It's held together by a pair of scroll pins, which have to be tapped out with a drift.
I brace the box against a bit of wood, so that none of the protruding prongs will be hurt, and the pins gently tap out quite easily with a big drift of the right diameter.
The thing is, after the pins are removed, it's all very much stuck together The solenoids are right in the middle, they have slightly conical prongs, and when wedged into the rubber seals on the chassis of the box, it all sticks together very tightly. Add in 15yrs of heat cycles, and it's very much baked together with heaps of stiction between the prongs and the rubber seals, acting like a strong glue.
To take it further, I gently prise each prong apart (which knocks around the rubber seals a bit)...
And very carefully prise it apart all the way around its circumference, a tiny little bit at a time. Slowly but surely, the halves start to come apart, and when there's about 4mm gap you can grab each half and gently wiggle them apart.
With the top off, you can see that it isn't a box at all. It's a rack of 7 solenoids, that all plug into the top, bottom and side chassis.
Now we have to take the side chassis off, too, and that's another round of gentle prising and wiggling.
Initially it's quite hard to get them to budge, but after a while, the rubber seals release their grip and they slide apart.
With the side pieces off. Each part of the chassis has a maze of passages inside, so if you blow into hole A, it comes out of prong F. Some are shared, presumably the inlet is a boost supply and a couple of the solenoide use it.
The black box, with its maze of internal passages, is an elegant way of simplifying what used to look like this, in the early FDs (LOL)
The next step is to remove the Charge Control Solenoid. Years ago, I bought one, knowing that it would be the first thing to fail in the black box, but as we know...eventually I just replaced the whole box.
The solenoid just unplugs from the bottom chassis, and the new one slides in its place (and this is not the correct solenoid that I have removed...the charge control solenoid is actually the one on the extreme right on the top row).
The rubber seals are still a little soft, but I'm conscious of them being a little dry, and so reinserting the solenoid prongs (oo-er) might grab and tear the rubber seal inside...and then you have an untraceable, invisible leak. So, rightly or wrongly, I give each prong a very thin smear of grease. The grease should stay thick with engine bay heat, and not leak out, and hopefully provide a nice seal.
Gently press it all together again, and tap the scroll pins back in place and...we have a new restored black box!
Last step is to test the resistance of all the solenoids, and they all register 39.9-40.1 Ohms, with the new solenoid leading the charge with the lowest resistance.
But the second part of the test is to measure the resistance with the box at operating temperature...so it, and the old solenoid go into an 80C oven for about 15mins or so.
The result was that all of the solenoids in the box (including the new one) went up to 42 Ohms, but the old one screamed up to 45 Ohms. The cutoff is 44 Ohms, so the old Charge Control Solenoid seems to just be on the wrong side of factory tolerance.
Well, now we have a healthy black box again, a second one ...I'm not entirely sure what I'm going to do with it, though.
I've been hoarding some JDM goodies, and it seemed as good a time as any to finally install them
First item are Cusco trailing arms.
They replace these arms...the FD rear suspension is mostly bushed with metal to metal pillowballs, but the trailing arm (and the toe control arm above it) are two spots where there is a conventional rubber bush.
The FD has some toe-control geometry at the back, that toes-in under load and induces some calming mid corner understeer. The soft bushes also allow for a lot of axle tramp on launches, so a reasonably common mod in Japan is to replace these rubber bushes with solid spherical balljoints. It reduces axle tramp and eliminates the toe control geometry.
In Japan, the stock trailing arm had a solid spherical joint pressed into it, and the toe control arm was replaced by a solid Border Racing unit....so I've already got this upgrade, really. But it's nice to have shiny new things
I adjust the new arm to be the same length as the old one, and it reinstalls easily enough.
The next batch were these; Endless braided brake lines
The old brake line nuts came off easily (I guess they're not really that old) and replacing the lines was straightforward, if a little messy.
The last bit came today, an Autoexe carbon intake. Autoexe sort of picked up where Mazdaspeed left off, and campaigned a rotary LMP2 car at Le Mans in 2002. It's run by Yojiro Terada, and he drove the 767 and 787B at Le Mans back on the day. They make pretty nice stuff.
The stock airbox breathes through this black plastic plenum at the nose of the car.
Which breathes from a chamber inside the bumper (which is fed by a duct behind the number plate). The inlet to the airbox itself is pretty small, although the stock box seems to flow quite well.
First the stock airbox is removed, which is always a little fiddly, since there are so many stiff hoses that attach to it.
And then you attach the filter baseplate. It's nicely made, with neat little machined bellmouths inside, and apparently the staggered lengths are to help smooth the transition from small to big turbo. The little narrow pipe contains the "anti-moo" valve. If you just whack pod filters onto an FD, the airpump pollution control device will emit a "moo" sound. So the Autoexe baseplate has a length of narrow pipe, with a anti-moo valve for the pipe from air filter to airpump. I can confirm that I put the valve to my lips and said "moo" and the sound that came out the other side was not Moo.
Sadly the old black plastic plenum had been rubbing on the lovely crackle paint on the ARC intercooler, so I had to remove it for repainting at this stage. I had applied a bit of adhesive foam tape to that spot, but it looks like the heat made the adhesive go funny and it slipped out of position.
I don't know if it flows any better than the stock airbox, but it sure looks nice.
The last step is to check for fitment, since quite a lot of Autoexe intakes seem to have scratched up carbon, from rubbing against the underside of the bonnet. So I apply strips of blu-tac here and there, and it's 4mm thick, which is a nice gap to maintain, I think. I can see that the underside of the bonnet juuust touches the blu-tac, but doesn't squish it, so that'd good.
The only place where it did squish it, was above the filter...
But it looks like a 2-3mm gap, rather than actual contact. Mazdaspeed had its own carbon intake which was quite similar, so perhaps the Mazdaspeed carbon bonnets have a bit more room underneath than a stock bonnet does.
So how does it drive? I have no idea...it's storming outside
It's MUCH easier to install compared to the stock airbox, as it's more compact. It's a bit of a struggle to get the hoses on with the airbox, because once it's bolted in placer there's hardly any space.
But as for how the latest round of mods feel, firstly the Cusco trailing arms are functionally no different to the modified stock arms they replaced (apart from being shiny). So no change there and the Endless brake lines make for a crisper pedal feel, when you're braking hard.
The intake is a surprise, though...as a power-adder, I think it's made a much more dramatic difference than adding the catback. Where it was quiet before, the engine bay is now a riot of hissing, sighing, chirruping and BOV noises. But the immediate impression is how much faster it spools up on the small turbo. From 2500-3500 it pulls much harder. Subjectively, I always felt like the small turbo peaked at 3000rpm and while the power was still smooth, the response from 3000-4000rpm was certainly flatter than what it was on either side. But it's really responsive between 3-4000, and it's actually a sweet spot now. In terms of low rev driveability, it feels stronger and peppier now with the a/c on, than it did before with the a/c off.
Top end is a bit sparklier, but it doesn't seem to be as dramatic an improvement as the bottom end. On the stock gauge, there doesn't seem to be any boost spiking, and it looks to be peaking at the same 11psi as before. It's just flicking the boost needle around much more quickly.
It's uncorked the motor more than I expected, so I reckon I'll be getting the car onto a dyno asap, just to make sure the stock tune is safe.
An opportunity has arisen, to get one of the cars I've always wanted, so after 3 very happy years of ownership, I am offering the Fd for sale.
- Dec 2001 Type R Bathurst R
- it will be sold with a stock engine and exhaust, and stock body
- only mods accompanying the car will be the Mazdaspeed MS01S wheels, Aragosta coilovers and other minor suspension and brake upgrades.
- the car is totally immaculate, has been maintained and restored without regard to cost, and is possibly one of Australia's best-condition FDs