GTSBoy

Just about any auto-electrician would be the right place to take it. It's probably the switch or the fuse anyway.

+ supercharger. Nice big Whipple.

There is no power supply to the speed sensor. It generates the +/-1V signal when it turns. Follow my advice ref cont checking the wiring from there to the dash first. The VSS signal at the ECU is a product of the speed sensor and the speedo working. No point in looking for that signal until the speedo is working. The lack of ABS shouldn't affect it. The ABS uses the speed signal after it is produced. But does the car even have ABS? Does it have sensor rings at the front hubs? Does it have the ABS rig in the engine bay? The missing ABS modulw would be explained by the car never having it.

Your plan is fine. And don't listen to anyone who tells you to ditch the plenum.

Replace the broken bit, probably. Gauge head or cable. I had to put a new cable in mine because the top end broke.

You can also damage it so that it won't "clip in". Put the car up on stands, run it in gear and see if the speedo works with you pushing the cable into the back of the speedo head manually.

It should be the same shape as the end of the cable (ie, both square). If one is broken, then you have square plug in round hole, or vice versa.

It's easy to break the little plastic square end on the drive cable or the receptacle for same in the speedo. Have a close look at both and see which one you broke.

Fitment of caliper and pads on the rotors doesn't look right. That's what happens when they're not really fitted - just sat for e-fame photo op.

If you get a wiring diagram for the R34, you will find the wire identification for the connection from sensor to the dash. Pull the dash out and continuity check each wire of the pair from top to bottom. If that's all good, take the speed sensor out, connect its terminals to an analog multimeter (or better, an oscilloscope) and spin the drive. See if it makes an AC signal. Don't try it with a digital multimeter. Waste of time. See this photo. It's an RB20DET box. Same box as RB25DE. Small details may be different. But note the following. The reverse and neutral switches are 1. towards the front of the box, just behind where the bellhousing starts to swell and 2. at the rear of the box, up high, with the yellow wire visible. The speedo drive is below that, at the bottom just a bit rearward. You can see the speedo drive cable cut off to about 3" length and sticking out downward at ~45°. That same spot is where an electronic drive would be if the gearbox had one. If you have nothing there, then the speedo sender must be on the diff.

Nistune is a standard ECU. The ROM is sucked out of a real Neo ECU.. I just read the number off the screen.

What? You want to run the turbo auto box with the non-turbo auto box's TCU? Why would you do that? The non turbo box's TCU is not the right TCU. You want to use the one in the Neo ECU. So you need the Neo engine loom (which you probably have) and you want the other looms that connect the ECU/TCU to the tranny. If you don't get the looms, then you're going to have to consult the wiring diagrams and build them from scratch, which does not sound like fun.

Might have broken the drive gear on the sender. Electrically, the sender sends a +/-1V AC/sawtooth signal out - exactly what you'd expect from a rotating coil/magnet arrangement. The dash works with that signal. The dash converts it to a 0-5V square wave signal for the ECU. There's nothing that could have happened from changing the ECU (because it's at the tail end of the signal chain) that could have caused the speedo to stop working. The only possibility is that you damaged the wiring from the speed sensor up to the speedo, but you say that you've checked it and it's OK. We have to trust you on that. But there's a couple of other points to suggest/query. The RB25DET gearbox's speed sender is on the gearbox. I thought that the R34 N/A manuals had the speed sender on the diff nose. In which case....if you've been looking at wiring plugs on the gearbox, you may have been looking at the neutral or reverse switch and not the speed sender. Perhaps worth another look and a rethink. The speed sender is down low on the RHS, towards the rear end of the box. The other two elect connectors on that side of the box are the neutral and reverse switches. If you do not have a working speedo, then there a number of ECU functions that will not work properly. You really need the speed signal to the ECU or it won't run things completely properly. Things like having the idle sit higher when the vehicle is rolling with clutch in or in neutral won't happen without it. And lastly, drive it gently. Those skinny little RB20 gearboxes do not last very long if you give them RB25 torque. I killed 2 of them just with a boosted RB20. Wore out the input shaft bearings.

Also, according to my quick look at Nistune just then, Neo turbo switches at 5400rpm.

Dude. It's 20 years old. Just replace it with a stock one and wait another 20 years before worrying about it again.

I did. But to do it, I made sure that I put a non-HICAS rear subframe in (from a Cefiro, of all things, yuck), so that I did not have a HICAS eliminator kit installed. It was all stock Nissan toe arms, so did not look like it was missing anything. The reason I did that is that I could not afford to stuff around. It isn't legal to modify a steering system without engineering, and sadly, HICAS is a steering system. The unknown is how the Regency inspectors would react to a HICAS eliminator kit. You wouldn't have one on there and not mention it, because if they see it (and they will) and it is not on the list of mods that you're applying to get approved, they will want an explanation. If you disclose it in advance on your application.....they may demand engineering. I took the coward's option.

Where your fuel rail is, you can see the injectors. Where they enter the inlet manifold runners is the spot where the vacuum signal comes from. But the vacuum manifold I described is UNDER the inlet. If the hose is not still present and just blocked off, it is going to be difficult.

There's a little vacuum manifold that connects to all the inlet runners between the throttle blades and the head. This is where the 26 gets vacuum signal to run the brakes, and boost gauge, etc. You will not have fun trying to work under there.

I wouldn't count on it fitting older 25s. The advert explicitly talks about ONLY putting it on Neo 25s. (and 26s as a retro with the other stuff you need to do). I don't know for 100% sure, but I think that the difference between cam front end details on older 25 to Neos means they are not same same.

You can safely leave it open to atmosphere. It was only connected to the intake for "emissions" reasons.

Ah, but there's the rub. Rod ends make the caster rod work like it should - stops the wheel moving fore-aft under load. The car improved out of sight when I replaced adjustable Whiteline urethaned caster rods with Teins. I've been preaching that line for years. With the GKTech FUCAs, I set them to stock length when I installed them, having no other guide to a starting number. Ended up with a bit more camber than I wanted so had to wind them out a few mm. Car is at legal height.

Nismo arms solve nothing. They are actually worse in almost every sense. They only make sense at stock ride height when combined with the Nismo upper bracket and the Nismo caster rod. The problem is that they are shorter than the stockers. Most of us actually need to lengthen the upper arms to undo the extra camber from (even sensible) lowering. Only need ~1.5° of camber on a streeter, but can easily have lots more than that (and also different values side to side) with stock arms. This is where the GKTech arms looked good to me. Apart from Duncan's shit news about someone breaking one on the track, they look strong and they handle the twisting that gets jammed into the FUCA when the 32 suspension moves. Oh...and they are adjustable for length. I had to lengthen mine compared to stock to get the right camber, and had to have the RHS one ~5mm longer than the left. In reality, adjustable poly bushes in stock arms would make a lot of sense, if they didn't get annihilated by the incorrect geometry caused by winding on even just a tiny bit more caster. They even crap themselves without winding in any extra caster.

The usual suspects, Amayama, Nengun, Just Jap, various bods on eBay.

Not really. It's the plastic itself changing colour in response to heat. So it's not like yellowed headlight lenses from UV, just on the surface. It's all the way through the plastic. So you can't scour the surface off or treat it with something to reverse the discolouration. They're also getting older and weaker....so messing about with them is not recommended. If you do, you might be replacing them anyway!

That's not really what I wanted to hear about the GK-Tech uppers. I'm going to have to cross my fingers and hope, because I'm not going back to stock arms. The recommendation for stock arms is all well and good, but if you need to correct camber you're up shit creek with the stockers. That's the reason that I put (originally) Whiteline and then at least 2 sets of Superpro in the front of my car over the years. Even with grease nipples added (I added them myself in ~2002) the bushes take a beating. I might have to modify my spare brackets to Nismo spec and try with new urethanes in my adjustable stockers if I break a GK-Tech arm.