MX83/JZX81 swap...done to death but this is how i did it!

[Bowlsclubboy]

Theres so many conflicting stories about this lol...and so many people getting ripped off imo.Theres also a few ppl pming me looking for my version of events, so this is it. Im tired of writing each person that PMs me the same story haha.

If you have the right half cut ( i had a jzx81 1991 cut) and the right cressida (beats me whats right but mine is a 1992 grande with abs and everything) then a 5 year old could do it.

Start by stripping your cressida of basically everything forward of the front seats. even the wiring that goes to headlights etc. You can split the loom casing to remove it from both the cressida and the chaser at a point around where the abs unit sits (below your airbox/intake) so that the loom can be easily removed. ie: a loom for each side of the engine bay, around the mudguards etc. oh and it makes it easier if you remove the guards and bonnet.

Unclip the looms inside the drivers and passenger footwell and rip everything forward of this out....when removing dash wiring (after taking all the plastic shizzle off), it pays to take shitloads of pics as to how everything is routed (i didnt get this one right and had to guess haha...it fits pretty well though)

Then just start taking 1 piece out of the half cut at a time and screwing it into the cressida....all the holes for everything should be there, even the factory jzx81 strut brace. Youll have to drill a couple of holes and screw the 1jz ignitor to the firewall with self tappers in the correct location which is over one of your vin plates and 1 or 2 of the stock intercooler bolt holes will need some attention, otherwise its a piece of piss! I welded some big flat washers onto some 10mm nuts which were then welded onto the existing punched holes already in my front rad support.

I bolted in the jzx81 xmember and the power steer rack as the lines are all different and the mx83 and jzx housings that bolt onto the rack are different.

For the motor side of things as a gregories manual states "installation is reverse of removal". So in other words, if you cant manage to pry/cut/jiggle an engine out then you should be paying someone to do this.

The only parts that needed modifying were the wiring for parkers/side indicators as the jdm lights are different to ours. Just run around with a test light and then cut some of your old loom up to lengthen the wires accordingly...remember, solder and heatshrink, not scotchlocks!

Okay, this is probably the part of the story where people get someone else to do the work.
my car is destined to be canaried indefinatly one day, so it was also destined to become a track car. So therefore, ABS wasnt needed by me. If you follow my guide using a mx83 with ABS, please unplug the rear ABS computer! 10 months of frustration passed before i finally figured out the reason for my non functioning trans. It didnt go into 4th for 10 months!
This was due to the car thinking the abs was working and looking for the abs sensors so that the trans knew when to change gears....once the abs computer is removed it uses the other speed sensor in the trans like it should. The abs wont work because A)the plugs from the jdm abs unit are different to the adm one. and B)Apparenly the jdm system uses a different number of wires for its abs sensors on the wheels.

So anyway, if you dont mind not having abs, and i feel that if you need abs to stop (mind you, late 80s abs), you shouldn't be driving a 1jz. So do yourself a favour and remove the ABS unit in the rhf guard, replace it with lines from a GLX and youll have yourself a huge space for cold air, oil/ps coolers etc.

if there's anything major ive missed of you want to argue, post here

Happy boosting,

Troy

PS Sorry for the long post but i tried to cover a lot of stuff.

[AmperSand]

I did this conversion over the 4th week of December.

Had a JZX81 cut, 1989 GLX MX83 Cressida.

My version of events is a little different. Started by removing everything i could from the dash/interior of my JZX81 halfcut, ECU, digidash, panels, shifter, made sure everything was unplugged.
I then moved onto the engine bay, removing everything i needed. Unbolted the crossmember (with motor attached) and gearbox crossmember. Rolled it out from underneath.

Now onto the Cressida. Same deal with engine bay and ECU. Removed crossmember (engine attached) and gearbox crossmember, had cressida jacked up high enough to roll the motor/gearbox out on 3 trolley jacks. Moved motor to side, chocked up on woodblocks, then used same jacks under 1JZGTE (crossmembers and all attatched).
Rolled 1JZ under cressida, With a 4th trolley jack, slowly brought the cressida down as low as i could, then started jacking the 1JZ up with the other trolley jacks. Lined up crossmember bolts. Secured and threw sway bar/other random suspension parts i had to take out back in.

Went onto wiring. Cut the body plugs (2 square ones) off cressida engine harness, cut the plugs the 2 squares 1JZ connectors go in (from halfcut body) and made adaptors. Also spliced the 22pin rectangle dash plug into cressida body loom. Took the connector for the flying lead from the halfcut body, and only connectored the overdrive lockup clutch speed sensor wires (spliced into Body Plug adaptors).
Also using the JZX81 bar. (being a 1989 model, had to cut lower part of quarter panels that join the standard metal airdam that runs across the bottom of the 2 piece guard.)

Took 4 days in total including wiring!

Started first go, havent looked back since

PS. It was quite a vague description, if anyone wants to know anything else, just let me know.

PPS. Sorry for the thread hi-jack, just throught i would throw a different perspective in.

[joecoolmk2]

is there anything different about putting a manual in a jz/mx83?
or would that be easier due to less wiring?

this sounds bloody easy, might buy a mx83 for my next car!

[AmperSand]

Well, only part that would be harder i guess would be getting the tailshaft modded? Probably about 6-7 wires different in wiring, and in the grand scheme of things, thats not much.

Also keep in mind, the JZX81 didnt come out in manual, so if you can source a preconverted halfcut, cool. If not, either a W58 from JZA80 2JZGE, or JZA70 R154 i believe gives you the desired shifter positioning, but dont quote me on that, if this is incorrect please correct me.

Todd

[Bowlsclubboy]

Nah thats cool amp, the more (factual) information in one spot the better. at least you covered the engine removing haha. What made you decide to cut into the looms? or are the 1st series mx83s a fair bit different?
Im one of those people that would rather spend hours spinning a spanner rather than hours nutting out wiring to achieve the same result i guess hehe

I have a R154 from a jzx90 chaser in my cress now...shift position is perfect for me and i think when i get a Cs shifter soon, it will be for a jzx90 as opposed to jza70. I think they have a slight bend backwards in the shaft, so it clears my jzx81 cupholders beautifully

If you find a halfcut without cup holders...dont buy it! The only thing that stopped cressidas being rebadged as Rolls Royces in oz was their lack of cupholders haha
Cheers,
Troy

[TTMX83]

Series I MX83 has a different x-member to the series II. The series II is the same as the JZX81.

Series I MX83 has a cable speedo as opposed to the electronic of the Series II. To over come this you can swap the rear extension housing over and still use your MX83 cable speedo dash. Series II needs no mods.

Series I has not got ABS.

When I did my conversion I was fortunate enough to buy a damaged MX83 that already had the wiring done and a 1JZ fitted. All I had to change was the connector from the ECU to the MX83 body loom (22pin) I just copied the doner car. Everything worked once I put the engine in my car, ABS, cruise, tacho. I didn't change the cross member, I pulled the 7M out with auto attatched and slid the 1J and auto in as one. I found I had to raise the front of the car at least a foot to allow the gearbox to swing on an angle so I didn't have to cut the radiator support.

Everything bolts on from the JZX81 apart from the igniter and the heat shield near the brake booster.

Tips:
Fit a T piece to the rear turbos wastegate line before putting the engine in the car. It's hard to get to with it in the bay.
Get dump pipes from the start, also way easier with the engine out. But the standard MX83 exhaust bolts up to the 1JZ anyway.
Use the hydrolic fan setup, they are great.
Do the timing belt and the fan belt with the engine out.
The power steering reservior from the JZX81 wants to live where the cruise actuator does in the MX83. I moved the PS res a little bit so I could have the cruise where it belongs so I didn't have to make new brackets, cable or re-wire it.
The AC wiring needs to be modified to get the AC to work. I think just extend it so it will reach the compressor.
Main wires from the alternator to the fuse box needed to be made.
7M and 1J starter motors are the same.
JZX81 rotors are bigger (280mm vs 256mm) and thicker. The calipers use the same pad as the MX83 - bonus. Another upgrade is the combination of BA Falcon rotors, locating rings and R33 GTS-T calipers. But you willl need bigger rims.
If you use the digi dash, the MX83 fuel sender is not compatile.

I hope I got all that right. Above all. if you are thinking of doing this conversion, DO IT!!! It makes the car so much better to drive....

[mumblezzz]

I'll chime in with my experience. I wanted a manual to start with so I began with a JZA70 supra front cut. I also purchased a front sump and engine mounts from a JZX90 Chaser.

I started by pulling the mid sump off and fitted the front sump and pickup. To make the JZX90 engine mounts work, you need to bolt them on backwards. (They're marked Intake> and <exhaust side) Then take the gearbox mount off the standard cressida auto and bolt it to the R154. This should now bolt in providing you have the right engine crossmember. (mine is a late model)

You will need custom power steering lines to be made up as well a bracket to hold the power steering resovoir. I removed cruise control so I mounted it there. I also deleted the air conditioning but I beleive you can swap the plate on the A/C compressor with the 7M one so the standard A/C lines fit. Otherwise you need customer A/C lines.

For the clutch pedal I used the JZA70 one. You need to redrill the holes in the firewall to make it work. It's not perfect but it works well enough. I cut down the stock auto brake pedal as well.

The wiring was a bit tricky as the diagrams i had were a bit unclear on a few points but its much simpler with the manual conversion. Anything related to the auto can be deleted and in my case, the A/C, cruise control, hydraulic fan and speed sensitive power steering. My front cut was also missing traction control and ABS.

I had an aftermarket intcooler and exhaust fitted but the JZA intercooler will not bolt in. I also needed a custom tailshaft but that can be made using the parts from the standard tailshaft. I ended up using the Supra radiator as the Mx83 one was stuffed. All that is needed there is a mount to be fabbed up on the passenger side. The standard hydraulic fan will work.

I think that covers most of it. I can clarify some points if needed.

[MacroP]

Series I MX83 has a different x-member to the series II. The series II is the same as the JZX81.

That's not entirely true. The crossmember change was done nearish the end of the Series 1 cycle. In fact it was done in Feb90(my EPC tells me this) where as the Series 2's began in August 1990. I have a March 90 Series 1 MX83 with the later 15 degree crossmember. It's identical to my 91 Grande's one.
So it's not all bad for some people with Series 1 cars to do a 1JZ swap. Some may have a late Series 1 with the correct crossmember.

[TTMX83]

That's not entirely true. The crossmember change was done nearish the end of the Series 1 cycle. In fact it was done in Feb90(my EPC tells me this) where as the Series 2's began in August 1990. I have a March 90 Series 1 MX83 with the later 15 degree crossmember. It's identical to my 91 Grande's one.
So it's not all bad for some people with Series 1 cars to do a 1JZ swap. Some may have a late Series 1 with the correct crossmember.

Yeah I thought that but didn't know the exact date. Cheers.

[jzk25]

Everything worked once I put the engine in my car, ABS, cruise, tacho. ..

Hey mate, I have just wired up my Brothers MX83 in the same way yours is(engine, loom and ecu only) and the tacho doesn't work at this stage. Can you give me an idea how I can wire this? I believe the tacho signal comes from the 1J ignitor but I have no info on the original 7M and it had no engine in it when the car was purchased. Does the 1J ignitor give the same signal the 7M did?
Any help is appreciated, thanks.

[MacroP]

Hey mate, I have just wired up my Brothers MX83 in the same way yours is(engine, loom and ecu only) and the tacho doesn't work at this stage. Can you give me an idea how I can wire this? I believe the tacho signal comes from the 1J ignitor but I have no info on the original 7M and it had no engine in it when the car was purchased. Does the 1J ignitor give the same signal the 7M did?
Any help is appreciated, thanks.

The tacho signal back to the cluster comes from the white multi-pin plug behind the glovebox from memory. I only put my MX83 glovebox back in today(I did a 1UZ conversion) and I've already forgotten. The 1UZ igniter works fine on the MX83 tacho so the 1JZ unit won't have any issues. The other plugs behind the glovebox should be all grey, there's 3 or 4 of these. This tacho wire will be all black and goes in the same part of the MX83 loom and white plug as the oil switch and temp guage.

The 1JZ engine loom wire will most certainly all black too.

[jzk25]

Cool, thanks for the info. that is the only plug I have so far left alone.

[BrianRA23]

I had been planning to do the conversion while living in Portugal and when we got back I needed a car. I was not in a hurry but two days later I was the owner of a 89 GLX completely original but with a very knocky bottom end from being run out of oil. If I didn't push it hard, it went well, but being summer and the AC didn't work I decided that instead of getting it regased I would order a JZX81 front cut.

1 week later it arrived
Working on my own with someone helping when I needed to use the engine crane it was back on the road in 2 1/2 days.

The complete dash stays in the car, just remove the glovebox - don't remove anything else, pull down the computer disconnect and then pull the harness through from the engine bay and sit it on top of the engine.

Now it is just a case of doing what is required to remove the old engine and gearbox.

Other stuff has been covered including the harness that goes across under the radiator support - required since the alternator and ac are on the opposite side.

Once the engine is in (after doing belts fluids etc) and you are ready to do the ECU wiring just pass it back through the hole to where the glovebox sits. Now using two of the plugs from the JZX81 harness for the ECU and a small flat jewery screwdriver sit down and re-pin (that is removing the wire from the connector with the female clip on the end from the plug and putting it into another) one by one you can have enough wires done in about half an hour to get things running.

I got my diagrams from Grant and with his permission I can pass them on.

I later converted the 1JZ to LPG and for this I had to remove the harness from the engine and split the power for the injectors and igniters and this is much easier with the engine out.

Not that it can't be done properly, but I have seen a couple times where people have tried to splice in the dash harness and made a real mess of it.

The BA rotor conversion is a must and the whole thing sits behind the 16" Soarer rims nicely.

As said to start with - childs play but make sure you plan it from the outset.

[Jabtronic]

So which method for the wiring would be recommended as the best?


Bowlsclubboy's method of removing the dash etc.
or
BrianRA23's method which involves only removing the glovebox.

Cheers.

[TTMX83]

Depends if you want to keep your gauge cluster or not. If you swap the whole loom over and use the digital dash, you need a new fuel sender.

There isn't a heap of wiring changes needed anyway. Taking the dash out is a pain in the ass. I'd say just repinning the plugs is easier.