Otherworldview

Hi all,
I'm looking at starting up an RB25 swap and found a cross member, but it's from an R32. I know the R32's had the RB25DE so I wasn't sure if there's a difference between it and the R33 cross member w/ an RB25DET? I don't want to go spend money on something that won't work and I've already searched otherwise I wouldn't be asking, but I'm still a .

Thanks in advance.

__________________
1990 240sx: Bone stock

ch1873857

Putting a Neo into an R32 .

It bolts straight in. Period.

In terms of things you need to know:

The radiator surround from your r32 will not fit around the viscous fan due to the exact placement / offset of the fan / water pump. RB20 and 26 have the same water pump. RB25 is different.

Use your rb20 power steering pump and it’s mounting bracket as well as you’re A/C compressor and it’s mounting bracket. This is because the lines for each ie from r32/rb20 to rb25 are different. If you use your original ps and ac, the brackets bolt straight onto the engine (rb25) so you do not have to modify any lines for your systems.

If you use an rb20 box, it will bolt straight onto the neo engine so no further modification is necessary. If you use the neo box, there are a few things:
1. The gearbox cross member does not line up perfectly. The holes are out by about 10-15mm. I had 5mm flat bar steel welded onto the existing cross member (32 and 34 had identical member btw) and drilled the holes in the flat bar to line up with the vehicles holes. I also placed a piece of drilled flat bar steel between the box and the cross member to ensure the box remained at it’s original height as opposed to 5mm lower.
2. You will need the yoke from the 34 driveshaft to fit into the box. Get the 34 yoke put onto your 32 shaft. This way the drive shaft can still be mid span supported at the factory mounts. Take your full 32 shaft and 34 yoke (or entire 34 shaft) to a driveshaft place (eg BDC) and they will transfer the yokes, lengthen your 32 shaft by 23mm? (from memory), balance and fit it. Take the car as well so they can measure it for the vehicle as doing a straight yoke swap is pointless as the shaft length needs to be altered.
3. Your 32 slave cylinder can still be used with it’s lines, however you must take the rubber section of the line out of it’s holding clip (the sprung loaded U clip like on your brake lines) as the slave cylinder acts in the opposite direction as a 32 is a push clutch and the neo is a pull clutch. Or you can find a brake line that has the ability to clip in and reach around to the new cylinder position
4. If you use your 32 instrument panel, your speedo will no longer work as the 32 uses a cable. The 33 is electric. If you use the 32 panel apparently you can get a speedo cable that will fit in to the box and to your speedo. I do not know of which one if it is at all true. I have only heard there is one out there. You can use your 32 panel with an AVC-R or RSM for your rev and speed if you want. I modified my instrument panel by removing the speedo and tacho and placing an avcr in the instrument panel whilst I tracked down an r34 panel. If you use the 32 panel you MUST place your rb20 coolant temp sensor into the neo engine ie the one for the gauge (the 1 wire sensor NOT the 2 wire sensor you need to swap) as they are calibrated differently and if you use the 34 sensor with a 32 panel, if you ever see the temp gauge reading what SHOULD be normal operating temperature, it is too late. Your engine is cooked. If you use an r34 panel, you need 15-20cm of the wiring loom and the plugs that go into the panel and rewire it. You will also need to run a wire from the ecu to the check engine light wire on the 34 loom as 32’s do not have such a light, but the 34 ecu has an output for one for the 34 panel. You can either look at wiring diagrams from a 32 and a 34 to work out which wire from the 32 loom you need to join to the 34 loom section, or, if you read the back of the panel on the circuitry it actually says what each wire does on the circuit, so you can make a list of what does what with what wire colour for each panel, then join the corresponding wires. If you put in the 34 panel, you MUST run the speed signal wire FROM THE GEARBOX TO THE PANEL, then from the panel to the ecu. The signal is altered by the speedo itself prior to going to the ecu. If you run it the other way round ie box  ecu  speedo the ecu thinks you are doing over 6 times the speed you actually are, so you hit speed shut off at under 30km/h!!! SO, the speed signal wire (SIGNAL OUT) from the GEARBOX goes TO the SIGNAL OUT of the SPEEDO. SIGNAL IN FROM the speedo GOES TO THE ECU. This is because it is the wire that keeps it’s name, not the terminal it connects to.

The fuel level sensor for the fuel gauge is the same so you do not need to change that, likewise the regulated earth for the fuel pump is compatible so you can keep all that end r32.

All intercooler piping and fuel lines marry up perfectly too.

If you want to put an r34 diff into your 32 you can (not sure why you would as 32 can have lsd, 34 doesn’t). All you have to do is swap the diff carrier (the back plate of the diff that is bolted through the rear sub frame) from your 32 diff to the 34 one. Everything else is the same in terms of drive shaft and axel shaft connection.

If you want r33 or r34 rear brakes, if yours is already 2 pot at the rear, don’t bother. They are the same. The only benefit you will get is having newer calipers. If you want to put 34 brakes onto the front, you need r34 disks AND r34 front hub assemblies. The hub assembly bolts straight in, it is identical to the 32 one, with one major exception: where the actual caliper bolts onto the hub. As the 34 uses such a larger disk, and the 32/33/34 4 pot calipers are the same, the bolt mounts on the 34 hub are further out than on the 32 hub so the caliper can get over the disk. The mounts for the hub onto the steering and supports are the same, but the caliper mount is different. So use any r32/33/34 4 pot caliper onto the 34 hub assembly with a 34 disk.

The R32 has one boost pressure sensor. The Neo has 4. One for the gauge, one for fuel mapping, one for ignition mapping and one for boost cut (about 0.9 bar). The vacuum hose that feeds the boost cut sensor can be pulled off and plugged up. The sensor for boost cut will never kick in. But leave the sensor itself plugged in it the loom plug to the sensor or the check engine light comes on.

If you still want to run A/C, you will need the r34 drier sensor and it’s plug as the 34 runs a 3 wire sensor and the 32 a 2 wire. 2 wires are joined, the third must be run and added to the engine loom to go to the ecu.

You will need to cut off the 34 AC and PS plugs and swap them for the 32 ones so you can plug them into your 32 AC and PS pumps you fitted.

The internal wiring is the only hard part. You need to place the wires from the 34 loom into the factory 32 internal loom. This is easy if you know what every wire from the 32 and 34 ecu’s is and what thus each wire in each plug in the 32 and 34 kick panel is. It is easiest (in my opinion) to cut the internal loom plugs off the 34 loom and off the 32 loom where it went onto the main ecu loom, and attach the 32 plugs onto the 34 ecu loom. This way, if you crash your 32 or whatever and want to put the neo into a new 32 all your wiring is done basically. If you do it the other way, you will also need all the corresponding 34 internal plugs from the internal loom. I say do it the first way. It’s your choice.

The only point to really note and emphasise here is this:
The r32 is basic. The 34 had TCS and ABS. Each system in the 34 has it’s own computer ie for the
1. Engine
2. TCS
3. ABS

Each computer works both independently, receiving the signals it needs to and consequently processing them, and together. They all talk to each other. If you remove the ABS computer (or in the 32’s case, it was never there to start with) the engine computer does not see a signal from the ABS computer, so it thinks the car has no brakes. And it won’t go. So you need to trick the ECU into thinking that the TCS and ABS computers are their, functioning properly, and sending a signal so the ecu thinks you have never locked up braking or lost traction whilst driving. The information on how to do this, along with spreadsheets of what every wire in the 32 and 34 kick panels is, the plug layouts, ecu pinouts etc is all available via application in writing




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Well my conversion has been finished for a few weeks. I did pretty much 100% of the work myself, with a bit of help from my flatmate in getting the engine in one day. It is not difficult, and I saved 1000's.

I will write up a more comprehensive guide to appear on my site soon (with photos), but for now I will just run down what I discovered. A few details I found when doing the conversion are not really mentioned in other threads on the topic so are covered here.

I also need to add, this is how *I* did the conversion. Others may have their own methods to do certain things, but all I can go on is how I did things and what I needed to do.

Special thanks to bhdave, bh_slo32, and others for the useful info in threads here and there on the various things that were required.


Engine removal

Pretty straight forward. Can be done in a couple of hours. No need to be a gun mechanic.

1. Remove the radiator and shroud totally for easier access (drain before-hand). Also recommend removing the clutch fan (engine fan), using 10mm spanner.. Just so there is a bit more room to bring the motor forward.

2. Remove all stuff on the top of the engine, cross over pipe, intercooler piping, and turbo heat shield (use 10mm spanner to get down there, fiddly). Remove passenger side rectangular block (fuel pump backup resistor).

3. Remove battery, to give a bit more room. Remove negative terminal from block. Follow negative lead to wear it bolts to block and remove there.

4. Remove bonnet and set aside. Requires 2x people.


Start on passenger side of motor. ..

5. Remove aircon belt and aircon compressor from block. 2 bolts bottom. One bold top I believe. Pull it aside, being careful not to puncture lines (if you have any gas).

6. Remove belt, and then remove power steering pump from block as one unit with all lines still together. You'll have to undo the tensioner, and the main lock bolt. Wiggle it back and forward on the bracket until it slips out.

7. Remove dump pipe totally from car. You may get away with leaving cat-back part still on car.


Switch to driver side area..

8. Remove starter motor wiring, noting / marking wiring position. Undo starter (difficult access). Remove first bolt from top, and remove bottom bolt. It's not too difficult with around 60cm of extenders stacked together, as can manuever with more room near the battery. Remove starter.

9. Not necessary to remove alternator, but can if you like. Remove wiring from back, note wiring.

10. Remove Oil pressure sender plug. Sender is metal can like thing near oil filter with rubber plug.

11. Remove the ecu from passenger foot well. Unplug ECU plug from ECU.. Remove ECCS and IGN relays (just unplug the tops) to allow easier pull through the firewall. In engine bay, remove foam access panel. Pretty much pull the loom, check for blockages, go back into the footwell, move it a little, back into engine bay, pull some more. Eventually it will come out. Leave engine/ecu loom ontop of engine. You may need to cut the factory cable ties to the firewall to get the loom free.

12. Jack up car at front. Get under engine and remove sump plug. Drain oil into pan. Recommended, as can be difficult / messy to do later.

13. Remove tailshaft.. bolts near diff. Center bearing bracket, and pull forward from gearbox. Set aside. Place oil pan near back of box (as now angled, gearbox oil will leak out the back of the box). Fit couple of plastic bags or similar over end of gearbox, using string or cable ties to keep oil from leaking out gearbox when lifted.

14. Support gearbox with second jack. Undo 4x bolts at gearbox mount. Use 14mm socket. Gradually lower jack to take weight of gearbox.


Remove RB20

15. Remove nuts for engine mounts (14mm socket). 1x nut at top, 1x nut at bottom on each side (there is one mount per side). The engine mounts are at the bottom of the motor, just in front of each of the strut towers.

16. Attach chains to back and front of engine. Secure around alternator bracket, or similar. Attach securely at back of the engine.

17. Angle engine forward, and lift out using engine crane. If you have a few people, you can use one to hold the correct angle of the motor and gearbox (and to manuever when on crane), and another to roll the whole car back. Makes it a bit easier. Lift crane back, and set engine down.

18. Sit rb20 next to rb25.


Transfer rb20det items to RB25

19. Remove block bracket for power steering. Transfer to rb25 (same bolt pattern)

20. Remove block bracket for aircon. Transfer to rb25 (same bolt pattern)

21. Transfer rb20 oil pressure sender to rb25. Unscrew rb20 oil pressure sender using 17mm spanner behind, and screw into rb25 block. Rb25 one may be the same, not sure. I used rb20 one (using r32 gauges after all).

21. Transfer clutch, gearbox etc to rb25 from rb20. You can use all rb20 gear if you like on the rb25 (including flywheel). Machine of flywheel recommended. Inspect clutch, replace if well worn (much easier to do now!).

22. Transfer starter and alternator to rb25. Rb20 stuff will work fine on Rb25.

23. Transfer engine mount bracket where bolts to block from RB20det (about 4x bolts on each side). Don't use rb25 mounts.

24. You can transfer rb20 exhaust manifold, all turbo lines and turbo to rb25 if not included on your rb25. They all fit and to me appear identical. You may have to bend the rb20 water feed line where it goes behind the block to get the correct angle on rb25.

This should be it.


RB25 engine installation

25. Dropping the engine in is as easy as dropping in an original engine. Angle inwards, using mates to get correct angle into transmission tunnel.. Another mate guides engine crane. Align engine, slowly dropping, make sure is aligned properly to engine mounts. Do it slowly until it aligns correctly with the mounts.

26. Reattach power steering pump, aircon to rb25

27. Reattach tailshaft. I had to use rear end of auto tailshaft, and front part of rb20 manual shaft (auto and manual are different splines/end bit) to get correct length. Standard rb20 tailshaft seemed about 3cm too long, and too long to fit diff with rb25 with rb20 box. You need the correct input spline to suit the gearbox you are using, rb20 manual end for rb20 box, rb25 end for rb25 box, etc.

28. Attach loom to rb25 and all sensors, feed ecu side through firewall to footwell.

29. Reattach body side loom to rb25 as per rb20. All gauges should work fine, starter should turn over engine, etc even without ecu hooked up. Starting car requires ECU to be hooked up though.


Misc things to note

1. I had to use rb25 accelerator cable, and custom bracket to move it forward. Cable is slightly longer than rb20 cable and is required or throttle will be constantly on (ouch)

2. Heater hoses are different diameter to rb20 ones. Can't reuse rb20 heater hoses. I used some aftermarket standard hose from engine side, cut rb20 standard hoses halfway across the firewall and joined via hose adapter, .. Or use rb25 factory hoses (these are around $60 each in 4 x pieces from nissan, ouch).

3. With rb20 gearbox, gearbox sits about 2cm further forward than standard. In mine, required cutting of rubber tunnel boot at top a little, to stop gearshifter popping out of gear. You'll see what I mean when you do it.

4. Don't use a twin plate or the like if you want your rb20 gearbox to last behind an rb25. Cushioned ceramic seems to work nicely at not putting too much straight on gearbox

5. Going from auto rb20 to manual rb20 box + rb25, I need a custom gearbox mount fabricated, as only 2x bolts line up.

6. I lost my speed sensitive steering. I believe this is due to a difference between the HICAS setup on r33 (electric) and r32 (hydraulic) and/or speedo. Or maybe it is just a wiring issue I didn't sort out correctly. I prefer the firmer steering anyhow.

7. If using rb20 box, just use standard r32 speedo cable to get speedo to work fine. Otherwise use the top r32/bottom r33 sensor method to rig up rb25 box. This adapts the electronic sender to the manual cable.

8. For temp gauge, the default temp sensor i had on my rb25 was slow to pickup the correct temp (although it may have been an aftermarket one). I swapped the one from rb20 and it fixed the problem. The gauge sensor is the skinnier one near the top radiator hose. The fatter one is the ECU sender.

9. I believe you can use a standard rb25 top radiator hose. Transfer bottom radiator hose to rb25. I ended up using an aussie R31 top radiator hose as the bend is the same, and cutting longer length side off to fit rb20 radiator.

10. You can use rb20 knock sensors and/or knock sub-loom, but you will need to cut the plug and wire directly into rb25 loom as end plug is different.

11. RB20det and rb25det coil packs are identical. Mix and match you better ones.


Wiring

Wiring is pretty straight forward if you have the correct diagrams and ecu pin outs. I'd recommend using the RB25 loom and ECU, which is what I used. This a) allows easy engineering to meet polution standards b) Allows you to run the cheaper and more readily available RB25 powerFC. Once you can get the stock ECU working fine, just drop in the PowerFc and it should work right away.

I won't go through the whole lot here, but a few things to note.

1. Grey wire near the main engine bay plug is your 12v constant injector feed. Make sure this is hooked up to a 12v line. Without this the car won't start.

2. It's not a bad idea to splice in your original engine bay resistor (passenger strut tower, silver block thing) from the rb20 loom back through the firewall and to the thick black and white wires of the r32 body loom. This provides backup ground to your fuel pump incase you lose the grounding in the boot area. It will work without it, but is a valuable safety measure which is worth keeping if you value the engine.

3. Use the O2 sensor from an RB25. I believe the R32 one is different. Effects fuel economy

4. To get the wipers working, you can use the r33 loom plug as a direct fit into your wiper.

There is another plug nearby which looks similar. You'll need to connect the orange in this plug as well or your wipers won't turn off once turned on until IGN is turned off Cut the orange up near the plug, and run a wire to this through the firewall, and this connects to one of the wider R32 body loom plugs. There is like a thick orange and a thick green next to each other. Connect this to the orange. This turns the wipers off when you whack the wiper switch back to "off". Took a while to work this out.

You also need to attach 12v IGN source to blue w/ red stripe on that plug. Hook the black with silver blotches to GND (or chasis).

The rest of the r33 plug is 'spare' and the other wires can be left disconnected down near the r33 ecu part of the loom as well.. On the R33 it connects to a brown junction box on the passenger side...but on the R32, this is on the driver side and can stay there.

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found some r32 rb25det swap info should help. ONLY because of your avatar. what part of md you from?

Otherworldview

WHOA! lol
I was just wondering if the r32 cross member is the same as the r33 cross member so when I get my RB25 (series 1/2) it would still line up.
Thank you very much though for the huge swap list I'll be sure to read over it and add it to my notes from other FAQs.

I'm over at Fort Meade in MD.

__________________
1990 240sx: Bone stock

drifts135

Yay, more RBs!

THe R32 cross memeber will work fine.

Which mount brackets (bolts to motor), and mounts (has rubber stuff) do you have? RB25 stuff still hooked to block? I am not 100%, but you MAY have to bolt RB20 brackets to your motor.... If I remember correctly, the RB25 puts the rubber thingy at a screwy angle with R32 crossmemeber (not 100% on that).


I am in MD about 30min from you and I may have some for freeish. If I cant find mine, I have some friends with em that would prob give em up for $20 or some other stupid cheap price.

If you need help with wiring or anything else, just PM me, I have done many.

We also have a bunch or random RB crap around here if something on yer set is busted from shipping or whatever.

Otherworldview

Thanks a lot Drifts135! I'm in the process of gathering little things at the moment while I save up on the engine (will probably buy through Jarco or Import Specialists here on the forum). Will be going with the Syko mounts for my setup.

Help on the wiring will be much appreciated. I just got a DOHC harness I'm going to look over tomorrow so I won't have as much down time when I do the swap.

__________________
1990 240sx: Bone stock