DatsunBanana

Had a go at the stuck crush tube this afternoon. Tried things like grips and a chain wrench first but wouldn't just twist straight off. So got to work with a drill. Started small and kept a depth stop on to make sure I didn't drill into the bolt. Made a line of drill holes all the way up and enlarged them. Then a combination of chisel and Dremel to split it all the way up. Levered the split to get oil in there and eventually it gave a bit while levering. Worked it back and forth with loads more oil till it was spinning freely, then with grips I could work it downwards and off. And no significant damage to the bolt (not by me anyway - just the 27 years of rust)

Drilled the rubber out on a slow speed and it didn't catch much at all. Probably only half a dozen holes was enough to shred the rubber and it dropped off easily leaving the inner sleeve behind. Will tackle that later

Thanks both. All good advice. Reminds me of drilling through stone wall for drainage pipe 😬 I'll let you know how I get on if I still have use of my hands afterwards 😅

So ... I got everything disconnected and started dropping the frame. Three of the four mounts started to come down but the fourth one (the one with the nut that gave me all the trouble) won't budge. The inner metal sleeve stays up tight against the chassis rail although the outer part of the mount drops a bit (and can be levered quite a lot more) but it's just stretching the rubber bushing. So I reckon there's some serious corrosion inside the inner sleeve and holding it tight to the lug at the top of the bolt. Tried everything I can think of so far: penetrating oil, whacking the top of the sleeve to vibrate it and wedge a screwdriver blade in there. I also tried to turn the inner sleeve a bit by hitting it with a chisel at the bottom. It's stuck solid. What do you think about cutting the rubber with a blade so I can drop the subframe around it anyway. Then worry about getting the inner sleeve off after? Will that work? Is it gonna give me even more problems?

I didn't know about induction heaters but checked them out and they look awesome but too pricey for the occasional job like this. And I'm too nervous to take a flame anywhere near there as the petrol tank is so close, although I was intrigued with the crayons suggestion 😁 I filled a coke bottle lid with penetrating fluid and raised it on the jack so the nut was submerged in it all night. Then went in with a tiny cold chisel and got it almost to the point of splitting but not quite (I didn't want to damage the bolt threads). Then I hammered a socket back on and gently worked it until I felt movement. And it's off 😀

Thanks everyone for the replies and suggestions. Got the seats out (hoping I could find some existing grommets but no such luck). By tapping and measuring etc. I could figure out where I could drill through if needed. But first I borrowed an inspection camera and managed to go through factory holes in the chassis rail and could see that the captive nut was holding steady which is why it could retighten. So it was indeed a stripped section of thread, so I applied downforce by levering the bolt head with a screwdriver and went slowly back and forth until it came out. Camera helped a lot cos I could monitor that the captive nut was holding tight. Now I just have one very seized main subframe nut to tackle 😅

Yeah, I'm pretty sure that's how it's going to end up. Mechanic suggested I cut a hole in the chassis/body to access the inside. I can cut the hole for access but will have to get someone else to help if any welding is needed afterwards. Things I'd like to know are: Assuming there's a captive nut inside, how's it fixed? And how can it be tightening but not fully loosening? If I cut a hole to access/replace a captive nut, is there a good place to cut for this one? Does it have to be at the side, or is there somewhere I can cut from above inside the car?

Trying to swap the rear subframe on my R34 and can't remove the L-shaped stay brackets between the front subframe mounts and the sill/chassis. I'm in the UK so rust is a problem. I've used loads of WD40 and then Tunap 103 for days beforehand. I backed off the bolts forward a bit, backward a bit repeatedly for ages to try and avoid snapping. They have all moved a few full turns. The one I've spent most time on has come loose and I can turn with fingers, and it will pull down and push up 2-3mm. But it won't come out. I can tighten it back up and loosen it off again repeatedly but it still won't come out. I assumed there's a captive nut inside but if that's broken loose then I can't understand why I can always tighten the bolt back up - I'd expect it to just spin both ways. Any ideas what's happening here? I can't visualise what's inside there to cause this.

Nice! That makes perfect sense now - thanks 👍

Couldn't quite see what you mean from your photos, can you share a pic of the drilled hole and spacer? Still promising myself that one day I'll fit all the manual bits I've got in the garage. Is the rusty one the R33 pedal?

You may have already seen it but there's been a bit more discussion on this and the other valves (swirl valves) in the NA RB20 and 25 NEO differences thread in the Naturally Aspirated Performance forum. When I posted above I was still trying to decide what to do. I've been running 5 years now with the hose just disconnected from the diaphragm and all runs really well. You've got me thinking again about trying to connect a boost/vacuum line from the plenum now to see if there's any noticeable difference.

That 'pump' is a vacuum tank, I guess just a reservoir for holding the vacuum. On the 20DE looks like it's used for both the swirl and torque butterflies. One line is to the plenum and the other two will go to your torque valve solenoid and swirl solenoid. The solenoids will have their own lines to the actuators. The solenoids seem to switch the actuator hose to either the vacuum tank or the air filter side of the throttle body. This is from page EC-3 in the manual. On 25DE the tank is just for the torque valve so I binned that and the solenoid and related hoses and used the old tank take-off for my boost gauge I think. From experience I know the torque valve is under spring pressure keeping it in the default open position. I don't know about the swirl valves but if they are sprung to open position then removing the vacuum tank, solenoid and hoses from the actuator would (I'm guessing here) let them spring quite firmly open (??) Page EC-44 in the manual gives info on the RPM threshold for the solenoid ON/OFF signal.

The main torque valve shouldn't need hacking as it defaults to open without the vacuum pipe connected (at least on the 25DE). Not sure about the swirl valves but in your pic they look open by default. On the 25DE I used a GTT ECU but it doesn't have the signal to control the valve. Other discussions seem to suggest at boost the valves won't do much but would still be cool to know what it's like controlled by an aftermarket ECU.

Have you tried Conceptua tuning on eBay? They have a few options for 33 gtst. Great to deal with too.

I was always of the same opinion as Kinkstaah that using a GTT auto ECU would be complicated. If you've got the R34 service manual, pages EC11/12 show that GT auto and manual have the same ECU wiring that uses a separate transmission control unit and the GTT auto has the transmission control built in to it. Page AT3 states that plainly. As per the diagrams, wiring for manual GTT ECU is same as GT auto/manual so that's what I used on my auto NA+t. It works fine and just uses the original GT transmission control unit to look after the auto box. As mentioned above, popular opinion is that there could be problems if the transmission circuit inside the GTT auto ECU creates conflict or doesn't talk with the GT transmission control unit still in the car. Pages EC13/14 will show you which pins are different and what they control. On page EC11, pin 79 of a GTT auto ECU (multiplex communication) is shown as only being for TCS/ABS but on page EC12 for non-turbo it also goes to the separate GT TCU. Pages AT8/9 have the transmission circuit diagrams (top right corner on page AT9 shows the connections from separate TCU to ECU). If you're gonna give it a go, those refs might help and if you get it working report back to feed the knowledge base. R34Nur posted a couple of weeks ago and said it worked fine with auto GTT ECU but that does go against popular opinion.

When I did this few years back I read everything I could find on the subject including the thread here for example: I was happy to give it a go based on Dan666's experience but only after I checked out EC-11,12,13,14 and AT-8,9 in the workshop manual for myself. As I understand it, the required signals will still be connected between the manual GTT ECU and the existing separate TCU via the GT loom (e.g. pin 29 speed signal and pin 37 throttle opening signal). I'd suggest to anyone planning this swap to look at those pages and get an idea of the similarities and differences. Apart from that I can only speak from experience - I swapped in the manual GTT ECU and it's been fine on my NA+t. I said 'almost' plug and play because there will be errors related to traction control and boost sensor which aren't physically there on a GT. But those were easy enough to workaround - I fed suitable voltages to the correct pins on the ECU via diodes to stop the check engine light coming on. Pin 104 signal has different purposes between GT/GTT ECUs so a GTT ECU won't control the GT inlet manifold valve if that's still fitted. Little bit of info on page EC-44 for anyone interested. The signals for A/T position indicator dash lights are not present on the manual GT ECU. Mine never worked before I did the conversion so I can't say for sure what will happen to those but I don't see why they wouldn't get the signals from the existing GT TCU. Pin 79 is an interesting one. Looking at page EC-18, that signal relates to malfunction detection. For GTT it relates to TCS/ABS e.g. 'Malfunction (open/short circuit, etc.) is detected in multiplex communication line between engine and TCS/ABS'. And for GT it's different: Malfunction (open circuit, short circuit, etc.) is detected in multiplex communication line between ECM and TCM. [RB25DE). That difference hasn't caused any issues for me in the past 4 years as a daily driver. For anyone Googling for answers I'd say some of us have had success and some haven't. It's inconclusive. But for the OP who's invested in this already, a manual GTT ECU can work and might be worth a try compared to the GTT auto ECU which will be a pain for the reasons already pointed out.

You could just try and sell the auto ECU, keep the Nistune and put it in a GTT manual ECU. That will allow the existing NA TCU and wiring to run the gearbox. That's what I've got on my NA+t and is 'almost' plug and play. It won't be a GTT but it'll get you to the next step of sorting out the map.

This article appears to be talking about the swirl valves ... https://carscanners.net/nissan-skyline-r34-and-laurel-c35-with-rb20-de-neo/ And this is one of the old discussions with dead pic links. https://www.skylineowners.com/threads/rb20de-r34-gtt-neo-engine.155290/

Back to your original question, the RB20DE NEO has butterfly valves for swirl (see page EC-3 in the R34 manual). I remember seeing some pics once but so many pics have dead links now I can only find the discussions by googling. So I can't remember exactly where the valves are - in the runners maybe? The RB25DE NEO doesn't have them although both have the variable air intake butterfly valve in the inlet plenum.

I'm running a stock NEO non-turbo AFM without any problems. I'm using GTT injectors and stock GTT ECU. At first I kept the NGK BKR5EIX iridium plugs that I already had before the turbo conversion. Not ideal maybe but they worked ok. I've been running the conversion for 3 or 4 years. Recently I did have a misfire that felt a bit like hitting the rev limiter. I found some Splitfire coil packs on a spare engine I have so fitted those. At the same time I changed to NGK BKR7ESC-11 that one of the tuners here in the UK recommended for my +t and that misfire is gone.

I'm sure someone will come up with a better suggestion more local to you but here in the UK, Conceptua are a reputable dealer who stock these for the non-turbo intake and will post worldwide ... https://www.ebay.co.uk/itm/New-Throttle-Body-to-Plenum-Specs-Gasket-For-R34-GT-Skyline-RB25DE-Neo/111878477184?hash=item1a0c7a1580:g:5D4AAOSwoydWnOLe Alternatively use https://nissan.epc-data.com/skyline to find your model and in the engine and fuel system section find the manifold gasket and click through to the amayama shop and have it delivered from Japan. I've had stuff sent to the UK this way no problem. Import tax and waiting a couple of weeks is a pain though. But I thought you guys over there can buy most stuff off the shelf?

Fuel filter made no difference. I might just let it go now and not worry about it as the issue is negligible. Or if I can be bothered I might check the pump is still mounted in the tank ok and might swap the AAC for my spare cos years ago I lost the spring while cleaning it and replaced it with one from a ball point pen ? Anyway re. the direct voltage conversion, I checked the wiring diagram and thought I'd post this in case anyone else is interested. I believe that stock GT wiring will run the fuel pump at 13.5V as standard. In the attached wiring diagram, red lines I've marked are all battery voltage from the ignition switch and I've taken a confirmed reading of 13.5V at the solenoid plug I've marked. The fuel pump dropping resistor (and control module) don't exist on the non-turbo so the other side of the pump is direct to ground (green line on diagram). So although I haven't measured it directly at the pump, I reckon that means a non-turbo car will already have full battery voltage at the pump. Happy to be corrected if I'm wrong though.

Interesting point about the pump. Here's a pic from another thread showing what I had to do to mount it in the cradle. I think a Walbro 342 would have fitted better than a 341 but I tried to make sure it was secure. But in theory the hose clip could have slipped and who knows! Maybe I'll check that. Ordered a fuel filter too as it's about time I changed that.

Yep stock GTT injectors and ECU on a DE+t conversion. Would the two stage fuel pump relay even exist on what was originally an NA car? By the way, the PCV hose was split at the inlet end. Swapped that and the grommet in the cam cover but it's made no difference. At least I know that's done now though. What about the AAC valve ... anything in there that could flop about on a slope and cause rough idling? Any other ideas are welcome ?

Thanks for the replies. I'll have a look at the PCV valve and hoses etc. but yeah, it's not a major worry ... I'm still smiling at finding a 'free' set of splitfires ?