrity of a 30 year old banana. After some tactical bin-bag placement the water ingress stopped, suggesting the windscreen rubber is alright. The rust is inaccessible from above due to the double skinned metal ie non-removable cover, so it'll be a dash out, loom out, interior out to fix. Read: not happening any time soon. I was looking forward to driving this thing, so it's a bit of a kick in the pants. I'll fix it, but it may not be soon. Good opportunity to get my freshly cracking dash reskinned too, as well as taking out the roof lining and fixing a few rattles.

I've just ordered rear shocks at last. We've now decided to go with Koni 80-2134. Off the shelf, these have an open length of 472mm, closed length of 293mm, much better suited to a Piazza but still too long open for my application.
In the words of my shock guy it's easy to limit the open length, but not much can be done about closed length. They fit limiter blocks in 5mm increments, we're going for 3x 5mm limiters hence 457mm open length.
I've asked for them to use Gemini red rears (80-2597) as a valving reference then go 75-80% tougher to account for the 45 degree layover, and the fact that I run the Gemini rears flat out in most Geminis - I'd rather have a little headroom to wind them back.
Price wise I'm looking at around $625 for the pair, including shortening and re-valving, also including GST and freight (Adelaide).

Seems odd to be spending money on it when it's become a basket case for some time, but that's how I roll. I should have a shed in the next 6 months anyway, so I can happily tear it down and fix it properly then.